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Changes between Version 5 and Version 6 of Openvpn23ManPage

Timestamp:: 03/28/13 10:02:11 (11 years ago)
Author:: Samuli Seppänen
Comment:: Updated to man-page from OpenVPN 2.3.1

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Openvpn23ManPage

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 {{{
 openvpn(8)                                                          openvpn(8)
+openvpn(8)                                                             openvpn(8)
 …
 INTRODUCTION
        OpenVPN  is  an open source VPN daemon by James Yonan.  Because OpenVPN
        tries to be a universal VPN tool offering a great deal of  flexibility,
        there are a lot of options on this manual page.  If you're new to Open‐
        VPN, you might want to skip ahead to the  examples  section  where  you
        will  see how to construct simple VPNs on the command line without even
        needing a configuration file.
        Also note that there's more documentation and examples on  the  OpenVPN
        web site: http://openvpn.net/
        And  if you would like to see a shorter version of this manual, see the
        openvpn usage message which can be obtained by running openvpn  without
        any parameters.
+       OpenVPN  is  an  open  source  VPN daemon by James Yonan.  Because OpenVPN
+       tries to be a universal VPN tool offering a  great  deal  of  flexibility,
+       there are a lot of options on this manual page.  If you're new to OpenVPN,
+       you might want to skip ahead to the examples section where  you  will  see
+       how  to  construct  simple VPNs on the command line without even needing a
+       configuration file.
+       Also note that there's more documentation and examples on the OpenVPN  web
+       site: http://openvpn.net/
+       And  if  you  would  like to see a shorter version of this manual, see the
+       openvpn usage message which can be obtained by running openvpn without any
+       parameters.
 DESCRIPTION
+       OpenVPN  is  a robust and highly flexible VPN daemon.  OpenVPN supports
+       SSL/TLS security,  ethernet  bridging,  TCP  or  UDP  tunnel  transport
+       through  proxies  or  NAT,  support  for dynamic IP addresses and DHCP,
+       scalability to hundreds or thousands of users, and portability to  most
+       major OS platforms.
+       OpenVPN  is  tightly  bound to the OpenSSL library, and derives much of
+       its crypto capabilities from it.
+       OpenVPN supports conventional encryption using a pre-shared secret  key
+       (Static  Key mode) or public key security (SSL/TLS mode) using client &
+       server certificates.  OpenVPN also supports non-encrypted TCP/UDP  tun‐
+       nels.
+       OpenVPN  is designed to work with the TUN/TAP virtual networking inter‐
+       face that exists on most platforms.
+       Overall, OpenVPN aims to offer many of the key features  of  IPSec  but
+       with a relatively lightweight footprint.
+       OpenVPN  is  a  robust  and  highly flexible VPN daemon.  OpenVPN supports
+       SSL/TLS security, ethernet bridging, TCP or UDP tunnel  transport  through
+       proxies  or NAT, support for dynamic IP addresses and DHCP, scalability to
+       hundreds or thousands of users, and portability to  most  major  OS  plat‐
+       forms.
+       OpenVPN  is  tightly bound to the OpenSSL library, and derives much of its
+       crypto capabilities from it.
+       OpenVPN supports conventional encryption using  a  pre-shared  secret  key
+       (Static  Key  mode)  or  public key security (SSL/TLS mode) using client &
+       server certificates.  OpenVPN also supports non-encrypted TCP/UDP tunnels.
+       OpenVPN is designed to work with the TUN/TAP virtual networking  interface
+       that exists on most platforms.
+       Overall,  OpenVPN aims to offer many of the key features of IPSec but with
+       a relatively lightweight footprint.
 OPTIONS
        OpenVPN allows any option to be placed either on the command line or in
        a configuration file.  Though all command line options are preceded  by
        a double-leading-dash ("--"), this prefix can be removed when an option
        is placed in a configuration file.
+       OpenVPN allows any option to be placed either on the command line or in  a
+       configuration  file.   Though  all  command line options are preceded by a
+       double-leading-dash ("--"), this prefix can be removed when an  option  is
+       placed in a configuration file.
        --help Show options.
        --config file
               Load additional config options from file where each line  corre‐
               sponds  to  one  command  line option, but with the leading '--'
+              Load  additional  config  options  from file where each line corre‐
+              sponds to one command  line  option,  but  with  the  leading  '--'
               removed.
               If --config file is the only option to the openvpn command,  the
               --config can be removed, and the command can be given as openvpn
+              If  --config  file  is  the only option to the openvpn command, the
+              --config can be removed, and the command can be  given  as  openvpn
               file
+              Note that configuration files can  be  nested  to  a  reasonable
+              depth.
+              Double  quotation or single quotation characters ("", '') can be
+              used to enclose single parameters containing whitespace, and "#"
+              or ";" characters in the first column can be used to denote com‐
+              ments.
+              Note that OpenVPN 2.0 and higher performs backslash-based  shell
+              escaping for characters not in single quotations, so the follow‐
+              ing mappings should be observed:
+              Note that configuration files can be nested to a reasonable depth.
+              Double  quotation  or  single  quotation characters ("", '') can be
+              used to enclose single parameters containing whitespace, and "#" or
+              ";" characters in the first column can be used to denote comments.
+              Note  that  OpenVPN  2.0  and higher performs backslash-based shell
+              escaping for characters not in single quotations, so the  following
+              mappings should be observed:
                   \\       Maps to a single backslash character (\).
 …
                            interpret it as a parameter delimiter.
               For example on Windows,  use  double  backslashes  to  represent
               pathnames:
+              For  example  on Windows, use double backslashes to represent path‐
+              names:
                   secret "c:\\OpenVPN\\secret.key"
               For   examples   of   configuration   files,   see  http://open‐
               vpn.net/examples.html
+              For examples of configuration files,  see  http://openvpn.net/exam‐
+              ples.html
               Here is an example configuration file:
 …
    Tunnel Options:
        --mode m
               Set OpenVPN major mode.  By default, OpenVPN runs  in  point-to-
               point   mode   ("p2p").   OpenVPN  2.0  introduces  a  new  mode
               ("server") which implements a multi-client server capability.
+              Set OpenVPN major mode.  By default, OpenVPN runs in point-to-point
+              mode ("p2p").  OpenVPN 2.0 introduces a new mode  ("server")  which
+              implements a multi-client server capability.
        --local host
               Local host name or IP address for bind.  If  specified,  OpenVPN
               will  bind  to  this address only.  If unspecified, OpenVPN will
               bind to all interfaces.
+              Local host name or IP address for bind.  If specified, OpenVPN will
+              bind to this address only.  If unspecified, OpenVPN  will  bind  to
+              all interfaces.
        --remote host [port] [proto]
+              Remote host  name  or  IP  address.   On  the  client,  multiple
+              --remote options may be specified for redundancy, each referring
+              to a different OpenVPN  server.   Specifying  multiple  --remote
+              options  for  this purpose is a special case of the more general
+              connection-profile feature.  See the <connection>  documentation
+              below.
+              The  OpenVPN client will try to connect to a server at host:port
+              in the order specified by the list of --remote options.
+              proto indicates the protocol to use  when  connecting  with  the
+              Remote  host  name or IP address.  On the client, multiple --remote
+              options may be specified for redundancy, each referring to  a  dif‐
+              ferent  OpenVPN  server.   Specifying multiple --remote options for
+              this purpose is a special case of the more general  connection-pro‐
+              file feature.  See the <connection> documentation below.
+              The  OpenVPN client will try to connect to a server at host:port in
+              the order specified by the list of --remote options.
+              proto indicates the  protocol  to  use  when  connecting  with  the
               remote, and may be "tcp" or "udp".
               The  client  will  move  on to the next host in the list, in the
               event of connection failure.  Note that at any given  time,  the
               OpenVPN client will at most be connected to one server.
               Note  that  since  UDP  is connectionless, connection failure is
+              The  client will move on to the next host in the list, in the event
+              of connection failure.  Note that at any given  time,  the  OpenVPN
+              client will at most be connected to one server.
+              Note  that  since  UDP  is  connectionless,  connection  failure is
               defined by the --ping and --ping-restart options.
+              Note the following corner case:  If you  use  multiple  --remote
+              options, AND you are dropping root privileges on the client with
+              --user and/or --group, AND the client is running  a  non-Windows
+              OS,  if  the  client  needs to switch to a different server, and
+              that server pushes back different TUN/TAP or route settings, the
+              client may lack the necessary privileges to close and reopen the
+              TUN/TAP interface.  This could cause the client to exit  with  a
+              fatal error.
+              If --remote is unspecified, OpenVPN will listen for packets from
+              any IP address, but will not act on those  packets  unless  they
+              pass all authentication tests.  This requirement for authentica‐
+              tion is binding on all potential peers, even  those  from  known
+              and  supposedly trusted IP addresses (it is very easy to forge a
+              source IP address on a UDP packet).
+              When used in TCP mode, --remote will act as a filter,  rejecting
+              Note the following corner  case:   If  you  use  multiple  --remote
+              options,  AND  you  are dropping root privileges on the client with
+              --user and/or --group, AND the client is running a non-Windows  OS,
+              if  the  client  needs  to  switch  to a different server, and that
+              server pushes back different TUN/TAP or route settings, the  client
+              may  lack  the necessary privileges to close and reopen the TUN/TAP
+              interface.  This could cause the client to exit with a fatal error.
+              If --remote is unspecified, OpenVPN will listen  for  packets  from
+              any  IP address, but will not act on those packets unless they pass
+              all authentication tests.  This requirement for  authentication  is
+              binding  on  all potential peers, even those from known and suppos‐
+              edly trusted IP addresses (it is very easy to  forge  a  source  IP
+              address on a UDP packet).
+              When  used  in  TCP  mode, --remote will act as a filter, rejecting
               connections from any host which does not match host.
               If  host  is a DNS name which resolves to multiple IP addresses,
               one will be randomly chosen, providing a sort of basic load-bal‐
               ancing and failover capability.
+              If host is a DNS name which resolves to multiple IP addresses,  one
+              will  be  randomly chosen, providing a sort of basic load-balancing
+              and failover capability.
        --remote-random-hostname
               Add  a  random string (6 characters) to first DNS label of host‐
               name to prevent DNS caching.  For example,  "foo.bar.gov"  would
               be modified to "<random-chars>.foo.bar.gov".
+              Add a random string (6 characters) to first DNS label  of  hostname
+              to  prevent DNS caching.  For example, "foo.bar.gov" would be modi‐
+              fied to "<random-chars>.foo.bar.gov".
        <connection>
               Define  a client connection profile.  Client connection profiles
               are groups of OpenVPN options that describe how to connect to  a
               given  OpenVPN server.  Client connection profiles are specified
               within an OpenVPN configuration file, and each profile is brack‐
               eted by <connection> and </connection>.
               An  OpenVPN client will try each connection profile sequentially
+              Define a client connection profile.  Client connection profiles are
+              groups  of  OpenVPN options that describe how to connect to a given
+              OpenVPN server.  Client connection profiles are specified within an
+              OpenVPN  configuration file, and each profile is bracketed by <con‐
+              nection> and </connection>.
+              An OpenVPN client will try  each  connection  profile  sequentially
               until it achieves a successful connection.
               --remote-random can be used to initially "scramble" the  connec‐
               tion list.
+              --remote-random  can be used to initially "scramble" the connection
+              list.
               Here is an example of connection profile usage:
 …
                   verb 3
               First  we  try to connect to a server at 198.19.34.56:1194 using
               UDP.  If that fails, we then try to connect to  198.19.34.56:443
               using  TCP.   If that also fails, then try connecting through an
               HTTP proxy at 192.168.0.8:8080 to  198.19.34.56:443  using  TCP.
               Finally,  try  to  connect through the same proxy to a server at
 .19.36.99:443 using TCP.
               The following OpenVPN options may be used inside of  a  <connec‐
               tion> block:
               bind,  connect-retry, connect-retry-max, connect-timeout, float,
               http-proxy,  http-proxy-option,  http-proxy-retry,   http-proxy-
               timeout,  local,  lport,  nobind,  port,  proto,  remote, rport,
               socks-proxy, and socks-proxy-retry.
+              A defaulting mechanism exists for specifying options to apply to
               all  <connection>  profiles.   If any of the above options (with
               the exception of remote  )  appear  outside  of  a  <connection>
               block,  but  in a configuration file which has one or more <con‐
               nection> blocks, the option setting will be used  as  a  default
               for  <connection>  blocks  which  follow it in the configuration
               file.
               For example, suppose the nobind option were placed in the sample
               configuration  file  above, near the top of the file, before the
               first <connection> block.  The effect would be as if nobind were
+              First we try to connect to a server at 198.19.34.56:1194 using UDP.
+              If  that  fails,  we  then try to connect to 198.19.34.56:443 using
+              TCP.  If that also fails, then try connecting through an HTTP proxy
+              at 192.168.0.8:8080 to 198.19.34.56:443 using TCP.  Finally, try to
+              connect through the same proxy  to  a  server  at  198.19.36.99:443
+              using TCP.
+              The  following OpenVPN options may be used inside of a <connection>
+              block:
+              bind, connect-retry, connect-retry-max, connect-timeout,  explicit-
+              exit-notify,  float, fragment, http-proxy, http-proxy-option, http-
+              proxy-retry, http-proxy-timeout, link-mtu,  local,  lport,  mssfix,
+              mtu-disc,  nobind,  port, proto, remote, rport, socks-proxy, socks-
+              proxy-retry, tun-mtu and tun-mtu-extra.
+              A defaulting mechanism exists for specifying options  to  apply  to
+              all  <connection>  profiles.  If any of the above options (with the
+              exception of remote ) appear outside of a <connection>  block,  but
+              in  a configuration file which has one or more <connection> blocks,
+              the option setting will be  used  as  a  default  for  <connection>
+              blocks which follow it in the configuration file.
+              For  example,  suppose  the nobind option were placed in the sample
+              configuration file above, near the top  of  the  file,  before  the
+              first  <connection>  block.   The effect would be as if nobind were
               declared in all <connection> blocks below it.
        --proto-force p
               When  iterating  through connection profiles, only consider pro‐
               files using protocol p ('tcp'|'udp').
+              When iterating through connection profiles, only consider  profiles
+              using protocol p ('tcp'|'udp').
        --remote-random
               When multiple --remote address/ports are specified, or  if  con‐
               nection  profiles  are being used, initially randomize the order
               of the list as a kind of basic load-balancing measure.
+              When  multiple  --remote address/ports are specified, or if connec‐
+              tion profiles are being used, initially randomize the order of  the
+              list as a kind of basic load-balancing measure.
        --proto p
               Use protocol p for communicating with remote  host.   p  can  be
               udp, tcp-client, or tcp-server.
+              Use  protocol  p for communicating with remote host.  p can be udp,
+              tcp-client, or tcp-server.
               The default protocol is udp when --proto is not specified.
+              For  UDP  operation,  --proto  udp  should  be specified on both
+              peers.
+              For TCP operation, one peer must use --proto tcp-server and  the
+              other  must  use  --proto  tcp-client.  A peer started with tcp-
+              server will wait indefinitely for  an  incoming  connection.   A
+              peer  started  with  tcp-client  will attempt to connect, and if
+              that fails, will sleep for 5 seconds (adjustable via the  --con‐
+              nect-retry  option)  and  try  again infinite or up to N retries
+              (adjustable  via  the  --connect-retry-max  option).   Both  TCP
+              client  and  server  will  simulate  a SIGUSR1 restart signal if
+              either side resets the connection.
+              OpenVPN is designed to operate optimally over UDP, but TCP capa‐
+              bility  is provided for situations where UDP cannot be used.  In
+              comparison with UDP, TCP will usually be somewhat less efficient
+              and less robust when used over unreliable or congested networks.
+              This  article  outlines  some of problems with tunneling IP over
+              TCP:
+              For UDP operation, --proto udp should be specified on both peers.
+              For TCP operation, one peer must use  --proto  tcp-server  and  the
+              other  must use --proto tcp-client.  A peer started with tcp-server
+              will wait indefinitely for an incoming connection.  A peer  started
+              with  tcp-client  will  attempt to connect, and if that fails, will
+              sleep for 5 seconds (adjustable via the --connect-retry option) and
+              try  again  infinite  or up to N retries (adjustable via the --con‐
+              nect-retry-max option).  Both TCP client and server will simulate a
+              SIGUSR1 restart signal if either side resets the connection.
+              OpenVPN is designed to operate optimally over UDP, but TCP capabil‐
+              ity is provided for situations where UDP cannot be used.   In  com‐
+              parison  with  UDP, TCP will usually be somewhat less efficient and
+              less robust when used over unreliable or congested networks.
+              This article outlines some of problems with tunneling IP over TCP:
               http://sites.inka.de/sites/bigred/devel/tcp-tcp.html
               There are certain cases, however, where using TCP may be  advan‐
               tageous from a security and robustness perspective, such as tun‐
               neling non-IP or application-level UDP protocols,  or  tunneling
               protocols which don't possess a built-in reliability layer.
+              There are certain cases, however, where using TCP may  be  advanta‐
+              geous from a security and robustness perspective, such as tunneling
+              non-IP or application-level UDP protocols, or  tunneling  protocols
+              which don't possess a built-in reliability layer.
        --connect-retry n
               For  --proto tcp-client, take n as the number of seconds to wait
+              For  --proto  tcp-client,  take  n as the number of seconds to wait
               between connection retries (default=5).
        --connect-timeout n
               For --proto tcp-client, set  connection  timeout  to  n  seconds
+              For  --proto  tcp-client,  set  connection  timeout  to  n  seconds
               (default=10).
        --connect-retry-max n
               For  --proto tcp-client, take n as the number of retries of con‐
               nection attempt (default=infinite).
+              For  --proto tcp-client, take n as the number of retries of connec‐
+              tion attempt (default=infinite).
        --show-proxy-settings
               Show sensed HTTP or SOCKS proxy settings. Currently,  only  Win‐
               dows clients support this option.
+              Show sensed HTTP or SOCKS proxy settings. Currently,  only  Windows
+              clients support this option.
        --http-proxy server port [authfile|'auto'|'auto-nct'] [auth-method]
               Connect  to  remote host through an HTTP proxy at address server
               and port port.  If HTTP Proxy-Authenticate is required, authfile
               is  a  file  containing  a  username and password on 2 lines, or
               "stdin" to prompt from console.
+              Connect  to remote host through an HTTP proxy at address server and
+              port port.  If HTTP Proxy-Authenticate is required, authfile  is  a
+              file  containing  a username and password on 2 lines, or "stdin" to
+              prompt from console.
               auth-method should be one of "none", "basic", or "ntlm".
               HTTP Digest authentication is supported as well,  but  only  via
               the auto or auto-nct flags (below).
               The  auto  flag  causes  OpenVPN  to automatically determine the
               auth-method and query stdin  or  the  management  interface  for
               username/password credentials, if required.  This flag exists on
               OpenVPN 2.1 or higher.
               The auto-nct flag (no  clear-text  auth)  instructs  OpenVPN  to
               automatically determine the authentication method, but to reject
               weak authentication protocols such as HTTP Basic Authentication.
+              HTTP Digest authentication is supported as well, but only  via  the
+              auto or auto-nct flags (below).
+              The  auto  flag causes OpenVPN to automatically determine the auth-
+              method and query  stdin  or  the  management  interface  for  user‐
+              name/password  credentials, if required.  This flag exists on Open‐
+              VPN 2.1 or higher.
+              The auto-nct flag (no clear-text auth) instructs OpenVPN  to  auto‐
+              matically  determine  the authentication method, but to reject weak
+              authentication protocols such as HTTP Basic Authentication.
        --http-proxy-retry
               Retry indefinitely on HTTP proxy errors.  If an HTTP proxy error
+              Retry indefinitely on HTTP proxy errors.  If an  HTTP  proxy  error
               occurs, simulate a SIGUSR1 reset.
 …
        --http-proxy-option type [parm]
+              Set  extended  HTTP  proxy  options.   Repeat  to  set  multiple
+              options.
+              VERSION  version  --  Set  HTTP  version   number   to   version
+              Set extended HTTP proxy options.  Repeat to set multiple options.
+              VERSION   version   --   Set   HTTP   version   number  to  version
               (default=1.0).
 …
        --socks-proxy server [port]
               Connect  to remote host through a Socks5 proxy at address server
               and port port (default=1080).
+              Connect to remote host through a Socks5 proxy at address server and
+              port port (default=1080).
        --socks-proxy-retry
               Retry indefinitely on Socks proxy  errors.   If  a  Socks  proxy
               error occurs, simulate a SIGUSR1 reset.
+              Retry  indefinitely  on Socks proxy errors.  If a Socks proxy error
+              occurs, simulate a SIGUSR1 reset.
        --resolv-retry n
               If hostname resolve fails for --remote, retry resolve for n sec‐
               onds before failing.
+              If hostname resolve fails for --remote, retry resolve for n seconds
+              before failing.
               Set n to "infinite" to retry indefinitely.
               By default, --resolv-retry infinite is enabled.  You can disable
               by setting n=0.
+              By default, --resolv-retry infinite is enabled.  You can disable by
+              setting n=0.
        --float
               Allow  remote  peer to change its IP address and/or port number,
               such as due to DHCP (this is the  default  if  --remote  is  not
               used).   --float  when specified with --remote allows an OpenVPN
               session to initially connect to a peer at a known address,  how‐
               ever if packets arrive from a new address and pass all authenti‐
               cation tests, the new address will take control of the  session.
               This  is  useful when you are connecting to a peer which holds a
               dynamic address such as a dial-in user or DHCP client.
               Essentially, --float tells OpenVPN to accept authenticated pack‐
               ets  from  any address, not only the address which was specified
               in the --remote option.
+              Allow remote peer to change its IP address and/or port number, such
+              as  due  to  DHCP  (this  is  the default if --remote is not used).
+              --float when specified with --remote allows an OpenVPN  session  to
+              initially  connect to a peer at a known address, however if packets
+              arrive from a new address and pass all  authentication  tests,  the
+              new  address will take control of the session.  This is useful when
+              you are connecting to a peer which holds a dynamic address such  as
+              a dial-in user or DHCP client.
+              Essentially,  --float tells OpenVPN to accept authenticated packets
+              from any address, not only the address which was specified  in  the
+              --remote option.
        --ipchange cmd
               Run command cmd when our remote ip-address is initially  authen‐
               ticated or changes.
               cmd  consists  of  a  path  to  script  (or executable program),
               optionally followed by arguments. The path and arguments may  be
               single-  or  double-quoted and/or escaped using a backslash, and
               should be separated by one or more spaces.
               When cmd is executed two arguments are appended after any  argu‐
               ments specified in cmd , as follows:
+              Run  command  cmd when our remote ip-address is initially authenti‐
+              cated or changes.
+              cmd consists of a path to script (or executable  program),  option‐
+              ally  followed  by arguments. The path and arguments may be single-
+              or double-quoted and/or escaped using a backslash,  and  should  be
+              separated by one or more spaces.
+              When cmd is executed two arguments are appended after any arguments
+              specified in cmd , as follows:
               cmd ip_address port_number
               Don't use --ipchange in --mode server mode.  Use a --client-con‐
               nect script instead.
               See the "Environmental Variables" section below  for  additional
+              Don't use --ipchange in --mode server mode.  Use a --client-connect
+              script instead.
+              See  the  "Environmental  Variables"  section  below for additional
               parameters passed as environmental variables.
               If you are running in a dynamic IP address environment where the
               IP addresses of either peer could change without notice, you can
               use  this  script, for example, to edit the /etc/hosts file with
               the current address of the peer.  The script will be  run  every
               time the remote peer changes its IP address.
               Similarly  if our IP address changes due to DHCP, we should con‐
               figure our IP address change script (see man page for  dhcpcd(8)
               )  to  deliver  a  SIGHUP or SIGUSR1 signal to OpenVPN.  OpenVPN
               will then  reestablish  a  connection  with  its  most  recently
               authenticated peer on its new IP address.
+              If you are running in a dynamic IP address environment where the IP
+              addresses  of  either peer could change without notice, you can use
+              this script, for example, to edit the /etc/hosts file with the cur‐
+              rent  address  of  the peer.  The script will be run every time the
+              remote peer changes its IP address.
+              Similarly if our IP address changes due to DHCP, we should  config‐
+              ure  our  IP address change script (see man page for dhcpcd(8) ) to
+              deliver a SIGHUP or SIGUSR1 signal to OpenVPN.  OpenVPN  will  then
+              reestablish  a connection with its most recently authenticated peer
+              on its new IP address.
        --port port
               TCP/UDP  port  number  for  both  local and remote.  The current
               default of 1194 represents the official IANA port number assign‐
               ment  for  OpenVPN  and  has been used since version 2.0-beta17.
               Previous versions used port 5000 as the default.
+              TCP/UDP port number for both local and remote.  The current default
+              of  1194  represents  the  official IANA port number assignment for
+              OpenVPN and has been used since version 2.0-beta17.  Previous  ver‐
+              sions used port 5000 as the default.
        --lport port
 …
               TCP/UDP port number for remote.
        --bind Bind to local address and port. This is the default  unless  any
               of --proto tcp-client , --http-proxy or --socks-proxy are used.
+       --bind Bind  to  local address and port. This is the default unless any of
+              --proto tcp-client , --http-proxy or --socks-proxy are used.
        --nobind
               Do  not bind to local address and port.  The IP stack will allo‐
               cate a dynamic port for returning packets.  Since the  value  of
               the  dynamic  port could not be known in advance by a peer, this
               option is only suitable for peers which will be initiating  con‐
               nections by using the --remote option.
+              Do not bind to local address and port.  The IP stack will  allocate
+              a  dynamic  port  for  returning  packets.   Since the value of the
+              dynamic port could not be known in advance by a peer,  this  option
+              is  only suitable for peers which will be initiating connections by
+              using the --remote option.
        --dev tunX | tapX | null
               TUN/TAP  virtual network device ( X can be omitted for a dynamic
+              TUN/TAP virtual network device ( X can be  omitted  for  a  dynamic
               device.)
               See examples section below for an example on setting  up  a  TUN
+              See  examples  section  below  for  an  example on setting up a TUN
               device.
               You  must  use either tun devices on both ends of the connection
               or tap devices on both ends.  You cannot mix them, as they  rep‐
               resent different underlying network layers.
               tun  devices  encapsulate  IPv4  or IPv6 (OSI Layer 3) while tap
+              You must use either tun devices on both ends of the  connection  or
+              tap  devices  on both ends.  You cannot mix them, as they represent
+              different underlying network layers.
+              tun devices encapsulate IPv4  or  IPv6  (OSI  Layer  3)  while  tap
               devices encapsulate Ethernet 802.3 (OSI Layer 2).
        --dev-type device-type
               Which device type are we using?  device-type should be tun  (OSI
               Layer  3)  or  tap  (OSI  Layer 2).  Use this option only if the
               TUN/TAP device used with --dev does not begin with tun or tap.
+              Which  device  type  are  we using?  device-type should be tun (OSI
+              Layer 3) or tap (OSI Layer 2).  Use this option only if the TUN/TAP
+              device used with --dev does not begin with tun or tap.
        --topology mode
               Configure virtual addressing topology when running in --dev  tun
               mode.   This  directive  has no meaning in --dev tap mode, which
+              Configure  virtual  addressing  topology  when running in --dev tun
+              mode.  This directive has no  meaning  in  --dev  tap  mode,  which
               always uses a subnet topology.
               If you set this  directive  on  the  server,  the  --server  and
               --server-bridge  directives  will automatically push your chosen
               topology setting to clients as well.  This directive can also be
               manually  pushed  to  clients.   Like  the --dev directive, this
               directive must always be compatible between client and server.
+              If you set this directive on the server, the --server and --server-
+              bridge directives will automatically push your chosen topology set‐
+              ting  to  clients  as  well.   This  directive can also be manually
+              pushed to clients.  Like the --dev directive, this  directive  must
+              always be compatible between client and server.
               mode can be one of:
               net30 -- Use a point-to-point topology, by  allocating  one  /30
               subnet  per  client.   This  is designed to allow point-to-point
               semantics when some or all of the connecting  clients  might  be
               Windows systems.  This is the default on OpenVPN 2.0.
               p2p  --  Use a point-to-point topology where the remote endpoint
               of the client's tun interface always points to  the  local  end‐
               point of the server's tun interface.  This mode allocates a sin‐
               gle IP address per connecting client.  Only use when none of the
               connecting  clients are Windows systems.  This mode is function‐
               ally equivalent to the --ifconfig-pool-linear directive which is
               available in OpenVPN 2.0 and is now deprecated.
               subnet  -- Use a subnet rather than a point-to-point topology by
               configuring the tun interface with a local IP address and subnet
               mask,  similar  to  the  topology used in --dev tap and ethernet
               bridging mode.  This mode allocates a single IP address per con‐
               necting  client  and  works  on Windows as well.  Only available
               when server and clients are OpenVPN 2.1 or  higher,  or  OpenVPN
 .0.x which has been manually patched with the --topology direc‐
               tive code.  When used on Windows, requires version 8.2 or higher
               of  the  TAP-Win32 driver.  When used on *nix, requires that the
               tun driver supports an ifconfig(8) command which sets  a  subnet
               instead of a remote endpoint IP address.
+              net30  -- Use a point-to-point topology, by allocating one /30 sub‐
+              net per client.  This is designed to allow point-to-point semantics
+              when  some  or  all of the connecting clients might be Windows sys‐
+              tems.  This is the default on OpenVPN 2.0.
+              p2p -- Use a point-to-point topology where the remote  endpoint  of
+              the  client's  tun interface always points to the local endpoint of
+              the server's tun  interface.   This  mode  allocates  a  single  IP
+              address  per connecting client.  Only use when none of the connect‐
+              ing clients are Windows systems.  This mode is functionally equiva‐
+              lent  to the --ifconfig-pool-linear directive which is available in
+              OpenVPN 2.0 and is now deprecated.
+              subnet -- Use a subnet rather than  a  point-to-point  topology  by
+              configuring  the  tun  interface with a local IP address and subnet
+              mask, similar to the topology used in --dev tap and ethernet bridg‐
+              ing  mode.   This mode allocates a single IP address per connecting
+              client and works on Windows as well.  Only  available  when  server
+              and  clients  are OpenVPN 2.1 or higher, or OpenVPN 2.0.x which has
+              been manually patched with the  --topology  directive  code.   When
+              used  on  Windows,  requires version 8.2 or higher of the TAP-Win32
+              driver.  When used on *nix, requires that the tun  driver  supports
+              an ifconfig(8) command which sets a subnet instead of a remote end‐
+              point IP address.
               This option exists in OpenVPN 2.1 or higher.
        --tun-ipv6
               Build  a tun link capable of forwarding IPv6 traffic.  Should be
               used in conjunction with --dev tun or  --dev  tunX.   A  warning
               will  be  displayed  if no specific IPv6 TUN support for your OS
               has been compiled into OpenVPN.
+              Build a tun link capable of forwarding  IPv6  traffic.   Should  be
+              used  in  conjunction with --dev tun or --dev tunX.  A warning will
+              be displayed if no specific IPv6 TUN support for your OS  has  been
+              compiled into OpenVPN.
               See below for further IPv6-related configuration options.
        --dev-node node
               Explicitly set the device node rather than  using  /dev/net/tun,
               /dev/tun,  /dev/tap,  etc.  If OpenVPN cannot figure out whether
               node is a TUN or TAP device based on the name, you  should  also
               specify --dev-type tun or --dev-type tap.
               On  Windows systems, select the TAP-Win32 adapter which is named
               node in the Network Connections Control Panel or the raw GUID of
               the  adapter  enclosed  by  braces.   The --show-adapters option
               under Windows can also be used to enumerate all  available  TAP-
               Win32  adapters  and will show both the network connections con‐
               trol panel name and the GUID for each TAP-Win32 adapter.
+              Explicitly  set  the  device  node  rather than using /dev/net/tun,
+              /dev/tun, /dev/tap, etc.  If OpenVPN cannot figure out whether node
+              is  a  TUN or TAP device based on the name, you should also specify
+              --dev-type tun or --dev-type tap.
+              On Windows systems, select the TAP-Win32  adapter  which  is  named
+              node  in  the  Network Connections Control Panel or the raw GUID of
+              the adapter enclosed by braces.  The --show-adapters  option  under
+              Windows  can  also  be  used  to  enumerate all available TAP-Win32
+              adapters and will show both the network connections  control  panel
+              name and the GUID for each TAP-Win32 adapter.
        --lladdr address
               Specify the link layer address, more commonly known as  the  MAC
+              Specify  the  link  layer  address,  more commonly known as the MAC
               address.  Only applied to TAP devices.
        --iproute cmd
               Set  alternate  command  to  execute instead of default iproute2
               command.  May be used in order to execute  OpenVPN  in  unprivi‐
               leged environment.
+              Set alternate command to execute instead of default  iproute2  com‐
+              mand.   May  be  used  in  order to execute OpenVPN in unprivileged
+              environment.
        --ifconfig l rn
+              Set  TUN/TAP  adapter  parameters.   l  is the IP address of the
+              local VPN endpoint.  For TUN devices, rn is the  IP  address  of
+              the remote VPN endpoint.  For TAP devices, rn is the subnet mask
+              of the virtual ethernet segment which is being created  or  con‐
+              nected to.
+              For TUN devices, which facilitate virtual point-to-point IP con‐
+              nections, the proper usage of --ifconfig is to use  two  private
+              IP addresses which are not a member of any existing subnet which
+              is in use.  The IP addresses may be consecutive and should  have
+              their  order  reversed  on  the  remote  peer.  After the VPN is
+              established, by pinging rn, you will be pinging across the VPN.
+              For TAP devices, which provide the  ability  to  create  virtual
+              ethernet  segments,  --ifconfig is used to set an IP address and
+              subnet mask just as a physical ethernet adapter would  be  simi‐
+              larly  configured.  If you are attempting to connect to a remote
+              ethernet bridge, the IP address and subnet should be set to val‐
+              ues  which  would  be  valid on the the bridged ethernet segment
+              (note also that DHCP can be used for the same purpose).
+              This option, while primarily a proxy for  the  ifconfig(8)  com‐
+              mand,  is  designed  to simplify TUN/TAP tunnel configuration by
+              providing a standard interface to the different ifconfig  imple‐
+              mentations on different platforms.
+              --ifconfig  parameters which are IP addresses can also be speci‐
+              fied as a DNS or /etc/hosts file resolvable name.
+              For TAP devices, --ifconfig should not be used if the TAP inter‐
+              face will be getting an IP address lease from a DHCP server.
+              Set TUN/TAP adapter parameters.  l is the IP address of  the  local
+              VPN  endpoint.  For TUN devices, rn is the IP address of the remote
+              VPN endpoint.  For TAP devices, rn is the subnet mask of  the  vir‐
+              tual ethernet segment which is being created or connected to.
+              For TUN devices, which facilitate virtual point-to-point IP connec‐
+              tions, the proper usage of --ifconfig is  to  use  two  private  IP
+              addresses which are not a member of any existing subnet which is in
+              use.  The IP addresses may be consecutive  and  should  have  their
+              order  reversed  on the remote peer.  After the VPN is established,
+              by pinging rn, you will be pinging across the VPN.
+              For TAP devices, which provide the ability to create virtual ether‐
+              net  segments,  --ifconfig  is used to set an IP address and subnet
+              mask just as a physical ethernet adapter would be similarly config‐
+              ured.   If  you  are  attempting  to  connect  to a remote ethernet
+              bridge, the IP address and subnet should be  set  to  values  which
+              would  be valid on the the bridged ethernet segment (note also that
+              DHCP can be used for the same purpose).
+              This option, while primarily a proxy for the  ifconfig(8)  command,
+              is designed to simplify TUN/TAP tunnel configuration by providing a
+              standard interface to the  different  ifconfig  implementations  on
+              different platforms.
+              --ifconfig  parameters which are IP addresses can also be specified
+              as a DNS or /etc/hosts file resolvable name.
+              For TAP devices, --ifconfig should not be used if the TAP interface
+              will be getting an IP address lease from a DHCP server.
        --ifconfig-noexec
               Don't  actually  execute  ifconfig/netsh  commands, instead pass
+              Don't   actually  execute  ifconfig/netsh  commands,  instead  pass
               --ifconfig parameters to scripts using environmental variables.
        --ifconfig-nowarn
+              Don't  output  an  options  consistency  check  warning  if  the
+              --ifconfig  option  on this side of the connection doesn't match
+              the remote side.  This is useful when you  want  to  retain  the
+              overall  benefits  of  the  options  consistency check (also see
+              --disable-occ option) while only disabling the  ifconfig  compo‐
+              nent of the check.
+              For  example,  if  you have a configuration where the local host
+              uses --ifconfig but the remote host does  not,  use  --ifconfig-
+              nowarn on the local host.
+              This  option  will also silence warnings about potential address
+              conflicts which occasionally annoy  more  experienced  users  by
+              triggering "false positive" warnings.
+              Don't output an options consistency check warning if the --ifconfig
+              option  on  this  side  of  the connection doesn't match the remote
+              side.  This is useful when you want to retain the overall  benefits
+              of  the  options  consistency check (also see --disable-occ option)
+              while only disabling the ifconfig component of the check.
+              For example, if you have a configuration where the local host  uses
+              --ifconfig  but  the remote host does not, use --ifconfig-nowarn on
+              the local host.
+              This option will also silence warnings about potential address con‐
+              flicts  which occasionally annoy more experienced users by trigger‐
+              ing "false positive" warnings.
        --route network/IP [netmask] [gateway] [metric]
               Add  route  to  routing  table  after connection is established.
               Multiple routes can be specified.  Routes will be  automatically
               torn down in reverse order prior to TUN/TAP device close.
               This  option is intended as a convenience proxy for the route(8)
               shell command, while at the same time providing portable  seman‐
               tics across OpenVPN's platform space.
+              Add route to routing table after connection is established.  Multi‐
+              ple  routes  can  be  specified.  Routes will be automatically torn
+              down in reverse order prior to TUN/TAP device close.
+              This option is intended as a convenience  proxy  for  the  route(8)
+              shell  command, while at the same time providing portable semantics
+              across OpenVPN's platform space.
               netmask default -- 255.255.255.255
               gateway  default  --  taken  from  --route-gateway or the second
               parameter to --ifconfig when --dev tun is specified.
+              gateway default -- taken from --route-gateway or the second parame‐
+              ter to --ifconfig when --dev tun is specified.
               metric default -- taken from --route-metric otherwise 0.
               The default can be specified by leaving an option blank or  set‐
               ting it to "default".
               The  network  and  gateway parameters can also be specified as a
               DNS or /etc/hosts file resolvable name, or as one of three  spe‐
               cial keywords:
               vpn_gateway  --  The remote VPN endpoint address (derived either
               from --route-gateway or the second parameter to --ifconfig  when
               --dev tun is specified).
               net_gateway  --  The  pre-existing IP default gateway, read from
               the routing table (not supported on all OSes).
               remote_host -- The --remote address if OpenVPN is being  run  in
+              The  default can be specified by leaving an option blank or setting
+              it to "default".
+              The network and gateway parameters can also be specified as  a  DNS
+              or /etc/hosts file resolvable name, or as one of three special key‐
+              words:
+              vpn_gateway -- The remote VPN endpoint address (derived either from
+              --route-gateway  or  the  second parameter to --ifconfig when --dev
+              tun is specified).
+              net_gateway -- The pre-existing IP default gateway, read  from  the
+              routing table (not supported on all OSes).
+              remote_host  --  The  --remote  address  if OpenVPN is being run in
               client mode, and is undefined in server mode.
        --max-routes n
               Allow  a  maximum  number  of n --route options to be specified,
               either in the local configuration file, or pulled from an  Open‐
               VPN server.  By default, n=100.
+              Allow a maximum number of n --route options to be specified, either
+              in  the local configuration file, or pulled from an OpenVPN server.
+              By default, n=100.
        --route-gateway gw|'dhcp'
               Specify a default gateway gw for use with --route.
+              If  dhcp is specified as the parameter, the gateway address will
+              be extracted from a DHCP negotiation with  the  OpenVPN  server-
+              side LAN.
+              If dhcp is specified as the parameter, the gateway address will  be
+              extracted from a DHCP negotiation with the OpenVPN server-side LAN.
        --route-metric m
 …
        --route-delay [n] [w]
               Delay  n  seconds  (default=0)  after  connection establishment,
               before adding routes. If n is 0, routes will  be  added  immedi‐
               ately  upon connection establishment.  If --route-delay is omit‐
               ted, routes will be added immediately after TUN/TAP device  open
               and  --up  script execution, before any --user or --group privi‐
               lege downgrade (or --chroot execution.)
               This option is designed to be useful in scenarios where DHCP  is
               used to set tap adapter addresses.  The delay will give the DHCP
+              Delay  n seconds (default=0) after connection establishment, before
+              adding routes. If n is 0, routes will  be  added  immediately  upon
+              connection establishment.  If --route-delay is omitted, routes will
+              be added immediately after TUN/TAP device open and --up script exe‐
+              cution,  before  any  --user  or  --group  privilege  downgrade (or
+              --chroot execution.)
+              This option is designed to be useful in  scenarios  where  DHCP  is
+              used  to  set  tap adapter addresses.  The delay will give the DHCP
               handshake time to complete before routes are added.
               On Windows, --route-delay tries to be more intelligent by  wait‐
               ing  w  seconds  (w=30  by default) for the TAP-Win32 adapter to
               come up before adding routes.
+              On Windows, --route-delay tries to be more intelligent by waiting w
+              seconds  (w=30  by  default)  for  the TAP-Win32 adapter to come up
+              before adding routes.
        --route-up cmd
+              Run command cmd after routes  are  added,  subject  to  --route-
+              delay.
+              cmd  consists  of  a  path  to  script  (or executable program),
+              optionally followed by arguments. The path and arguments may  be
+              single-  or  double-quoted and/or escaped using a backslash, and
+              should be separated by one or more spaces.
+              See the "Environmental Variables" section below  for  additional
+              Run command cmd after routes are added, subject to --route-delay.
+              cmd consists of a path to script (or executable  program),  option‐
+              ally  followed  by arguments. The path and arguments may be single-
+              or double-quoted and/or escaped using a backslash,  and  should  be
+              separated by one or more spaces.
+              See  the  "Environmental  Variables"  section  below for additional
               parameters passed as environmental variables.
 …
               Run command cmd before routes are removed upon disconnection.
               cmd  consists  of  a  path  to  script  (or executable program),
               optionally followed by arguments. The path and arguments may  be
               single-  or  double-quoted and/or escaped using a backslash, and
               should be separated by one or more spaces.
               See the "Environmental Variables" section below  for  additional
+              cmd consists of a path to script (or executable  program),  option‐
+              ally  followed  by arguments. The path and arguments may be single-
+              or double-quoted and/or escaped using a backslash,  and  should  be
+              separated by one or more spaces.
+              See  the  "Environmental  Variables"  section  below for additional
               parameters passed as environmental variables.
        --route-noexec
               Don't  add  or remove routes automatically.  Instead pass routes
               to --route-up script using environmental variables.
+              Don't add or remove routes automatically.  Instead pass  routes  to
+              --route-up script using environmental variables.
        --route-nopull
               When used with --client or  --pull,  accept  options  pushed  by
               server EXCEPT for routes and dhcp options like DNS servers.
               When used on the client, this option effectively bars the server
               from adding routes to the client's routing table,  however  note
               that this option still allows the server to set the TCP/IP prop‐
               erties of the client's TUN/TAP interface.
+              When  used with --client or --pull, accept options pushed by server
+              EXCEPT for routes and dhcp options like DNS servers.
+              When used on the client, this option effectively  bars  the  server
+              from adding routes to the client's routing table, however note that
+              this option still allows the server to set the TCP/IP properties of
+              the client's TUN/TAP interface.
        --allow-pull-fqdn
+              Allow client to pull DNS names from server  (rather  than  being
+              limited  to  IP  address)  for --ifconfig, --route, and --route-
+              gateway.
+              Allow  client to pull DNS names from server (rather than being lim‐
+              ited to IP address) for --ifconfig, --route, and --route-gateway.
        --client-nat snat|dnat network netmask alias
               This pushable client option sets up a stateless  one-to-one  NAT
               rule  on  packet  addresses  (not ports), and is useful in cases
               where routes or ifconfig settings pushed  to  the  client  would
               create an IP numbering conflict.
               network/netmask  (for  example  192.168.0.0/255.255.0.0) defines
               the local view of a resource from the client perspective,  while
               alias/netmask  (for  example  10.64.0.0/255.255.0.0) defines the
+              This pushable client option sets up a stateless one-to-one NAT rule
+              on  packet  addresses  (not  ports),  and  is useful in cases where
+              routes or ifconfig settings pushed to the client would create an IP
+              numbering conflict.
+              network/netmask  (for  example 192.168.0.0/255.255.0.0) defines the
+              local view  of  a  resource  from  the  client  perspective,  while
+              alias/netmask   (for  example  10.64.0.0/255.255.0.0)  defines  the
               remote view from the server perspective.
               Use snat (source NAT) for resources owned by the client and dnat
+              Use snat (source NAT) for resources owned by the  client  and  dnat
               (destination NAT) for remote resources.
               Set  --verb  6  for debugging info showing the transformation of
+              Set  --verb  6  for  debugging  info  showing the transformation of
               src/dest addresses in packets.
        --redirect-gateway flags...
               Automatically execute routing commands to cause all outgoing  IP
               traffic  to  be  redirected over the VPN.  This is a client-side
+              Automatically execute routing commands to  cause  all  outgoing  IP
+              traffic  to  be  redirected  over  the  VPN.  This is a client-side
               option.
               This option performs three steps:
               (1) Create a static route for the --remote  address  which  for‐
               wards to the pre-existing default gateway.  This is done so that
               (3) will not create a routing loop.
+              (1) Create a static route for the --remote address  which  forwards
+              to the pre-existing default gateway.  This is done so that (3) will
+              not create a routing loop.
               (2) Delete the default gateway route.
               (3) Set the new default gateway to be the VPN  endpoint  address
               (derived  either from --route-gateway or the second parameter to
+              (3) Set the new default gateway to  be  the  VPN  endpoint  address
+              (derived  either  from  --route-gateway  or the second parameter to
               --ifconfig when --dev tun is specified).
               When the tunnel is  torn  down,  all  of  the  above  steps  are
               reversed so that the original default route is restored.
+              When the tunnel is torn down, all of the above steps  are  reversed
+              so that the original default route is restored.
               Option flags:
               local -- Add the local flag if both OpenVPN servers are directly
               connected via a common subnet, such as with wireless.  The local
+              local  --  Add  the local flag if both OpenVPN servers are directly
+              connected via a common subnet, such as with  wireless.   The  local
               flag will cause step 1 above to be omitted.
+              autolocal  --  Try  to automatically determine whether to enable
+              local flag above.
+              def1 -- Use this flag to override the default gateway  by  using
+.0.0.0/1  and  128.0.0.0/1 rather than 0.0.0.0/0.  This has the
+              benefit of overriding but not wiping out  the  original  default
+              gateway.
+              bypass-dhcp  --  Add a direct route to the DHCP server (if it is
+              non-local) which  bypasses  the  tunnel  (Available  on  Windows
+              clients, may not be available on non-Windows clients).
+              bypass-dns  --  Add a direct route to the DNS server(s) (if they
+              are non-local) which bypasses the tunnel (Available  on  Windows
+              clients, may not be available on non-Windows clients).
+              block-local  --  Block  access  to  local LAN when the tunnel is
+              active, except for the LAN gateway itself.  This is accomplished
+              by  routing  the  local LAN (except for the LAN gateway address)
+              into the tunnel.
+              autolocal -- Try to automatically determine whether to enable local
+              flag above.
+              def1 -- Use this flag to override  the  default  gateway  by  using
+.0.0.0/1 and 128.0.0.0/1 rather than 0.0.0.0/0.  This has the ben‐
+              efit of overriding but not wiping out the original default gateway.
+              bypass-dhcp -- Add a direct route to the DHCP server (if it is non-
+              local) which bypasses the tunnel (Available on Windows clients, may
+              not be available on non-Windows clients).
+              bypass-dns -- Add a direct route to the DNS server(s) (if they  are
+              non-local) which bypasses the tunnel (Available on Windows clients,
+              may not be available on non-Windows clients).
+              block-local -- Block access to local LAN when the tunnel is active,
+              except for the LAN gateway itself.  This is accomplished by routing
+              the local LAN (except for the LAN gateway address) into the tunnel.
        --link-mtu n
               Sets an upper bound on the size of UDP packets  which  are  sent
               between  OpenVPN  peers.   It's  best  not to set this parameter
               unless you know what you're doing.
+              Sets an upper bound on the size  of  UDP  packets  which  are  sent
+              between  OpenVPN peers.  It's best not to set this parameter unless
+              you know what you're doing.
        --redirect-private [flags]
               Like --redirect-gateway, but omit actually changing the  default
+              Like --redirect-gateway, but omit  actually  changing  the  default
               gateway.  Useful when pushing private subnets.
        --tun-mtu n
               Take  the TUN device MTU to be n and derive the link MTU from it
               (default=1500).  In most cases, you will probably want to  leave
+              Take  the  TUN  device  MTU to be n and derive the link MTU from it
+              (default=1500).  In most cases, you will  probably  want  to  leave
               this parameter set to its default value.
               The  MTU  (Maximum  Transmission  Units) is the maximum datagram
               size in bytes that can be sent unfragmented  over  a  particular
               network  path.   OpenVPN requires that packets on the control or
               data channels be sent unfragmented.
               MTU problems often manifest themselves as connections which hang
+              The  MTU  (Maximum Transmission Units) is the maximum datagram size
+              in bytes that can be sent unfragmented over  a  particular  network
+              path.   OpenVPN  requires that packets on the control or data chan‐
+              nels be sent unfragmented.
+              MTU problems often manifest themselves as  connections  which  hang
               during periods of active usage.
               It's  best to use the --fragment and/or --mssfix options to deal
+              It's  best  to  use  the --fragment and/or --mssfix options to deal
               with MTU sizing issues.
        --tun-mtu-extra n
+              Assume that the TUN/TAP device might return as many as  n  bytes
+              more  than  the --tun-mtu size on read.  This parameter defaults
+              to 0, which is sufficient for most TUN devices.  TAP devices may
+              introduce  additional  overhead in excess of the MTU size, and a
+              setting of 32 is the default when TAP devices  are  used.   This
+              parameter only controls internal OpenVPN buffer sizing, so there
+              is no transmission  overhead  associated  with  using  a  larger
+              value.
+              Assume that the TUN/TAP device might return as many as n bytes more
+              than  the  --tun-mtu  size  on read.  This parameter defaults to 0,
+              which is sufficient for most TUN devices.  TAP devices  may  intro‐
+              duce  additional  overhead in excess of the MTU size, and a setting
+              of 32 is the default when TAP devices  are  used.   This  parameter
+              only controls internal OpenVPN buffer sizing, so there is no trans‐
+              mission overhead associated with using a larger value.
        --mtu-disc type
               Should  we  do Path MTU discovery on TCP/UDP channel?  Only sup‐
               ported on OSes such as Linux that supports the necessary  system
               call to set.
+              Should we do Path MTU discovery on TCP/UDP channel?  Only supported
+              on  OSes  such  as Linux that supports the necessary system call to
+              set.
               'no' -- Never send DF (Don't Fragment) frames
 …
        --mtu-test
               To empirically measure MTU on connection startup, add the --mtu-
               test option to your configuration.  OpenVPN will send ping pack‐
               ets  of various sizes to the remote peer and measure the largest
               packets  which  were  successfully  received.   The   --mtu-test
               process normally takes about 3 minutes to complete.
+              To empirically measure MTU on connection startup,  add  the  --mtu-
+              test  option to your configuration.  OpenVPN will send ping packets
+              of various sizes to the remote peer and measure the largest packets
+              which  were successfully received.  The --mtu-test process normally
+              takes about 3 minutes to complete.
        --fragment max
+              Enable  internal datagram fragmentation so that no UDP datagrams
+              are sent which are larger than max bytes.
+              The max parameter is interpreted in the same way as the  --link-
+              mtu  parameter,  i.e.  the  UDP  packet size after encapsulation
+              overhead has been added in, but not  including  the  UDP  header
+              itself.
+              The  --fragment  option  only makes sense when you are using the
+              UDP protocol ( --proto udp ).
+              Enable internal datagram fragmentation so that no UDP datagrams are
+              sent which are larger than max bytes.
+              The  max parameter is interpreted in the same way as the --link-mtu
+              parameter, i.e. the UDP packet size  after  encapsulation  overhead
+              has been added in, but not including the UDP header itself.
+              The  --fragment  option only makes sense when you are using the UDP
+              protocol ( --proto udp ).
               --fragment adds 4 bytes of overhead per datagram.
               See the --mssfix option below for an important related option to
+              See the --mssfix option below for an important  related  option  to
               --fragment.
+              It should also be noted that this option is not meant to replace
+              UDP fragmentation at the IP stack level.  It is only meant as  a
+              last  resort  when  path  MTU  discovery  is broken.  Using this
+              option is less efficient than fixing path MTU discovery for your
+              IP link and using native IP fragmentation instead.
+              Having  said that, there are circumstances where using OpenVPN's
+              internal fragmentation capability may be your only option,  such
+              as  tunneling  a  UDP multicast stream which requires fragmenta‐
+              tion.
+              It  should  also  be noted that this option is not meant to replace
+              UDP fragmentation at the IP stack level.  It is  only  meant  as  a
+              last  resort  when path MTU discovery is broken.  Using this option
+              is less efficient than fixing path MTU discovery for your  IP  link
+              and using native IP fragmentation instead.
+              Having  said  that,  there  are circumstances where using OpenVPN's
+              internal fragmentation capability may be your only option, such  as
+              tunneling a UDP multicast stream which requires fragmentation.
        --mssfix max
+              Announce to TCP sessions  running  over  the  tunnel  that  they
+              should limit their send packet sizes such that after OpenVPN has
+              encapsulated them, the resulting UDP packet  size  that  OpenVPN
+              sends  to  its peer will not exceed max bytes. The default value
+              is 1450.
+              The max parameter is interpreted in the same way as the  --link-
+              mtu  parameter,  i.e.  the  UDP  packet size after encapsulation
+              overhead has been added in, but not  including  the  UDP  header
+              itself.
+              The  --mssfix option only makes sense when you are using the UDP
+              protocol for OpenVPN peer-to-peer communication,  i.e.   --proto
+              udp.
+              --mssfix  and  --fragment  can  be  ideally used together, where
+              --mssfix will try to keep TCP from needing packet  fragmentation
+              in the first place, and if big packets come through anyhow (from
+              protocols other than TCP), --fragment will  internally  fragment
+              them.
+              Both  --fragment  and --mssfix are designed to work around cases
+              where Path MTU discovery is broken on the network  path  between
+              Announce  to  TCP sessions running over the tunnel that they should
+              limit their send packet sizes such that after OpenVPN has  encapsu‐
+              lated them, the resulting UDP packet size that OpenVPN sends to its
+              peer will not exceed max bytes. The default value is 1450.
+              The max parameter is interpreted in the same way as the  --link-mtu
+              parameter,  i.e.  the  UDP packet size after encapsulation overhead
+              has been added in, but not including the UDP header itself.
+              The --mssfix option only makes sense when you  are  using  the  UDP
+              protocol for OpenVPN peer-to-peer communication, i.e.  --proto udp.
+              --mssfix  and --fragment can be ideally used together, where --mss‐
+              fix will try to keep TCP from needing packet fragmentation  in  the
+              first place, and if big packets come through anyhow (from protocols
+              other than TCP), --fragment will internally fragment them.
+              Both --fragment and --mssfix are  designed  to  work  around  cases
+              where  Path  MTU  discovery  is  broken on the network path between
               OpenVPN peers.
               The  usual  symptom of such a breakdown is an OpenVPN connection
+              The usual symptom of such a  breakdown  is  an  OpenVPN  connection
               which successfully starts, but then stalls during active usage.
               If --fragment and --mssfix are used together, --mssfix will take
+              If  --fragment  and  --mssfix are used together, --mssfix will take
               its default max parameter from the --fragment max option.
               Therefore,  one  could lower the maximum UDP packet size to 1300
               (a good first try for solving MTU-related  connection  problems)
               with the following options:
+              Therefore, one could lower the maximum UDP packet size to  1300  (a
+              good  first  try  for solving MTU-related connection problems) with
+              the following options:
               --tun-mtu 1500 --fragment 1300 --mssfix
        --sndbuf size
               Set  the TCP/UDP socket send buffer size.  Currently defaults to
+              Set the TCP/UDP socket send buffer  size.   Currently  defaults  to
 bytes.
        --rcvbuf size
               Set the TCP/UDP socket receive buffer size.  Currently  defaults
               to 65536 bytes.
+              Set  the TCP/UDP socket receive buffer size.  Currently defaults to
+bytes.
        --mark value
               Mark encrypted packets being sent with value. The mark value can
               be matched in policy routing and packetfilter rules. This option
               is  only  supported in Linux and does nothing on other operating
               systems.
+              Mark encrypted packets being sent with value. The mark value can be
+              matched  in  policy  routing and packetfilter rules. This option is
+              only supported in Linux and does nothing on  other  operating  sys‐
+              tems.
        --socket-flags flags...
+              Apply the given flags to the  OpenVPN  transport  socket.   Cur‐
+              rently, only TCP_NODELAY is supported.
+              The  TCP_NODELAY  socket  flag is useful in TCP mode, and causes
+              the kernel to send tunnel packets immediately over the TCP  con‐
+              nection  without  trying to group several smaller packets into a
+              larger packet.  This can result in a considerably improvement in
+              latency.
+              This  option  is  pushable  from server to client, and should be
+              used on both client and server for maximum effect.
+              Apply  the given flags to the OpenVPN transport socket.  Currently,
+              only TCP_NODELAY is supported.
+              The TCP_NODELAY socket flag is useful in TCP mode, and  causes  the
+              kernel  to  send tunnel packets immediately over the TCP connection
+              without trying to group  several  smaller  packets  into  a  larger
+              packet.  This can result in a considerably improvement in latency.
+              This  option  is pushable from server to client, and should be used
+              on both client and server for maximum effect.
        --txqueuelen n
               (Linux only) Set the TX queue length on the  TUN/TAP  interface.
+              (Linux only) Set the TX queue  length  on  the  TUN/TAP  interface.
               Currently defaults to 100.
        --shaper n
               Limit bandwidth of outgoing tunnel data to n bytes per second on
               the TCP/UDP port.  If you want to limit the  bandwidth  in  both
+              Limit  bandwidth  of  outgoing tunnel data to n bytes per second on
+              the TCP/UDP port.  If you want  to  limit  the  bandwidth  in  both
               directions, use this option on both peers.
+              OpenVPN  uses the following algorithm to implement traffic shap‐
+              ing: Given a shaper rate of n bytes per second, after a datagram
+              write  of  b bytes is queued on the TCP/UDP port, wait a minimum
+              of (b / n) seconds before queuing the next write.
+              It should  be  noted  that  OpenVPN  supports  multiple  tunnels
+              between the same two peers, allowing you to construct full-speed
+              and reduced bandwidth tunnels at the same time, routing low-pri‐
+              ority  data  such as off-site backups over the reduced bandwidth
+              tunnel, and other data over the full-speed tunnel.
+              Also note that for low bandwidth tunnels (under 1000  bytes  per
+              second),  you  should probably use lower MTU values as well (see
+              above), otherwise the packet latency will grow so  large  as  to
+              trigger  timeouts  in  the TLS layer and TCP connections running
+              over the tunnel.
+              OpenVPN  uses the following algorithm to implement traffic shaping:
+              Given a shaper rate of n bytes per second, after a  datagram  write
+              of b bytes is queued on the TCP/UDP port, wait a minimum of (b / n)
+              seconds before queuing the next write.
+              It should be noted that OpenVPN supports multiple  tunnels  between
+              the  same  two  peers,  allowing  you  to  construct full-speed and
+              reduced bandwidth tunnels at the same  time,  routing  low-priority
+              data  such  as  off-site backups over the reduced bandwidth tunnel,
+              and other data over the full-speed tunnel.
+              Also note that for low bandwidth tunnels (under 1000 bytes per sec‐
+              ond), you should probably use lower MTU values as well (see above),
+              otherwise the packet latency will grow so large as to trigger time‐
+              outs in the TLS layer and TCP connections running over the tunnel.
               OpenVPN allows n to be between 100 bytes/sec and 100 Mbytes/sec.
        --inactive n [bytes]
+              Causes OpenVPN to exit after n  seconds  of  inactivity  on  the
+              TUN/TAP  device. The time length of inactivity is measured since
+              the last incoming or outgoing tunnel packet.  The default  value
+              is 0 seconds, which disables this feature.
+              If  the  optional bytes parameter is included, exit if less than
+              bytes of combined in/out traffic are  produced  on  the  tun/tap
+              device in n seconds.
+              In  any  case,  OpenVPN's  internal ping packets (which are just
+              keepalives) and TLS control packets are not  considered  "activ‐
+              ity",  nor  are they counted as traffic, as they are used inter‐
+              nally by OpenVPN and are not an indication of actual user activ‐
+              ity.
+              Causes OpenVPN to exit after n seconds of inactivity on the TUN/TAP
+              device. The time length of inactivity is measured  since  the  last
+              incoming  or  outgoing  tunnel packet.  The default value is 0 sec‐
+              onds, which disables this feature.
+              If the optional bytes parameter is  included,  exit  if  less  than
+              bytes of combined in/out traffic are produced on the tun/tap device
+              in n seconds.
+              In any case,  OpenVPN's  internal  ping  packets  (which  are  just
+              keepalives)  and TLS control packets are not considered "activity",
+              nor are they counted as traffic, as they  are  used  internally  by
+              OpenVPN and are not an indication of actual user activity.
        --ping n
               Ping  remote over the TCP/UDP control channel if no packets have
               been sent for at least n seconds (specify --ping on  both  peers
               to  cause ping packets to be sent in both directions since Open‐
               VPN ping packets are not echoed like  IP  ping  packets).   When
               used  in  one  of OpenVPN's secure modes (where --secret, --tls-
               server, or --tls-client is specified), the ping packet  will  be
               cryptographically secure.
+              Ping  remote  over  the  TCP/UDP control channel if no packets have
+              been sent for at least n seconds (specify --ping on both  peers  to
+              cause ping packets to be sent in both directions since OpenVPN ping
+              packets are not echoed like IP ping packets).  When used in one  of
+              OpenVPN's  secure  modes  (where  --secret, --tls-server, or --tls-
+              client is specified), the ping  packet  will  be  cryptographically
+              secure.
               This option has two intended uses:
               (1)  Compatibility  with  stateful firewalls.  The periodic ping
               will ensure that a stateful firewall rule which  allows  OpenVPN
               UDP packets to pass will not time out.
               (2)  To  provide a basis for the remote to test the existence of
               its peer using the --ping-exit option.
+              (1)  Compatibility with stateful firewalls.  The periodic ping will
+              ensure that a stateful firewall rule which allows OpenVPN UDP pack‐
+              ets to pass will not time out.
+              (2)  To provide a basis for the remote to test the existence of its
+              peer using the --ping-exit option.
        --ping-exit n
               Causes OpenVPN to exit after n seconds pass without reception of
               a ping or other packet from remote.  This option can be combined
               with --inactive, --ping, and --ping-exit to create a  two-tiered
               inactivity disconnect.
+              Causes OpenVPN to exit after n seconds pass without reception of  a
+              ping or other packet from remote.  This option can be combined with
+              --inactive, --ping, and --ping-exit to create a two-tiered inactiv‐
+              ity disconnect.
               For example,
 …
               openvpn [options...] --inactive 3600 --ping 10 --ping-exit 60
               when  used  on  both  peers will cause OpenVPN to exit within 60
               seconds if its peer disconnects, but will exit after one hour if
               no actual tunnel data is exchanged.
+              when  used  on both peers will cause OpenVPN to exit within 60 sec‐
+              onds if its peer disconnects, but will exit after one  hour  if  no
+              actual tunnel data is exchanged.
        --ping-restart n
+              Similar  to  --ping-exit,  but trigger a SIGUSR1 restart after n
+              seconds pass without reception of a ping or  other  packet  from
+              remote.
+              This  option  is  useful  in  cases  where the remote peer has a
+              dynamic IP address and a low-TTL DNS name is used to  track  the
+              IP  address  using  a  service  such  as  http://dyndns.org/ + a
+              dynamic DNS client such as ddclient.
+              If the peer cannot be reached,  a  restart  will  be  triggered,
+              causing  the  hostname  used with --remote to be re-resolved (if
+              --resolv-retry is also specified).
+              In server mode, --ping-restart, --inactive, or any other type of
+              internally generated signal will always be applied to individual
+              client instance objects, never to  whole  server  itself.   Note
+              also  in  server mode that any internally generated signal which
+              would normally cause a restart, will cause the deletion  of  the
+              client instance object instead.
+              In  client mode, the --ping-restart parameter is set to 120 sec‐
+              onds by default.  This default will hold until the client  pulls
+              a  replacement  value  from the server, based on the --keepalive
+              setting in the server configuration.  To disable the 120  second
+              default, set --ping-restart 0 on the client.
+              Similar  to --ping-exit, but trigger a SIGUSR1 restart after n sec‐
+              onds pass without reception of a ping or other packet from remote.
+              This option is useful in cases where the remote peer has a  dynamic
+              IP  address  and a low-TTL DNS name is used to track the IP address
+              using a service such as http://dyndns.org/ + a dynamic  DNS  client
+              such as ddclient.
+              If the peer cannot be reached, a restart will be triggered, causing
+              the hostname used with --remote to  be  re-resolved  (if  --resolv-
+              retry is also specified).
+              In  server  mode,  --ping-restart, --inactive, or any other type of
+              internally generated signal will always be  applied  to  individual
+              client  instance  objects, never to whole server itself.  Note also
+              in server mode that any internally  generated  signal  which  would
+              normally  cause  a  restart,  will cause the deletion of the client
+              instance object instead.
+              In client mode, the --ping-restart parameter is set to 120  seconds
+              by  default.   This  default  will  hold  until  the client pulls a
+              replacement value from the server, based on the --keepalive setting
+              in  the  server  configuration.  To disable the 120 second default,
+              set --ping-restart 0 on the client.
               See the signals section below for more information on SIGUSR1.
               Note  that the behavior of SIGUSR1 can be modified by the --per‐
               sist-tun,  --persist-key,  --persist-local-ip,  and   --persist-
               remote-ip options.
               Also  note  that  --ping-exit  and  --ping-restart  are mutually
               exclusive and cannot be used together.
+              Note that the behavior of SIGUSR1 can be modified by the --persist-
+              tun,  --persist-key,  --persist-local-ip,  and  --persist-remote-ip
+              options.
+              Also note that --ping-exit and --ping-restart are  mutually  exclu‐
+              sive and cannot be used together.
        --keepalive n m
               A helper directive designed to simplify the expression of --ping
+              A  helper  directive  designed to simplify the expression of --ping
               and --ping-restart in server mode configurations.
               The  server  timeout  is set twice the value of the second argu‐
               ment.  This ensures that a timeout is dectected on  client  side
               before the server side drops the connection.
+              The server timeout is set twice the value of the  second  argument.
+              This  ensures that a timeout is dectected on client side before the
+              server side drops the connection.
               For example, --keepalive 10 60 expands as follows:
 …
        --ping-timer-rem
+              Run  the  --ping-exit  /  --ping-restart timer only if we have a
+              remote address.  Use this option if you are starting the  daemon
+              in listen mode (i.e. without an explicit --remote peer), and you
+              don't want to start clocking timeouts until a remote  peer  con‐
+              nects.
+              Run the --ping-exit / --ping-restart timer only if we have a remote
+              address.   Use this option if you are starting the daemon in listen
+              mode (i.e. without an explicit --remote peer), and you  don't  want
+              to start clocking timeouts until a remote peer connects.
        --persist-tun
               Don't  close  and  reopen  TUN/TAP device or run up/down scripts
               across SIGUSR1 or --ping-restart restarts.
               SIGUSR1 is a restart signal similar to SIGHUP, but which  offers
+              Don't close and reopen TUN/TAP device or run up/down scripts across
+              SIGUSR1 or --ping-restart restarts.
+              SIGUSR1 is a restart signal similar to  SIGHUP,  but  which  offers
               finer-grained control over reset options.
 …
               Don't re-read key files across SIGUSR1 or --ping-restart.
               This option can be combined with --user nobody to allow restarts
               triggered by the SIGUSR1 signal.   Normally  if  you  drop  root
               privileges  in  OpenVPN, the daemon cannot be restarted since it
               will now be unable to re-read protected key files.
               This option solves the problem by persisting keys across SIGUSR1
+              This  option  can  be combined with --user nobody to allow restarts
+              triggered by the SIGUSR1 signal.  Normally if you drop root  privi‐
+              leges  in OpenVPN, the daemon cannot be restarted since it will now
+              be unable to re-read protected key files.
+              This option solves the problem by persisting  keys  across  SIGUSR1
               resets, so they don't need to be re-read.
        --persist-local-ip
               Preserve  initially  resolved  local  IP address and port number
               across SIGUSR1 or --ping-restart restarts.
+              Preserve initially resolved local IP address and port number across
+              SIGUSR1 or --ping-restart restarts.
        --persist-remote-ip
               Preserve most recently authenticated remote IP address and  port
+              Preserve most recently authenticated remote  IP  address  and  port
               number across SIGUSR1 or --ping-restart restarts.
        --mlock
               Disable paging by calling the POSIX mlockall function.  Requires
               that OpenVPN be initially run as root (though OpenVPN can subse‐
+              Disable  paging  by  calling the POSIX mlockall function.  Requires
+              that OpenVPN be initially run as root (though  OpenVPN  can  subse‐
               quently downgrade its UID using the --user option).
+              Using  this option ensures that key material and tunnel data are
+              never written to disk due to virtual  memory  paging  operations
+              which  occur  under  most  modern operating systems.  It ensures
+              that even if an attacker was able to crack the box running Open‐
+              VPN,  he  would  not  be  able  to  scan the system swap file to
+              recover previously used ephemeral keys, which  are  used  for  a
+              period of time governed by the --reneg options (see below), then
+              are discarded.
+              The downside of using --mlock is that it will reduce the  amount
+              of physical memory available to other applications.
+              Using  this  option  ensures  that key material and tunnel data are
+              never written to disk due to virtual memory paging operations which
+              occur under most modern operating systems.  It ensures that even if
+              an attacker was able to crack the box running OpenVPN, he would not
+              be  able  to  scan  the system swap file to recover previously used
+              ephemeral keys, which are used for a period of time governed by the
+              --reneg options (see below), then are discarded.
+              The  downside of using --mlock is that it will reduce the amount of
+              physical memory available to other applications.
        --up cmd
               Run command cmd after successful TUN/TAP device open (pre --user
+              Run command cmd after successful TUN/TAP device  open  (pre  --user
               UID change).
               cmd consists of  a  path  to  script  (or  executable  program),
               optionally  followed by arguments. The path and arguments may be
               single- or double-quoted and/or escaped using a  backslash,  and
               should be separated by one or more spaces.
               The  up  command  is  useful for specifying route commands which
               route IP traffic destined for private subnets which exist at the
               other end of the VPN connection into the tunnel.
+              cmd  consists  of a path to script (or executable program), option‐
+              ally followed by arguments. The path and arguments may  be  single-
+              or  double-quoted  and/or  escaped using a backslash, and should be
+              separated by one or more spaces.
+              The up command is useful for specifying route commands which  route
+              IP  traffic  destined  for private subnets which exist at the other
+              end of the VPN connection into the tunnel.
               For --dev tun execute as:
               cmd    tun_dev   tun_mtu   link_mtu   ifconfig_local_ip   ifcon‐
               fig_remote_ip [ init | restart ]
+              cmd tun_dev tun_mtu link_mtu ifconfig_local_ip ifconfig_remote_ip [
+              init | restart ]
               For --dev tap execute as:
               cmd tap_dev tap_mtu link_mtu ifconfig_local_ip  ifconfig_netmask
               [ init | restart ]
               See  the  "Environmental Variables" section below for additional
+              cmd  tap_dev  tap_mtu link_mtu ifconfig_local_ip ifconfig_netmask [
+              init | restart ]
+              See the "Environmental  Variables"  section  below  for  additional
               parameters passed as environmental variables.
               Note that if cmd includes arguments, all OpenVPN-generated argu‐
               ments  will  be  appended to them to build an argument list with
               which the executable will be called.
+              Note  that  if  cmd includes arguments, all OpenVPN-generated argu‐
+              ments will be appended to them to build an argument list with which
+              the executable will be called.
               Typically, cmd will run a script to add routes to the tunnel.
+              Normally the up script is called after  the  TUN/TAP  device  is
+              opened.  In this context, the last command line parameter passed
+              to the script will be init.  If the --up-restart option is  also
+              used,  the  up  script  will  be called for restarts as well.  A
+              restart is considered to be a partial reinitialization of  Open‐
+              VPN  where  the TUN/TAP instance is preserved (the --persist-tun
+              option will enable such preservation).  A restart can be  gener‐
+              ated by a SIGUSR1 signal, a --ping-restart timeout, or a connec‐
+              tion reset when the TCP protocol is  enabled  with  the  --proto
+              option.   If  a restart occurs, and --up-restart has been speci‐
+              fied, the up script will be called  with  restart  as  the  last
+              parameter.
+              The  following  standalone example shows how the --up script can
+              be called in both an initialization and restart context.  (NOTE:
+              for security reasons, don't run the following example unless UDP
+              port 9999 is blocked by your firewall.  Also, the  example  will
+              run indefinitely, so you should abort with control-c).
+              openvpn  --dev  tun  --port 9999 --verb 4 --ping-restart 10 --up
+              'echo up' --down 'echo down' --persist-tun --up-restart
+              Note that OpenVPN also provides the --ifconfig option  to  auto‐
+              matically  ifconfig  the  TUN  device,  eliminating  the need to
+              define an --up script, unless you also want to configure  routes
+              in the --up script.
+              If  --ifconfig is also specified, OpenVPN will pass the ifconfig
+              local and remote endpoints on  the  command  line  to  the  --up
+              script so that they can be used to configure routes such as:
+              Normally  the  up  script  is  called  after  the TUN/TAP device is
+              opened.  In this context, the last command line parameter passed to
+              the  script will be init.  If the --up-restart option is also used,
+              the up script will be called for restarts as well.   A  restart  is
+              considered  to  be  a partial reinitialization of OpenVPN where the
+              TUN/TAP instance is preserved (the --persist-tun option will enable
+              such  preservation).   A restart can be generated by a SIGUSR1 sig‐
+              nal, a --ping-restart timeout, or a connection reset when  the  TCP
+              protocol  is enabled with the --proto option.  If a restart occurs,
+              and --up-restart has been specified, the up script will  be  called
+              with restart as the last parameter.
+              The  following  standalone example shows how the --up script can be
+              called in both an initialization and restart context.   (NOTE:  for
+              security  reasons,  don't run the following example unless UDP port
+is blocked by your  firewall.   Also,  the  example  will  run
+              indefinitely, so you should abort with control-c).
+              openvpn --dev tun --port 9999 --verb 4 --ping-restart 10 --up 'echo
+              up' --down 'echo down' --persist-tun --up-restart
+              Note that OpenVPN also provides the --ifconfig option to  automati‐
+              cally  ifconfig  the  TUN device, eliminating the need to define an
+              --up script, unless you also want to configure routes in  the  --up
+              script.
+              If  --ifconfig  is  also  specified, OpenVPN will pass the ifconfig
+              local and remote endpoints on the command line to the  --up  script
+              so that they can be used to configure routes such as:
               route add -net 10.0.0.0 netmask 255.255.255.0 gw $5
        --up-delay
+              Delay  TUN/TAP  open  and  possible  --up script execution until
+              after TCP/UDP connection establishment with peer.
+              In --proto udp mode, this option normally requires  the  use  of
+              --ping  to  allow  connection  initiation  to  be  sensed in the
+              absence of tunnel data, since UDP is a  "connectionless"  proto‐
+              col.
+              On  Windows,  this  option  will delay the TAP-Win32 media state
+              transitioning to  "connected"  until  connection  establishment,
+              i.e.  the  receipt  of  the  first authenticated packet from the
+              peer.
+              Delay  TUN/TAP  open and possible --up script execution until after
+              TCP/UDP connection establishment with peer.
+              In --proto udp mode, this  option  normally  requires  the  use  of
+              --ping  to  allow connection initiation to be sensed in the absence
+              of tunnel data, since UDP is a "connectionless" protocol.
+              On Windows, this option will delay the TAP-Win32 media state  tran‐
+              sitioning  to  "connected" until connection establishment, i.e. the
+              receipt of the first authenticated packet from the peer.
        --down cmd
+              Run command cmd after TUN/TAP  device  close  (post  --user  UID
+              change  and/or --chroot ).  cmd consists of a path to script (or
+              executable program), optionally followed by arguments. The  path
+              and  arguments  may  be  single- or double-quoted and/or escaped
+              using a backslash, and should be separated by one or  more  spa‐
+              ces.
+              Called  with  the same parameters and environmental variables as
+              the --up option above.
+              Note that if  you  reduce  privileges  by  using  --user  and/or
+              --group, your --down script will also run at reduced privilege.
+              Run command cmd after TUN/TAP device close (post --user UID  change
+              and/or --chroot ).  cmd consists of a path to script (or executable
+              program), optionally followed by arguments. The path and  arguments
+              may  be  single- or double-quoted and/or escaped using a backslash,
+              and should be separated by one or more spaces.
+              Called with the same parameters and environmental variables as  the
+              --up option above.
+              Note  that if you reduce privileges by using --user and/or --group,
+              your --down script will also run at reduced privilege.
        --down-pre
 …
        --up-restart
               Enable  the --up and --down scripts to be called for restarts as
               well as initial program start.  This option  is  described  more
               fully above in the --up option documentation.
+              Enable the --up and --down scripts to be  called  for  restarts  as
+              well as initial program start.  This option is described more fully
+              above in the --up option documentation.
        --setenv name value
+              Set  a  custom  environmental  variable  name=value  to  pass to
+              Set a custom environmental variable name=value to pass to script.
+       --setenv FORWARD_COMPATIBLE 1
+              Relax config file syntax checking so that unknown  directives  will
+              trigger  a  warning but not a fatal error, on the assumption that a
+              given unknown directive might be valid in future OpenVPN versions.
+              This option should be used with caution, as there are good security
+              reasons  for having OpenVPN fail if it detects problems in a config
+              file.  Having said that, there are valid reasons  for  wanting  new
+              software  features  to gracefully degrade when encountered by older
+              software versions.
+       --setenv-safe name value
+              Set a custom environmental variable OPENVPN_name=value to  pass  to
               script.
+       --setenv FORWARD_COMPATIBLE 1
+              Relax config file syntax checking  so  that  unknown  directives
+              will  trigger a warning but not a fatal error, on the assumption
+              that a given unknown directive might be valid in future  OpenVPN
+              versions.
+              This option should be used with caution, as there are good secu‐
+              rity reasons for having OpenVPN fail if it detects problems in a
+              config  file.   Having  said  that,  there are valid reasons for
+              wanting new software features to gracefully degrade when encoun‐
+              tered by older software versions.
+       --setenv-safe name value
+              Set  a  custom environmental variable OPENVPN_name=value to pass
+              to script.
+              This directive is  designed  to  be  pushed  by  the  server  to
+              clients,  and  the prepending of "OPENVPN_" to the environmental
+              variable is a safety precaution to prevent  a  LD_PRELOAD  style
+              attack from a malicious or compromised server.
+              This  directive  is designed to be pushed by the server to clients,
+              and the prepending of "OPENVPN_" to the environmental variable is a
+              safety precaution to prevent a LD_PRELOAD style attack from a mali‐
+              cious or compromised server.
        --script-security level
               This  directive offers policy-level control over OpenVPN's usage
               of external programs and scripts.  Lower level values  are  more
               restrictive,  higher  values  are more permissive.  Settings for
+              This directive offers policy-level control over OpenVPN's usage  of
+              external  programs  and  scripts.   Lower  level  values  are  more
+              restrictive, higher  values  are  more  permissive.   Settings  for
               level:
 -- Strictly no calling of external programs.
 -- (Default) Only call built-in executables such as  ifconfig,
               ip, route, or netsh.
   --  Allow  calling  of  built-in executables and user-defined
+-- (Default) Only call built-in executables such as ifconfig, ip,
+              route, or netsh.
+  --  Allow  calling  of  built-in  executables  and  user-defined
               scripts.
 -- Allow passwords to be passed to scripts  via  environmental
+ --  Allow  passwords  to  be passed to scripts via environmental
               variables (potentially unsafe).
               OpenVPN  releases before v2.3 also supported a method flag which
               indicated how OpenVPN should call external commands and scripts.
               This could be either execve or system.  As of OpenVPN v2.3, this
               flag is no longer  accepted.   In  most  *nix  environments  the
               execve() approach has been used without any issues.
               To run scripts in Windows in earlier OpenVPN versions you needed
               to either add a full path to the script  interpreter  which  can
               parse  the  script  or use the system flag to run these scripts.
               As of OpenVPN v2.3 it is now a strict requirement to  have  full
               path  to  the  script  interpreter  when running non-executables
               files.  This is not needed for executable files, such  as  .exe,
               .com,  .bat  or  .cmd  files.  For example, if you have a Visual
               Basic script, you must use this syntax now:
+              OpenVPN releases before v2.3 also supported  a  method  flag  which
+              indicated  how  OpenVPN  should call external commands and scripts.
+              This could be either execve or system.  As of  OpenVPN  v2.3,  this
+              flag is no longer accepted.  In most *nix environments the execve()
+              approach has been used without any issues.
+              To run scripts in Windows in earlier OpenVPN versions you needed to
+              either  add  a  full path to the script interpreter which can parse
+              the script or use the system flag to  run  these  scripts.   As  of
+              OpenVPN  v2.3  it  is now a strict requirement to have full path to
+              the script interpreter when running non-executables files.  This is
+              not  needed  for executable files, such as .exe, .com, .bat or .cmd
+              files.  For example, if you have a Visual Basic  script,  you  must
+              use this syntax now:
                   --up 'C:\\Windows\\System32\\wscript.exe C:\\Program\ Files\\OpenVPN\\config\\my-up-script.vbs'
               Please note the single quote marks and the escaping of the back‐
+              Please  note  the  single quote marks and the escaping of the back‐
               slashes (\) and the space character.
               The reason the support for the system flag was removed is due to
               the security implications with shell expansions  when  executing
+              The reason the support for the system flag was removed  is  due  to
+              the  security  implications  with  shell  expansions when executing
               scripts via the system() call.
        --disable-occ
               Don't  output  a  warning  message if option inconsistencies are
               detected between peers.  An example of an  option  inconsistency
               would be where one peer uses --dev tun while the other peer uses
+              Don't output  a  warning  message  if  option  inconsistencies  are
+              detected  between  peers.   An  example  of an option inconsistency
+              would be where one peer uses --dev tun while the  other  peer  uses
               --dev tap.
               Use of this option is discouraged, but is provided as  a  tempo‐
               rary  fix  in  situations where a recent version of OpenVPN must
               connect to an old version.
+              Use  of  this option is discouraged, but is provided as a temporary
+              fix in situations where a recent version of OpenVPN must connect to
+              an old version.
        --user user
+              Change the user ID of the OpenVPN process to user after initial‐
+              ization,  dropping  privileges  in  the process.  This option is
+              useful to protect the system in  the  event  that  some  hostile
+              party  was  able  to gain control of an OpenVPN session.  Though
+              OpenVPN's security features make this unlikely, it  is  provided
+              as a second line of defense.
+              By  setting  user  to nobody or somebody similarly unprivileged,
+              the hostile party would be limited in  what  damage  they  could
+              cause.   Of  course  once  you  take away privileges, you cannot
+              return them to an OpenVPN session.   This  means,  for  example,
+              that  if you want to reset an OpenVPN daemon with a SIGUSR1 sig‐
+              nal (for example in response to a DHCP reset), you  should  make
+              use of one or more of the --persist options to ensure that Open‐
+              VPN doesn't need to execute any privileged operations  in  order
+              to  restart (such as re-reading key files or running ifconfig on
+              the TUN device).
+              Change the user ID of the OpenVPN process to user after initializa‐
+              tion, dropping privileges in the process.  This option is useful to
+              protect the system in the event that some hostile party was able to
+              gain control of an OpenVPN session.  Though OpenVPN's security fea‐
+              tures  make  this  unlikely,  it  is  provided  as a second line of
+              defense.
+              By setting user to nobody or somebody similarly  unprivileged,  the
+              hostile party would be limited in what damage they could cause.  Of
+              course once you take away privileges, you cannot return them to  an
+              OpenVPN  session.   This  means,  for  example, that if you want to
+              reset an OpenVPN daemon with  a  SIGUSR1  signal  (for  example  in
+              response  to  a  DHCP reset), you should make use of one or more of
+              the --persist options to ensure that OpenVPN doesn't need  to  exe‐
+              cute  any  privileged  operations  in order to restart (such as re-
+              reading key files or running ifconfig on the TUN device).
        --group group
               Similar to the --user option, this option changes the  group  ID
               of the OpenVPN process to group after initialization.
+              Similar to the --user option, this option changes the group  ID  of
+              the OpenVPN process to group after initialization.
        --cd dir
               Change  directory to dir prior to reading any files such as con‐
               figuration files, key files, scripts, etc.   dir  should  be  an
               absolute path, with a leading "/", and without any references to
               the current directory such as "." or "..".
               This option is useful when you are running OpenVPN  in  --daemon
               mode,  and  you  want to consolidate all of your OpenVPN control
               files in one location.
+              Change directory to dir prior to reading any files such as configu‐
+              ration files, key files, scripts, etc.  dir should be  an  absolute
+              path, with a leading "/", and without any references to the current
+              directory such as "." or "..".
+              This option is useful when you  are  running  OpenVPN  in  --daemon
+              mode, and you want to consolidate all of your OpenVPN control files
+              in one location.
        --chroot dir
               Chroot to dir after initialization.  --chroot essentially  rede‐
               fines  dir  as  being the top level directory tree (/).  OpenVPN
               will therefore be unable to access any files outside this  tree.
               This can be desirable from a security standpoint.
               Since  the  chroot  operation is delayed until after initializa‐
               tion, most OpenVPN options that reference files will operate  in
               a pre-chroot context.
               In  many  cases,  the dir parameter can point to an empty direc‐
               tory, however complications can result when scripts or  restarts
               are executed after the chroot operation.
+              Chroot to dir after initialization.  --chroot essentially redefines
+              dir as being the top level directory tree (/).  OpenVPN will there‐
+              fore be unable to access any files outside this tree.  This can  be
+              desirable from a security standpoint.
+              Since  the  chroot operation is delayed until after initialization,
+              most OpenVPN options that reference files will operate  in  a  pre-
+              chroot context.
+              In  many  cases, the dir parameter can point to an empty directory,
+              however complications can result when scripts or restarts are  exe‐
+              cuted after the chroot operation.
        --setcon context
+              Apply  SELinux  context  after  initialization. This essentially
+              provides the ability to restrict OpenVPN's rights to  only  net‐
+              work  I/O  operations, thanks to SELinux. This goes further than
+              --user and --chroot in that those two, while being  great  secu‐
+              rity  features,  unfortunately  do not protect against privilege
+              escalation by exploitation of a vulnerable system call. You  can
+              of  course  combine all three, but please note that since setcon
+              requires access to /proc you will have to provide it inside  the
+              chroot directory (e.g. with mount --bind).
+              Since  the  setcon  operation is delayed until after initializa‐
+              tion, OpenVPN can be restricted to just  network-related  system
+              calls,  whereas  by applying the context before startup (such as
+              the OpenVPN one provided in the SELinux Reference Policies)  you
+              will  have to allow many things required only during initializa‐
+              tion.
+              Like with chroot,  complications  can  result  when  scripts  or
+              restarts  are  executed after the setcon operation, which is why
+              you should really consider using the  --persist-key  and  --per‐
+              sist-tun options.
+              Apply  SELinux  context after initialization. This essentially pro‐
+              vides the ability to restrict OpenVPN's rights to only network  I/O
+              operations,  thanks  to  SELinux. This goes further than --user and
+              --chroot in that those two, while being  great  security  features,
+              unfortunately  do  not  protect  against  privilege  escalation  by
+              exploitation of a vulnerable system call. You can of course combine
+              all  three,  but  please  note that since setcon requires access to
+              /proc you will have to provide it inside the chroot directory (e.g.
+              with mount --bind).
+              Since  the  setcon operation is delayed until after initialization,
+              OpenVPN can be restricted to  just  network-related  system  calls,
+              whereas by applying the context before startup (such as the OpenVPN
+              one provided in the SELinux Reference Policies) you  will  have  to
+              allow many things required only during initialization.
+              Like with chroot, complications can result when scripts or restarts
+              are executed after the setcon operation, which is  why  you  should
+              really consider using the --persist-key and --persist-tun options.
        --daemon [progname]
+              Become  a  daemon  after  all  initialization functions are com‐
+              pleted.  This option will cause all message and error output  to
+              be  sent  to the syslog file (such as /var/log/messages), except
+              for the output of scripts and ifconfig commands, which  will  go
+              to  /dev/null unless otherwise redirected.  The syslog redirect‐
+              ion occurs immediately at the point that --daemon is  parsed  on
+              the  command  line  even  though  the daemonization point occurs
+              later.  If  one  of  the  --log  options  is  present,  it  will
+              supercede syslog redirection.
+              The optional progname parameter will cause OpenVPN to report its
+              program name to the system logger as progname.  This can be use‐
+              ful in linking OpenVPN messages in the syslog file with specific
+              tunnels.  When unspecified, progname defaults to "openvpn".
+              When OpenVPN is run with the --daemon option,  it  will  try  to
+              delay  daemonization  until the majority of initialization func‐
+              tions which are capable of generating fatal errors are complete.
+              This  means that initialization scripts can test the return sta‐
+              tus of the openvpn command for a fairly reliable  indication  of
+              whether  the  command  has correctly initialized and entered the
+              packet forwarding event loop.
+              In OpenVPN, the vast majority of errors which occur  after  ini‐
+              tialization are non-fatal.
+              Become  a  daemon after all initialization functions are completed.
+              This option will cause all message and error output to be  sent  to
+              the  syslog file (such as /var/log/messages), except for the output
+              of scripts and ifconfig commands, which will go to /dev/null unless
+              otherwise redirected.  The syslog redirection occurs immediately at
+              the point that --daemon is parsed on the command line  even  though
+              the  daemonization point occurs later.  If one of the --log options
+              is present, it will supercede syslog redirection.
+              The optional progname parameter will cause OpenVPN  to  report  its
+              program  name to the system logger as progname.  This can be useful
+              in linking OpenVPN messages in the syslog file with  specific  tun‐
+              nels.  When unspecified, progname defaults to "openvpn".
+              When  OpenVPN is run with the --daemon option, it will try to delay
+              daemonization until the majority of initialization functions  which
+              are  capable  of  generating fatal errors are complete.  This means
+              that initialization scripts can test the return status of the open‐
+              vpn command for a fairly reliable indication of whether the command
+              has correctly initialized and entered the packet  forwarding  event
+              loop.
+              In  OpenVPN, the vast majority of errors which occur after initial‐
+              ization are non-fatal.
        --syslog [progname]
+              Direct  log output to system logger, but do not become a daemon.
+              See --daemon directive above for description of progname parame‐
+              ter.
+              Direct log output to system logger, but do  not  become  a  daemon.
+              See --daemon directive above for description of progname parameter.
        --errors-to-stderr
               Output  errors  to stderr instead of stdout unless log output is
+              Output  errors  to  stderr  instead  of stdout unless log output is
               redirected by one of the --log options.
        --passtos
               Set the TOS field of the tunnel packet to what the payload's TOS
+              Set the TOS field of the tunnel packet to what  the  payload's  TOS
               is.
        --inetd [wait|nowait] [progname]
               Use  this  option  when  OpenVPN  is being run from the inetd or
+              Use  this  option  when  OpenVPN  is  being  run  from the inetd or
               xinetd(8) server.
+              The wait/nowait option must  match  what  is  specified  in  the
+              inetd/xinetd config file.  The nowait mode can only be used with
+              --proto tcp-server.  The default is wait.  The nowait  mode  can
+              be  used  to  instantiate  the  OpenVPN  daemon as a classic TCP
+              server, where client connection requests are serviced on a  sin‐
+              gle  port  number.   For  additional information on this kind of
+              configuration,    see    the    OpenVPN    FAQ:     http://open‐
+              vpn.net/faq.html#oneport
+              This option precludes the use of --daemon, --local, or --remote.
+              Note that this option causes message and error output to be han‐
+              dled in the same way as the --daemon option.  The optional prog‐
+              name parameter is also handled exactly as in --daemon.
+              Also note that in wait mode, each OpenVPN tunnel requires a sep‐
+              arate  TCP/UDP  port  and a separate inetd or xinetd entry.  See
+              the OpenVPN 1.x HOWTO for  an  example  on  using  OpenVPN  with
+              xinetd: http://openvpn.net/1xhowto.html
+              The  wait/nowait  option  must  match  what  is  specified  in  the
+              inetd/xinetd  config  file.   The nowait mode can only be used with
+              --proto tcp-server.  The default is wait.  The nowait mode  can  be
+              used  to  instantiate  the  OpenVPN daemon as a classic TCP server,
+              where client connection requests are serviced on a single port num‐
+              ber.  For additional information on this kind of configuration, see
+              the OpenVPN FAQ: http://openvpn.net/faq.html#oneport
+              This option precludes the use of --daemon,  --local,  or  --remote.
+              Note that this option causes message and error output to be handled
+              in the same way as the  --daemon  option.   The  optional  progname
+              parameter is also handled exactly as in --daemon.
+              Also  note  that in wait mode, each OpenVPN tunnel requires a sepa‐
+              rate TCP/UDP port and a separate inetd or xinetd  entry.   See  the
+              OpenVPN  1.x  HOWTO  for  an  example on using OpenVPN with xinetd:
+              http://openvpn.net/1xhowto.html
        --log file
+              Output  logging  messages  to  file,  including  output  to std‐
+              out/stderr which  is  generated  by  called  scripts.   If  file
+              already  exists  it will be truncated.  This option takes effect
+              immediately when it is parsed  in  the  command  line  and  will
+              supercede  syslog  output  if --daemon or --inetd is also speci‐
+              fied.  This option is persistent over the entire  course  of  an
+              OpenVPN  instantiation and will not be reset by SIGHUP, SIGUSR1,
+              or --ping-restart.
+              Note that on Windows, when OpenVPN is started as a service, log‐
+              ging occurs by default without the need to specify this option.
+              Output logging messages to file, including output to  stdout/stderr
+              which  is  generated  by called scripts.  If file already exists it
+              will be truncated.  This option takes effect immediately when it is
+              parsed  in  the  command  line  and will supercede syslog output if
+              --daemon or --inetd is also specified.  This option  is  persistent
+              over  the entire course of an OpenVPN instantiation and will not be
+              reset by SIGHUP, SIGUSR1, or --ping-restart.
+              Note that on Windows, when OpenVPN is started as a service, logging
+              occurs by default without the need to specify this option.
        --log-append file
               Append  logging  messages  to  file.  If file does not exist, it
               will be created.  This option behaves exactly like --log  except
               that it appends to rather than truncating the log file.
+              Append  logging  messages to file.  If file does not exist, it will
+              be created.  This option behaves exactly like --log except that  it
+              appends to rather than truncating the log file.
        --suppress-timestamps
               Avoid  writing timestamps to log messages, even when they other‐
               wise would be prepended. In particular, this applies to log mes‐
               sages sent to stdout.
+              Avoid  writing timestamps to log messages, even when they otherwise
+              would be prepended. In particular, this  applies  to  log  messages
+              sent to stdout.
        --writepid file
 …
        --nice n
               Change  process priority after initialization ( n greater than 0
               is lower priority, n less than zero is higher priority).
+              Change  process priority after initialization ( n greater than 0 is
+              lower priority, n less than zero is higher priority).
        --fast-io
               (Experimental) Optimize TUN/TAP/UDP I/O  writes  by  avoiding  a
               call  to  poll/epoll/select  prior  to the write operation.  The
               purpose of such a call would normally  be  to  block  until  the
               device or socket is ready to accept the write.  Such blocking is
               unnecessary on some platforms which don't support write blocking
               on UDP sockets or TUN/TAP devices.  In such cases, one can opti‐
               mize the event loop  by  avoiding  the  poll/epoll/select  call,
               improving CPU efficiency by 5% to 10%.
               This  option  can  only  be  used  on  non-Windows systems, when
               --proto udp is specified, and when --shaper is NOT specified.
+              (Experimental) Optimize TUN/TAP/UDP I/O writes by avoiding  a  call
+              to  poll/epoll/select prior to the write operation.  The purpose of
+              such a call would normally be to block until the device  or  socket
+              is ready to accept the write.  Such blocking is unnecessary on some
+              platforms which don't support write  blocking  on  UDP  sockets  or
+              TUN/TAP devices.  In such cases, one can optimize the event loop by
+              avoiding the poll/epoll/select call, improving CPU efficiency by 5%
+              to 10%.
+              This  option  can only be used on non-Windows systems, when --proto
+              udp is specified, and when --shaper is NOT specified.
        --multihome
+              Configure a multi-homed UDP server.  This  option  can  be  used
+              when  OpenVPN  has  been configured to listen on all interfaces,
+              and will attempt to bind client sessions  to  the  interface  on
+              which  packets are being received, so that outgoing packets will
+              be sent out of the same interface.  Note  that  this  option  is
+              only  relevant for UDP servers and currently is only implemented
+              on Linux.
+              Note: clients connecting to a --multihome server  should  always
+              use the --nobind option.
+              Configure a multi-homed UDP server.  This option can be  used  when
+              OpenVPN  has  been configured to listen on all interfaces, and will
+              attempt to bind client sessions to the interface on  which  packets
+              are  being  received,  so that outgoing packets will be sent out of
+              the same interface.  Note that this option is only relevant for UDP
+              servers and currently is only implemented on Linux.
+              Note:  clients connecting to a --multihome server should always use
+              the --nobind option.
        --echo [parms...]
               Echo parms to log output.
               Designed  to  be used to send messages to a controlling applica‐
               tion which is receiving the OpenVPN log output.
+              Designed to be used to send messages to a  controlling  application
+              which is receiving the OpenVPN log output.
        --remap-usr1 signal
               Control whether internally or externally generated SIGUSR1  sig‐
               nals  are  remapped to SIGHUP (restart without persisting state)
               or SIGTERM (exit).
               signal can be set to "SIGHUP"  or  "SIGTERM".   By  default,  no
               remapping occurs.
+              Control  whether internally or externally generated SIGUSR1 signals
+              are remapped  to  SIGHUP  (restart  without  persisting  state)  or
+              SIGTERM (exit).
+              signal  can be set to "SIGHUP" or "SIGTERM".  By default, no remap‐
+              ping occurs.
        --verb n
+              Set  output  verbosity  to  n (default=1).  Each level shows all
+              info from the previous levels.  Level 3 is  recommended  if  you
+              want a good summary of what's happening without being swamped by
+              output.
+              Set output verbosity to n (default=1).  Each level shows  all  info
+              from  the  previous  levels.   Level 3 is recommended if you want a
+              good summary of what's happening without being swamped by output.
 -- No output except fatal errors.
 to 4 -- Normal usage range.
 -- Output R and W characters to the console  for  each  packet
               read and write, uppercase is used for TCP/UDP packets and lower‐
               case is used for TUN/TAP packets.
 to 11 -- Debug  info  range  (see  errlevel.h  for  additional
               information on debug levels).
+-- Output R and W characters to the console for each packet  read
+              and  write,  uppercase is used for TCP/UDP packets and lowercase is
+              used for TUN/TAP packets.
+to 11 -- Debug info range (see errlevel.h for additional informa‐
+              tion on debug levels).
        --status file [n]
               Write operational status to file every n seconds.
               Status  can  also  be written to the syslog by sending a SIGUSR2
               signal.
+              Status  can also be written to the syslog by sending a SIGUSR2 sig‐
+              nal.
        --status-version [n]
               Choose the status file format version number.  Currently  n  can
               be 1, 2, or 3 and defaults to 1.
+              Choose the status file format version number.  Currently n  can  be
+, 2, or 3 and defaults to 1.
        --mute n
               Log  at  most n consecutive messages in the same category.  This
               is useful to limit repetitive logging of similar message types.
+              Log  at  most n consecutive messages in the same category.  This is
+              useful to limit repetitive logging of similar message types.
        --comp-lzo [mode]
               Use fast LZO compression -- may add up to 1 byte per packet  for
               incompressible  data.   mode  may  be "yes", "no", or "adaptive"
+              Use fast LZO compression -- may add up to 1  byte  per  packet  for
+              incompressible  data.   mode  may  be  "yes",  "no",  or "adaptive"
               (default).
               In a server mode setup, it is possible to selectively turn  com‐
               pression on or off for individual clients.
               First,  make  sure the client-side config file enables selective
               compression by having at least one --comp-lzo directive, such as
               --comp-lzo  no.   This will turn off compression by default, but
               allow a future directive push from  the  server  to  dynamically
               change the on/off/adaptive setting.
               Next in a --client-config-dir file, specify the compression set‐
               ting for the client, for example:
+              In a server mode setup, it is possible to selectively turn compres‐
+              sion on or off for individual clients.
+              First, make sure the client-side config file enables selective com‐
+              pression by having at  least  one  --comp-lzo  directive,  such  as
+              --comp-lzo  no.   This  will  turn  off compression by default, but
+              allow a future directive push from the server to dynamically change
+              the on/off/adaptive setting.
+              Next in a --client-config-dir file, specify the compression setting
+              for the client, for example:
                   comp-lzo yes
                   push "comp-lzo yes"
               The first line sets the comp-lzo setting for the server side  of
               the link, the second sets the client side.
+              The first line sets the comp-lzo setting for the server side of the
+              link, the second sets the client side.
        --comp-noadapt
               When  used in conjunction with --comp-lzo, this option will dis‐
               able OpenVPN's adaptive compression algorithm.  Normally,  adap‐
               tive compression is enabled with --comp-lzo.
               Adaptive  compression  tries to optimize the case where you have
               compression enabled, but you are  sending  predominantly  uncom‐
               pressible  (or  pre-compressed) packets over the tunnel, such as
               an FTP or rsync transfer of  a  large,  compressed  file.   With
               adaptive  compression, OpenVPN will periodically sample the com‐
               pression process to measure its efficiency.  If the  data  being
               sent  over  the  tunnel  is  already compressed, the compression
               efficiency will be very low, triggering openvpn to disable  com‐
               pression for a period of time until the next re-sample test.
+              When  used in conjunction with --comp-lzo, this option will disable
+              OpenVPN's adaptive compression algorithm.  Normally, adaptive  com‐
+              pression is enabled with --comp-lzo.
+              Adaptive compression tries to optimize the case where you have com‐
+              pression enabled, but you are sending predominantly  uncompressible
+              (or  pre-compressed)  packets  over  the  tunnel, such as an FTP or
+              rsync transfer of a large, compressed file.  With adaptive compres‐
+              sion,  OpenVPN  will periodically sample the compression process to
+              measure its efficiency.  If the data being sent over the tunnel  is
+              already  compressed,  the  compression efficiency will be very low,
+              triggering openvpn to disable compression  for  a  period  of  time
+              until the next re-sample test.
        --management IP port [pw-file]
               Enable a TCP server on IP:port to handle daemon management func‐
               tions.  pw-file, if specified, is a password file  (password  on
               first line) or "stdin" to prompt from standard input.  The pass‐
               word provided will set the password which TCP clients will  need
               to provide in order to access management functions.
               The  management  interface  can  also  listen  on  a unix domain
               socket, for those platforms that support  it.   To  use  a  unix
               domain  socket,  specify the unix socket pathname in place of IP
               and set port to 'unix'.  While the default behavior is to create
               a  unix  domain  socket that may be connected to by any process,
               the   --management-client-user   and   --management-client-group
               directives can be used to restrict access.
               The  management  interface provides a special mode where the TCP
               management link can operate over the tunnel itself.   To  enable
               this  mode,  set IP = "tunnel".  Tunnel mode will cause the man‐
               agement interface to listen for a TCP connection  on  the  local
               VPN address of the TUN/TAP interface.
               While  the  management port is designed for programmatic control
               of OpenVPN by other applications, it is possible  to  telnet  to
               the  port, using a telnet client in "raw" mode.  Once connected,
               type "help" for a list of commands.
               For detailed documentation on the management interface, see  the
               management-notes.txt  file in the management folder of the Open‐
               VPN source distribution.
               It is strongly recommended that IP be set to  127.0.0.1  (local‐
               host)  to  restrict  accessibility  of  the management server to
               local clients.
+              Enable  a  TCP  server on IP:port to handle daemon management func‐
+              tions.  pw-file, if specified, is  a  password  file  (password  on
+              first line) or "stdin" to prompt from standard input.  The password
+              provided will set the password which TCP clients will need to  pro‐
+              vide in order to access management functions.
+              The  management  interface can also listen on a unix domain socket,
+              for those platforms that support it.  To use a unix domain  socket,
+              specify  the  unix  socket  pathname in place of IP and set port to
+              'unix'.  While the default behavior is  to  create  a  unix  domain
+              socket  that  may be connected to by any process, the --management-
+              client-user and --management-client-group directives can be used to
+              restrict access.
+              The management interface provides a special mode where the TCP man‐
+              agement link can operate over the tunnel itself.   To  enable  this
+              mode,  set  IP  =  "tunnel".  Tunnel mode will cause the management
+              interface to listen for a TCP connection on the local  VPN  address
+              of the TUN/TAP interface.
+              While  the  management port is designed for programmatic control of
+              OpenVPN by other applications, it is  possible  to  telnet  to  the
+              port,  using  a  telnet client in "raw" mode.  Once connected, type
+              "help" for a list of commands.
+              For detailed documentation on the  management  interface,  see  the
+              management-notes.txt  file  in the management folder of the OpenVPN
+              source distribution.
+              It is strongly recommended that IP be set to 127.0.0.1  (localhost)
+              to  restrict  accessibility  of  the  management  server  to  local
+              clients.
        --management-client
               Management interface will connect as a TCP/unix domain client to
               IP:port  specified  by  --management rather than listen as a TCP
+              Management interface will connect as a TCP/unix  domain  client  to
+              IP:port  specified  by  --management  rather  than  listen as a TCP
               server or on a unix domain socket.
               If the client connection fails to connect or is disconnected,  a
+              If the client connection fails to connect  or  is  disconnected,  a
               SIGTERM signal will be generated causing OpenVPN to quit.
        --management-query-passwords
+              Query  management  channel  for private key password and --auth-
+              user-pass username/password.  Only query the management  channel
+              for  inputs  which  ordinarily  would have been queried from the
+              console.
+              Query  management channel for private key password and --auth-user-
+              pass username/password.  Only  query  the  management  channel  for
+              inputs which ordinarily would have been queried from the console.
        --management-query-proxy
               Query management channel for proxy server information for a spe‐
+              Query  management  channel  for proxy server information for a spe‐
               cific --remote (client-only).
        --management-query-remote
               Allow  management  interface  to  override  --remote  directives
               (client-only).   --management-external-key  Allows   usage   for
               external private key file instead of --key option (client-only).
+              Allow management interface to override --remote directives (client-
+              only).  --management-external-key Allows usage for external private
+              key file instead of --key option (client-only).
        --management-forget-disconnect
+              Make  OpenVPN  forget  passwords when management session discon‐
+              nects.
+              This directive does not affect the  --http-proxy  username/pass‐
+              word.  It is always cached.
+              Make OpenVPN forget passwords when management session disconnects.
+              This directive does not affect the --http-proxy  username/password.
+              It is always cached.
        --management-hold
+              Start OpenVPN in a hibernating state, until a client of the man‐
+              agement interface explicitly starts it  with  the  hold  release
+              command.
+              Start OpenVPN in a hibernating state, until a client of the manage‐
+              ment interface explicitly starts it with the hold release command.
        --management-signal
               Send  SIGUSR1  signal  to  OpenVPN if management session discon‐
               nects.  This is useful when you wish to  disconnect  an  OpenVPN
               session  on  user logoff. For --management-client this option is
               not needed since a disconnect will always generate a SIGTERM.
+              Send SIGUSR1 signal to OpenVPN if management  session  disconnects.
+              This  is  useful  when you wish to disconnect an OpenVPN session on
+              user logoff. For --management-client  this  option  is  not  needed
+              since a disconnect will always generate a SIGTERM.
        --management-log-cache n
               Cache the most recent n lines of log file history for  usage  by
               the management channel.
+              Cache  the most recent n lines of log file history for usage by the
+              management channel.
        --management-up-down
 …
        --management-client-auth
+              Gives  management interface client the responsibility to authen‐
+              ticate clients after their client certificate has been verified.
+              See  management-notes.txt  in  OpenVPN distribution for detailed
+              notes.
+              Gives management interface client the responsibility  to  authenti‐
+              cate clients after their client certificate has been verified.  See
+              management-notes.txt in OpenVPN distribution for detailed notes.
        --management-client-pf
               Management interface clients must specify a packet  filter  file
               for each connecting client.  See management-notes.txt in OpenVPN
               distribution for detailed notes.
+              Management interface clients must specify a packet filter file  for
+              each  connecting  client.  See management-notes.txt in OpenVPN dis‐
+              tribution for detailed notes.
        --management-client-user u
               When the management interface is  listening  on  a  unix  domain
               socket, only allow connections from user u.
+              When the management interface is listening on a unix domain socket,
+              only allow connections from user u.
        --management-client-group g
               When  the  management  interface  is  listening on a unix domain
               socket, only allow connections from group g.
+              When the management interface is listening on a unix domain socket,
+              only allow connections from group g.
        --plugin module-pathname [init-string]
+              Load plug-in module from the file module-pathname, passing init-
+              string  as  an  argument  to the module initialization function.
+              Multiple plugin modules may be loaded into one OpenVPN process.
+              For more information and examples on how to build OpenVPN  plug-
+              in  modules,  see  the  README  file in the plugin folder of the
+              OpenVPN source distribution.
+              If you are using an RPM install of OpenVPN, see /usr/share/open‐
+              vpn/plugin.   The  documentation is in doc and the actual plugin
+              modules are in lib.
+              Multiple plugin modules can be cascaded, and modules can be used
+              in  tandem  with scripts.  The modules will be called by OpenVPN
+              in the order that they are declared in the config file.  If both
+              a  plugin  and  script are configured for the same callback, the
+              script will be called last.  If the  return  code  of  the  mod‐
+              ule/script controls an authentication function (such as tls-ver‐
+              ify, auth-user-pass-verify, or client-connect), then every  mod‐
+              ule  and script must return success (0) in order for the connec‐
+              tion to be authenticated.
+              Load plug-in module from the file  module-pathname,  passing  init-
+              string  as an argument to the module initialization function.  Mul‐
+              tiple plugin modules may be loaded into one OpenVPN process.
+              For more information and examples on how to build  OpenVPN  plug-in
+              modules,  see  the  README file in the plugin folder of the OpenVPN
+              source distribution.
+              If you are using an RPM install of  OpenVPN,  see  /usr/share/open‐
+              vpn/plugin.  The documentation is in doc and the actual plugin mod‐
+              ules are in lib.
+              Multiple plugin modules can be cascaded, and modules can be used in
+              tandem  with scripts.  The modules will be called by OpenVPN in the
+              order that they are declared in the config file.  If both a  plugin
+              and script are configured for the same callback, the script will be
+              called last.  If the return code of the module/script  controls  an
+              authentication function (such as tls-verify, auth-user-pass-verify,
+              or client-connect), then every module and script must  return  suc‐
+              cess (0) in order for the connection to be authenticated.
    Server Mode
        Starting with OpenVPN 2.0, a multi-client TCP/UDP server mode  is  sup‐
        ported,  and  can  be enabled with the --mode server option.  In server
        mode, OpenVPN will listen on a single port for incoming client  connec‐
        tions.   All  client connections will be routed through a single tun or
        tap interface.  This mode is designed for  scalability  and  should  be
        able  to  support hundreds or even thousands of clients on sufficiently
        fast hardware.  SSL/TLS authentication must be used in this mode.
+       Starting  with  OpenVPN  2.0,  a  multi-client TCP/UDP server mode is sup‐
+       ported, and can be enabled with the --mode server option.  In server mode,
+       OpenVPN will listen on a single port for incoming client connections.  All
+       client connections will be routed through a single tun or  tap  interface.
+       This  mode  is designed for scalability and should be able to support hun‐
+       dreds or even thousands of clients on sufficiently fast hardware.  SSL/TLS
+       authentication must be used in this mode.
        --server network netmask
               A helper directive designed to  simplify  the  configuration  of
               OpenVPN's  server  mode.   This directive will set up an OpenVPN
               server which will allocate addresses to clients out of the given
               network/netmask.   The  server itself will take the ".1" address
               of the given network for use as the server-side endpoint of  the
               local TUN/TAP interface.
+              A  helper directive designed to simplify the configuration of Open‐
+              VPN's server mode.  This directive will set up  an  OpenVPN  server
+              which  will  allocate  addresses  to  clients out of the given net‐
+              work/netmask.  The server itself will take the ".1" address of  the
+              given  network  for  use  as  the server-side endpoint of the local
+              TUN/TAP interface.
               For example, --server 10.8.0.0 255.255.255.0 expands as follows:
 …
                      push "route-gateway 10.8.0.1"
               Don't  use --server if you are ethernet bridging.  Use --server-
+              Don't use --server if you are  ethernet  bridging.   Use  --server-
               bridge instead.
 …
        --server-bridge ['nogw']
+              A helper directive similar to --server which is designed to sim‐
+              plify  the  configuration  of  OpenVPN's server mode in ethernet
+              bridging configurations.
+              If --server-bridge is  used  without  any  parameters,  it  will
+              enable  a DHCP-proxy mode, where connecting OpenVPN clients will
+              receive an IP address for their TAP adapter from the DHCP server
+              running  on the OpenVPN server-side LAN.  Note that only clients
+              that support the binding of a DHCP client with the  TAP  adapter
+              (such as Windows) can support this mode.  The optional nogw flag
+              (advanced) indicates that  gateway  information  should  not  be
+              pushed to the client.
+              To  configure  ethernet  bridging,  you must first use your OS's
+              bridging capability to bridge the TAP interface with the  ether‐
+              net  NIC interface.  For example, on Linux this is done with the
+              brctl tool, and with Windows XP it is done in the  Network  Con‐
+              nections  Panel  by  selecting the ethernet and TAP adapters and
+              right-clicking on "Bridge Connections".
+              Next you you must manually set  the  IP/netmask  on  the  bridge
+              interface.   The  gateway  and  netmask  parameters to --server-
+              bridge can be set to either the IP/netmask of the bridge  inter‐
+              face,  or  the  IP/netmask  of the default gateway/router on the
+              bridged subnet.
+              Finally, set aside a IP range in the bridged subnet, denoted  by
+              pool-start-IP  and  pool-end-IP, for OpenVPN to allocate to con‐
+              necting clients.
+              For example,  server-bridge  10.8.0.4  255.255.255.0  10.8.0.128
+              A  helper  directive  similar to --server which is designed to sim‐
+              plify the configuration of OpenVPN's server mode in ethernet bridg‐
+              ing configurations.
+              If --server-bridge is used without any parameters, it will enable a
+              DHCP-proxy mode, where connecting OpenVPN clients will  receive  an
+              IP  address  for  their TAP adapter from the DHCP server running on
+              the OpenVPN server-side LAN.  Note that only clients  that  support
+              the binding of a DHCP client with the TAP adapter (such as Windows)
+              can support this mode.  The optional nogw flag (advanced) indicates
+              that gateway information should not be pushed to the client.
+              To configure ethernet bridging, you must first use your OS's bridg‐
+              ing capability to bridge the TAP interface with  the  ethernet  NIC
+              interface.  For example, on Linux this is done with the brctl tool,
+              and with Windows XP it is done in the Network Connections Panel  by
+              selecting  the  ethernet  and  TAP  adapters  and right-clicking on
+              "Bridge Connections".
+              Next you you must manually set the IP/netmask on the bridge  inter‐
+              face.  The gateway and netmask parameters to --server-bridge can be
+              set to either the  IP/netmask  of  the  bridge  interface,  or  the
+              IP/netmask of the default gateway/router on the bridged subnet.
+              Finally,  set  aside  a  IP range in the bridged subnet, denoted by
+              pool-start-IP and pool-end-IP, for OpenVPN to allocate to  connect‐
+              ing clients.
+              For   example,   server-bridge  10.8.0.4  255.255.255.0  10.8.0.128
 .8.0.254 expands as follows:
 …
                   push "route-gateway 10.8.0.4"
               In another example, --server-bridge (without parameters) expands
               as follows:
+              In another example, --server-bridge (without parameters) expands as
+              follows:
                   mode server
 …
        --push option
+              Push a config file option back to the client for  remote  execu‐
+              tion.   Note that option must be enclosed in double quotes ("").
+              The client must specify --pull in its config file.  The  set  of
+              options  which  can be pushed is limited by both feasibility and
+              security.  Some  options  such  as  those  which  would  execute
+              scripts are banned, since they would effectively allow a compro‐
+              mised server to execute arbitrary code  on  the  client.   Other
+              options  such  as TLS or MTU parameters cannot be pushed because
+              the client needs to know  them  before  the  connection  to  the
+              server can be initiated.
+              This is a partial list of options which can currently be pushed:
+              --route,  --route-gateway,  --route-delay,   --redirect-gateway,
+              --ip-win32,   --dhcp-option,  --inactive,  --ping,  --ping-exit,
+              --ping-restart, --setenv, --persist-key, --persist-tun,  --echo,
+              --comp-lzo, --socket-flags, --sndbuf, --rcvbuf
+              Push  a config file option back to the client for remote execution.
+              Note that option must be  enclosed  in  double  quotes  ("").   The
+              client  must specify --pull in its config file.  The set of options
+              which can be pushed is limited by both  feasibility  and  security.
+              Some  options such as those which would execute scripts are banned,
+              since they would effectively allow a compromised server to  execute
+              arbitrary  code  on  the  client.  Other options such as TLS or MTU
+              parameters cannot be pushed because the client needs to  know  them
+              before the connection to the server can be initiated.
+              This  is  a  partial list of options which can currently be pushed:
+              --route, --route-gateway, --route-delay, --redirect-gateway,  --ip-
+              win32,  --dhcp-option,  --inactive,  --ping,  --ping-exit,  --ping-
+              restart, --setenv, --persist-key,  --persist-tun,  --echo,  --comp-
+              lzo, --socket-flags, --sndbuf, --rcvbuf
        --push-reset
               Don't  inherit  the  global  push  list  for  a  specific client
               instance.  Specify this option in a client-specific context such
               as  with  a --client-config-dir configuration file.  This option
               will ignore --push options at the global config file level.
+              Don't  inherit the global push list for a specific client instance.
+              Specify this option in a client-specific context  such  as  with  a
+              --client-config-dir  configuration  file.   This option will ignore
+              --push options at the global config file level.
        --push-peer-info
               Push additional information about the  client  to  server.   The
               additional information consists of the following data:
+              Push additional information about the client to server.  The  addi‐
+              tional information consists of the following data:
               IV_VER=<version> -- the client OpenVPN version
               IV_PLAT=[linux|solaris|openbsd|mac|netbsd|freebsd|win]   --  the
+              IV_PLAT=[linux|solaris|openbsd|mac|netbsd|freebsd|win]    --    the
               client OS platform
               IV_HWADDR=<mac address> -- the MAC address  of  clients  default
               gateway
+              IV_HWADDR=<mac address> -- the MAC address of clients default gate‐
+              way
               IV_LZO_STUB=1 -- if client was built with LZO stub capability
               UV_<name>=<value>  --  client  environment variables whose names
               start with "UV_"
+              UV_<name>=<value> -- client environment variables whose names start
+              with "UV_"
        --disable
               Disable a particular client (based on the common name) from con‐
               necting.   Don't  use this option to disable a client due to key
               or password compromise.  Use a CRL (certificate revocation list)
+              Disable a particular client (based on the common  name)  from  con‐
+              necting.   Don't  use this option to disable a client due to key or
+              password compromise.   Use  a  CRL  (certificate  revocation  list)
               instead (see the --crl-verify option).
               This  option must be associated with a specific client instance,
               which means that  it  must  be  specified  either  in  a  client
               instance  config  file  using --client-config-dir or dynamically
               generated using a --client-connect script.
+              This  option  must  be  associated with a specific client instance,
+              which means that it must be specified either in a  client  instance
+              config  file  using  --client-config-dir  or  dynamically generated
+              using a --client-connect script.
        --ifconfig-pool start-IP end-IP [netmask]
               Set aside a pool of subnets to be dynamically allocated to  con‐
               necting  clients,  similar to a DHCP server.  For tun-style tun‐
               nels, each client will be given a /30 subnet (for interoperabil‐
               ity  with  Windows  clients).  For tap-style tunnels, individual
               addresses will be allocated, and the optional netmask  parameter
               will also be pushed to clients.
+              Set aside a pool of subnets to be dynamically allocated to connect‐
+              ing clients, similar to a DHCP server.  For tun-style tunnels, each
+              client will be given a /30 subnet (for interoperability  with  Win‐
+              dows clients).  For tap-style tunnels, individual addresses will be
+              allocated, and the optional netmask parameter will also  be  pushed
+              to clients.
        --ifconfig-pool-persist file [seconds]
               Persist/unpersist  ifconfig-pool data to file, at seconds inter‐
               vals (default=600), as well as on program startup and shutdown.
               The goal of this option is to provide  a  long-term  association
               between  clients  (denoted by their common name) and the virtual
               IP address assigned to them from the ifconfig-pool.  Maintaining
               a  long-term  association  is good for clients because it allows
               them to effectively use the --persist-tun option.
               file is a comma-delimited  ASCII  file,  formatted  as  <Common-
+              Persist/unpersist  ifconfig-pool data to file, at seconds intervals
+              (default=600), as well as on program startup and shutdown.
+              The goal of this option  is  to  provide  a  long-term  association
+              between  clients  (denoted by their common name) and the virtual IP
+              address assigned to them from  the  ifconfig-pool.   Maintaining  a
+              long-term association is good for clients because it allows them to
+              effectively use the --persist-tun option.
+              file  is  a  comma-delimited  ASCII  file,  formatted  as  <Common-
               Name>,<IP-address>.
               If seconds = 0, file will be treated as read-only.  This is use‐
               ful if you would like to treat file as a configuration file.
               Note that the entries in this file are  treated  by  OpenVPN  as
               suggestions  only,  based  on past associations between a common
               name and IP address.  They do not guarantee that the given  com‐
               mon  name will always receive the given IP address.  If you want
               guaranteed assignment, use --ifconfig-push
+              If  seconds = 0, file will be treated as read-only.  This is useful
+              if you would like to treat file as a configuration file.
+              Note that the entries in this file are treated by OpenVPN  as  sug‐
+              gestions only, based on past associations between a common name and
+              IP address.  They do not guarantee that the given common name  will
+              always  receive  the  given  IP  address.   If  you want guaranteed
+              assignment, use --ifconfig-push
        --ifconfig-pool-linear
               Modifies the --ifconfig-pool directive  to  allocate  individual
               TUN  interface  addresses  for  clients rather than /30 subnets.
               NOTE:  This option is incompatible with Windows clients.
               This option is deprecated, and should be replaced with  --topol‐
               ogy p2p which is functionally equivalent.
+              Modifies the --ifconfig-pool directive to allocate  individual  TUN
+              interface  addresses  for  clients  rather than /30 subnets.  NOTE:
+              This option is incompatible with Windows clients.
+              This option is deprecated, and should be replaced  with  --topology
+              p2p which is functionally equivalent.
        --ifconfig-push local remote-netmask [alias]
               Push  virtual  IP  endpoints  for  client tunnel, overriding the
+              Push  virtual  IP  endpoints  for  client  tunnel,  overriding  the
               --ifconfig-pool dynamic allocation.
+              The parameters local and remote-netmask are set according to the
+              --ifconfig  directive  which  you  want to execute on the client
+              machine to configure the remote end of the  tunnel.   Note  that
+              the parameters local and remote-netmask are from the perspective
+              of the client, not the server.  They may  be  DNS  names  rather
+              than  IP  addresses,  in which case they will be resolved on the
+              server at the time of client connection.
+              The optional alias parameter may be  used  in  cases  where  NAT
+              causes  the client view of its local endpoint to differ from the
+              server view.  In this case local/remote-netmask  will  refer  to
+              the  server  view  while  alias/remote-netmask will refer to the
+              client view.
+              This option must be associated with a specific client  instance,
+              which  means  that  it  must  be  specified  either  in a client
+              instance config file using  --client-config-dir  or  dynamically
+              generated using a --client-connect script.
+              Remember also to include a --route directive in the main OpenVPN
+              config file which encloses local, so that the kernel  will  know
+              to route it to the server's TUN/TAP interface.
+              OpenVPN's  internal  client IP address selection algorithm works
+              as follows:
+-- Use --client-connect script generated file  for  static  IP
+              The parameters local and remote-netmask are set  according  to  the
+              --ifconfig  directive  which  you  want  to  execute  on the client
+              machine to configure the remote end of the tunnel.  Note  that  the
+              parameters local and remote-netmask are from the perspective of the
+              client, not the server.  They may  be  DNS  names  rather  than  IP
+              addresses, in which case they will be resolved on the server at the
+              time of client connection.
+              The optional alias parameter may be used in cases where NAT  causes
+              the  client  view  of  its local endpoint to differ from the server
+              view.  In this case local/remote-netmask will refer to  the  server
+              view while alias/remote-netmask will refer to the client view.
+              This  option  must  be  associated with a specific client instance,
+              which means that it must be specified either in a  client  instance
+              config  file  using  --client-config-dir  or  dynamically generated
+              using a --client-connect script.
+              Remember also to include a --route directive in  the  main  OpenVPN
+              config  file  which encloses local, so that the kernel will know to
+              route it to the server's TUN/TAP interface.
+              OpenVPN's internal client IP address selection algorithm  works  as
+              follows:
+  --  Use  --client-connect  script  generated  file for static IP
               (first choice).
 -- Use --client-config-dir file for static IP (next choice).
+  --  Use  --ifconfig-pool  allocation  for  dynamic  IP  (last
+              choice).
+-- Use --ifconfig-pool allocation for dynamic IP (last choice).
        --iroute network [netmask]
+              Generate an internal route to a  specific  client.  The  netmask
+              parameter, if omitted, defaults to 255.255.255.255.
+              This  directive  can  be  used  to route a fixed subnet from the
+              server to a particular client, regardless of where the client is
+              connecting  from.   Remember that you must also add the route to
+              the system routing table as well (such as by using  the  --route
+              directive).   The  reason  why two routes are needed is that the
+              --route directive routes the packet from the kernel to  OpenVPN.
+              Once  in  OpenVPN, the --iroute directive routes to the specific
+              client.
+              This option must be specified either in a client instance config
+              file  using --client-config-dir or dynamically generated using a
+              Generate an internal route to a specific client. The netmask param‐
+              eter, if omitted, defaults to 255.255.255.255.
+              This  directive can be used to route a fixed subnet from the server
+              to a particular client, regardless of where the client is  connect‐
+              ing  from.  Remember that you must also add the route to the system
+              routing table as well (such as by  using  the  --route  directive).
+              The  reason why two routes are needed is that the --route directive
+              routes the packet from the kernel to OpenVPN.  Once in OpenVPN, the
+              --iroute directive routes to the specific client.
+              This  option  must  be specified either in a client instance config
+              file using --client-config-dir or  dynamically  generated  using  a
               --client-connect script.
+              The --iroute directive also has an  important  interaction  with
+              --push "route ...".  --iroute essentially defines a subnet which
+              is owned by a particular client (we will call  this  client  A).
+              If  you would like other clients to be able to reach A's subnet,
+              you can use --push "route ..."  together with --client-to-client
+              to  effect  this.   In  order for all clients to see A's subnet,
+              OpenVPN must push this route to all clients EXCEPT for A,  since
+              the  subnet is already owned by A.  OpenVPN accomplishes this by
+              not not pushing a route to a client if it  matches  one  of  the
+              client's iroutes.
+              The  --iroute  directive  also  has  an  important interaction with
+              --push "route ...".  --iroute essentially defines a subnet which is
+              owned  by a particular client (we will call this client A).  If you
+              would like other clients to be able to reach A's  subnet,  you  can
+              use  --push "route ..."  together with --client-to-client to effect
+              this.  In order for all clients to see  A's  subnet,  OpenVPN  must
+              push  this  route  to all clients EXCEPT for A, since the subnet is
+              already owned by A.  OpenVPN accomplishes this by not not pushing a
+              route to a client if it matches one of the client's iroutes.
        --client-to-client
               Because the OpenVPN server mode handles multiple clients through
               a single tun or tap interface, it is effectively a router.   The
               --client-to-client   flag  tells  OpenVPN  to  internally  route
               client-to-client traffic rather than pushing  all  client-origi‐
               nating traffic to the TUN/TAP interface.
               When  this  option  is  used,  each  client will "see" the other
               clients which are currently connected.  Otherwise,  each  client
               will  only see the server.  Don't use this option if you want to
               firewall tunnel traffic using custom, per-client rules.
+              Because  the OpenVPN server mode handles multiple clients through a
+              single tun or tap interface,  it  is  effectively  a  router.   The
+              --client-to-client  flag  tells OpenVPN to internally route client-
+              to-client traffic rather than pushing all client-originating  traf‐
+              fic to the TUN/TAP interface.
+              When  this option is used, each client will "see" the other clients
+              which are currently connected.  Otherwise, each  client  will  only
+              see the server.  Don't use this option if you want to firewall tun‐
+              nel traffic using custom, per-client rules.
        --duplicate-cn
               Allow multiple clients with the same common name to concurrently
               connect.  In the absence of this option, OpenVPN will disconnect
               a client instance upon connection of a  new  client  having  the
               same common name.
+              Allow multiple clients with the same common  name  to  concurrently
+              connect.   In the absence of this option, OpenVPN will disconnect a
+              client instance upon connection of a new  client  having  the  same
+              common name.
        --client-connect cmd
               Run command cmd on client connection.
+              cmd  consists  of  a  path  to  script  (or executable program),
+              optionally followed by arguments. The path and arguments may  be
+              single-  or  double-quoted and/or escaped using a backslash, and
+              should be separated by one or more spaces.
+              The command is passed the common name  and  IP  address  of  the
+              just-authenticated  client as environmental variables (see envi‐
+              ronmental variable section below).  The command is  also  passed
+              the  pathname  of  a  freshly created temporary file as the last
+              argument (after any arguments specified in cmd ), to be used  by
+              the command to pass dynamically generated config file directives
+              back to OpenVPN.
+              If the script wants to generate a  dynamic  config  file  to  be
+              applied  on the server when the client connects, it should write
+              it to the file named by the last argument.
+              See the --client-config-dir option below for options  which  can
+              be legally used in a dynamically generated config file.
+              Note  that the return value of script is significant.  If script
+              returns a non-zero error status, it will cause the client to  be
+              cmd  consists  of a path to script (or executable program), option‐
+              ally followed by arguments. The path and arguments may  be  single-
+              or  double-quoted  and/or  escaped using a backslash, and should be
+              separated by one or more spaces.
+              The command is passed the common name and IP address of  the  just-
+              authenticated  client as environmental variables (see environmental
+              variable section below).  The command is also passed  the  pathname
+              of a freshly created temporary file as the last argument (after any
+              arguments specified in cmd ), to be used by  the  command  to  pass
+              dynamically generated config file directives back to OpenVPN.
+              If the script wants to generate a dynamic config file to be applied
+              on the server when the client connects, it should write it  to  the
+              file named by the last argument.
+              See  the  --client-config-dir option below for options which can be
+              legally used in a dynamically generated config file.
+              Note that the return value of script  is  significant.   If  script
+              returns  a  non-zero  error  status, it will cause the client to be
               disconnected.
        --client-disconnect cmd
               Like  --client-connect  but  called on client instance shutdown.
               Will not be called unless the --client-connect script and  plug‐
               ins  (if  defined)  were previously called on this instance with
               successful (0) status returns.
               The exception to this rule is if the --client-disconnect command
               or  plugins  are cascaded, and at least one client-connect func‐
               tion succeeded, then ALL of the client-disconnect functions  for
               scripts  and  plugins  will  be called on client instance object
               deletion, even in cases where some of the related client-connect
               functions returned an error status.
               The  --client-disconnect  command is passed the same pathname as
               the corresponding --client-connect command as its last argument.
               (after any arguments specified in cmd ).
+              Like --client-connect but called on client instance shutdown.  Will
+              not  be  called  unless the --client-connect script and plugins (if
+              defined) were previously called on this  instance  with  successful
+              (0) status returns.
+              The exception to this rule is if the --client-disconnect command or
+              plugins are cascaded, and at least one client-connect function suc‐
+              ceeded, then ALL of the client-disconnect functions for scripts and
+              plugins will be called on client instance object deletion, even  in
+              cases  where  some of the related client-connect functions returned
+              an error status.
+              The --client-disconnect command is passed the same pathname as  the
+              corresponding --client-connect command as its last argument. (after
+              any arguments specified in cmd ).
        --client-config-dir dir
+              Specify a directory dir for custom client config files.  After a
+              connecting client has been authenticated, OpenVPN will  look  in
+              this  directory  for a file having the same name as the client's
+              X509 common name.  If a matching file exists, it will be  opened
+              and  parsed  for  client-specific  configuration options.  If no
+              matching file is found, OpenVPN will instead  try  to  open  and
+              parse a default file called "DEFAULT", which may be provided but
+              is not required. Note that the configuration files must be read‐
+              able by the OpenVPN process after it has dropped it's root priv‐
+              ileges.
+              This file can specify a fixed IP  address  for  a  given  client
+              using  --ifconfig-push,  as  well  as fixed subnets owned by the
+              client using --iroute.
+              One of the useful properties of this option is  that  it  allows
+              client  configuration  files to be conveniently created, edited,
+              or removed while the server is live, without needing to  restart
+              the server.
+              The  following  options  are legal in a client-specific context:
+              Specify a directory dir for custom client config  files.   After  a
+              connecting client has been authenticated, OpenVPN will look in this
+              directory for a file having the same name as the client's X509 com‐
+              mon  name.  If a matching file exists, it will be opened and parsed
+              for client-specific configuration options.  If no matching file  is
+              found,  OpenVPN  will  instead try to open and parse a default file
+              called "DEFAULT", which may be provided but is not  required.  Note
+              that  the  configuration  files  must  be  readable  by the OpenVPN
+              process after it has dropped it's root privileges.
+              This file can specify a fixed IP address for a given  client  using
+              --ifconfig-push, as well as fixed subnets owned by the client using
+              --iroute.
+              One of the useful properties of  this  option  is  that  it  allows
+              client  configuration  files to be conveniently created, edited, or
+              removed while the server is live, without needing  to  restart  the
+              server.
+              The  following  options  are  legal  in  a client-specific context:
               --push, --push-reset, --iroute, --ifconfig-push, and --config.
        --ccd-exclusive
               Require, as a condition of  authentication,  that  a  connecting
               client has a --client-config-dir file.
+              Require, as a condition of authentication, that a connecting client
+              has a --client-config-dir file.
        --tmp-dir dir
               Specify  a  directory  dir  for temporary files.  This directory
               will be used by openvpn processes and script to communicate tem‐
               porary  data  with openvpn main process. Note that the directory
               must be writable by the OpenVPN process  after  it  has  dropped
               it's root privileges.
+              Specify  a  directory dir for temporary files.  This directory will
+              be used by openvpn processes and script  to  communicate  temporary
+              data  with  openvpn  main  process. Note that the directory must be
+              writable by the OpenVPN process after  it  has  dropped  it's  root
+              privileges.
               This directory will be used by in the following cases:
+              *  --client-connect  scripts to dynamically generate client-spe‐
+              cific configuration files.
+              * OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY  plugin  hook  to  return
+              success/failure  via  auth_control_file when using deferred auth
+              method
+              * OPENVPN_PLUGIN_ENABLE_PF plugin hook to pass  filtering  rules
+              via pf_file
+              *  --client-connect scripts to dynamically generate client-specific
+              configuration files.
+              * OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY plugin hook to  return  suc‐
+              cess/failure via auth_control_file when using deferred auth method
+              *  OPENVPN_PLUGIN_ENABLE_PF plugin hook to pass filtering rules via
+              pf_file
        --hash-size r v
               Set the size of the real address hash table to r and the virtual
               address table to v.  By default, both tables are  sized  at  256
               buckets.
+              Set the size of the real address hash table to r  and  the  virtual
+              address table to v.  By default, both tables are sized at 256 buck‐
+              ets.
        --bcast-buffers n
 …
               Maximum number of output packets queued before TCP (default=64).
               When OpenVPN is tunneling data from a TUN/TAP device to a remote
               client over a TCP connection, it is possible  that  the  TUN/TAP
               device  might produce data at a faster rate than the TCP connec‐
               tion can support.  When the  number  of  output  packets  queued
               before  sending to the TCP socket reaches this limit for a given
               client connection, OpenVPN will start to drop  outgoing  packets
               directed at this client.
+              When OpenVPN is tunneling data from a TUN/TAP device  to  a  remote
+              client  over  a  TCP  connection,  it  is possible that the TUN/TAP
+              device might produce data at a faster rate than the TCP  connection
+              can support.  When the number of output packets queued before send‐
+              ing to the TCP socket reaches this limit for a given client connec‐
+              tion,  OpenVPN will start to drop outgoing packets directed at this
+              client.
        --tcp-nodelay
               This  macro  sets  the  TCP_NODELAY socket flag on the server as
               well as pushes it to connecting clients.  The  TCP_NODELAY  flag
               disables  the  Nagle algorithm on TCP sockets causing packets to
               be transmitted immediately with low latency, rather than waiting
               a  short  period  of  time in order to aggregate several packets
               into a larger containing packet.  In VPN applications over  TCP,
               TCP_NODELAY is generally a good latency optimization.
+              This macro sets the TCP_NODELAY socket flag on the server  as  well
+              as  pushes it to connecting clients.  The TCP_NODELAY flag disables
+              the Nagle algorithm on TCP sockets causing packets to be  transmit‐
+              ted  immediately  with  low  latency,  rather  than waiting a short
+              period of time in order to aggregate several packets into a  larger
+              containing  packet.   In  VPN applications over TCP, TCP_NODELAY is
+              generally a good latency optimization.
               The macro expands as follows:
 …
        --max-routes-per-client n
+              Allow  a  maximum of n internal routes per client (default=256).
+              This is designed to help contain DoS attacks where an  authenti‐
+              cated  client  floods  the server with packets appearing to come
+              from many unique MAC addresses, forcing the  server  to  deplete
+              virtual  memory  as  its  internal  routing table expands.  This
+              directive can be used in a --client-config-dir file or auto-gen‐
+              erated by a --client-connect script to override the global value
+              for a particular client.
+              Note that this directive affects OpenVPN's internal routing  ta‐
+              ble, not the kernel routing table.
+              Allow a maximum of n  internal  routes  per  client  (default=256).
+              This is designed to help contain DoS attacks where an authenticated
+              client floods the server with packets appearing to come  from  many
+              unique  MAC addresses, forcing the server to deplete virtual memory
+              as its internal routing table expands.  This directive can be  used
+              in  a --client-config-dir file or auto-generated by a --client-con‐
+              nect script to override the global value for a particular client.
+              Note that this directive affects OpenVPN's internal routing  table,
+              not the kernel routing table.
        --stale-routes-check n [t]
               Remove  routes haven't had activity for n seconds (i.e. the age‐
               ing time).
+              Remove  routes  haven't had activity for n seconds (i.e. the ageing
+              time).
               This check is ran every t seconds (i.e. check interval).
 …
               If t is not present it defaults to n
               This option helps to keep the dynamic routing table small.   See
+              This option helps to keep the dynamic  routing  table  small.   See
               also --max-routes-per-client
        --connect-freq n sec
               Allow  a  maximum  of  n  new  connections  per sec seconds from
               clients.  This is designed to contain DoS  attacks  which  flood
               the  server  with  connection  requests using certificates which
               will ultimately fail to authenticate.
               This is an imperfect solution however, because  in  a  real  DoS
               scenario, legitimate connections might also be refused.
               For  the best protection against DoS attacks in server mode, use
+              Allow  a maximum of n new connections per sec seconds from clients.
+              This is designed to contain DoS attacks which flood the server with
+              connection  requests  using certificates which will ultimately fail
+              to authenticate.
+              This is an imperfect solution however, because in a real  DoS  sce‐
+              nario, legitimate connections might also be refused.
+              For  the  best  protection  against DoS attacks in server mode, use
               --proto udp and --tls-auth.
 …
               Run command cmd to validate client virtual addresses or routes.
               cmd consists of  a  path  to  script  (or  executable  program),
               optionally  followed by arguments. The path and arguments may be
               single- or double-quoted and/or escaped using a  backslash,  and
               should be separated by one or more spaces.
               Three arguments will be appended to any arguments in cmd as fol‐
+              cmd consists of a path to script (or executable  program),  option‐
+              ally  followed  by arguments. The path and arguments may be single-
+              or double-quoted and/or escaped using a backslash,  and  should  be
+              separated by one or more spaces.
+              Three  arguments  will  be appended to any arguments in cmd as fol‐
               lows:
               [1] operation -- "add", "update", or "delete" based  on  whether
               or  not the address is being added to, modified, or deleted from
               OpenVPN's internal routing table.
               [2] address -- The address being learned or unlearned.  This can
               be  an IPv4 address such as "198.162.10.14", an IPv4 subnet such
               as "198.162.10.0/24", or an ethernet MAC address (when --dev tap
               is being used) such as "00:FF:01:02:03:04".
               [3] common name -- The common name on the certificate associated
               with the client linked to this address.  Only present for  "add"
               or "update" operations, not "delete".
               On  "add"  or  "update" methods, if the script returns a failure
               code (non-zero), OpenVPN will reject the address  and  will  not
               modify its internal routing table.
               Normally, the cmd script will use the information provided above
               to set appropriate firewall entries on the  VPN  TUN/TAP  inter‐
               face.  Since OpenVPN provides the association between virtual IP
               or MAC address and the client's authenticated  common  name,  it
               allows  a user-defined script to configure firewall access poli‐
               cies with regard to the client's high-level common name,  rather
               than the low level client virtual addresses.
+              [1] operation -- "add", "update", or "delete" based on  whether  or
+              not  the address is being added to, modified, or deleted from Open‐
+              VPN's internal routing table.
+              [2] address -- The address being learned or unlearned.  This can be
+              an  IPv4  address  such  as "198.162.10.14", an IPv4 subnet such as
+              "198.162.10.0/24", or an ethernet MAC address (when  --dev  tap  is
+              being used) such as "00:FF:01:02:03:04".
+              [3]  common  name  -- The common name on the certificate associated
+              with the client linked to this address.  Only present for "add"  or
+              "update" operations, not "delete".
+              On  "add" or "update" methods, if the script returns a failure code
+              (non-zero), OpenVPN will reject the address and will not modify its
+              internal routing table.
+              Normally, the cmd script will use the information provided above to
+              set appropriate firewall entries  on  the  VPN  TUN/TAP  interface.
+              Since  OpenVPN  provides  the association between virtual IP or MAC
+              address and the client's authenticated common  name,  it  allows  a
+              user-defined  script  to  configure  firewall  access policies with
+              regard to the client's high-level common name, rather than the  low
+              level client virtual addresses.
        --auth-user-pass-verify cmd method
               Require  the  client to provide a username/password (possibly in
+              Require  the  client  to  provide  a username/password (possibly in
               addition to a client certificate) for authentication.
+              OpenVPN will run command cmd to validate  the  username/password
+              provided by the client.
+              cmd  consists  of  a  path  to  script  (or executable program),
+              optionally followed by arguments. The path and arguments may  be
+              single-  or  double-quoted and/or escaped using a backslash, and
+              should be separated by one or more spaces.
+              If method is set to "via-env", OpenVPN will call script with the
+              environmental  variables  username and password set to the user‐
+              name/password strings provided by the  client.   Be  aware  that
+              this  method  is insecure on some platforms which make the envi‐
+              ronment of a process publicly visible to other unprivileged pro‐
+              cesses.
+              If  method is set to "via-file", OpenVPN will write the username
+              and password to the first two lines of a  temporary  file.   The
+              filename  will  be passed as an argument to script, and the file
+              will be  automatically  deleted  by  OpenVPN  after  the  script
+              returns.   The  location  of the temporary file is controlled by
+              the --tmp-dir option, and will default to the current  directory
+              if  unspecified.   For security, consider setting --tmp-dir to a
+              volatile storage medium such as /dev/shm (if available) to  pre‐
+              vent the username/password file from touching the hard drive.
+              The script should examine the username and password, returning a
+              success exit code (0) if the client's authentication request  is
+              to be accepted, or a failure code (1) to reject the client.
+              This  directive  is  designed to enable a plugin-style interface
+              for extending OpenVPN's authentication capabilities.
+              To protect against a client passing a maliciously  formed  user‐
+              name  or  password string, the username string must consist only
+              of these characters: alphanumeric, underbar ('_'),  dash  ('-'),
+              dot  ('.'), or at ('@').  The password string can consist of any
+              printable characters except for CR or LF.  Any  illegal  charac‐
+              ters in either the username or password string will be converted
+              to underbar ('_').
+              Care must be taken by any user-defined scripts to avoid creating
+              a  security vulnerability in the way that these strings are han‐
+              dled.  Never use these strings in such a way that they might  be
+              escaped or evaluated by a shell interpreter.
+              For  a  sample script that performs PAM authentication, see sam‐
+              ple-scripts/auth-pam.pl in the OpenVPN source distribution.
+              OpenVPN will run command cmd to validate the username/password pro‐
+              vided by the client.
+              cmd  consists  of a path to script (or executable program), option‐
+              ally followed by arguments. The path and arguments may  be  single-
+              or  double-quoted  and/or  escaped using a backslash, and should be
+              separated by one or more spaces.
+              If method is set to "via-env", OpenVPN will call  script  with  the
+              environmental  variables  username  and  password  set to the user‐
+              name/password strings provided by the client.  Be aware  that  this
+              method  is insecure on some platforms which make the environment of
+              a process publicly visible to other unprivileged processes.
+              If method is set to "via-file", OpenVPN will write the username and
+              password  to the first two lines of a temporary file.  The filename
+              will be passed as an argument to script, and the file will be auto‐
+              matically  deleted  by OpenVPN after the script returns.  The loca‐
+              tion of the temporary file is controlled by the  --tmp-dir  option,
+              and  will  default  to  the  current directory if unspecified.  For
+              security, consider setting --tmp-dir to a volatile  storage  medium
+              such  as  /dev/shm  (if available) to prevent the username/password
+              file from touching the hard drive.
+              The script should examine the username and  password,  returning  a
+              success  exit code (0) if the client's authentication request is to
+              be accepted, or a failure code (1) to reject the client.
+              This directive is designed to enable a plugin-style  interface  for
+              extending OpenVPN's authentication capabilities.
+              To  protect  against a client passing a maliciously formed username
+              or password string, the username string must consist only of  these
+              characters: alphanumeric, underbar ('_'), dash ('-'), dot ('.'), or
+              at ('@').  The password string can consist of any printable charac‐
+              ters  except  for  CR  or LF.  Any illegal characters in either the
+              username or password string will be converted to underbar ('_').
+              Care must be taken by any user-defined scripts to avoid creating  a
+              security  vulnerability  in the way that these strings are handled.
+              Never use these strings in such a way that they might be escaped or
+              evaluated by a shell interpreter.
+              For  a  sample script that performs PAM authentication, see sample-
+              scripts/auth-pam.pl in the OpenVPN source distribution.
        --opt-verify
               Clients that connect with options  that  are  incompatible  with
               those of the server will be disconnected.
               Options  that  will  be  compared for compatibility include dev-
               type, link-mtu, tun-mtu, proto,  tun-ipv6,  ifconfig,  comp-lzo,
               fragment,  keydir, cipher, auth, keysize, secret, no-replay, no-
               iv, tls-auth, key-method, tls-server, and tls-client.
+              Clients that connect with options that are incompatible with  those
+              of the server will be disconnected.
+              Options  that  will be compared for compatibility include dev-type,
+              link-mtu, tun-mtu, proto, tun-ipv6, ifconfig,  comp-lzo,  fragment,
+              keydir,  cipher, auth, keysize, secret, no-replay, no-iv, tls-auth,
+              key-method, tls-server, and tls-client.
               This option requires that --disable-occ NOT be used.
        --auth-user-pass-optional
+              Allow connections  by  clients  that  do  not  specify  a  user‐
+              name/password.  Normally, when --auth-user-pass-verify or --man‐
+              agement-client-auth is specified (or  an  authentication  plugin
+              module),  the  OpenVPN  server  daemon  will  require connecting
+              clients to specify a username and password.  This  option  makes
+              the submission of a username/password by clients optional, pass‐
+              ing the responsibility to the user-defined  authentication  mod‐
+              ule/script  to  accept or deny the client based on other factors
+              (such as the setting of X509  certificate  fields).   When  this
+              option  is used, and a connecting client does not submit a user‐
+              name/password,  the  user-defined  authentication  module/script
+              will see the username and password as being set to empty strings
+              ("").  The  authentication  module/script  MUST  have  logic  to
+              detect this condition and respond accordingly.
+              Allow connections by clients that do not specify  a  username/pass‐
+              word.   Normally,  when  --auth-user-pass-verify  or  --management-
+              client-auth is specified (or an authentication plugin module),  the
+              OpenVPN  server daemon will require connecting clients to specify a
+              username and password.  This option makes the submission of a user‐
+              name/password  by  clients  optional, passing the responsibility to
+              the user-defined authentication module/script to accept or deny the
+              client based on other factors (such as the setting of X509 certifi‐
+              cate fields).  When this option is used, and  a  connecting  client
+              does  not  submit a username/password, the user-defined authentica‐
+              tion module/script will see the username and password as being  set
+              to  empty strings ("").  The authentication module/script MUST have
+              logic to detect this condition and respond accordingly.
        --client-cert-not-required
               Don't require client certificate, client will authenticate using
               username/password only.  Be aware that using this  directive  is
               less secure than requiring certificates from all clients.
               If  you use this directive, the entire responsibility of authen‐
               tication will rest on your  --auth-user-pass-verify  script,  so
               keep  in mind that bugs in your script could potentially compro‐
               mise the security of your VPN.
               If you don't use this directive, but you also specify an --auth-
               user-pass-verify   script,  then  OpenVPN  will  perform  double
               authentication.  The client  certificate  verification  AND  the
               --auth-user-pass-verify script will need to succeed in order for
               a client to be authenticated and accepted onto the VPN.
+              Don't require client certificate, client  will  authenticate  using
+              username/password only.  Be aware that using this directive is less
+              secure than requiring certificates from all clients.
+              If you use this directive, the entire responsibility of authentica‐
+              tion  will  rest on your --auth-user-pass-verify script, so keep in
+              mind that bugs in your  script  could  potentially  compromise  the
+              security of your VPN.
+              If  you  don't  use this directive, but you also specify an --auth-
+              user-pass-verify script, then OpenVPN will perform double authenti‐
+              cation.   The  client certificate verification AND the --auth-user-
+              pass-verify script will need to succeed in order for a client to be
+              authenticated and accepted onto the VPN.
        --username-as-common-name
               For --auth-user-pass-verify authentication,  use  the  authenti‐
               cated  username  as the common name, rather than the common name
               from the client cert.
        --compat-names [no-remapping]
               Until OpenVPN v2.3 the format of the X.509  Subject  fields  was
               formatted like this:
+              For  --auth-user-pass-verify  authentication, use the authenticated
+              username as the common name, rather than the common name  from  the
+              client cert.
+       --compat-names [no-remapping] (DEPRECATED)
+              Until  OpenVPN v2.3 the format of the X.509 Subject fields was for‐
+              matted like this:
               /C=US/L=Somewhere/CN=John Doe/emailAddress=john@example.com
               In  addition the old behavivour was to remap any character other
               than alphanumeric, underscore ('_'), dash ('-'), dot ('.'),  and
               slash  ('/')  to  underscore ('_').  The X.509 Subject string as
               returned by the tls_id environmental variable,  could  addition‐
               ally contain colon (':') or equal ('=').
               When  using  the  --compat-names option, this old formatting and
               remapping will be re-enabled again.  This is purely  implemented
               for  compatibility  reasons when using older plug-ins or scripts
               which does not handle the new formatting or UTF-8 characters.
               In OpenVPN v2.3 the formatting of these fields  changed  into  a
               more standardised format.  It now looks like:
+              In addition the old behavivour was to  remap  any  character  other
+              than  alphanumeric,  underscore  ('_'),  dash ('-'), dot ('.'), and
+              slash ('/') to underscore  ('_').   The  X.509  Subject  string  as
+              returned  by  the tls_id environmental variable, could additionally
+              contain colon (':') or equal ('=').
+              When using the  --compat-names  option,  this  old  formatting  and
+              remapping will be re-enabled again.  This is purely implemented for
+              compatibility reasons when using older plug-ins  or  scripts  which
+              does not handle the new formatting or UTF-8 characters.
+              In  OpenVPN v2.3 the formatting of these fields changed into a more
+              standardised format.  It now looks like:
               C=US, L=Somewhere, CN=John Doe, emailAddress=john@example.com
+              The  new  default  format  in  OpenVPN v2.3 also does not do the
+              character remapping which happened  earlier.   This  new  format
+              enables  proper  support  for UTF-8 characters in the usernames,
+              X.509 Subject fields and Common Name variables and  it  complies
+              to  the  RFC  2253, UTF-8 String Representation of Distinguished
+              Names.
+              As a backwards compatibility for the removed --no-name-remapping
+              feature  in  older  OpenVPN versions, the no-remapping mode flag
+              can be used with the --compat-names option.  When this mode flag
+              is  used,  the  Common  Name,  Subject, and username strings are
+              allowed to include any printable character including space,  but
+              excluding control characters such as tab, newline, and carriage-
+              return. It ensures compatibility  with  the  --no-name-remapping
+              option of OpenVPN versions before v2.3.
+              Please note: This option will not be around for a long time.  It
+              is only implemented to make the transition to the new formatting
+              less  intrusive.   It  will be removed either in OpenVPN v2.4 or
+              v2.5.  So please make sure you start the process to support  the
+              new formatting as soon as possible.
+              The new default format in OpenVPN v2.3 also does not do the charac‐
+              ter  remapping  which  happened  earlier.   This new format enables
+              proper support for UTF-8 characters in the usernames, X.509 Subject
+              fields  and  Common Name variables and it complies to the RFC 2253,
+              UTF-8 String Representation of Distinguished Names.
+              The no-remapping mode flag can  be  used  with  the  --compat-names
+              option to be compatible with the now deprecated --no-name-remapping
+              option.  It is only available at the server. When this mode flag is
+              used, the Common Name, Subject, and username strings are allowed to
+              include any printable character including space, but excluding con‐
+              trol  characters  such  as  tab,  newline, and carriage-return. no-
+              remapping is only available on the server side.
+              Please note: This option is immediately  deprecated.   It  is  only
+              implemented  to  make  the  transition  to  the new formatting less
+              intrusive.  It will be removed either in OpenVPN v2.4 or v2.5.   So
+              please  make  sure you use the --verify-x509-name option instead of
+              --tls-remote as soon as possible and update your scripts where nec‐
+              essary.
+       --no-name-remapping (DEPRECATED)
+              The   --no-name-remapping   option   is   an   alias   for   --com‐
+              pat-names no-remapping.  It ensures compatibility with server  con‐
+              figurations using the --no-name-remapping option.
+              Please  note:  This  option  is now deprecated.  It will be removed
+              either in OpenVPN v2.4 or v2.5.  So please make  sure  you  support
+              the  new  X.509  name  formatting described with the --compat-names
+              option as soon as possible.
        --port-share host port [dir]
               When run in TCP server mode, share the OpenVPN port with another
               application, such as an HTTPS server.  If OpenVPN senses a  con‐
               nection  to  its  port which is using a non-OpenVPN protocol, it
               will proxy the connection to the server at host:port.  Currently
               only  designed to work with HTTP/HTTPS, though it would be theo‐
               retically possible to extend to other protocols such as ssh.
               dir specifies an optional directory where a temporary file  with
               name  N  containing  content C will be dynamically generated for
               each proxy connection, where N is  the  source  IP:port  of  the
               client  connection and C is the source IP:port of the connection
               to the proxy receiver.  This directory can be used as a  dictio‐
               nary  by  the proxy receiver to determine the origin of the con‐
               nection.  Each generated file will be automatically deleted when
               the proxied connection is torn down.
+              When run in TCP server mode, share the OpenVPN  port  with  another
+              application,  such as an HTTPS server.  If OpenVPN senses a connec‐
+              tion to its port which is using a  non-OpenVPN  protocol,  it  will
+              proxy  the  connection  to the server at host:port.  Currently only
+              designed to work with HTTP/HTTPS, though it would be  theoretically
+              possible to extend to other protocols such as ssh.
+              dir  specifies  an  optional  directory where a temporary file with
+              name N containing content C will be dynamically generated for  each
+              proxy  connection, where N is the source IP:port of the client con‐
+              nection and C is the source IP:port of the connection to the  proxy
+              receiver.   This directory can be used as a dictionary by the proxy
+              receiver to determine the origin of the connection.  Each generated
+              file  will  be automatically deleted when the proxied connection is
+              torn down.
               Not implemented on Windows.
    Client Mode
        Use  client  mode  when  connecting  to  an  OpenVPN  server  which has
        --server, --server-bridge, or --mode server in it's configuration.
+       Use client mode when connecting to an OpenVPN server which  has  --server,
+       --server-bridge, or --mode server in it's configuration.
        --client
               A helper directive designed to  simplify  the  configuration  of
               OpenVPN's client mode.  This directive is equivalent to:
+              A  helper directive designed to simplify the configuration of Open‐
+              VPN's client mode.  This directive is equivalent to:
                    pull
                    tls-client
        --pull This  option  must  be used on a client which is connecting to a
               multi-client server.  It indicates to  OpenVPN  that  it  should
               accept  options  pushed by the server, provided they are part of
               the legal set of pushable options (note that the  --pull  option
               is implied by --client ).
               In  particular,  --pull  allows the server to push routes to the
               client, so you should not use --pull or --client  in  situations
               where  you  don't  trust  the  server  to  have control over the
               client's routing table.
+       --pull This option must be used on a  client  which  is  connecting  to  a
+              multi-client server.  It indicates to OpenVPN that it should accept
+              options pushed by the server, provided they are part of  the  legal
+              set  of pushable options (note that the --pull option is implied by
+              --client ).
+              In particular, --pull allows the  server  to  push  routes  to  the
+              client,  so  you  should  not  use --pull or --client in situations
+              where you don't trust the server to have control over the  client's
+              routing table.
        --auth-user-pass [up]
               Authenticate with server using username/password.  up is a  file
               containing username/password on 2 lines (Note: OpenVPN will only
               read passwords from a  file  if  it  has  been  built  with  the
               --enable-password-save configure option, or on Windows by defin‐
               ing ENABLE_PASSWORD_SAVE in win/settings.in).
               If up is omitted, username/password will be  prompted  from  the
               console.
               The server configuration must specify an --auth-user-pass-verify
+              Authenticate  with  server  using  username/password.  up is a file
+              containing username/password on 2 lines (Note:  OpenVPN  will  only
+              read  passwords from a file if it has been built with the --enable-
+              password-save  configure  option,  or  on   Windows   by   defining
+              ENABLE_PASSWORD_SAVE in win/settings.in).
+              If  up is omitted, username/password will be prompted from the con‐
+              sole.
+              The server configuration must  specify  an  --auth-user-pass-verify
               script to verify the username/password provided by the client.
        --auth-retry type
+              Controls how OpenVPN responds to username/password  verification
+              errors  such  as the client-side response to an AUTH_FAILED mes‐
+              sage from the server or verification failure of the private  key
+              password.
+              Normally  used  to  prevent  auth errors from being fatal on the
+              client side, and to permit username/password requeries  in  case
+              of error.
+              An  AUTH_FAILED message is generated by the server if the client
+              fails --auth-user-pass authentication,  or  if  the  server-side
+              --client-connect  script returns an error status when the client
+              Controls  how  OpenVPN  responds  to username/password verification
+              errors such as the client-side response to an  AUTH_FAILED  message
+              from  the  server  or verification failure of the private key pass‐
+              word.
+              Normally used to prevent auth errors from being fatal on the client
+              side, and to permit username/password requeries in case of error.
+              An  AUTH_FAILED  message  is  generated by the server if the client
+              fails  --auth-user-pass  authentication,  or  if  the   server-side
+              --client-connect  script  returns  an  error status when the client
               tries to connect.
               type can be one of:
+              none -- Client will  exit  with  a  fatal  error  (this  is  the
+              default).
+              nointeract  -- Client will retry the connection without requery‐
+              ing for an --auth-user-pass username/password.  Use this  option
+              for unattended clients.
+              interact  --  Client  will requery for an --auth-user-pass user‐
+              name/password and/or private key password  before  attempting  a
+              none -- Client will exit with a fatal error (this is the default).
+              nointeract -- Client will retry the connection  without  requerying
+              for  an  --auth-user-pass  username/password.   Use this option for
+              unattended clients.
+              interact -- Client  will  requery  for  an  --auth-user-pass  user‐
+              name/password  and/or  private  key  password  before  attempting a
               reconnection.
               Note  that  while  this  option cannot be pushed, it can be con‐
               trolled from the management interface.
+              Note that while this option cannot be pushed, it can be  controlled
+              from the management interface.
        --static-challenge t e
               Enable static challenge/response protocol using  challenge  text
               t, with echo flag given by e (0|1).
               The  echo  flag  indicates whether or not the user's response to
               the challenge should be echoed.
               See management-notes.txt  in  the  OpenVPN  distribution  for  a
               description of the OpenVPN challenge/response protocol.
+              Enable  static  challenge/response protocol using challenge text t,
+              with echo flag given by e (0|1).
+              The echo flag indicates whether or not the user's response  to  the
+              challenge should be echoed.
+              See management-notes.txt in the OpenVPN distribution for a descrip‐
+              tion of the OpenVPN challenge/response protocol.
        --server-poll-timeout n
               when  polling  possible remote servers to connect to in a round-
               robin fashion, spend no  more  than  n  seconds  waiting  for  a
               response before trying the next server.
+              when polling possible remote servers to connect to in a round-robin
+              fashion, spend no more than n seconds waiting for a response before
+              trying the next server.
        --explicit-exit-notify [n]
               In  UDP  client mode or point-to-point mode, send server/peer an
               exit notification if tunnel is restarted or OpenVPN  process  is
               exited.   In client mode, on exit/restart, this option will tell
               the server to  immediately  close  its  client  instance  object
               rather  than waiting for a timeout.  The n parameter (default=1)
               controls the maximum number of attempts that the client will try
               to  resend the exit notification message.  OpenVPN will not send
               any exit notifications unless this option is enabled.
+              In UDP client mode or point-to-point mode, send server/peer an exit
+              notification  if  tunnel is restarted or OpenVPN process is exited.
+              In client mode, on exit/restart, this option will tell  the  server
+              to immediately close its client instance object rather than waiting
+              for a timeout.  The n parameter (default=1)  controls  the  maximum
+              number  of  attempts  that  the  client will try to resend the exit
+              notification message.  OpenVPN will not send any exit notifications
+              unless this option is enabled.
    Data Channel Encryption Options:
        These options are meaningful for both Static & TLS-negotiated key modes
+       These  options  are  meaningful for both Static & TLS-negotiated key modes
        (must be compatible between peers).
        --secret file [direction]
+              Enable  Static  Key  encryption  mode (non-TLS).  Use pre-shared
+              secret file which was generated with --genkey.
+              The optional direction parameter enables the use of  4  distinct
+              keys  (HMAC-send, cipher-encrypt, HMAC-receive, cipher-decrypt),
+              so that each data flow direction has a different set of HMAC and
+              cipher keys.  This has a number of desirable security properties
+              including eliminating certain kinds of DoS  and  message  replay
+              attacks.
+              When  the  direction parameter is omitted, 2 keys are used bidi‐
+              rectionally, one for HMAC and the other  for  encryption/decryp‐
+              tion.
+              The direction parameter should always be complementary on either
+              side of the connection, i.e. one side should  use  "0"  and  the
+              other should use "1", or both sides should omit it altogether.
+              The  direction  parameter requires that file contains a 2048 bit
+              key.  While pre-1.5 versions of OpenVPN generate  1024  bit  key
+              files,  any  version  of  OpenVPN  which  supports the direction
+              parameter, will also support 2048 bit key file generation  using
+              the --genkey option.
+              Static  key  encryption mode has certain advantages, the primary
+              Enable Static Key encryption mode (non-TLS).  Use pre-shared secret
+              file which was generated with --genkey.
+              The optional direction parameter enables the use of 4 distinct keys
+              (HMAC-send, cipher-encrypt, HMAC-receive, cipher-decrypt), so  that
+              each  data  flow  direction  has a different set of HMAC and cipher
+              keys.  This has a number of desirable security properties including
+              eliminating certain kinds of DoS and message replay attacks.
+              When  the  direction parameter is omitted, 2 keys are used bidirec‐
+              tionally, one for HMAC and the other for encryption/decryption.
+              The direction parameter should always be  complementary  on  either
+              side  of the connection, i.e. one side should use "0" and the other
+              should use "1", or both sides should omit it altogether.
+              The direction parameter requires that file contains a 2048 bit key.
+              While  pre-1.5 versions of OpenVPN generate 1024 bit key files, any
+              version of OpenVPN which supports  the  direction  parameter,  will
+              also  support  2048  bit  key  file  generation  using the --genkey
+              option.
+              Static key encryption mode  has  certain  advantages,  the  primary
               being ease of configuration.
               There are no certificates or certificate authorities or  compli‐
               cated  negotiation  handshakes and protocols.  The only require‐
               ment is that you have a pre-existing secure  channel  with  your
               peer  (such  as  ssh ) to initially copy the key.  This require‐
               ment, along with the fact that your key never changes unless you
               manually  generate a new one, makes it somewhat less secure than
               TLS mode (see below).  If an attacker manages to steal your key,
               everything that was ever encrypted with it is compromised.  Con‐
               trast that to the perfect forward secrecy features of  TLS  mode
               (using  Diffie  Hellman key exchange), where even if an attacker
               was able to steal your private key, he would gain no information
               to help him decrypt past sessions.
               Another  advantageous  aspect  of  Static Key encryption mode is
               that it is a handshake-free protocol without any  distinguishing
               signature  or  feature  (such  as a header or protocol handshake
               sequence) that would mark the ciphertext packets as being gener‐
               ated  by  OpenVPN.   Anyone  eavesdropping on the wire would see
               nothing but random-looking data.
+              There are no certificates or certificate authorities or complicated
+              negotiation handshakes and protocols.  The only requirement is that
+              you  have a pre-existing secure channel with your peer (such as ssh
+              ) to initially copy the key.  This requirement, along with the fact
+              that your key never changes unless you manually generate a new one,
+              makes it somewhat less secure than TLS mode  (see  below).   If  an
+              attacker  manages  to  steal  your  key,  everything  that was ever
+              encrypted with it is compromised.  Contrast  that  to  the  perfect
+              forward  secrecy  features  of  TLS  mode (using Diffie Hellman key
+              exchange), where even if an attacker was able to steal your private
+              key,  he  would  gain  no information to help him decrypt past ses‐
+              sions.
+              Another advantageous aspect of Static Key encryption mode  is  that
+              it  is  a handshake-free protocol without any distinguishing signa‐
+              ture or feature (such as a header or protocol  handshake  sequence)
+              that  would mark the ciphertext packets as being generated by Open‐
+              VPN.  Anyone eavesdropping on the wire would see nothing  but  ran‐
+              dom-looking data.
        --key-direction
               Alternative way of specifying the optional  direction  parameter
               for  the  --tls-auth  and  --secret  options.  Useful when using
               inline files (See section on inline files).
+              Alternative  way of specifying the optional direction parameter for
+              the --tls-auth and --secret options. Useful when using inline files
+              (See section on inline files).
        --auth alg
               Authenticate packets with HMAC using  message  digest  algorithm
               alg.   (The  default is SHA1 ).  HMAC is a commonly used message
               authentication algorithm (MAC) that uses a data string, a secure
               hash algorithm, and a key, to produce a digital signature.
               OpenVPN's  usage of HMAC is to first encrypt a packet, then HMAC
               the resulting ciphertext.
               In static-key encryption mode, the HMAC key is included  in  the
               key  file  generated  by --genkey.  In TLS mode, the HMAC key is
               dynamically generated and shared between peers via the TLS  con‐
               trol  channel.   If OpenVPN receives a packet with a bad HMAC it
               will drop the packet.  HMAC usually adds  16  or  20  bytes  per
               packet.  Set alg=none to disable authentication.
               For        more        information       on       HMAC       see
+              Authenticate  packets with HMAC using message digest algorithm alg.
+              (The default is SHA1 ).  HMAC is a commonly used message  authenti‐
+              cation algorithm (MAC) that uses a data string, a secure hash algo‐
+              rithm, and a key, to produce a digital signature.
+              OpenVPN's usage of HMAC is to first encrypt a packet, then HMAC the
+              resulting ciphertext.
+              In  static-key encryption mode, the HMAC key is included in the key
+              file generated by --genkey.  In TLS mode, the HMAC key  is  dynami‐
+              cally  generated and shared between peers via the TLS control chan‐
+              nel.  If OpenVPN receives a packet with a bad HMAC it will drop the
+              packet.  HMAC usually adds 16 or 20 bytes per packet.  Set alg=none
+              to disable authentication.
+              For        more        information        on        HMAC        see
               http://www.cs.ucsd.edu/users/mihir/papers/hmac.html
        --cipher alg
               Encrypt packets with cipher algorithm alg.  The default  is  BF-
               CBC, an abbreviation for Blowfish in Cipher Block Chaining mode.
               Blowfish has the advantages of  being  fast,  very  secure,  and
               allowing  key  sizes of up to 448 bits.  Blowfish is designed to
               be used in situations where keys are changed infrequently.
               For  more  information  on  blowfish,  see   http://www.counter‐
+              Encrypt  packets with cipher algorithm alg.  The default is BF-CBC,
+              an abbreviation for Blowfish in Cipher Block Chaining mode.   Blow‐
+              fish  has  the  advantages of being fast, very secure, and allowing
+              key sizes of up to 448 bits.  Blowfish is designed to  be  used  in
+              situations where keys are changed infrequently.
+              For   more   information   on   blowfish,  see  http://www.counter‐
               pane.com/blowfish.html
               To  see  other  ciphers that are available with OpenVPN, use the
+              To see other ciphers that  are  available  with  OpenVPN,  use  the
               --show-ciphers option.
+              OpenVPN supports the CBC, CFB, and OFB cipher modes, however CBC
+              is  recommended  and  CFB  and OFB should be considered advanced
+              modes.
+              OpenVPN supports the CBC, CFB, and OFB cipher modes, however CBC is
+              recommended and CFB and OFB should be considered advanced modes.
               Set alg=none to disable encryption.
        --keysize n
               Size of cipher key in bits (optional).  If unspecified, defaults
               to  cipher-specific  default.   The  --show-ciphers  option (see
               below) shows all available OpenSSL ciphers,  their  default  key
               sizes,  and  whether  the  key size can be changed.  Use care in
               changing a cipher's default key size.   Many  ciphers  have  not
               been  extensively  cryptanalyzed  with non-standard key lengths,
               and a larger key may offer no real guarantee  of  greater  secu‐
               rity, or may even reduce security.
+              Size of cipher key in bits (optional).  If unspecified, defaults to
+              cipher-specific  default.   The  --show-ciphers  option (see below)
+              shows all available OpenSSL ciphers, their default key  sizes,  and
+              whether  the  key  size  can  be  changed.   Use care in changing a
+              cipher's default key size.  Many ciphers have not been  extensively
+              cryptanalyzed  with  non-standard key lengths, and a larger key may
+              offer no real guarantee of greater security,  or  may  even  reduce
+              security.
        --prng alg [nsl]
+              (Advanced) For PRNG (Pseudo-random number generator), use digest
+              algorithm alg (default=sha1), and set nsl  (default=16)  to  the
+              size in bytes of the nonce secret length (between 16 and 64).
+              Set  alg=none to disable the PRNG and use the OpenSSL RAND_bytes
+              function instead  for  all  of  OpenVPN's  pseudo-random  number
+              needs.
+              (Advanced)  For  PRNG  (Pseudo-random number generator), use digest
+              algorithm alg (default=sha1), and set nsl (default=16) to the  size
+              in bytes of the nonce secret length (between 16 and 64).
+              Set  alg=none  to  disable  the PRNG and use the OpenSSL RAND_bytes
+              function instead for all of OpenVPN's pseudo-random number needs.
        --engine [engine-name]
               Enable OpenSSL hardware-based crypto engine functionality.
               If  engine-name is specified, use a specific crypto engine.  Use
               the --show-engines standalone option to list the crypto  engines
               which are supported by OpenSSL.
+              If engine-name is specified, use a specific crypto engine.  Use the
+              --show-engines  standalone  option to list the crypto engines which
+              are supported by OpenSSL.
        --no-replay
               (Advanced)  Disable OpenVPN's protection against replay attacks.
               Don't use this option unless you are prepared to make a tradeoff
               of greater efficiency in exchange for less security.
+              (Advanced) Disable OpenVPN's  protection  against  replay  attacks.
+              Don't use this option unless you are prepared to make a tradeoff of
+              greater efficiency in exchange for less security.
               OpenVPN provides datagram replay protection by default.
               Replay protection is accomplished by tagging each outgoing data‐
               gram with an identifier that is guaranteed to be unique for  the
               key  being used.  The peer that receives the datagram will check
               for the uniqueness of the identifier.   If  the  identifier  was
               already  received  in a previous datagram, OpenVPN will drop the
               packet.  Replay protection is important to defeat  attacks  such
               as  a  SYN flood attack, where the attacker listens in the wire,
               intercepts a TCP SYN packet (identifying it by  the  context  in
               which  it  occurs in relation to other packets), then floods the
               receiving peer with copies of this packet.
               OpenVPN's replay protection is implemented in slightly different
+              Replay protection is accomplished by tagging each outgoing datagram
+              with  an  identifier  that  is  guaranteed to be unique for the key
+              being used.  The peer that receives the datagram will check for the
+              uniqueness  of  the  identifier.   If  the  identifier  was already
+              received in a previous datagram,  OpenVPN  will  drop  the  packet.
+              Replay  protection  is  important  to  defeat attacks such as a SYN
+              flood attack, where the attacker listens in the wire, intercepts  a
+              TCP SYN packet (identifying it by the context in which it occurs in
+              relation to other packets), then floods  the  receiving  peer  with
+              copies of this packet.
+              OpenVPN's  replay  protection  is implemented in slightly different
               ways, depending on the key management mode you have selected.
               In  Static  Key  mode  or  when using an CFB or OFB mode cipher,
               OpenVPN uses a 64 bit unique identifier  that  combines  a  time
               stamp with an incrementing sequence number.
               When  using  TLS  mode  for  key exchange and a CBC cipher mode,
               OpenVPN uses only a 32 bit sequence number without a time stamp,
               since  OpenVPN  can  guarantee  the uniqueness of this value for
               each key.  As in IPSec, if the sequence number is close to wrap‐
               ping back to zero, OpenVPN will trigger a new key exchange.
               To  check for replays, OpenVPN uses the sliding window algorithm
+              In Static Key mode or when using an CFB or OFB mode cipher, OpenVPN
+              uses  a 64 bit unique identifier that combines a time stamp with an
+              incrementing sequence number.
+              When using TLS mode for key exchange and a CBC cipher mode, OpenVPN
+              uses  only  a  32  bit  sequence number without a time stamp, since
+              OpenVPN can guarantee the uniqueness of this value  for  each  key.
+              As  in  IPSec,  if the sequence number is close to wrapping back to
+              zero, OpenVPN will trigger a new key exchange.
+              To check for replays, OpenVPN uses  the  sliding  window  algorithm
               used by IPSec.
        --replay-window n [t]
               Use a replay protection sliding-window of size n and a time win‐
               dow of t seconds.
+              Use  a replay protection sliding-window of size n and a time window
+              of t seconds.
               By default n is 64 (the IPSec default) and t is 15 seconds.
+              This  option  is  only  relevant  in UDP mode, i.e.  when either
+              --proto udp is specifed, or no --proto option is specified.
+              When OpenVPN tunnels IP packets over UDP, there is the possibil‐
+              ity  that  packets  might  be dropped or delivered out of order.
+              Because OpenVPN, like IPSec, is emulating the  physical  network
+              layer,  it will accept an out-of-order packet sequence, and will
+              deliver such packets in the same order they were received to the
+              TCP/IP  protocol  stack,  provided  they  satisfy  several  con‐
+              straints.
+              (a) The packet cannot be a replay (unless --no-replay is  speci‐
+              fied, which disables replay protection altogether).
+              (b)  If  a packet arrives out of order, it will only be accepted
+              if the difference between its sequence number  and  the  highest
+              sequence number received so far is less than n.
+              (c)  If  a packet arrives out of order, it will only be accepted
+              if it arrives no later than t seconds after any packet  contain‐
+              ing a higher sequence number.
+              If  you  are using a network link with a large pipeline (meaning
+              that the product of bandwidth and latency is high), you may want
+              to  use  a  larger  value  for n.  Satellite links in particular
+              often require this.
+              If you run OpenVPN  at  --verb  4,  you  will  see  the  message
+              "Replay-window  backtrack  occurred  [x]" every time the maximum
+              sequence number backtrack seen thus far increases.  This can  be
+              used to calibrate n.
+              There  is some controversy on the appropriate method of handling
+              This option is only relevant in UDP mode, i.e.  when either --proto
+              udp is specifed, or no --proto option is specified.
+              When  OpenVPN tunnels IP packets over UDP, there is the possibility
+              that packets might be dropped or delivered out of  order.   Because
+              OpenVPN,  like  IPSec,  is emulating the physical network layer, it
+              will accept an out-of-order packet sequence, and will deliver  such
+              packets in the same order they were received to the TCP/IP protocol
+              stack, provided they satisfy several constraints.
+              (a) The packet cannot be a replay (unless --no-replay is specified,
+              which disables replay protection altogether).
+              (b)  If  a packet arrives out of order, it will only be accepted if
+              the difference between its sequence number and the highest sequence
+              number received so far is less than n.
+              (c)  If  a packet arrives out of order, it will only be accepted if
+              it arrives no later than t seconds after any  packet  containing  a
+              higher sequence number.
+              If you are using a network link with a large pipeline (meaning that
+              the product of bandwidth and latency is high), you may want to  use
+              a  larger value for n.  Satellite links in particular often require
+              this.
+              If you run OpenVPN at --verb 4, you will see the  message  "Replay-
+              window backtrack occurred [x]" every time the maximum sequence num‐
+              ber backtrack seen thus far increases.  This can be used  to  cali‐
+              brate n.
+              There  is  some  controversy  on the appropriate method of handling
               packet reordering at the security layer.
+              Namely, to what extent should the  security  layer  protect  the
+              encapsulated protocol from attacks which masquerade as the kinds
+              of normal packet loss and reordering that  occur  over  IP  net‐
+              works?
+              The  IPSec  and  OpenVPN  approach is to allow packet reordering
+              within a certain fixed sequence number window.
+              OpenVPN adds to the IPSec model by limiting the window  size  in
+              time as well as sequence space.
+              OpenVPN  also  adds  TCP  transport as an option (not offered by
+              IPSec) in which case OpenVPN can adopt a  very  strict  attitude
+              towards message deletion and reordering:  Don't allow it.  Since
+              TCP guarantees reliability, any packet loss or reordering  event
+              can be assumed to be an attack.
+              In  this  sense, it could be argued that TCP tunnel transport is
+              preferred when tunneling non-IP  or  UDP  application  protocols
+              which  might  be  vulnerable to a message deletion or reordering
+              attack which falls within the normal operational  parameters  of
+              IP networks.
+              So  I  would  make  the statement that one should never tunnel a
+              non-IP protocol or UDP application protocol  over  UDP,  if  the
+              protocol might be vulnerable to a message deletion or reordering
+              attack that falls within the normal operating parameters of what
+              is  to  be  expected from the physical IP layer.  The problem is
+              easily fixed by simply using TCP as the VPN transport layer.
+              Namely, to what extent should the security layer protect the encap‐
+              sulated protocol from attacks which masquerade as the kinds of nor‐
+              mal packet loss and reordering that occur over IP networks?
+              The IPSec and OpenVPN approach is to allow packet reordering within
+              a certain fixed sequence number window.
+              OpenVPN adds to the IPSec model by limiting the window size in time
+              as well as sequence space.
+              OpenVPN also adds TCP transport as an option (not offered by IPSec)
+              in which case OpenVPN can adopt a very strict attitude towards mes‐
+              sage deletion and reordering:  Don't allow it.  Since  TCP  guaran‐
+              tees  reliability,  any  packet  loss  or  reordering  event can be
+              assumed to be an attack.
+              In this sense, it could be argued that TCP tunnel transport is pre‐
+              ferred  when  tunneling  non-IP  or UDP application protocols which
+              might be vulnerable to a  message  deletion  or  reordering  attack
+              which  falls  within  the  normal operational parameters of IP net‐
+              works.
+              So I would make the statement that one should never tunnel a non-IP
+              protocol  or  UDP  application  protocol  over UDP, if the protocol
+              might be vulnerable to a message deletion or reordering attack that
+              falls  within  the  normal  operating  parameters  of what is to be
+              expected from the physical IP layer.  The problem is  easily  fixed
+              by simply using TCP as the VPN transport layer.
        --mute-replay-warnings
               Silence the output of replay warnings, which are a common  false
               alarm  on  WiFi networks.  This option preserves the security of
               the replay protection code without the verbosity associated with
               warnings about duplicate packets.
+              Silence  the  output  of  replay warnings, which are a common false
+              alarm on WiFi networks.  This option preserves the security of  the
+              replay  protection code without the verbosity associated with warn‐
+              ings about duplicate packets.
        --replay-persist file
               Persist  replay-protection  state  across sessions using file to
               save and reload the state.
               This option will strengthen protection against  replay  attacks,
               especially when you are using OpenVPN in a dynamic context (such
               as with --inetd) when OpenVPN sessions  are  frequently  started
               and stopped.
               This  option will keep a disk copy of the current replay protec‐
               tion state (i.e. the most recent packet timestamp  and  sequence
               number  received  from  the  remote peer), so that if an OpenVPN
               session is stopped and restarted, it will reject any replays  of
               packets which were already received by the prior session.
               This  option  only makes sense when replay protection is enabled
               (the default) and you are using either  --secret  (shared-secret
               key mode) or TLS mode with --tls-auth.
+              Persist replay-protection state across sessions using file to  save
+              and reload the state.
+              This  option  will  strengthen  protection  against replay attacks,
+              especially when you are using OpenVPN in a dynamic context (such as
+              with  --inetd)  when  OpenVPN  sessions  are frequently started and
+              stopped.
+              This option will keep a disk copy of the current replay  protection
+              state  (i.e.  the  most recent packet timestamp and sequence number
+              received from the remote peer), so that if an  OpenVPN  session  is
+              stopped  and restarted, it will reject any replays of packets which
+              were already received by the prior session.
+              This option only makes sense when replay protection is enabled (the
+              default) and you are using either --secret (shared-secret key mode)
+              or TLS mode with --tls-auth.
        --no-iv
               (Advanced)  Disable  OpenVPN's  use of IV (cipher initialization
               vector).  Don't use this option unless you are prepared to  make
               a tradeoff of greater efficiency in exchange for less security.
               OpenVPN  uses  an IV by default, and requires it for CFB and OFB
               cipher modes (which are totally insecure without it).  Using  an
               IV  is  important  for security when multiple messages are being
+              (Advanced) Disable OpenVPN's use of IV (cipher initialization  vec‐
+              tor).   Don't  use  this  option  unless you are prepared to make a
+              tradeoff of greater efficiency in exchange for less security.
+              OpenVPN uses an IV by default, and requires  it  for  CFB  and  OFB
+              cipher  modes (which are totally insecure without it).  Using an IV
+              is  important  for  security  when  multiple  messages  are   being
               encrypted/decrypted with the same key.
 …
               In CBC mode, OpenVPN uses a pseudo-random IV for each packet.
               In CFB/OFB mode, OpenVPN uses a unique sequence number and  time
               stamp as the IV.  In fact, in CFB/OFB mode, OpenVPN uses a data‐
               gram space-saving optimization that uses the  unique  identifier
               for datagram replay protection as the IV.
+              In  CFB/OFB  mode,  OpenVPN  uses a unique sequence number and time
+              stamp as the IV.  In fact, in CFB/OFB mode, OpenVPN uses a datagram
+              space-saving optimization that uses the unique identifier for data‐
+              gram replay protection as the IV.
        --use-prediction-resistance
               Enable prediction resistance on PolarSSL's RNG.
               Enabling  prediction resistance causes the RNG to reseed in each
               call for random. Reseeding this often can  quickly  deplete  the
               kernel entropy pool.
               If  you  need this option, please consider running a daemon that
               adds entropy to the kernel pool.
               Note that this option only works with PolarSSL versions  greater
+              Enabling prediction resistance causes the RNG  to  reseed  in  each
+              call  for random. Reseeding this often can quickly deplete the ker‐
+              nel entropy pool.
+              If you need this option, please consider running a daemon that adds
+              entropy to the kernel pool.
+              Note  that  this  option  only works with PolarSSL versions greater
               than 1.1.
        --test-crypto
+              Do  a  self-test  of  OpenVPN's crypto options by encrypting and
+              decrypting  test  packets  using  the  data  channel  encryption
+              options specified above.  This option does not require a peer to
+              function, and  therefore  can  be  specified  without  --dev  or
+              --remote.
+              Do a self-test  of  OpenVPN's  crypto  options  by  encrypting  and
+              decrypting  test  packets using the data channel encryption options
+              specified above.  This option does not require a peer to  function,
+              and therefore can be specified without --dev or --remote.
               The typical usage of --test-crypto would be something like this:
 …
               openvpn --test-crypto --secret key --verb 9
               This  option  is  very  useful to test OpenVPN after it has been
               ported to a new platform, or to isolate  problems  in  the  com‐
               piler,  OpenSSL crypto library, or OpenVPN's crypto code.  Since
               it is a self-test mode, problems with encryption and authentica‐
               tion can be debugged independently of network and tunnel issues.
+              This option is very useful to test OpenVPN after it has been ported
+              to a new platform, or to isolate problems in the compiler,  OpenSSL
+              crypto  library, or OpenVPN's crypto code.  Since it is a self-test
+              mode, problems with encryption and authentication can  be  debugged
+              independently of network and tunnel issues.
    TLS Mode Options:
+       TLS  mode  is the most powerful crypto mode of OpenVPN in both security
+       and flexibility.  TLS mode works by establishing control and data chan‐
+       nels  which are multiplexed over a single TCP/UDP port.  OpenVPN initi‐
+       ates a TLS session over the control channel and  uses  it  to  exchange
+       cipher  and  HMAC  keys  to  protect the data channel.  TLS mode uses a
+       robust reliability layer over the UDP connection for all control  chan‐
+       nel  communication, while the data channel, over which encrypted tunnel
+       data passes, is forwarded without any mediation.   The  result  is  the
+       best  of  both  worlds: a fast data channel that forwards over UDP with
+       only the overhead of encrypt, decrypt, and HMAC functions, and  a  con‐
+       trol channel that provides all of the security features of TLS, includ‐
+       ing  certificate-based  authentication  and  Diffie   Hellman   forward
+       secrecy.
+       To  use TLS mode, each peer that runs OpenVPN should have its own local
+       certificate/key pair ( --cert and --key ), signed by the root  certifi‐
+       cate which is specified in --ca.
+       When  two OpenVPN peers connect, each presents its local certificate to
+       the other.  Each peer will then check that its partner peer presented a
+       certificate  which  was signed by the master root certificate as speci‐
+       fied in --ca.
+       If that check on both peers succeeds, then  the  TLS  negotiation  will
+       succeed,  both  OpenVPN peers will exchange temporary session keys, and
+       the tunnel will begin passing data.
+       The OpenVPN distribution contains a set of  scripts  for  managing  RSA
+       certificates & keys, located in the easy-rsa subdirectory.
+       The  easy-rsa  package  is also rendered in web form here: http://open‐
+       TLS  mode is the most powerful crypto mode of OpenVPN in both security and
+       flexibility.  TLS mode works by establishing  control  and  data  channels
+       which are multiplexed over a single TCP/UDP port.  OpenVPN initiates a TLS
+       session over the control channel and uses it to exchange cipher  and  HMAC
+       keys  to  protect  the  data  channel.  TLS mode uses a robust reliability
+       layer over the UDP connection for all control channel communication, while
+       the  data  channel,  over which encrypted tunnel data passes, is forwarded
+       without any mediation.  The result is the best of both worlds: a fast data
+       channel that forwards over UDP with only the overhead of encrypt, decrypt,
+       and HMAC functions, and a control channel that provides all of  the  secu‐
+       rity  features  of  TLS,  including  certificate-based  authentication and
+       Diffie Hellman forward secrecy.
+       To use TLS mode, each peer that runs OpenVPN should  have  its  own  local
+       certificate/key  pair ( --cert and --key ), signed by the root certificate
+       which is specified in --ca.
+       When two OpenVPN peers connect, each presents its local certificate to the
+       other.   Each  peer will then check that its partner peer presented a cer‐
+       tificate which was signed by the master root certificate as  specified  in
+       --ca.
+       If  that  check on both peers succeeds, then the TLS negotiation will suc‐
+       ceed, both OpenVPN peers will exchange temporary  session  keys,  and  the
+       tunnel will begin passing data.
+       The  OpenVPN  distribution contains a set of scripts for managing RSA cer‐
+       tificates & keys, located in the easy-rsa subdirectory.
+       The easy-rsa package is also  rendered  in  web  form  here:  http://open‐
        vpn.net/easyrsa.html
        --tls-server
               Enable TLS and assume server role during  TLS  handshake.   Note
               that  OpenVPN  is  designed  as a peer-to-peer application.  The
               designation of client or server is only for the purpose of nego‐
               tiating the TLS control channel.
+              Enable  TLS and assume server role during TLS handshake.  Note that
+              OpenVPN is designed as a peer-to-peer application.  The designation
+              of  client or server is only for the purpose of negotiating the TLS
+              control channel.
        --tls-client
 …
        --ca file
               Certificate authority (CA) file in .pem format, also referred to
               as the root certificate.  This file can have  multiple  certifi‐
               cates  in .pem format, concatenated together.  You can construct
               your own certificate authority certificate and  private  key  by
               using a command such as:
+              Certificate authority (CA) file in .pem format, also referred to as
+              the  root certificate.  This file can have multiple certificates in
+              .pem format, concatenated together.  You  can  construct  your  own
+              certificate  authority  certificate and private key by using a com‐
+              mand such as:
               openssl req -nodes -new -x509 -keyout ca.key -out ca.crt
               Then  edit  your openssl.cnf file and edit the certificate vari‐
               able to point to your new root certificate ca.crt.
               For testing purposes only, the OpenVPN distribution  includes  a
               sample  CA certificate (ca.crt).  Of course you should never use
               the test certificates and test keys distributed with OpenVPN  in
               a  production environment, since by virtue of the fact that they
               are distributed with OpenVPN, they are totally insecure.
+              Then edit your openssl.cnf file and edit the  certificate  variable
+              to point to your new root certificate ca.crt.
+              For testing purposes only, the OpenVPN distribution includes a sam‐
+              ple CA certificate (ca.crt).  Of course you should  never  use  the
+              test  certificates and test keys distributed with OpenVPN in a pro‐
+              duction environment, since by virtue of the fact that they are dis‐
+              tributed with OpenVPN, they are totally insecure.
        --capath dir
               Directory  containing  trusted  certificates  (CAs  and   CRLs).
               Available with OpenSSL version >= 0.9.7 dev.  Not available with
+              Directory  containing  trusted certificates (CAs and CRLs).  Avail‐
+              able with  OpenSSL  version  >=  0.9.7  dev.   Not  available  with
               PolarSSL.
        --dh file
               File  containing  Diffie  Hellman  parameters  in  .pem   format
               (required for --tls-server only). Use
+              File  containing Diffie Hellman parameters in .pem format (required
+              for --tls-server only). Use
               openssl dhparam -out dh1024.pem 1024
               to  generate  your  own,  or  use  the  existing dh1024.pem file
               included with the OpenVPN distribution.  Diffie Hellman  parame‐
               ters may be considered public.
+              to generate your own, or use the existing dh1024.pem file  included
+              with  the  OpenVPN  distribution.  Diffie Hellman parameters may be
+              considered public.
        --cert file
+              Local peer's signed certificate in .pem format -- must be signed
+              by a certificate authority whose certificate is  in  --ca  file.
+              Each peer in an OpenVPN link running in TLS mode should have its
+              own certificate and private key file.  In  addition,  each  cer‐
+              tificate  should  have  been  signed by the key of a certificate
+              authority whose public  key  resides  in  the  --ca  certificate
+              authority  file.   You  can  easily  make  your  own certificate
+              authority (see above) or pay money to use a  commercial  service
+              such as thawte.com (in which case you will be helping to finance
+              the world's second space tourist :).  To generate a certificate,
+              you can use a command such as:
+              Local peer's signed certificate in .pem format -- must be signed by
+              a  certificate  authority  whose certificate is in --ca file.  Each
+              peer in an OpenVPN link running in TLS mode  should  have  its  own
+              certificate  and  private  key file.  In addition, each certificate
+              should have been signed by the key of a certificate authority whose
+              public key resides in the --ca certificate authority file.  You can
+              easily make your own certificate authority (see above) or pay money
+              to  use  a commercial service such as thawte.com (in which case you
+              will be helping to finance the world's second space tourist :).  To
+              generate a certificate, you can use a command such as:
               openssl req -nodes -new -keyout mycert.key -out mycert.csr
+              If  your  certificate  authority  private  key  lives on another
+              machine, copy the certificate signing  request  (mycert.csr)  to
+              this  other  machine  (this can be done over an insecure channel
+              such as email).  Now sign the certificate with  a  command  such
+              as:
+              If your certificate authority private key lives on another machine,
+              copy the certificate signing request  (mycert.csr)  to  this  other
+              machine  (this can be done over an insecure channel such as email).
+              Now sign the certificate with a command such as:
               openssl ca -out mycert.crt -in mycert.csr
               Now  copy  the  certificate  (mycert.crt) back to the peer which
               initially generated the .csr file (this can  be  over  a  public
               medium).  Note that the openssl ca command reads the location of
               the certificate authority key from its configuration  file  such
               as  /usr/share/ssl/openssl.cnf -- note also that for certificate
               authority functions, you must set up the files index.txt (may be
+              Now copy the certificate (mycert.crt) back to the peer  which  ini‐
+              tially  generated the .csr file (this can be over a public medium).
+              Note that the openssl ca command reads the location of the certifi‐
+              cate   authority   key   from   its   configuration  file  such  as
+              /usr/share/ssl/openssl.cnf  --  note  also  that  for   certificate
+              authority  functions,  you  must set up the files index.txt (may be
               empty) and serial (initialize to 01 ).
        --extra-certs file
               Specify  a  file  containing one or more PEM certs (concatenated
+              Specify a file containing  one  or  more  PEM  certs  (concatenated
               together) that complete the local certificate chain.
+              This option is useful for "split" CAs, where the CA  for  server
+              certs  is different than the CA for client certs.  Putting certs
+              in this file allows them to be used to complete the  local  cer‐
+              tificate  chain without trusting them to verify the peer-submit‐
+              ted certificate, as would be the case if the certs  were  placed
+              in the ca file.
+              This  option  is  useful  for  "split" CAs, where the CA for server
+              certs is different than the CA for client certs.  Putting certs  in
+              this  file allows them to be used to complete the local certificate
+              chain without trusting them to verify the  peer-submitted  certifi‐
+              cate, as would be the case if the certs were placed in the ca file.
        --key file
               Local  peer's  private  key in .pem format.  Use the private key
               which was generated when you built your peer's certificate  (see
               -cert file above).
+              Local peer's private key in .pem format.  Use the private key which
+              was generated when you built your  peer's  certificate  (see  -cert
+              file above).
        --pkcs12 file
+              Specify a PKCS #12 file containing local private key, local cer‐
+              tificate, and root CA certificate.   This  option  can  be  used
+              instead   of  --ca,  --cert,  and  --key.   Not  available  with
+              PolarSSL.
+              Specify  a  PKCS  #12 file containing local private key, local cer‐
+              tificate, and root CA certificate.  This option can be used instead
+              of --ca, --cert, and --key.  Not available with PolarSSL.
        --verify-hash hash
               Specify SHA1 fingerprint for level-1 cert.  The level-1 cert  is
               the  CA  (or intermediate cert) that signs the leaf certificate,
               and is one removed from the leaf certificate in the direction of
               the  root.  When accepting a connection from a peer, the level-1
               cert fingerprint must match  hash  or  certificate  verification
               will  fail.   Hash  is  specified  as  XX:XX:...   For  example:
+              Specify SHA1 fingerprint for level-1 cert.  The level-1 cert is the
+              CA (or intermediate cert) that signs the leaf certificate,  and  is
+              one removed from the leaf certificate in the direction of the root.
+              When accepting a connection from a peer, the level-1  cert  finger‐
+              print  must match hash or certificate verification will fail.  Hash
+              is      specified      as       XX:XX:...        For       example:
               AD:B0:95:D8:09:C8:36:45:12:A9:89:C8:90:09:CB:13:72:A6:AD:16
        --pkcs11-cert-private [0|1]...
               Set if access to certificate object should  be  performed  after
+              Set  if  access  to  certificate  object  should be performed after
               login.  Every provider has its own setting.
        --pkcs11-id name
               Specify  the serialized certificate id to be used. The id can be
+              Specify the serialized certificate id to be used.  The  id  can  be
               gotten by the standalone --show-pkcs11-ids option.
        --pkcs11-id-management
               Acquire PKCS#11 id from management interface.  In  this  case  a
               NEED-STR  'pkcs11-id-request'  real-time  message  will be trig‐
               gered, application may use pkcs11-id-count command  to  retrieve
               available  number  of certificates, and pkcs11-id-get command to
               retrieve certificate id and certificate body.
+              Acquire  PKCS#11 id from management interface. In this case a NEED-
+              STR 'pkcs11-id-request' real-time message will be triggered, appli‐
+              cation may use pkcs11-id-count command to retrieve available number
+              of certificates, and pkcs11-id-get command to retrieve  certificate
+              id and certificate body.
        --pkcs11-pin-cache seconds
               Specify how many seconds the PIN can be cached, the  default  is
+              Specify  how  many  seconds  the  PIN can be cached, the default is
               until the token is removed.
        --pkcs11-protected-authentication [0|1]...
+              Use  PKCS#11 protected authentication path, useful for biometric
+              and external keypad devices.  Every provider has  its  own  set‐
+              ting.
+              Use PKCS#11 protected authentication path, useful for biometric and
+              external keypad devices.  Every provider has its own setting.
        --pkcs11-providers provider...
               Specify  a RSA Security Inc. PKCS #11 Cryptographic Token Inter‐
               face (Cryptoki) providers to load.   This  option  can  be  used
               instead of --cert, --key, and --pkcs12.
+              Specify  a RSA Security Inc. PKCS #11 Cryptographic Token Interface
+              (Cryptoki) providers to load.  This option can be used  instead  of
+              --cert, --key, and --pkcs12.
        --pkcs11-private-mode mode...
+              Specify  which  method  to  use  in order to perform private key
+              operations.   A  different  mode  can  be  specified  for   each
+              provider.   Mode is encoded as hex number, and can be a mask one
+              of the following:
+              Specify  which method to use in order to perform private key opera‐
+              tions.  A different mode can be specified for each provider.   Mode
+              is encoded as hex number, and can be a mask one of the following:
 (default) -- Try to determind automatically.
 …
        --cryptoapicert select-string
               Load the certificate and private key from the  Windows  Certifi‐
               cate System Store (Windows/OpenSSL Only).
+              Load  the  certificate and private key from the Windows Certificate
+              System Store (Windows/OpenSSL Only).
               Use this option instead of --cert and --key.
               This  makes it possible to use any smart card, supported by Win‐
               dows, but also any kind of certificate,  residing  in  the  Cert
               Store,  where  you  have access to the private key.  This option
               has been tested with a couple of different smart cards (GemSAFE,
               Cryptoflex, and Swedish Post Office eID) on the client side, and
               also an imported PKCS12 software certificate on the server side.
               To select a certificate, based on a substring search in the cer‐
+              This makes it possible to use any smart card, supported by Windows,
+              but also any kind of certificate, residing in the Cert Store, where
+              you have access to the private key.  This option  has  been  tested
+              with  a  couple  of different smart cards (GemSAFE, Cryptoflex, and
+              Swedish Post Office eID) on the client side, and also  an  imported
+              PKCS12 software certificate on the server side.
+              To  select  a  certificate, based on a substring search in the cer‐
               tificate's subject:
 …
               cryptoapicert "THUMB:f6 49 24 41 01 b4 ..."
               The thumbprint hex string can easily be copy-and-pasted from the
+              The thumbprint hex string can easily be  copy-and-pasted  from  the
               Windows Certificate Store GUI.
        --key-method m
               Use data channel key negotiation method m.  The key method  must
+              Use  data  channel  key  negotiation method m.  The key method must
               match on both sides of the connection.
               After  OpenVPN  negotiates  a TLS session, a new set of keys for
               protecting the tunnel data channel is  generated  and  exchanged
               over the TLS session.
               In  method  1 (the default for OpenVPN 1.x), both sides generate
               random encrypt and HMAC-send keys which  are  forwarded  to  the
               other host over the TLS channel.
               In  method 2, (the default for OpenVPN 2.0) the client generates
               a random key.  Both client and server also generate some  random
               seed  material.   All  key source material is exchanged over the
               TLS channel. The actual keys are generated  using  the  TLS  PRF
               function,  taking  source  entropy  from both client and server.
               Method 2 is designed to  closely  parallel  the  key  generation
               process used by TLS 1.0.
+              After OpenVPN negotiates a TLS session, a new set of keys for  pro‐
+              tecting the tunnel data channel is generated and exchanged over the
+              TLS session.
+              In method 1 (the default for OpenVPN 1.x), both sides generate ran‐
+              dom  encrypt  and  HMAC-send  keys which are forwarded to the other
+              host over the TLS channel.
+              In method 2, (the default for OpenVPN 2.0) the client  generates  a
+              random  key.  Both client and server also generate some random seed
+              material.  All key source material is exchanged over the TLS  chan‐
+              nel. The actual keys are generated using the TLS PRF function, tak‐
+              ing source entropy from  both  client  and  server.   Method  2  is
+              designed to closely parallel the key generation process used by TLS
+.0.
               Note that in TLS mode, two separate levels of keying occur:
               (1)  The TLS connection is initially negotiated, with both sides
               of the connection producing certificates and verifying the  cer‐
               tificate  (or  other  authentication info provided) of the other
               side.  The --key-method parameter has no effect on this process.
               (2) After the TLS connection is established, the tunnel  session
               keys  are  separately  negotiated  over  the existing secure TLS
               channel.  Here, --key-method determines the  derivation  of  the
               tunnel session keys.
+              (1) The TLS connection is initially negotiated, with both sides  of
+              the connection producing certificates and verifying the certificate
+              (or other authentication info provided) of  the  other  side.   The
+              --key-method parameter has no effect on this process.
+              (2)  After  the  TLS  connection is established, the tunnel session
+              keys are separately negotiated over the existing secure  TLS  chan‐
+              nel.   Here,  --key-method  determines the derivation of the tunnel
+              session keys.
        --tls-cipher l
               A  list  l  of allowable TLS ciphers delimited by a colon (":").
               If you require a high level of security, you  may  want  to  set
               this  parameter  manually,  to prevent a version rollback attack
               where a man-in-the-middle attacker tries to force two  peers  to
               negotiate  to  the  lowest  level of security they both support.
               Use --show-tls to see a list of supported TLS ciphers.
+              A list l of allowable TLS ciphers delimited by a colon  (":").   If
+              you  require  a  high  level  of security, you may want to set this
+              parameter manually, to prevent a version rollback  attack  where  a
+              man-in-the-middle attacker tries to force two peers to negotiate to
+              the lowest level of security they both support.  Use --show-tls  to
+              see a list of supported TLS ciphers.
        --tls-timeout n
               Packet retransmit timeout on TLS control channel if no  acknowl‐
               edgment  from remote within n seconds (default=2).  When OpenVPN
               sends a control packet to its peer, it will expect to receive an
               acknowledgement  within  n  seconds  or  it  will retransmit the
               packet, subject to a  TCP-like  exponential  backoff  algorithm.
               This  parameter  only  applies to control channel packets.  Data
               channel packets (which carry encrypted tunnel  data)  are  never
               acknowledged, sequenced, or retransmitted by OpenVPN because the
               higher level network protocols running on top of the tunnel such
               as TCP expect this role to be left to them.
+              Packet  retransmit timeout on TLS control channel if no acknowledg‐
+              ment from remote within n seconds (default=2).  When OpenVPN  sends
+              a control packet to its peer, it will expect to receive an acknowl‐
+              edgement within n seconds or it will retransmit the packet, subject
+              to  a  TCP-like exponential backoff algorithm.  This parameter only
+              applies to control channel packets.  Data  channel  packets  (which
+              carry  encrypted tunnel data) are never acknowledged, sequenced, or
+              retransmitted by OpenVPN because the higher level network protocols
+              running  on  top  of  the tunnel such as TCP expect this role to be
+              left to them.
        --reneg-bytes n
               Renegotiate  data  channel  key  after  n bytes sent or received
               (disabled by default).  OpenVPN allows the lifetime of a key  to
               be  expressed as a number of bytes encrypted/decrypted, a number
               of packets, or a number of seconds.  A key renegotiation will be
+              Renegotiate data channel key after n bytes sent or  received  (dis‐
+              abled  by  default).   OpenVPN  allows  the lifetime of a key to be
+              expressed as a number of bytes  encrypted/decrypted,  a  number  of
+              packets,  or  a  number  of  seconds.   A key renegotiation will be
               forced if any of these three criteria are met by either peer.
        --reneg-pkts n
               Renegotiate  data  channel key after n packets sent and received
+              Renegotiate data channel key after  n  packets  sent  and  received
               (disabled by default).
 …
               Renegotiate data channel key after n seconds (default=3600).
+              When using dual-factor authentication, note  that  this  default
+              value  may  cause  the  end user to be challenged to reauthorize
+              once per hour.
+              Also, keep in mind that this option can  be  used  on  both  the
+              client  and  server,  and whichever uses the lower value will be
+              the one to trigger the renegotiation.  A common  mistake  is  to
+              set  --reneg-sec  to  a  higher  value  on  either the client or
+              server, while the other side of the connection  is  still  using
+              the  default  value of 3600 seconds, meaning that the renegotia‐
+              tion will still occur once per 3600 seconds.  The solution is to
+              increase --reneg-sec on both the client and server, or set it to
+on one side of the connection (to disable), and to your chosen
+              value on the other side.
+              When using dual-factor authentication, note that this default value
+              may cause the end user to be challenged  to  reauthorize  once  per
+              hour.
+              Also,  keep in mind that this option can be used on both the client
+              and server, and whichever uses the lower value will be the  one  to
+              trigger  the renegotiation.  A common mistake is to set --reneg-sec
+              to a higher value on either the client or server, while  the  other
+              side  of  the  connection  is still using the default value of 3600
+              seconds, meaning that the renegotiation will still occur  once  per
+  seconds.  The solution is to increase --reneg-sec on both the
+              client and server, or set it to 0 on one side of the connection (to
+              disable), and to your chosen value on the other side.
        --hand-window n
+              Handshake  Window  --  the  TLS-based key exchange must finalize
+              within n seconds of handshake initiation by any peer (default  =
+  seconds).   If  the handshake fails we will attempt to reset
+              our connection with our peer and try again.  Even in  the  event
+              of  handshake  failure we will still use our expiring key for up
+              to --tran-window seconds to maintain continuity of  transmission
+              of tunnel data.
+              Handshake Window -- the TLS-based key exchange must finalize within
+              n seconds of handshake initiation by any peer (default  =  60  sec‐
+              onds).  If the handshake fails we will attempt to reset our connec‐
+              tion with our peer and try again.  Even in the event  of  handshake
+              failure  we will still use our expiring key for up to --tran-window
+              seconds to maintain continuity of transmission of tunnel data.
        --tran-window n
               Transition  window  --  our  old  key can live this many seconds
               after a new a key renegotiation begins (default = 3600 seconds).
               This  feature  allows  for a graceful transition from old to new
               key, and removes the key renegotiation sequence from the  criti‐
               cal path of tunnel data forwarding.
+              Transition window -- our old key can live this many seconds after a
+              new a key renegotiation begins (default = 3600 seconds).  This fea‐
+              ture allows for a graceful transition from  old  to  new  key,  and
+              removes  the  key  renegotiation sequence from the critical path of
+              tunnel data forwarding.
        --single-session
               After  initially  connecting  to a remote peer, disallow any new
               connections.  Using this option means that a remote peer  cannot
               connect, disconnect, and then reconnect.
               If  the  daemon  is reset by a signal or --ping-restart, it will
               allow one new connection.
               --single-session can be used with --ping-exit or  --inactive  to
               create a single dynamic session that will exit when finished.
+              After initially connecting to a remote peer, disallow any new  con‐
+              nections.   Using  this option means that a remote peer cannot con‐
+              nect, disconnect, and then reconnect.
+              If the daemon is reset by a signal or --ping-restart, it will allow
+              one new connection.
+              --single-session can be used with --ping-exit or --inactive to cre‐
+              ate a single dynamic session that will exit when finished.
        --tls-exit
 …
        --tls-auth file [direction]
               Add an additional layer of HMAC authentication on top of the TLS
+              Add an additional layer of HMAC authentication on top  of  the  TLS
               control channel to protect against DoS attacks.
+              In a nutshell, --tls-auth enables a kind of "HMAC  firewall"  on
+              OpenVPN's  TCP/UDP port, where TLS control channel packets bear‐
+              ing an incorrect HMAC signature can be dropped immediately with‐
+              out response.
+              file  (required)  is  a key file which can be in one of two for‐
+              mats:
+              (1) An OpenVPN static key file generated by  --genkey  (required
+              if direction parameter is used).
+              (2)  A freeform passphrase file.  In this case the HMAC key will
+              be derived by taking a secure hash of this file, similar to  the
+              In  a  nutshell,  --tls-auth  enables  a kind of "HMAC firewall" on
+              OpenVPN's TCP/UDP port, where TLS control channel  packets  bearing
+              an  incorrect  HMAC  signature  can  be dropped immediately without
+              response.
+              file (required) is a key file which can be in one of two formats:
+              (1) An OpenVPN static key file generated by --genkey  (required  if
+              direction parameter is used).
+              (2)  A freeform passphrase file.  In this case the HMAC key will be
+              derived by taking a secure  hash  of  this  file,  similar  to  the
               md5sum(1) or sha1sum(1) commands.
+              OpenVPN  will  first  try  format  (1), and if the file fails to
+              parse as a static key file, format (2) will be used.
+              See the --secret option for more  information  on  the  optional
+              direction parameter.
+              --tls-auth is recommended when you are running OpenVPN in a mode
+              where it is listening for packets from any IP address,  such  as
+              when  --remote  is  not specified, or --remote is specified with
+              --float.
+              The rationale for this feature is as follows.   TLS  requires  a
+              multi-packet  exchange before it is able to authenticate a peer.
+              During this time before authentication,  OpenVPN  is  allocating
+              resources  (memory  and CPU) to this potential peer.  The poten‐
+              tial peer is also exposing many parts of OpenVPN and the OpenSSL
+              library  to  the packets it is sending.  Most successful network
+              attacks today seek to either exploit bugs in programs  (such  as
+              buffer  overflow  attacks) or force a program to consume so many
+              resources that it becomes unusable.  Of course the first line of
+              defense  is always to produce clean, well-audited code.  OpenVPN
+              has been written with buffer overflow attack prevention as a top
+              priority.   But  as  history  has shown, many of the most widely
+              used network applications have, from time  to  time,  fallen  to
+              buffer overflow attacks.
+              So  as  a  second  line  of defense, OpenVPN offers this special
+              layer of authentication on top of the  TLS  control  channel  so
+              that  every packet on the control channel is authenticated by an
+              HMAC signature and a unique ID for replay protection.  This sig‐
+              nature  will  also  help protect against DoS (Denial of Service)
+              attacks.  An important rule of thumb in  reducing  vulnerability
+              to  DoS  attacks is to minimize the amount of resources a poten‐
+              tial, but as yet unauthenticated, client is able to consume.
+              --tls-auth does this by signing every TLS control channel packet
+              with  an HMAC signature, including packets which are sent before
+              the TLS level has had a chance to authenticate  the  peer.   The
+              result  is  that  packets  without  the correct signature can be
+              dropped immediately upon reception, before they have a chance to
+              consume  additional system resources such as by initiating a TLS
+              handshake.   --tls-auth  can  be  strengthened  by  adding   the
+              --replay-persist option which will keep OpenVPN's replay protec‐
+              tion state in a file so that it is not lost across restarts.
+              It should be emphasized that this feature is optional  and  that
+              the  passphrase/key file used with --tls-auth gives a peer noth‐
+              ing more than the power to initiate a TLS handshake.  It is  not
+              used to encrypt or authenticate any tunnel data.
+              OpenVPN  will  first try format (1), and if the file fails to parse
+              as a static key file, format (2) will be used.
+              See the --secret option for more information on the optional direc‐
+              tion parameter.
+              --tls-auth  is  recommended  when you are running OpenVPN in a mode
+              where it is listening for packets from any IP address, such as when
+              --remote is not specified, or --remote is specified with --float.
+              The  rationale  for  this  feature  is  as follows.  TLS requires a
+              multi-packet exchange before it is able  to  authenticate  a  peer.
+              During  this  time  before  authentication,  OpenVPN  is allocating
+              resources (memory and CPU) to this potential peer.   The  potential
+              peer is also exposing many parts of OpenVPN and the OpenSSL library
+              to the packets it is  sending.   Most  successful  network  attacks
+              today seek to either exploit bugs in programs (such as buffer over‐
+              flow attacks) or force a program to consume so many resources  that
+              it becomes unusable.  Of course the first line of defense is always
+              to produce clean, well-audited code.  OpenVPN has been written with
+              buffer  overflow  attack prevention as a top priority.  But as his‐
+              tory has shown, many of the most widely used  network  applications
+              have, from time to time, fallen to buffer overflow attacks.
+              So  as  a second line of defense, OpenVPN offers this special layer
+              of authentication on top of the TLS control channel so  that  every
+              packet on the control channel is authenticated by an HMAC signature
+              and a unique ID for replay protection.  This  signature  will  also
+              help protect against DoS (Denial of Service) attacks.  An important
+              rule of thumb in reducing vulnerability to DoS attacks is to  mini‐
+              mize  the  amount  of resources a potential, but as yet unauthenti‐
+              cated, client is able to consume.
+              --tls-auth does this by signing every TLS  control  channel  packet
+              with an HMAC signature, including packets which are sent before the
+              TLS level has had a chance to authenticate the peer.  The result is
+              that  packets  without the correct signature can be dropped immedi‐
+              ately upon reception, before they have a chance  to  consume  addi‐
+              tional  system  resources  such  as  by initiating a TLS handshake.
+              --tls-auth can  be  strengthened  by  adding  the  --replay-persist
+              option  which will keep OpenVPN's replay protection state in a file
+              so that it is not lost across restarts.
+              It should be emphasized that this feature is optional and that  the
+              passphrase/key  file used with --tls-auth gives a peer nothing more
+              than the power to initiate a TLS handshake.   It  is  not  used  to
+              encrypt or authenticate any tunnel data.
        --askpass [file]
+              Get  certificate  password from console or file before we daemo‐
+              nize.
+              For the extremely security conscious, it is possible to  protect
+              your  private  key  with  a password.  Of course this means that
+              every time the OpenVPN daemon is started you must  be  there  to
+              type  the  password.   The  --askpass option allows you to start
+              OpenVPN from the command line.  It will query you for a password
+              before  it daemonizes.  To protect a private key with a password
+              you should omit the -nodes option when you use the openssl  com‐
+              mand line tool to manage certificates and private keys.
+              If  file  is specified, read the password from the first line of
+              file.  Keep in mind that storing your password in a  file  to  a
+              certain  extent invalidates the extra security provided by using
+              an encrypted key (Note: OpenVPN will only read passwords from  a
+              file  if  it has been built with the --enable-password-save con‐
+              figure option, or on Windows by defining ENABLE_PASSWORD_SAVE in
+              win/settings.in).
+              Get certificate password from console or file before we daemonize.
+              For  the  extremely  security  conscious, it is possible to protect
+              your private key with a password.  Of course this means that  every
+              time  the  OpenVPN  daemon is started you must be there to type the
+              password.  The --askpass option allows you to  start  OpenVPN  from
+              the  command line.  It will query you for a password before it dae‐
+              monizes.  To protect a private key with a password you should  omit
+              the  -nodes  option  when  you use the openssl command line tool to
+              manage certificates and private keys.
+              If file is specified, read the password  from  the  first  line  of
+              file.   Keep in mind that storing your password in a file to a cer‐
+              tain extent invalidates the extra security  provided  by  using  an
+              encrypted  key  (Note: OpenVPN will only read passwords from a file
+              if it has been  built  with  the  --enable-password-save  configure
+              option,  or on Windows by defining ENABLE_PASSWORD_SAVE in win/set‐
+              tings.in).
        --auth-nocache
               Don't  cache --askpass or --auth-user-pass username/passwords in
+              Don't cache --askpass  or  --auth-user-pass  username/passwords  in
               virtual memory.
               If specified, this directive will cause OpenVPN  to  immediately
               forget  username/password  inputs  after  they  are  used.  As a
               result, when OpenVPN needs a username/password, it  will  prompt
               for  input  from  stdin,  which may be multiple times during the
               duration of an OpenVPN session.
               This directive does not affect the  --http-proxy  username/pass‐
               word.  It is always cached.
+              If specified, this directive will cause OpenVPN to immediately for‐
+              get username/password inputs after they are  used.   As  a  result,
+              when  OpenVPN  needs  a username/password, it will prompt for input
+              from stdin, which may be multiple times during the duration  of  an
+              OpenVPN session.
+              This  directive does not affect the --http-proxy username/password.
+              It is always cached.
        --tls-verify cmd
               Run command cmd to verify the X509 name of a pending TLS connec‐
               tion that has otherwise passed all other tests of  certification
               (except  for  revocation via --crl-verify directive; the revoca‐
               tion test occurs after the --tls-verify test).
               cmd should return 0 to allow the TLS handshake to proceed, or  1
               to fail.
               cmd  consists  of  a  path  to  script  (or executable program),
               optionally followed by arguments. The path and arguments may  be
               single-  or  double-quoted and/or escaped using a backslash, and
               should be separated by one or more spaces.
               When cmd is executed two arguments are appended after any  argu‐
               ments specified in cmd , as follows:
+              Run command cmd to verify the X509 name of a pending TLS connection
+              that  has otherwise passed all other tests of certification (except
+              for revocation via  --crl-verify  directive;  the  revocation  test
+              occurs after the --tls-verify test).
+              cmd  should return 0 to allow the TLS handshake to proceed, or 1 to
+              fail.
+              cmd consists of a path to script (or executable  program),  option‐
+              ally  followed  by arguments. The path and arguments may be single-
+              or double-quoted and/or escaped using a backslash,  and  should  be
+              separated by one or more spaces.
+              When cmd is executed two arguments are appended after any arguments
+              specified in cmd , as follows:
               cmd certificate_depth subject
               These arguments are, respectively, the current certificate depth
+              These arguments are, respectively, the  current  certificate  depth
               and the X509 common name (cn) of the peer.
               This feature is useful if the peer you want to trust has a  cer‐
               tificate  which  was  signed by a certificate authority who also
               signed many other certificates, where you don't necessarily want
               to  trust  all of them, but rather be selective about which peer
               certificate you will accept.  This feature allows you to write a
               script which will test the X509 name on a certificate and decide
               whether or not it should be accepted.  For a simple perl  script
               which  will  test  the common name field on the certificate, see
               the file verify-cn in the OpenVPN distribution.
               See the "Environmental Variables" section below  for  additional
+              This feature is useful if the peer you want to trust has a certifi‐
+              cate which was signed by a certificate authority  who  also  signed
+              many  other certificates, where you don't necessarily want to trust
+              all of them, but rather be selective about which  peer  certificate
+              you  will  accept.  This feature allows you to write a script which
+              will test the X509 name on a certificate and decide whether or  not
+              it  should  be  accepted.  For a simple perl script which will test
+              the common name field on the certificate, see the file verify-cn in
+              the OpenVPN distribution.
+              See  the  "Environmental  Variables"  section  below for additional
               parameters passed as environmental variables.
        --tls-export-cert directory
               Store  the certificates the clients uses upon connection to this
               directory. This will be done before --tls-verify is called.  The
               certificates  will use a temporary name and will be deleted when
               the tls-verify script returns.  The file name used for the  cer‐
               tificate is available via the peer_cert environment variable.
+              Store the certificates the clients uses  upon  connection  to  this
+              directory.  This  will  be done before --tls-verify is called.  The
+              certificates will use a temporary name and will be deleted when the
+              tls-verify  script returns.  The file name used for the certificate
+              is available via the peer_cert environment variable.
        --x509-username-field fieldname
               Field  in  x509  certificate  subject  to  be  used  as username
               (default=CN).  Fieldname will  be  uppercased  before  matching.
               When  this  option  is  used, the --tls-remote option will match
+              Field  in  x509  certificate  subject  to  be  used   as   username
+              (default=CN).   Fieldname  will be uppercased before matching. When
+              this option is used, the --verify-x509-username option  will  match
               against the chosen fieldname instead of the CN.
+       --tls-remote name
+              Accept connections only from a host with  X509  name  or  common
+              name  equal  to  name.  The remote host must also pass all other
+              tests of verification.
+              NOTE: Because tls-remote may test against a common name  prefix,
+              only use this option when you are using OpenVPN with a custom CA
+              certificate that is under your control.  Never use  this  option
+              when  your client certificates are signed by a third party, such
+              as a commercial web CA.
+              Name can also be a common name prefix, for example if you want a
+              client  to  only  accept  connections to "Server-1", "Server-2",
+              etc., you can simply use --tls-remote Server
+              Using a common name prefix is a useful alternative to managing a
+              CRL (Certificate Revocation List) on the client, since it allows
+              the client to refuse all certificates except for  those  associ‐
+              ated with designated servers.
+              --tls-remote is a useful replacement for the --tls-verify option
+              to verify the remote  host,  because  --tls-remote  works  in  a
+              --chroot environment too.
+       --tls-remote name (DEPRECATED)
+              Accept  connections  only from a host with X509 name or common name
+              equal to name.  The remote host must also pass all other  tests  of
+              verification.
+              NOTE:  Because  tls-remote  may  test against a common name prefix,
+              only use this option when you are using OpenVPN with  a  custom  CA
+              certificate that is under your control.  Never use this option when
+              your client certificates are signed by a third  party,  such  as  a
+              commercial web CA.
+              Name  can  also  be a common name prefix, for example if you want a
+              client to only accept connections to "Server-1", "Server-2",  etc.,
+              you can simply use --tls-remote Server
+              Using  a  common  name prefix is a useful alternative to managing a
+              CRL (Certificate Revocation List) on the client,  since  it  allows
+              the  client  to refuse all certificates except for those associated
+              with designated servers.
+              --tls-remote is a useful replacement for the --tls-verify option to
+              verify  the  remote  host, because --tls-remote works in a --chroot
+              environment too.
+              Please also note: This  option  is  now  deprecated.   It  will  be
+              removed  either  in  OpenVPN v2.4 or v2.5.  So please make sure you
+              support the new X.509 name formatting described with the  --compat-
+              names option as soon as possible by updating your configurations to
+              use --verify-x509-name instead.
+       --verify-x509-name name type
+              Accept connections only if a host's X.509 name is  equal  to  name.
+              The remote host must also pass all other tests of verification.
+              Which  X.509  name  is  compared  to name depends on the setting of
+              type.  type can be "subject"  to  match  the  complete  subject  DN
+              (default),  "name" to match a subject RDN or "name-prefix" to match
+              a subject RDN prefix.  Which RDN is verified as name depends on the
+              --x509-username-field  option.  But  it defaults to the common name
+              (CN), e.g. a certificate with a subject DN "C=KG, ST=NA, L=Bishkek,
+              CN=Server-1" would be matched by:
+              --verify-x509-name 'C=KG, ST=NA, L=Bishkek, CN=Server-1' and --ver‐
+              ify-x509-name Server-1 name or  you  could  use  --verify-x509-name
+              Server- name-prefix if you want a client to only accept connections
+              to "Server-1", "Server-2", etc.
+              --verify-x509-name is a useful  replacement  for  the  --tls-verify
+              option  to verify the remote host, because --verify-x509-name works
+              in a --chroot environment without any dependencies.
+              Using a name prefix is a useful alternative to managing a CRL (Cer‐
+              tificate Revocation List) on the client, since it allows the client
+              to refuse all certificates except for those associated with  desig‐
+              nated servers.
+              NOTE:  Test  against  a name prefix only when you are using OpenVPN
+              with a custom CA certificate that is under your control.  Never use
+              this  option  with type "name-prefix" when your client certificates
+              are signed by a third party, such as a commercial web CA.
        --x509-track attribute
               Save peer X509 attribute value in environment for use by plugins
               and management interface.  Prepend a '+' to  attribute  to  save
               values  from  full  cert  chain.   Values  will  be  encoded  as
               X509_<depth>_<attribute>=<value>.  Multiple --x509-track options
               can be defined to track multiple attributes.  Not available with
+              Save peer X509 attribute value in environment for  use  by  plugins
+              and  management interface.  Prepend a '+' to attribute to save val‐
+              ues  from  full  cert   chain.    Values   will   be   encoded   as
+              X509_<depth>_<attribute>=<value>.   Multiple  --x509-track  options
+              can be defined to track multiple attributes.   Not  available  with
               PolarSSL.
        --ns-cert-type client|server
               Require that  peer  certificate  was  signed  with  an  explicit
               nsCertType designation of "client" or "server".
               This is a useful security option for clients, to ensure that the
+              Require  that  peer certificate was signed with an explicit nsCert‐
+              Type designation of "client" or "server".
+              This is a useful security option for clients, to  ensure  that  the
               host they connect with is a designated server.
+              See the easy-rsa/build-key-server script for an example  of  how
+              to  generate  a  certificate  with  the  nsCertType field set to
+              "server".
+              If the server certificate's nsCertType field is set to "server",
+              See  the  easy-rsa/build-key-server script for an example of how to
+              generate a certificate with the nsCertType field set to "server".
+              If the server certificate's nsCertType field is  set  to  "server",
               then the clients can verify this with --ns-cert-type server.
+              This  is  an  important security precaution to protect against a
+              man-in-the-middle attack where an authorized client attempts  to
+              connect  to  another  client  by  impersonating the server.  The
+              attack is easily prevented by having clients verify  the  server
+              certificate  using  any  one of --ns-cert-type, --tls-remote, or
+              --tls-verify.
+              This  is an important security precaution to protect against a man-
+              in-the-middle attack where an authorized client attempts to connect
+              to  another client by impersonating the server.  The attack is eas‐
+              ily prevented by having clients verify the server certificate using
+              any one of --ns-cert-type, --verify-x509-name, or --tls-verify.
        --remote-cert-ku v...
               Require that peer certificate was signed with  an  explicit  key
+              Require  that  peer  certificate  was  signed  with an explicit key
               usage.
               This is a useful security option for clients, to ensure that the
+              This is a useful security option for clients, to  ensure  that  the
               host they connect to is a designated server.
               The key usage should be encoded in hex, more than one key  usage
               can be specified.
+              The key usage should be encoded in hex, more than one key usage can
+              be specified.
        --remote-cert-eku oid
               Require  that  peer  certificate  was  signed  with  an explicit
               extended key usage.
               This is a useful security option for clients, to ensure that the
+              Require that peer certificate was signed with an explicit  extended
+              key usage.
+              This  is  a  useful security option for clients, to ensure that the
               host they connect to is a designated server.
               The  extended  key  usage  should be encoded in oid notation, or
+              The extended key usage  should  be  encoded  in  oid  notation,  or
               OpenSSL symbolic representation.
        --remote-cert-tls client|server
               Require that peer certificate was signed with  an  explicit  key
               usage and extended key usage based on RFC3280 TLS rules.
               This is a useful security option for clients, to ensure that the
+              Require that peer certificate was signed with an explicit key usage
+              and extended key usage based on RFC3280 TLS rules.
+              This is a useful security option for clients, to  ensure  that  the
               host they connect to is a designated server.
+              The --remote-cert-tls client option is equivalent  to  --remote-
+              cert-ku  80  08 88 --remote-cert-eku "TLS Web Client Authentica‐
+              tion"
+              The --remote-cert-tls client option is equivalent to --remote-cert-
+              ku 80 08 88 --remote-cert-eku "TLS Web Client Authentication"
               The key usage is digitalSignature and/or keyAgreement.
               The --remote-cert-tls server option is equivalent  to  --remote-
               cert-ku a0 88 --remote-cert-eku "TLS Web Server Authentication"
               The key usage is digitalSignature and ( keyEncipherment or keyA‐
+              The --remote-cert-tls server option is equivalent to --remote-cert-
+              ku a0 88 --remote-cert-eku "TLS Web Server Authentication"
+              The  key  usage  is digitalSignature and ( keyEncipherment or keyA‐
               greement ).
+              This is an important security precaution to  protect  against  a
+              man-in-the-middle  attack where an authorized client attempts to
+              connect to another client  by  impersonating  the  server.   The
+              attack  is  easily prevented by having clients verify the server
+              certificate using any one of --remote-cert-tls, --tls-remote, or
+              --tls-verify.
+              This is an important security precaution to protect against a  man-
+              in-the-middle attack where an authorized client attempts to connect
+              to another client by impersonating the server.  The attack is  eas‐
+              ily prevented by having clients verify the server certificate using
+              any one of --remote-cert-tls, --verify-x509-name, or --tls-verify.
        --crl-verify crl ['dir']
               Check peer certificate against the file crl in PEM format.
               A  CRL  (certificate  revocation list) is used when a particular
               key is compromised but when the overall PKI is still intact.
               Suppose you had a PKI consisting of a CA, root certificate,  and
               a number of client certificates.  Suppose a laptop computer con‐
               taining a client key and certificate was stolen.  By adding  the
               stolen certificate to the CRL file, you could reject any connec‐
               tion which attempts to use  it,  while  preserving  the  overall
               integrity of the PKI.
               The  only  time when it would be necessary to rebuild the entire
               PKI from scratch would be if the root certificate key itself was
               compromised.
               If  the  optional dir flag is specified, enable a different mode
               where crl is a  directory  containing  files  named  as  revoked
               serial  numbers  (the files may be empty, the contents are never
               read).  If a client requests a connection, where the client cer‐
               tificate  serial  number  (decimal string) is the name of a file
               present in the directory, it will be rejected.
+              A CRL (certificate revocation list) is used when a  particular  key
+              is compromised but when the overall PKI is still intact.
+              Suppose  you  had a PKI consisting of a CA, root certificate, and a
+              number of client certificates.  Suppose a laptop computer  contain‐
+              ing  a client key and certificate was stolen.  By adding the stolen
+              certificate to the CRL file, you could reject any connection  which
+              attempts  to  use it, while preserving the overall integrity of the
+              PKI.
+              The only time when it would be necessary to rebuild the entire  PKI
+              from  scratch  would be if the root certificate key itself was com‐
+              promised.
+              If the optional dir flag is  specified,  enable  a  different  mode
+              where  crl  is a directory containing files named as revoked serial
+              numbers (the files may be empty, the contents are never read).   If
+              a client requests a connection, where the client certificate serial
+              number (decimal string) is the name of a file present in the direc‐
+              tory, it will be rejected.
    SSL Library information:
        --show-ciphers
               (Standalone) Show all cipher algorithms to use with the --cipher
+              (Standalone)  Show  all  cipher algorithms to use with the --cipher
               option.
        --show-digests
               (Standalone)  Show all message digest algorithms to use with the
+              (Standalone) Show all message digest algorithms  to  use  with  the
               --auth option.
        --show-tls
               (Standalone) Show all TLS ciphers (TLS used only  as  a  control
               channel).   The  TLS ciphers will be sorted from highest prefer‐
               ence (most secure) to lowest.
+              (Standalone) Show all TLS ciphers (TLS used only as a control chan‐
+              nel).  The TLS ciphers will be sorted from highest preference (most
+              secure) to lowest.
        --show-engines
               (Standalone)  Show  currently  available  hardware-based  crypto
               acceleration engines supported by the OpenSSL library.
+              (Standalone)  Show currently available hardware-based crypto accel‐
+              eration engines supported by the OpenSSL library.
    Generate a random key:
 …
        --genkey
+              (Standalone)  Generate  a  random  key  to  be  used as a shared
+              secret, for use with the --secret option.   This  file  must  be
+              shared  with the peer over a pre-existing secure channel such as
+              scp(1)
+              (Standalone) Generate a random key to be used as a  shared  secret,
+              for  use  with  the --secret option.  This file must be shared with
+              the peer over a pre-existing secure channel such as scp(1)
        --secret file
 …
    TUN/TAP persistent tunnel config mode:
        Available with linux 2.4.7+.  These options comprise a standalone  mode
        of OpenVPN which can be used to create and delete persistent tunnels.
+       Available with linux 2.4.7+.  These options comprise a standalone mode  of
+       OpenVPN which can be used to create and delete persistent tunnels.
        --mktun
+              (Standalone)  Create a persistent tunnel on platforms which sup‐
+              port them such as Linux.  Normally TUN/TAP  tunnels  exist  only
+              for  the period of time that an application has them open.  This
+              option takes advantage of the TUN/TAP driver's ability to  build
+              persistent  tunnels that live through multiple instantiations of
+              OpenVPN and die only when they are deleted  or  the  machine  is
+              rebooted.
+              One  of the advantages of persistent tunnels is that they elimi‐
+              nate the need for separate --up and --down scripts  to  run  the
+              appropriate  ifconfig(8)  and route(8) commands.  These commands
+              can be placed in the the same shell script which starts or  ter‐
+              minates an OpenVPN session.
+              Another  advantage is that open connections through the TUN/TAP-
+              based tunnel will not be reset if  the  OpenVPN  peer  restarts.
+              This can be useful to provide uninterrupted connectivity through
+              the tunnel in the event of a DHCP reset of the peer's public  IP
+              address (see the --ipchange option above).
+              One  disadvantage  of persistent tunnels is that it is harder to
+              automatically configure their  MTU  value  (see  --link-mtu  and
+              --tun-mtu above).
+              On some platforms such as Windows, TAP-Win32 tunnels are persis‐
+              tent by default.
+              (Standalone)  Create a persistent tunnel on platforms which support
+              them such as Linux.  Normally TUN/TAP tunnels exist  only  for  the
+              period  of  time  that  an  application has them open.  This option
+              takes advantage of the TUN/TAP driver's ability to build persistent
+              tunnels  that  live  through multiple instantiations of OpenVPN and
+              die only when they are deleted or the machine is rebooted.
+              One of the advantages of persistent tunnels is that they  eliminate
+              the  need for separate --up and --down scripts to run the appropri‐
+              ate ifconfig(8) and  route(8)  commands.   These  commands  can  be
+              placed  in  the the same shell script which starts or terminates an
+              OpenVPN session.
+              Another advantage is that open  connections  through  the  TUN/TAP-
+              based  tunnel will not be reset if the OpenVPN peer restarts.  This
+              can be useful to provide  uninterrupted  connectivity  through  the
+              tunnel in the event of a DHCP reset of the peer's public IP address
+              (see the --ipchange option above).
+              One disadvantage of persistent tunnels is  that  it  is  harder  to
+              automatically  configure their MTU value (see --link-mtu and --tun-
+              mtu above).
+              On some platforms such as Windows, TAP-Win32 tunnels are persistent
+              by default.
        --rmtun
 …
    Windows-Specific Options:
        --win-sys path
+              Set the Windows system directory pathname to  use  when  looking
+              for  system  executables  such  as  route.exe and netsh.exe.  By
+              default, if this directive is not specified,  OpenVPN  will  use
+              the SystemRoot environment variable.
+              This  option have changed behaviour in OpenVPN 2.3.  Earlier you
+              had to define --win-sys env to use  the  SystemRoot  environment
+              variable,  otherwise  it  defaulted  to  C:\WINDOWS.   It is not
+              needed to use the env keyword any more,  and  it  will  just  be
+              ignored.  A warning is logged when this is found in the configu‐
+              ration file.
+              Set  the  Windows system directory pathname to use when looking for
+              system executables such as route.exe and netsh.exe.  By default, if
+              this  directive  is  not specified, OpenVPN will use the SystemRoot
+              environment variable.
+              This option have changed behaviour in OpenVPN 2.3.  Earlier you had
+              to define --win-sys env to use the SystemRoot environment variable,
+              otherwise it defaulted to C:\WINDOWS.  It is not needed to use  the
+              env  keyword  any  more,  and it will just be ignored. A warning is
+              logged when this is found in the configuration file.
        --ip-win32 method
+              When using --ifconfig on Windows, set the TAP-Win32  adapter  IP
+              address  and netmask using method.  Don't use this option unless
+              you are also using --ifconfig.
+              manual -- Don't set the IP  address  or  netmask  automatically.
+              Instead output a message to the console telling the user to con‐
+              figure the adapter manually and indicating the IP/netmask  which
+              OpenVPN expects the adapter to be set to.
+              dynamic  [offset]  [lease-time]  --  Automatically  set  the  IP
+              address and netmask by replying to DHCP query messages generated
+              by  the  kernel.   This mode is probably the "cleanest" solution
+              for setting the TCP/IP properties since it uses  the  well-known
+              DHCP  protocol.  There are, however, two prerequisites for using
+              this mode: (1) The TCP/IP properties for the  TAP-Win32  adapter
+              must  be  set  to  "Obtain an IP address automatically," and (2)
+              OpenVPN needs to claim an IP address in the subnet  for  use  as
+              the  virtual DHCP server address.  By default in --dev tap mode,
+              OpenVPN will take the normally unused first address in the  sub‐
+              net.   For  example,  if  your  subnet  is  192.168.4.0  netmask
+.255.255.0, then OpenVPN will take the IP address 192.168.4.0
+              to  use  as the virtual DHCP server address.  In --dev tun mode,
+              OpenVPN will cause the DHCP server to masquerade as if  it  were
+              coming  from the remote endpoint.  The optional offset parameter
+              is an integer which is > -256 and < 256 and which defaults to 0.
+              If offset is positive, the DHCP server will masquerade as the IP
+              address at network address + offset.  If offset is negative, the
+              DHCP  server  will  masquerade  as  the  IP address at broadcast
+              address + offset.  The Windows ipconfig /all command can be used
+              to show what Windows thinks the DHCP server address is.  OpenVPN
+              will "claim" this address, so make sure to use a  free  address.
+              Having  said  that,  different OpenVPN instantiations, including
+              different ends of the same connection, can share the  same  vir‐
+              tual DHCP server address.  The lease-time parameter controls the
+              lease time  of  the  DHCP  assignment  given  to  the  TAP-Win32
+              adapter,  and is denoted in seconds.  Normally a very long lease
+              time is preferred because it prevents routes involving the  TAP-
+              Win32  adapter  from  being  lost when the system goes to sleep.
+              The default lease time is one year.
+              netsh -- Automatically set the IP address and netmask using  the
+              Windows  command-line  "netsh"  command.  This method appears to
+              work correctly on Windows XP but not Windows 2000.
+              ipapi -- Automatically set the IP address and netmask using  the
+              Windows IP Helper API.  This approach does not have ideal seman‐
+              tics, though testing has indicated that it works okay  in  prac‐
+              tice.   If  you  use this option, it is best to leave the TCP/IP
+              properties for the TAP-Win32 adapter  in  their  default  state,
+              i.e. "Obtain an IP address automatically."
+              adaptive -- (Default) Try dynamic method initially and fail over
+              to netsh if the DHCP negotiation with the TAP-Win32 adapter does
+              not  succeed  in  20  seconds.  Such failures have been known to
+              occur when certain third-party firewall  packages  installed  on
+              the  client  machine block the DHCP negotiation used by the TAP-
+              Win32 adapter.  Note that if the netsh failover occurs, the TAP-
+              Win32  adapter  TCP/IP  properties  will  be  reset from DHCP to
+              static, and this will cause future OpenVPN  startups  using  the
+              adaptive  mode  to  use  netsh  immediately,  rather than trying
+              dynamic first.  To "unstick" the adaptive mode from using netsh,
+              run  OpenVPN at least once using the dynamic mode to restore the
+              TAP-Win32 adapter TCP/IP properties to a DHCP configuration.
+              When using --ifconfig on Windows,  set  the  TAP-Win32  adapter  IP
+              address and netmask using method.  Don't use this option unless you
+              are also using --ifconfig.
+              manual -- Don't  set  the  IP  address  or  netmask  automatically.
+              Instead output a message to the console telling the user to config‐
+              ure the adapter manually and indicating the IP/netmask which  Open‐
+              VPN expects the adapter to be set to.
+              dynamic  [offset]  [lease-time] -- Automatically set the IP address
+              and netmask by replying to DHCP query  messages  generated  by  the
+              kernel.   This mode is probably the "cleanest" solution for setting
+              the TCP/IP properties since it uses the well-known  DHCP  protocol.
+              There  are, however, two prerequisites for using this mode: (1) The
+              TCP/IP properties for the TAP-Win32 adapter must be set to  "Obtain
+              an  IP address automatically," and (2) OpenVPN needs to claim an IP
+              address in the subnet for use as the virtual DHCP  server  address.
+              By default in --dev tap mode, OpenVPN will take the normally unused
+              first address in the  subnet.   For  example,  if  your  subnet  is
+.168.4.0  netmask  255.255.255.0,  then OpenVPN will take the IP
+              address 192.168.4.0 to use as the virtual DHCP server address.   In
+              --dev tun mode, OpenVPN will cause the DHCP server to masquerade as
+              if it were coming from the remote endpoint.   The  optional  offset
+              parameter  is  an  integer  which  is  >  -256  and < 256 and which
+              defaults to 0.  If offset is positive, the DHCP  server  will  mas‐
+              querade  as  the IP address at network address + offset.  If offset
+              is negative, the DHCP server will masquerade as the IP  address  at
+              broadcast  address + offset.  The Windows ipconfig /all command can
+              be used to show what Windows thinks the  DHCP  server  address  is.
+              OpenVPN  will  "claim"  this  address,  so  make sure to use a free
+              address.   Having  said  that,  different  OpenVPN  instantiations,
+              including different ends of the same connection, can share the same
+              virtual DHCP server address.  The lease-time parameter controls the
+              lease  time  of the DHCP assignment given to the TAP-Win32 adapter,
+              and is denoted in seconds.  Normally a very long lease time is pre‐
+              ferred  because  it prevents routes involving the TAP-Win32 adapter
+              from being lost when the system goes to sleep.  The  default  lease
+              time is one year.
+              netsh  --  Automatically  set  the IP address and netmask using the
+              Windows command-line "netsh" command.  This method appears to  work
+              correctly on Windows XP but not Windows 2000.
+              ipapi  --  Automatically  set  the IP address and netmask using the
+              Windows IP Helper API.  This approach does not  have  ideal  seman‐
+              tics,  though testing has indicated that it works okay in practice.
+              If you use this option, it is best to leave the  TCP/IP  properties
+              for  the  TAP-Win32 adapter in their default state, i.e. "Obtain an
+              IP address automatically."
+              adaptive -- (Default) Try dynamic method initially and fail over to
+              netsh  if  the DHCP negotiation with the TAP-Win32 adapter does not
+              succeed in 20 seconds.  Such failures have been known to occur when
+              certain  third-party  firewall  packages  installed  on  the client
+              machine block the DHCP negotiation used by the  TAP-Win32  adapter.
+              Note  that  if  the  netsh  failover  occurs, the TAP-Win32 adapter
+              TCP/IP properties will be reset from DHCP to static, and this  will
+              cause  future OpenVPN startups using the adaptive mode to use netsh
+              immediately, rather than trying dynamic first.   To  "unstick"  the
+              adaptive mode from using netsh, run OpenVPN at least once using the
+              dynamic mode to restore the TAP-Win32 adapter TCP/IP properties  to
+              a DHCP configuration.
        --route-method m
               Which method m to use for adding routes on Windows?
               adaptive (default) -- Try IP helper API first.  If  that  fails,
               fall back to the route.exe shell command.
+              adaptive (default) -- Try IP helper API first.  If that fails, fall
+              back to the route.exe shell command.
               ipapi -- Use IP helper API.
               exe -- Call the route.exe shell command.
        --dhcp-option type [parm]
               Set  extended  TAP-Win32  TCP/IP  properties,  must be used with
               --ip-win32 dynamic or --ip-win32 adaptive.  This option  can  be
               used  to  set  additional  TCP/IP  properties  on  the TAP-Win32
               adapter, and is particularly useful for configuring  an  OpenVPN
               client to access a Samba server across the VPN.
+              Set extended TAP-Win32 TCP/IP properties, must be used  with  --ip-
+              win32  dynamic  or --ip-win32 adaptive.  This option can be used to
+              set additional TCP/IP properties on the TAP-Win32 adapter,  and  is
+              particularly  useful  for configuring an OpenVPN client to access a
+              Samba server across the VPN.
               DOMAIN name -- Set Connection-specific DNS Suffix.
               DNS addr -- Set primary domain name server address.  Repeat this
+              DNS addr -- Set primary domain name server  address.   Repeat  this
               option to set secondary DNS server addresses.
+              WINS addr -- Set  primary  WINS  server  address  (NetBIOS  over
+              TCP/IP  Name  Server).  Repeat this option to set secondary WINS
+              server addresses.
+              NBDD addr -- Set  primary  NBDD  server  address  (NetBIOS  over
+              TCP/IP  Datagram  Distribution Server) Repeat this option to set
+              secondary NBDD server addresses.
+              NTP addr -- Set primary NTP server address (Network Time  Proto‐
+              col).  Repeat this option to set secondary NTP server addresses.
+              NBT  type  --  Set  NetBIOS  over  TCP/IP  Node  type.  Possible
+              options: 1 = b-node (broadcasts),  2  =  p-node  (point-to-point
+              name queries to a WINS server), 4 = m-node (broadcast then query
+              name server), and 8 = h-node (query  name  server,  then  broad‐
+              cast).
+              NBS  scope-id  -- Set NetBIOS over TCP/IP Scope. A NetBIOS Scope
+              ID provides an extended naming  service  for  the  NetBIOS  over
+              TCP/IP  (Known  as NBT) module. The primary purpose of a NetBIOS
+              scope ID is to isolate NetBIOS traffic on a  single  network  to
+              only  those  nodes  with the same NetBIOS scope ID.  The NetBIOS
+              scope ID is a character string that is appended to  the  NetBIOS
+              name.  The  NetBIOS scope ID on two hosts must match, or the two
+              hosts will not be able to communicate. The NetBIOS Scope ID also
+              allows  computers  to  use  the same computer name, as they have
+              different scope IDs. The Scope ID becomes a part of the  NetBIOS
+              name,  making  the  name  unique.   (This description of NetBIOS
+              scopes courtesy of NeonSurge@abyss.com)
+              WINS  addr  -- Set primary WINS server address (NetBIOS over TCP/IP
+              Name Server).  Repeat this option  to  set  secondary  WINS  server
+              addresses.
+              NBDD  addr  -- Set primary NBDD server address (NetBIOS over TCP/IP
+              Datagram Distribution Server) Repeat this option to  set  secondary
+              NBDD server addresses.
+              NTP addr -- Set primary NTP server address (Network Time Protocol).
+              Repeat this option to set secondary NTP server addresses.
+              NBT type -- Set NetBIOS over TCP/IP Node type.  Possible options: 1
+              = b-node (broadcasts), 2 = p-node (point-to-point name queries to a
+              WINS server), 4 = m-node (broadcast then query name server), and  8
+              = h-node (query name server, then broadcast).
+              NBS  scope-id  -- Set NetBIOS over TCP/IP Scope. A NetBIOS Scope ID
+              provides an extended naming service for  the  NetBIOS  over  TCP/IP
+              (Known as NBT) module. The primary purpose of a NetBIOS scope ID is
+              to isolate NetBIOS traffic on a single network to only those  nodes
+              with  the same NetBIOS scope ID.  The NetBIOS scope ID is a charac‐
+              ter string that is appended to the NetBIOS name. The NetBIOS  scope
+              ID  on  two  hosts must match, or the two hosts will not be able to
+              communicate. The NetBIOS Scope ID also allows computers to use  the
+              same  computer name, as they have different scope IDs. The Scope ID
+              becomes a part of the NetBIOS name, making the name unique.   (This
+              description of NetBIOS scopes courtesy of NeonSurge@abyss.com)
               DISABLE-NBT -- Disable Netbios-over-TCP/IP.
+              Note that if --dhcp-option is pushed via --push to a non-windows
+              client,  the  option  will  be saved in the client's environment
+              before  the  up  script  is  called,  under   the   name   "for‐
+              eign_option_{n}".
+              Note  that  if  --dhcp-option is pushed via --push to a non-windows
+              client, the option will be saved in the client's environment before
+              the up script is called, under the name "foreign_option_{n}".
        --tap-sleep n
               Cause  OpenVPN to sleep for n seconds immediately after the TAP-
+              Cause  OpenVPN  to  sleep  for n seconds immediately after the TAP-
               Win32 adapter state is set to "connected".
               This option is intended to be used to troubleshoot problems with
               the  --ifconfig  and --ip-win32 options, and is used to give the
               TAP-Win32 adapter time to come up before Windows IP  Helper  API
               operations are applied to it.
+              This option is intended to be used to  troubleshoot  problems  with
+              the --ifconfig and --ip-win32 options, and is used to give the TAP-
+              Win32 adapter time to come up before Windows IP Helper  API  opera‐
+              tions are applied to it.
        --show-net-up
               Output  OpenVPN's  view  of the system routing table and network
               adapter list to the syslog or log file after the TUN/TAP adapter
+              Output  OpenVPN's  view  of  the  system  routing table and network
+              adapter list to the syslog or log file after  the  TUN/TAP  adapter
               has been brought up and any routes have been added.
        --dhcp-renew
               Ask  Windows  to  renew  the TAP adapter lease on startup.  This
               option is normally unnecessary, as Windows  automatically  trig‐
               gers  a  DHCP renegotiation on the TAP adapter when it comes up,
               however if you set the TAP-Win32 adapter Media  Status  property
               to "Always Connected", you may need this flag.
+              Ask Windows to renew the TAP adapter lease on startup.  This option
+              is normally unnecessary, as Windows automatically triggers  a  DHCP
+              renegotiation  on  the TAP adapter when it comes up, however if you
+              set the TAP-Win32 adapter Media Status  property  to  "Always  Con‐
+              nected", you may need this flag.
        --dhcp-release
               Ask  Windows to release the TAP adapter lease on shutdown.  This
+              Ask  Windows  to  release  the TAP adapter lease on shutdown.  This
               option has the same caveats as --dhcp-renew above.
        --register-dns
               Run net stop dnscache, net start  dnscache,  ipconfig  /flushdns
               and  ipconfig  /registerdns  on  connection initiation.  This is
               known to kick Windows into recognizing pushed DNS servers.
+              Run net stop dnscache, net start dnscache, ipconfig  /flushdns  and
+              ipconfig  /registerdns  on connection initiation.  This is known to
+              kick Windows into recognizing pushed DNS servers.
        --pause-exit
               Put up a "press any key to  continue"  message  on  the  console
               prior  to  OpenVPN  program  exit.  This option is automatically
               used by the Windows explorer when OpenVPN is run on a configura‐
               tion file using the right-click explorer menu.
+              Put up a "press any key to continue" message on the  console  prior
+              to  OpenVPN program exit.  This option is automatically used by the
+              Windows explorer when OpenVPN is run on a configuration file  using
+              the right-click explorer menu.
        --service exit-event [0|1]
+              Should  be  used when OpenVPN is being automatically executed by
+              another program in such a context that no interaction  with  the
+              user via display or keyboard is possible.  In general, end-users
+              should never need to explicitly use this option, as it is  auto‐
+              matically  added  by  the  OpenVPN  service wrapper when a given
+              OpenVPN configuration is being run as a service.
+              exit-event is the name of a Windows  global  event  object,  and
+              OpenVPN will continuously monitor the state of this event object
+              and exit when it becomes signaled.
+              The second parameter indicates the initial state  of  exit-event
+              and normally defaults to 0.
+              Multiple  OpenVPN  processes can be simultaneously executed with
+              the same exit-event parameter.  In  any  case,  the  controlling
+              process  can  signal  exit-event,  causing all such OpenVPN pro‐
+              cesses to exit.
+              When executing an OpenVPN process using the --service directive,
+              OpenVPN  will  probably not have a console window to output sta‐
+              tus/error messages, therefore it  is  useful  to  use  --log  or
+              --log-append to write these messages to a file.
+              Should  be  used  when  OpenVPN  is being automatically executed by
+              another program in such a context that no interaction with the user
+              via  display or keyboard is possible.  In general, end-users should
+              never need to explicitly use this option, as  it  is  automatically
+              added  by the OpenVPN service wrapper when a given OpenVPN configu‐
+              ration is being run as a service.
+              exit-event is the name of a Windows global event object, and  Open‐
+              VPN  will  continuously  monitor the state of this event object and
+              exit when it becomes signaled.
+              The second parameter indicates the initial state of exit-event  and
+              normally defaults to 0.
+              Multiple  OpenVPN processes can be simultaneously executed with the
+              same exit-event parameter.  In any case,  the  controlling  process
+              can signal exit-event, causing all such OpenVPN processes to exit.
+              When  executing  an  OpenVPN process using the --service directive,
+              OpenVPN will probably not have a  console  window  to  output  sta‐
+              tus/error  messages,  therefore it is useful to use --log or --log-
+              append to write these messages to a file.
        --show-adapters
               (Standalone)  Show  available  TAP-Win32  adapters  which can be
               selected using the --dev-node option.  On  non-Windows  systems,
               the ifconfig(8) command provides similar functionality.
+              (Standalone)  Show  available  TAP-Win32  adapters  which  can   be
+              selected  using the --dev-node option.  On non-Windows systems, the
+              ifconfig(8) command provides similar functionality.
        --allow-nonadmin [TAP-adapter]
+              (Standalone)  Set  TAP-adapter to allow access from non-adminis‐
+              trative accounts.  If TAP-adapter is omitted, all  TAP  adapters
+              on the system will be configured to allow non-admin access.  The
+              non-admin access setting will only persist  for  the  length  of
+              time  that the TAP-Win32 device object and driver remain loaded,
+              and will need to be re-enabled after a reboot, or if the  driver
+              is unloaded and reloaded.  This directive can only be used by an
+              administrator.
+              (Standalone) Set TAP-adapter to allow access  from  non-administra‐
+              tive  accounts.  If TAP-adapter is omitted, all TAP adapters on the
+              system will be configured to allow non-admin access.  The non-admin
+              access  setting  will  only persist for the length of time that the
+              TAP-Win32 device object and driver remain loaded, and will need  to
+              be  re-enabled  after  a  reboot,  or if the driver is unloaded and
+              reloaded.  This directive can only be used by an administrator.
        --show-valid-subnets
               (Standalone) Show valid subnets for --dev tun emulation.   Since
               the  TAP-Win32  driver exports an ethernet interface to Windows,
               and since TUN devices are point-to-point in nature, it is neces‐
               sary  for  the TAP-Win32 driver to impose certain constraints on
               TUN endpoint address selection.
               Namely, the point-to-point endpoints used in TUN  device  emula‐
               tion  must  be the middle two addresses of a /30 subnet (netmask
+              (Standalone) Show valid subnets for --dev tun emulation.  Since the
+              TAP-Win32  driver  exports  an  ethernet  interface to Windows, and
+              since TUN devices are point-to-point in nature, it is necessary for
+              the  TAP-Win32 driver to impose certain constraints on TUN endpoint
+              address selection.
+              Namely, the point-to-point endpoints used in TUN  device  emulation
+              must  be  the  middle  two  addresses  of  a  /30  subnet  (netmask
 .255.255.252).
        --show-net
               (Standalone) Show OpenVPN's view of the system routing table and
+              (Standalone) Show OpenVPN's view of the system  routing  table  and
               network adapter list.
    PKCS#11 Standalone Options:
        --show-pkcs11-ids provider [cert_private]
               (Standalone)  Show  PKCS#11 token object list. Specify cert_pri‐
               vate as 1 if certificates are stored as private objects.
               --verb option can be used BEFORE this option to  produce  debug‐
               ging information.
+              (Standalone)  Show  PKCS#11 token object list. Specify cert_private
+              as 1 if certificates are stored as private objects.
+              --verb option can be used BEFORE this option to  produce  debugging
+              information.
    IPv6 Related Options
        The  following  options exist to support IPv6 tunneling in peer-to-peer
        and client-server mode.  As of now, this is just very basic  documenta‐
        tion  of  the  IPv6-related options. More documentation can be found on
+       The  following options exist to support IPv6 tunneling in peer-to-peer and
+       client-server mode.  As of now, this is just very basic  documentation  of
+       the   IPv6-related   options.   More   documentation   can   be  found  on
        http://www.greenie.net/ipv6/openvpn.html.
        --ifconfig-ipv6 ipv6addr/bits ipv6remote
               configure IPv6 address ipv6addr/bits on the ``tun'' device.  The
               second  parameter is used as route target for --route-ipv6 if no
+              configure IPv6 address ipv6addr/bits on the  ``tun''  device.   The
+              second  parameter  is  used  as route target for --route-ipv6 if no
               gateway is specified.
        --route-ipv6 ipv6addr/bits [gateway] [metric]
               setup IPv6 routing in the system to send the specified IPv6 net‐
               work into OpenVPN's ``tun'' device
+              setup IPv6 routing in the system to send the specified IPv6 network
+              into OpenVPN's ``tun'' device
        --server-ipv6 ipv6addr/bits
               convenience-function  to enable a number of IPv6 related options
               at once, namely  --ifconfig-ipv6,  --ifconfig-ipv6-pool,  --tun-
               ipv6  and  --push tun-ipv6 Is only accepted if ``--mode server''
               or ``--server'' is set.
+              convenience-function  to enable a number of IPv6 related options at
+              once, namely --ifconfig-ipv6, --ifconfig-ipv6-pool, --tun-ipv6  and
+              --push   tun-ipv6   Is   only  accepted  if  ``--mode  server''  or
+              ``--server'' is set.
        --ifconfig-ipv6-pool ipv6addr/bits
               Specify an IPv6 address pool for dynamic assignment to  clients.
               The  pool  starts at ipv6addr and increments by +1 for every new
               client (linear mode).  The /bits setting controls  the  size  of
               the pool.
+              Specify an IPv6 address pool for  dynamic  assignment  to  clients.
+              The  pool  starts  at  ipv6addr  and increments by +1 for every new
+              client (linear mode).  The /bits setting controls the size  of  the
+              pool.
        --ifconfig-ipv6-push ipv6addr/bits ipv6remote
               for  ccd/  per-client  static  IPv6 interface configuration, see
+              for  ccd/  per-client  static  IPv6  interface  configuration,  see
               --client-config-dir and --ifconfig-push for more details.
        --iroute-ipv6 ipv6addr/bits
               for  ccd/  per-client  static  IPv6  route  configuration,   see
               --iroute  for  more  details  how to setup and use this, and how
               --iroute and --route interact.
+              for ccd/ per-client static IPv6 route configuration,  see  --iroute
+              for  more  details  how to setup and use this, and how --iroute and
+              --route interact.
 SCRIPTING AND ENVIRONMENTAL VARIABLES
        OpenVPN exports a series of environmental variables for  use  by  user-
+       OpenVPN exports a series of  environmental  variables  for  use  by  user-
        defined scripts.
 …
        --ipchange
               Executed  after  connection authentication, or remote IP address
+              Executed  after  connection  authentication,  or  remote IP address
               change.
        --client-connect
               Executed in --mode server mode immediately after client  authen‐
               tication.
+              Executed in --mode server mode immediately after client authentica‐
+              tion.
        --route-up
               Executed  after  connection  authentication,  either immediately
               after, or some  number  of  seconds  after  as  defined  by  the
               --route-delay option.
+              Executed after connection authentication, either immediately after,
+              or some number of seconds after as  defined  by  the  --route-delay
+              option.
        --route-pre-down
 …
        --learn-address
               Executed in --mode server mode whenever an IPv4 address/route or
+              Executed  in  --mode  server mode whenever an IPv4 address/route or
               MAC address is added to OpenVPN's internal routing table.
        --auth-user-pass-verify
               Executed in --mode server mode on new client  connections,  when
               the client is still untrusted.
+              Executed in --mode server mode on new client connections, when  the
+              client is still untrusted.
    String Types and Remapping
        In  certain  cases,  OpenVPN  will  perform  remapping of characters in
        strings.  Essentially, any characters  outside  the  set  of  permitted
        characters for each string type will be converted to underbar ('_').
+       In certain cases, OpenVPN will perform remapping of characters in strings.
+       Essentially, any characters outside the set of  permitted  characters  for
+       each string type will be converted to underbar ('_').
        Q: Why is string remapping necessary?
        A:  It's  an important security feature to prevent the malicious coding
        of strings from  untrusted  sources  to  be  passed  as  parameters  to
        scripts, saved in the environment, used as a common name, translated to
        a filename, etc.
+       A:  It's  an important security feature to prevent the malicious coding of
+       strings from untrusted sources to be  passed  as  parameters  to  scripts,
+       saved in the environment, used as a common name, translated to a filename,
+       etc.
        Q: Can string remapping be disabled?
        A: Yes, by using the --no-name-remapping option, however this should be
+       A: Yes, by using the --no-name-remapping option, however  this  should  be
        considered an advanced option.
+       Here  is a brief rundown of OpenVPN's current string types and the per‐
+       mitted character class for each string:
+       X509 Names: Alphanumeric, underbar ('_'), dash  ('-'),  dot  ('.'),  at
+       ('@'),  colon  (':'),  slash  ('/'),  and equal ('=').  Alphanumeric is
+       defined as a character which will cause the C library  isalnum()  func‐
+       tion to return true.
+       Common  Names: Alphanumeric, underbar ('_'), dash ('-'), dot ('.'), and
+       at ('@').
+       --auth-user-pass username: Same as Common  Name,  with  one  exception:
+       starting  with  OpenVPN  2.0.1,  the  username  is  passed to the OPEN‐
+       VPN_PLUGIN_AUTH_USER_PASS_VERIFY plugin in its raw form, without string
+       remapping.
+       --auth-user-pass  password:  Any "printable" character except CR or LF.
+       Printable is defined to be a character which will cause the  C  library
+       Here  is a brief rundown of OpenVPN's current string types and the permit‐
+       ted character class for each string:
+       X509 Names: Alphanumeric, underbar ('_'), dash ('-'), dot ('.'), at ('@'),
+       colon  (':'),  slash ('/'), and equal ('=').  Alphanumeric is defined as a
+       character which will cause the C  library  isalnum()  function  to  return
+       true.
+       Common  Names: Alphanumeric, underbar ('_'), dash ('-'), dot ('.'), and at
+       ('@').
+       --auth-user-pass username: Same as Common Name, with one exception: start‐
+       ing  with  OpenVPN  2.0.1,  the  username  is  passed to the OPENVPN_PLUG‐
+       IN_AUTH_USER_PASS_VERIFY plugin in its raw form, without string remapping.
+       --auth-user-pass password: Any "printable"  character  except  CR  or  LF.
+       Printable  is  defined  to  be  a character which will cause the C library
        isprint() function to return true.
+       --client-config-dir  filename  as derived from common name or username:
+       Alphanumeric, underbar ('_'), dash ('-'), and dot ('.') except for  "."
+       or ".." as standalone strings.  As of 2.0.1-rc6, the at ('@') character
+       has been added as well for compatibility with the common name character
+       class.
+       --client-config-dir filename as derived  from  common  name  or  username:
+       Alphanumeric,  underbar ('_'), dash ('-'), and dot ('.') except for "." or
+       ".." as standalone strings.  As of 2.0.1-rc6, the at ('@')  character  has
+       been added as well for compatibility with the common name character class.
        Environmental variable names: Alphanumeric or underbar ('_').
 …
        Environmental variable values: Any printable character.
+       For  all  cases,  characters  in  a string which are not members of the
+       legal character class for that string type will be remapped to underbar
+       ('_').
+       For  all  cases, characters in a string which are not members of the legal
+       character class for that string type will be remapped to underbar ('_').
    Environmental Variables
+       Once  set,  a variable is persisted indefinitely until it is reset by a
+       new value or a restart,
+       As of OpenVPN 2.0-beta12, in server mode, environmental  variables  set
+       by  OpenVPN are scoped according to the client objects they are associ‐
+       ated with, so there should not be any issues with scripts having access
+       to  stale,  previously  set  variables  which refer to different client
+       instances.
+       Once set, a variable is persisted indefinitely until it is reset by a  new
+       value or a restart,
+       As  of  OpenVPN 2.0-beta12, in server mode, environmental variables set by
+       OpenVPN are scoped according to the client  objects  they  are  associated
+       with,  so  there  should  not  be any issues with scripts having access to
+       stale, previously set variables which refer to different client instances.
        bytes_received
               Total number of bytes received from client during  VPN  session.
               Set prior to execution of the --client-disconnect script.
+              Total number of bytes received from client during VPN session.  Set
+              prior to execution of the --client-disconnect script.
        bytes_sent
               Total  number  of  bytes sent to client during VPN session.  Set
               prior to execution of the --client-disconnect script.
+              Total number of bytes sent to client during VPN session.  Set prior
+              to execution of the --client-disconnect script.
        common_name
               The X509 common name of an authenticated client.  Set  prior  to
               execution  of --client-connect, --client-disconnect, and --auth-
               user-pass-verify scripts.
        config Name of first --config file.   Set  on  program  initiation  and
               reset on SIGHUP.
        daemon Set to "1" if the --daemon directive is specified, or "0" other‐
+              The X509 common name of an authenticated client.  Set prior to exe‐
+              cution  of  --client-connect, --client-disconnect, and --auth-user-
+              pass-verify scripts.
+       config Name of first --config file.  Set on program initiation  and  reset
+              on SIGHUP.
+       daemon Set  to  "1"  if the --daemon directive is specified, or "0" other‐
               wise.  Set on program initiation and reset on SIGHUP.
        daemon_log_redirect
+              Set to "1" if the --log or --log-append  directives  are  speci‐
+              fied,  or "0" otherwise.  Set on program initiation and reset on
+              Set to "1" if the --log or --log-append directives  are  specified,
+              or "0" otherwise.  Set on program initiation and reset on SIGHUP.
+       dev    The  actual  name of the TUN/TAP device, including a unit number if
+              it exists.  Set prior to --up or --down script execution.
+       foreign_option_{n}
+              An option pushed via --push to a client  which  does  not  natively
+              support  it, such as --dhcp-option on a non-Windows system, will be
+              recorded to this environmental  variable  sequence  prior  to  --up
+              script execution.
+       ifconfig_broadcast
+              The  broadcast  address  for  the virtual ethernet segment which is
+              derived from the --ifconfig option when --dev  tap  is  used.   Set
+              prior  to OpenVPN calling the ifconfig or netsh (windows version of
+              ifconfig) commands which normally occurs prior to --up script  exe‐
+              cution.
+       ifconfig_ipv6_local
+              The  local  VPN  endpoint IPv6 address specified in the --ifconfig-
+              ipv6 option (first parameter).  Set prior to  OpenVPN  calling  the
+              ifconfig or netsh (windows version of ifconfig) commands which nor‐
+              mally occurs prior to --up script execution.
+       ifconfig_ipv6_netbits
+              The prefix length  of  the  IPv6  network  on  the  VPN  interface.
+              Derived from the /nnn parameter of the IPv6 address in the --ifcon‐
+              fig-ipv6 option (first parameter).  Set prior  to  OpenVPN  calling
+              the  ifconfig or netsh (windows version of ifconfig) commands which
+              normally occurs prior to --up script execution.
+       ifconfig_ipv6_remote
+              The remote VPN endpoint IPv6 address specified in  the  --ifconfig-
+              ipv6  option  (second parameter).  Set prior to OpenVPN calling the
+              ifconfig or netsh (windows version of ifconfig) commands which nor‐
+              mally occurs prior to --up script execution.
+       ifconfig_local
+              The  local  VPN  endpoint  IP  address  specified in the --ifconfig
+              option (first parameter).  Set prior to OpenVPN calling the  ifcon‐
+              fig  or netsh (windows version of ifconfig) commands which normally
+              occurs prior to --up script execution.
+       ifconfig_remote
+              The remote VPN endpoint IP  address  specified  in  the  --ifconfig
+              option  (second  parameter)  when  --dev tun is used.  Set prior to
+              OpenVPN calling the ifconfig or netsh (windows version of ifconfig)
+              commands which normally occurs prior to --up script execution.
+       ifconfig_netmask
+              The  subnet  mask of the virtual ethernet segment that is specified
+              as the second parameter to --ifconfig when --dev tap is being used.
+              Set prior to OpenVPN calling the ifconfig or netsh (windows version
+              of ifconfig) commands which normally occurs prior  to  --up  script
+              execution.
+       ifconfig_pool_local_ip
+              The  local  virtual IP address for the TUN/TAP tunnel taken from an
+              --ifconfig-push directive  if  specified,  or  otherwise  from  the
+              ifconfig pool (controlled by the --ifconfig-pool config file direc‐
+              tive).  Only set for --dev tun tunnels.  This option is set on  the
+              server prior to execution of the --client-connect and --client-dis‐
+              connect scripts.
+       ifconfig_pool_netmask
+              The virtual IP  netmask  for  the  TUN/TAP  tunnel  taken  from  an
+              --ifconfig-push  directive  if  specified,  or  otherwise  from the
+              ifconfig pool (controlled by the --ifconfig-pool config file direc‐
+              tive).   Only set for --dev tap tunnels.  This option is set on the
+              server prior to execution of the --client-connect and --client-dis‐
+              connect scripts.
+       ifconfig_pool_remote_ip
+              The  remote virtual IP address for the TUN/TAP tunnel taken from an
+              --ifconfig-push directive  if  specified,  or  otherwise  from  the
+              ifconfig pool (controlled by the --ifconfig-pool config file direc‐
+              tive).  This option is set on the server prior to execution of  the
+              --client-connect and --client-disconnect scripts.
+       link_mtu
+              The  maximum  packet  size  (not including the IP header) of tunnel
+              data in UDP tunnel transport mode.  Set prior  to  --up  or  --down
+              script execution.
+       local  The  --local  parameter.   Set  on  program initiation and reset on
               SIGHUP.
+       dev    The actual name of the TUN/TAP device, including a  unit  number
+              if it exists.  Set prior to --up or --down script execution.
+       foreign_option_{n}
+              An  option pushed via --push to a client which does not natively
+              support it, such as --dhcp-option on a non-Windows system,  will
+              be  recorded  to  this  environmental variable sequence prior to
+              --up script execution.
+       ifconfig_broadcast
+              The broadcast address for the virtual ethernet segment which  is
+              derived  from the --ifconfig option when --dev tap is used.  Set
+              prior to OpenVPN calling the ifconfig or netsh (windows  version
+              of ifconfig) commands which normally occurs prior to --up script
+       local_port
+              The local port number, specified by --port or --lport.  Set on pro‐
+              gram initiation and reset on SIGHUP.
+       password
+              The password provided by a connecting client.  Set prior to --auth-
+              user-pass-verify script execution only when the via-env modifier is
+              specified,  and  deleted  from  the  environment  after  the script
+              returns.
+       proto  The --proto parameter.  Set on  program  initiation  and  reset  on
+              SIGHUP.
+       remote_{n}
+              The  --remote  parameter.   Set  on program initiation and reset on
+              SIGHUP.
+       remote_port_{n}
+              The remote port number, specified by --port  or  --rport.   Set  on
+              program initiation and reset on SIGHUP.
+       route_net_gateway
+              The  pre-existing  default  IP gateway in the system routing table.
+              Set prior to --up script execution.
+       route_vpn_gateway
+              The default gateway used by --route options, as specified in either
+              the  --route-gateway  option  or the second parameter to --ifconfig
+              when --dev tun is specified.  Set prior to --up script execution.
+       route_{parm}_{n}
+              A set of variables which define each route to be added, and are set
+              prior to --up script execution.
+              parm will be one of "network", "netmask", "gateway", or "metric".
+              n is the OpenVPN route number, starting from 1.
+              If  the  network  or  gateway  are  resolvable  DNS names, their IP
+              address translations will be recorded rather than  their  names  as
+              denoted on the command line or configuration file.
+       route_ipv6_{parm}_{n}
+              A  set  of  variables which define each IPv6 route to be added, and
+              are set prior to --up script execution.
+              parm will be one of "network" or "gateway" ("netmask" is  contained
+              as  "/nnn"  in  the route_ipv6_network_{n}, unlike IPv4 where it is
+              passed in a separate environment variable).
+              n is the OpenVPN route number, starting from 1.
+              If the network or  gateway  are  resolvable  DNS  names,  their  IP
+              address  translations  will  be recorded rather than their names as
+              denoted on the command line or configuration file.
+       peer_cert
+              Temporary file name containing the client certificate upon  connec‐
+              tion.  Useful in conjunction with --tls-verify
+       script_context
+              Set  to "init" or "restart" prior to up/down script execution.  For
+              more information, see documentation for --up.
+       script_type
+              Prior to execution of any script, this variable is set to the  type
+              of  script  being  run.   It can be one of the following: up, down,
+              ipchange, route-up, tls-verify, auth-user-pass-verify,  client-con‐
+              nect,  client-disconnect, or learn-address.  Set prior to execution
+              of any script.
+       signal The reason for exit or restart.  Can be  one  of  sigusr1,  sighup,
+              sigterm,  sigint, inactive (controlled by --inactive option), ping-
+              exit (controlled by --ping-exit option),  ping-restart  (controlled
+              by  --ping-restart option), connection-reset (triggered on TCP con‐
+              nection reset), error, or unknown (unknown signal).  This  variable
+              is set just prior to down script execution.
+       time_ascii
+              Client  connection  timestamp,  formatted  as a human-readable time
+              string.  Set prior to execution of the --client-connect script.
+       time_duration
+              The duration (in seconds) of the client session which is  now  dis‐
+              connecting.   Set  prior  to  execution  of the --client-disconnect
+              script.
+       time_unix
+              Client connection timestamp, formatted as a unix integer  date/time
+              value.  Set prior to execution of the --client-connect script.
+       tls_id_{n}
+              A series of certificate fields from the remote peer, where n is the
+              verification level.  Only set for TLS connections.   Set  prior  to
+              execution of --tls-verify script.
+       tls_serial_{n}
+              The  serial number of the certificate from the remote peer, where n
+              is the verification level.  Only  set  for  TLS  connections.   Set
+              prior to execution of --tls-verify script. This is in the form of a
+              hex string like "37AB46E0", which is  suitable  for  doing  serial-
+              based  OCSP  queries (with OpenSSL, you have to prepend "0x" to the
+              string). If something goes wrong while reading the value  from  the
+              certificate  it  will be an empty string, so your code should check
+              that.  See the contrib/OCSP_check/OCSP_check.sh script for an exam‐
+              ple.
+       tun_mtu
+              The  MTU of the TUN/TAP device.  Set prior to --up or --down script
               execution.
-       ifconfig_ipv6_local
-              The local VPN endpoint IPv6 address specified in the --ifconfig-
-              ipv6 option (first parameter).  Set prior to OpenVPN calling the
-              ifconfig or netsh (windows version of ifconfig)  commands  which
-              normally occurs prior to --up script execution.
-       ifconfig_ipv6_netbits
-              The  prefix  length  of  the  IPv6 network on the VPN interface.
-              Derived from the /nnn parameter  of  the  IPv6  address  in  the
-              --ifconfig-ipv6  option (first parameter).  Set prior to OpenVPN
-              calling the ifconfig or netsh (windows version of ifconfig) com‐
-              mands which normally occurs prior to --up script execution.
-       ifconfig_ipv6_remote
-              The  remote  VPN endpoint IPv6 address specified in the --ifcon‐
-              fig-ipv6 option (second parameter).  Set prior to OpenVPN  call‐
-              ing the ifconfig or netsh (windows version of ifconfig) commands
-              which normally occurs prior to --up script execution.
-       ifconfig_local
-              The local VPN endpoint IP address specified  in  the  --ifconfig
-              option  (first  parameter).   Set  prior  to OpenVPN calling the
-              ifconfig or netsh (windows version of ifconfig)  commands  which
-              normally occurs prior to --up script execution.
-       ifconfig_remote
-              The  remote  VPN endpoint IP address specified in the --ifconfig
-              option (second parameter) when --dev tun is used.  Set prior  to
-              OpenVPN calling the ifconfig or netsh (windows version of ifcon‐
-              fig) commands which normally occurs prior to --up script  execu‐
-              tion.
-       ifconfig_netmask
-              The  subnet  mask of the virtual ethernet segment that is speci‐
-              fied as the second parameter to --ifconfig  when  --dev  tap  is
-              being  used.  Set prior to OpenVPN calling the ifconfig or netsh
-              (windows version of ifconfig)  commands  which  normally  occurs
-              prior to --up script execution.
-       ifconfig_pool_local_ip
-              The  local  virtual IP address for the TUN/TAP tunnel taken from
-              an --ifconfig-push directive if specified, or otherwise from the
-              ifconfig  pool  (controlled  by  the --ifconfig-pool config file
-              directive).  Only set for --dev tun tunnels.  This option is set
-              on  the  server  prior  to execution of the --client-connect and
-              --client-disconnect scripts.
-       ifconfig_pool_netmask
-              The virtual IP netmask for the  TUN/TAP  tunnel  taken  from  an
-              --ifconfig-push  directive  if  specified, or otherwise from the
-              ifconfig pool (controlled by  the  --ifconfig-pool  config  file
-              directive).  Only set for --dev tap tunnels.  This option is set
-              on the server prior to execution  of  the  --client-connect  and
-              --client-disconnect scripts.
-       ifconfig_pool_remote_ip
-              The  remote virtual IP address for the TUN/TAP tunnel taken from
-              an --ifconfig-push directive if specified, or otherwise from the
-              ifconfig  pool  (controlled  by  the --ifconfig-pool config file
-              directive).  This option is set on the server prior to execution
-              of the --client-connect and --client-disconnect scripts.
-       link_mtu
-              The  maximum packet size (not including the IP header) of tunnel
-              data in UDP tunnel transport mode.  Set prior to --up or  --down
-              script execution.
-       local  The  --local  parameter.  Set on program initiation and reset on
-              SIGHUP.
-       local_port
-              The local port number, specified by --port or --lport.   Set  on
-              program initiation and reset on SIGHUP.
-       password
-              The  password  provided  by  a  connecting client.  Set prior to
-              --auth-user-pass-verify script execution only when  the  via-env
-              modifier  is  specified,  and deleted from the environment after
-              the script returns.
-       proto  The --proto parameter.  Set on program initiation and  reset  on
-              SIGHUP.
-       remote_{n}
-              The  --remote parameter.  Set on program initiation and reset on
-              SIGHUP.
-       remote_port_{n}
-              The remote port number, specified by --port or --rport.  Set  on
-              program initiation and reset on SIGHUP.
-       route_net_gateway
-              The pre-existing default IP gateway in the system routing table.
-              Set prior to --up script execution.
-       route_vpn_gateway
-              The default gateway used by --route  options,  as  specified  in
-              either  the  --route-gateway  option  or the second parameter to
-              --ifconfig when --dev tun  is  specified.   Set  prior  to  --up
-              script execution.
-       route_{parm}_{n}
-              A  set of variables which define each route to be added, and are
-              set prior to --up script execution.
-              parm will be one of "network", "netmask",  "gateway",  or  "met‐
-              ric".
-              n is the OpenVPN route number, starting from 1.
-              If  the  network  or  gateway are resolvable DNS names, their IP
-              address translations will be recorded rather than their names as
-              denoted on the command line or configuration file.
-       route_ipv6_{parm}_{n}
-              A set of variables which define each IPv6 route to be added, and
-              are set prior to --up script execution.
-              parm will be one of "network" or "gateway"  ("netmask"  is  con‐
-              tained  as  "/nnn"  in  the  route_ipv6_network_{n}, unlike IPv4
-              where it is passed in a separate environment variable).
-              n is the OpenVPN route number, starting from 1.
-              If the network or gateway are resolvable  DNS  names,  their  IP
-              address translations will be recorded rather than their names as
-              denoted on the command line or configuration file.
-       peer_cert
-              Temporary file name containing the client certificate upon  con‐
-              nection.  Useful in conjunction with --tls-verify
-       script_context
-              Set  to  "init"  or "restart" prior to up/down script execution.
-              For more information, see documentation for --up.
-       script_type
-              Prior to execution of any script, this variable is  set  to  the
-              type  of  script being run.  It can be one of the following: up,
-              down,  ipchange,  route-up,  tls-verify,  auth-user-pass-verify,
-              client-connect,  client-disconnect, or learn-address.  Set prior
-              to execution of any script.
-       signal The reason for exit or restart.  Can be one of sigusr1,  sighup,
-              sigterm,  sigint,  inactive  (controlled  by --inactive option),
-              ping-exit (controlled by --ping-exit option), ping-restart (con‐
-              trolled  by  --ping-restart option), connection-reset (triggered
-              on TCP connection reset), error, or  unknown  (unknown  signal).
-              This variable is set just prior to down script execution.
-       time_ascii
-              Client  connection timestamp, formatted as a human-readable time
-              string.  Set prior to execution of the --client-connect script.
-       time_duration
-              The duration (in seconds) of the client  session  which  is  now
-              disconnecting.   Set  prior to execution of the --client-discon‐
-              nect script.
-       time_unix
-              Client  connection  timestamp,  formatted  as  a  unix   integer
-              date/time value.  Set prior to execution of the --client-connect
-              script.
-       tls_id_{n}
-              A series of certificate fields from the remote peer, where n  is
-              the  verification  level.   Only  set  for TLS connections.  Set
-              prior to execution of --tls-verify script.
-       tls_serial_{n}
-              The serial number of the certificate from the remote peer, where
-              n is the verification level.  Only set for TLS connections.  Set
-              prior to execution of --tls-verify script. This is in  the  form
-              of  a  hex  string  like "37AB46E0", which is suitable for doing
-              serial-based OCSP queries (with OpenSSL,  you  have  to  prepend
-              "0x"  to  the string). If something goes wrong while reading the
-              value from the certificate it will be an empty string,  so  your
-              code      should      check      that.      See     the     con‐
-              trib/OCSP_check/OCSP_check.sh script for an example.
-       tun_mtu
-              The MTU of the TUN/TAP device.  Set  prior  to  --up  or  --down
-              script execution.
        trusted_ip (or trusted_ip6)
               Actual  IP  address  of connecting client or peer which has been
               authenticated.  Set prior to execution of --ipchange,  --client-
               connect,  and  --client-disconnect  scripts.  If using ipv6 end‐
               points (udp6, tcp6), trusted_ip6 will be set instead.
+              Actual IP address of connecting  client  or  peer  which  has  been
+              authenticated.  Set prior to execution of --ipchange, --client-con‐
+              nect, and --client-disconnect scripts.   If  using  ipv6  endpoints
+              (udp6, tcp6), trusted_ip6 will be set instead.
        trusted_port
               Actual port number of connecting client or peer which  has  been
               authenticated.   Set prior to execution of --ipchange, --client-
               connect, and --client-disconnect scripts.
+              Actual  port  number  of  connecting  client or peer which has been
+              authenticated.  Set prior to execution of --ipchange, --client-con‐
+              nect, and --client-disconnect scripts.
        untrusted_ip (or untrusted_ip6)
               Actual IP address of connecting client or  peer  which  has  not
               been  authenticated  yet.  Sometimes used to nmap the connecting
               host in a --tls-verify script to ensure it is  firewalled  prop‐
               erly.   Set  prior to execution of --tls-verify and --auth-user-
               pass-verify scripts.  If  using  ipv6  endpoints  (udp6,  tcp6),
               untrusted_ip6 will be set instead.
+              Actual  IP  address of connecting client or peer which has not been
+              authenticated yet.  Sometimes used to nmap the connecting host in a
+              --tls-verify script to ensure it is firewalled properly.  Set prior
+              to execution of --tls-verify and  --auth-user-pass-verify  scripts.
+              If  using  ipv6  endpoints  (udp6, tcp6), untrusted_ip6 will be set
+              instead.
        untrusted_port
               Actual  port  number  of connecting client or peer which has not
               been authenticated yet.  Set prior to execution of  --tls-verify
               and --auth-user-pass-verify scripts.
+              Actual port number of connecting client or peer which has not  been
+              authenticated  yet.   Set  prior  to  execution of --tls-verify and
+              --auth-user-pass-verify scripts.
        username
               The  username  provided  by  a  connecting client.  Set prior to
               --auth-user-pass-verify script execution only when  the  via-env
               modifier is specified.
+              The username provided by a connecting client.  Set prior to --auth-
+              user-pass-verify script execution only when the via-env modifier is
+              specified.
        X509_{n}_{subject_field}
               An  X509 subject field from the remote peer certificate, where n
               is the verification level.  Only set for TLS  connections.   Set
               prior  to  execution  of  --tls-verify script.  This variable is
               similar to tls_id_{n} except the component X509  subject  fields
               are  broken  out,  and no string remapping occurs on these field
               values (except for remapping of control characters to "_").  For
               example,  the  following  variables  would be set on the OpenVPN
               server  using  the  sample  client  certificate  in  sample-keys
               (client.crt).   Note  that  the  verification level is 0 for the
               client certificate and 1 for the CA certificate.
+              An X509 subject field from the remote peer certificate, where n  is
+              the  verification  level.  Only set for TLS connections.  Set prior
+              to execution of --tls-verify script.  This variable is  similar  to
+              tls_id_{n} except the component X509 subject fields are broken out,
+              and no string remapping occurs on these field  values  (except  for
+              remapping  of control characters to "_").  For example, the follow‐
+              ing variables would be set on the OpenVPN server using  the  sample
+              client certificate in sample-keys (client.crt).  Note that the ver‐
+              ification level is 0 for the client certificate and 1  for  the  CA
+              certificate.
                   X509_0_emailAddress=me@myhost.mydomain
 …
 INLINE FILE SUPPORT
        OpenVPN allows including files in the main configuration for the  --ca,
        --cert,  --dh,  --extra-certs, --key, --pkcs12, --secret and --tls-auth
+       OpenVPN  allows  including  files  in the main configuration for the --ca,
+       --cert, --dh, --extra-certs,  --key,  --pkcs12,  --secret  and  --tls-auth
        options.
        Each inline file started by the line <option> and  ended  by  the  line
+       Each  inline  file  started  by  the  line  <option> and ended by the line
        </option>
 …
            </cert>
        When using the inline file feature with --pkcs12 the inline file has to
        be base64 encoded. Encoding of a .p12 file into base64 can be done  for
        example with OpenSSL by running openssl base64 -in input.p12
+       When using the inline file feature with --pkcs12 the inline file has to be
+       base64  encoded. Encoding of a .p12 file into base64 can be done for exam‐
+       ple with OpenSSL by running openssl base64 -in input.p12
 SIGNALS
        SIGHUP Cause  OpenVPN  to  close  all  TUN/TAP and network connections,
               restart, re-read the configuration file  (if  any),  and  reopen
+       SIGHUP Cause  OpenVPN  to  close  all  TUN/TAP  and  network  connections,
+              restart,  re-read  the  configuration  file  (if  any),  and reopen
               TUN/TAP and network connections.
        SIGUSR1
               Like SIGHUP, except don't re-read configuration file, and possi‐
               bly don't close and reopen TUN/TAP device,  re-read  key  files,
               preserve  local  IP  address/port,  or  preserve  most  recently
               authenticated remote IP  address/port  based  on  --persist-tun,
               --persist-key,   --persist-local-ip,   and   --persist-remote-ip
               options respectively (see above).
               This signal may also be internally generated by a timeout condi‐
+              Like SIGHUP, except don't re-read configuration file, and  possibly
+              don't  close and reopen TUN/TAP device, re-read key files, preserve
+              local IP address/port,  or  preserve  most  recently  authenticated
+              remote  IP  address/port  based  on  --persist-tun,  --persist-key,
+              --persist-local-ip, and  --persist-remote-ip  options  respectively
+              (see above).
+              This  signal  may  also be internally generated by a timeout condi‐
               tion, governed by the --ping-restart option.
               This signal, when combined with --persist-remote-ip, may be sent
               when the underlying parameters of the host's  network  interface
               change  such as when the host is a DHCP client and is assigned a
               new IP address.  See --ipchange above for more information.
+              This signal, when combined with --persist-remote-ip,  may  be  sent
+              when  the  underlying  parameters  of  the host's network interface
+              change such as when the host is a DHCP client and is assigned a new
+              IP address.  See --ipchange above for more information.
        SIGUSR2
               Causes OpenVPN to display its current statistics (to the  syslog
+              Causes  OpenVPN  to  display  its current statistics (to the syslog
               file if --daemon is used, or stdout otherwise).
 …
 TUN/TAP DRIVER SETUP
        If you are running Linux 2.4.7 or higher, you probably have the TUN/TAP
        driver already installed.  If so, there are still a few things you need
        to do:
+       If you are running Linux 2.4.7 or higher, you probably  have  the  TUN/TAP
+       driver already installed.  If so, there are still a few things you need to
+       do:
        Make device: mknod /dev/net/tun c 10 200
 …
 EXAMPLES
        Prior  to  running these examples, you should have OpenVPN installed on
        two machines with network connectivity between them.  If you  have  not
        yet installed OpenVPN, consult the INSTALL file included in the OpenVPN
        distribution.
+       Prior to running these examples, you should have OpenVPN installed on  two
+       machines  with  network  connectivity  between  them.  If you have not yet
+       installed OpenVPN, consult the INSTALL file included in the  OpenVPN  dis‐
+       tribution.
    TUN/TAP Setup:
        If you are using Linux 2.4 or higher, make the tun device node and load
+       If  you  are  using Linux 2.4 or higher, make the tun device node and load
        the tun module:
 …
               modprobe tun
        If  you  installed from RPM, the mknod step may be omitted, because the
        RPM install does that for you.
+       If you installed from RPM, the mknod step may be omitted, because the  RPM
+       install does that for you.
        Only Linux 2.4 and newer are supported.
        For  other  platforms,  consult  the  INSTALL  file   at   http://open‐
+       For   other   platforms,   consult   the   INSTALL  file  at  http://open‐
        vpn.net/install.html for more information.
    Firewall Setup:
+       If firewalls exist between the two machines, they should be set to for‐
+       ward UDP port 1194 in both directions.  If you do not have control over
+       the  firewalls  between  the two machines, you may still be able to use
+       OpenVPN by adding --ping 15 to each of the openvpn commands used  below
+       in  the  examples  (this will cause each peer to send out a UDP ping to
+       its remote peer once every 15 seconds which will  cause  many  stateful
+       firewalls  to  forward  packets  in both directions without an explicit
+       firewall rule).
+       If you are using a Linux iptables-based firewall, you may need to enter
+       If firewalls exist between the two machines, they should be set to forward
+       UDP  port  1194  in  both directions.  If you do not have control over the
+       firewalls between the two machines, you may still be able to  use  OpenVPN
+       by  adding  --ping  15  to  each of the openvpn commands used below in the
+       examples (this will cause each peer to send out a UDP ping to  its  remote
+       peer  once  every  15  seconds which will cause many stateful firewalls to
+       forward packets in both directions without an explicit firewall rule).
+       If you are using a Linux iptables-based firewall, you may  need  to  enter
        the following command to allow incoming packets on the TUN device:
               iptables -A INPUT -i tun+ -j ACCEPT
        See  the  firewalls  section  below for more information on configuring
        firewalls for use with OpenVPN.
+       See  the firewalls section below for more information on configuring fire‐
+       walls for use with OpenVPN.
    VPN Address Setup:
        For purposes of our example, our two machines will be called may.kg and
        june.kg.  If you are constructing a VPN over the internet, then replace
        may.kg and june.kg with the internet hostname or IP address  that  each
+       For purposes of our example, our two machines will be  called  may.kg  and
+       june.kg.   If  you  are constructing a VPN over the internet, then replace
+       may.kg and june.kg with the internet hostname  or  IP  address  that  each
        machine will use to contact the other over the internet.
        Now  we will choose the tunnel endpoints.  Tunnel endpoints are private
        IP addresses that only have meaning in the context of  the  VPN.   Each
        machine  will use the tunnel endpoint of the other machine to access it
        over the VPN.  In our example, the tunnel endpoint for may.kg  will  be
 .4.0.1 and for june.kg, 10.4.0.2.
        Once  the  VPN  is  established,  you have essentially created a secure
        alternate path between the two hosts which is addressed  by  using  the
        tunnel endpoints.  You can control which network traffic passes between
        the hosts (a) over the VPN or (b) independently of the VPN, by choosing
        whether  to use (a) the VPN endpoint address or (b) the public internet
        address, to access the remote host. For example if you  are  on  may.kg
        and you wish to connect to june.kg via ssh without using the VPN (since
        ssh has its own built-in  security)  you  would  use  the  command  ssh
        june.kg.   However in the same scenario, you could also use the command
        telnet 10.4.0.2 to create a telnet session with june.kg over  the  VPN,
        that would use the VPN to secure the session rather than ssh.
        You can use any address you wish for the tunnel endpoints but make sure
        that they are private addresses (such as those that begin  with  10  or
 .168)  and that they are not part of any existing subnet on the net‐
        works of either peer, unless you are bridging.  If you use  an  address
        that  is  part of your local subnet for either of the tunnel endpoints,
        you will get a weird feedback loop.
+       Now  we will choose the tunnel endpoints.  Tunnel endpoints are private IP
+       addresses that only have meaning in the context of the VPN.  Each  machine
+       will  use  the  tunnel endpoint of the other machine to access it over the
+       VPN.  In our example, the tunnel endpoint for may.kg will be 10.4.0.1  and
+       for june.kg, 10.4.0.2.
+       Once  the VPN is established, you have essentially created a secure alter‐
+       nate path between the two hosts which is addressed  by  using  the  tunnel
+       endpoints.  You can control which network traffic passes between the hosts
+       (a) over the VPN or (b) independently of the VPN, by choosing  whether  to
+       use  (a)  the  VPN endpoint address or (b) the public internet address, to
+       access the remote host. For example if you are on may.kg and you  wish  to
+       connect  to  june.kg  via ssh without using the VPN (since ssh has its own
+       built-in security) you would use the command ssh june.kg.  However in  the
+       same  scenario, you could also use the command telnet 10.4.0.2 to create a
+       telnet session with june.kg over the VPN, that would use the VPN to secure
+       the session rather than ssh.
+       You  can  use  any address you wish for the tunnel endpoints but make sure
+       that they are private addresses (such as  those  that  begin  with  10  or
+.168) and that they are not part of any existing subnet on the networks
+       of either peer, unless you are bridging.  If you use an  address  that  is
+       part of your local subnet for either of the tunnel endpoints, you will get
+       a weird feedback loop.
    Example 1: A simple tunnel without security
        On may:
               openvpn --remote june.kg --dev tun1 --ifconfig 10.4.0.1 10.4.0.2
+              openvpn --remote june.kg --dev tun1  --ifconfig  10.4.0.1  10.4.0.2
               --verb 9
        On june:
               openvpn  --remote may.kg --dev tun1 --ifconfig 10.4.0.2 10.4.0.1
+              openvpn  --remote  may.kg  --dev  tun1 --ifconfig 10.4.0.2 10.4.0.1
               --verb 9
 …
               ping 10.4.0.1
+       The --verb 9 option will produce verbose output, similar  to  the  tcp‐
+       dump(8) program.  Omit the --verb 9 option to have OpenVPN run quietly.
+   Example  2:  A  tunnel  with  static-key  security (i.e. using a pre-shared
+       secret)
+       The --verb 9 option will produce verbose output, similar to the tcpdump(8)
+       program.  Omit the --verb 9 option to have OpenVPN run quietly.
+   Example 2: A tunnel with static-key security (i.e. using a pre-shared secret)
        First build a static key on may.
               openvpn --genkey --secret key
        This command will build a random key file called key (in ascii format).
        Now  copy  key to june over a secure medium such as by using the scp(1)
        program.
+       This  command  will  build a random key file called key (in ascii format).
+       Now copy key to june over a secure medium such as by using the scp(1) pro‐
+       gram.
        On may:
               openvpn --remote june.kg --dev tun1 --ifconfig 10.4.0.1 10.4.0.2
+              openvpn  --remote  june.kg  --dev tun1 --ifconfig 10.4.0.1 10.4.0.2
               --verb 5 --secret key
        On june:
               openvpn  --remote may.kg --dev tun1 --ifconfig 10.4.0.2 10.4.0.1
+              openvpn --remote may.kg --dev  tun1  --ifconfig  10.4.0.2  10.4.0.1
               --verb 5 --secret key
 …
    Example 3: A tunnel with full TLS-based security
+       For this test, we will designate may as the TLS client and june as  the
+       TLS  server.   Note  that client or server designation only has meaning
+       for the TLS subsystem. It has no  bearing  on  OpenVPN's  peer-to-peer,
+       UDP-based communication model.
+       First, build a separate certificate/key pair for both may and june (see
+       above where --cert is discussed for more info).  Then construct  Diffie
+       Hellman  parameters  (see above where --dh is discussed for more info).
+       You can also  use  the  included  test  files  client.crt,  client.key,
+       server.crt,  server.key  and  ca.crt.   The  .crt  files  are  certifi‐
+       cates/public-keys, the .key files are private keys,  and  ca.crt  is  a
+       certification  authority who has signed both client.crt and server.crt.
+       For Diffie Hellman parameters you can use the included file dh1024.pem.
+       Note  that  all  client, server, and certificate authority certificates
+       and keys included in the OpenVPN distribution are totally insecure  and
+       should be used for testing only.
+       For this test, we will designate may as the TLS client and june as the TLS
+       server.  Note that client or server designation only has meaning  for  the
+       TLS subsystem. It has no bearing on OpenVPN's peer-to-peer, UDP-based com‐
+       munication model.
+       First, build a separate certificate/key pair for both may  and  june  (see
+       above  where  --cert  is  discussed for more info).  Then construct Diffie
+       Hellman parameters (see above where --dh is discussed for more info).  You
+       can  also  use the included test files client.crt, client.key, server.crt,
+       server.key and ca.crt.  The .crt files are  certificates/public-keys,  the
+       .key  files  are private keys, and ca.crt is a certification authority who
+       has signed both client.crt and server.crt.  For Diffie Hellman  parameters
+       you  can  use the included file dh1024.pem.  Note that all client, server,
+       and certificate authority certificates and keys included  in  the  OpenVPN
+       distribution are totally insecure and should be used for testing only.
        On may:
               openvpn --remote june.kg --dev tun1 --ifconfig 10.4.0.1 10.4.0.2
               --tls-client --ca  ca.crt  --cert  client.crt  --key  client.key
+              openvpn  --remote  june.kg  --dev tun1 --ifconfig 10.4.0.1 10.4.0.2
+              --tls-client  --ca  ca.crt  --cert  client.crt   --key   client.key
               --reneg-sec 60 --verb 5
        On june:
               openvpn  --remote may.kg --dev tun1 --ifconfig 10.4.0.2 10.4.0.1
               --tls-server --dh dh1024.pem --ca ca.crt --cert server.crt --key
+              openvpn  --remote  may.kg  --dev  tun1 --ifconfig 10.4.0.2 10.4.0.1
+              --tls-server --dh dh1024.pem --ca ca.crt  --cert  server.crt  --key
               server.key --reneg-sec 60 --verb 5
 …
               ping 10.4.0.1
        Notice  the --reneg-sec 60 option we used above.  That tells OpenVPN to
        renegotiate the data channel keys every minute.  Since we used --verb 5
+       Notice  the  --reneg-sec  60  option we used above.  That tells OpenVPN to
+       renegotiate the data channel keys every minute.  Since we  used  --verb  5
        above, you will see status information on each new key negotiation.
        For  production  operations, a key renegotiation interval of 60 seconds
        is probably too frequent.  Omit the --reneg-sec 60 option to use  Open‐
        VPN's default key renegotiation interval of one hour.
+       For  production  operations, a key renegotiation interval of 60 seconds is
+       probably too frequent.  Omit the --reneg-sec 60 option  to  use  OpenVPN's
+       default key renegotiation interval of one hour.
    Routing:
+       Assuming  you  can  ping across the tunnel, the next step is to route a
+       real subnet over the secure tunnel.  Suppose that may and june have two
+       network  interfaces  each, one connected to the internet, and the other
+       to a private network.  Our goal is to  securely  connect  both  private
+       networks.   We will assume that may's private subnet is 10.0.0.0/24 and
+       june's is 10.0.1.0/24.
+       First, ensure that IP forwarding is enabled on both peers.   On  Linux,
+       Assuming  you can ping across the tunnel, the next step is to route a real
+       subnet over the secure tunnel.  Suppose that may and june have two network
+       interfaces each, one connected to the internet, and the other to a private
+       network.  Our goal is to securely connect both private networks.  We  will
+       assume that may's private subnet is 10.0.0.0/24 and june's is 10.0.1.0/24.
+       First,  ensure  that  IP  forwarding  is enabled on both peers.  On Linux,
        enable routing:
 …
               route add -net 10.0.0.0 netmask 255.255.255.0 gw 10.4.0.1
        Now any machine on the 10.0.0.0/24 subnet can access any machine on the
+       Now any machine on the 10.0.0.0/24 subnet can access any  machine  on  the
 .0.1.0/24 subnet over the secure tunnel (or vice versa).
        In a production environment, you could put the route  command(s)  in  a
+       In  a  production  environment,  you  could  put the route command(s) in a
        script and execute with the --up option.
 FIREWALLS
        OpenVPN's usage of a single UDP port makes it fairly firewall-friendly.
        You should add an entry to your firewall rules to allow incoming  Open‐
        VPN packets.  On Linux 2.4+:
+       OpenVPN's usage of a single UDP port makes  it  fairly  firewall-friendly.
+       You  should  add an entry to your firewall rules to allow incoming OpenVPN
+       packets.  On Linux 2.4+:
               iptables -A INPUT -p udp -s 1.2.3.4 --dport 1194 -j ACCEPT
        This  will  allow  incoming packets on UDP port 1194 (OpenVPN's default
        UDP port) from an OpenVPN peer at 1.2.3.4.
        If you are using HMAC-based packet authentication (the default  in  any
        of  OpenVPN's  secure  modes),  having  the  firewall  filter on source
        address can be considered optional, since HMAC packet authentication is
        a  much  more  secure  method of verifying the authenticity of a packet
        source.  In that case:
+       This will allow incoming packets on UDP port 1194 (OpenVPN's  default  UDP
+       port) from an OpenVPN peer at 1.2.3.4.
+       If  you  are using HMAC-based packet authentication (the default in any of
+       OpenVPN's secure modes), having the firewall filter on source address  can
+       be  considered  optional,  since HMAC packet authentication is a much more
+       secure method of verifying the authenticity of a packet source.   In  that
+       case:
               iptables -A INPUT -p udp --dport 1194 -j ACCEPT
        would be adequate and would not render the host inflexible with respect
        to its peer having a dynamic IP address.
        OpenVPN  also works well on stateful firewalls.  In some cases, you may
        not need to add any static rules to the firewall list if you are  using
        a  stateful  firewall  that knows how to track UDP connections.  If you
        specify --ping n, OpenVPN will be guaranteed to send a  packet  to  its
        peer  at  least  once  every n seconds.  If n is less than the stateful
        firewall connection timeout, you can  maintain  an  OpenVPN  connection
        indefinitely without explicit firewall rules.
        You  should also add firewall rules to allow incoming IP traffic on TUN
        or TAP devices such as:
+       would be adequate and would not render the host inflexible with respect to
+       its peer having a dynamic IP address.
+       OpenVPN also works well on stateful firewalls.  In some cases, you may not
+       need  to  add  any  static  rules  to the firewall list if you are using a
+       stateful firewall that knows how to track UDP connections.  If you specify
+       --ping n, OpenVPN will be guaranteed to send a packet to its peer at least
+       once every n seconds.  If n is less than the stateful firewall  connection
+       timeout,  you  can  maintain  an  OpenVPN  connection indefinitely without
+       explicit firewall rules.
+       You should also add firewall rules to allow incoming IP traffic on TUN  or
+       TAP devices such as:
               iptables -A INPUT -i tun+ -j ACCEPT
 …
               iptables -A FORWARD -i tun+ -j ACCEPT
        to allow input packets from tun devices to be forwarded to other  hosts
        on the local network,
+       to  allow input packets from tun devices to be forwarded to other hosts on
+       the local network,
               iptables -A INPUT -i tap+ -j ACCEPT
 …
               iptables -A FORWARD -i tap+ -j ACCEPT
        to  allow input packets from tap devices to be forwarded to other hosts
        on the local network.
        These rules are secure if  you  use  packet  authentication,  since  no
        incoming packets will arrive on a TUN or TAP virtual device unless they
        first pass an HMAC authentication test.
+       to allow input packets from tap devices to be forwarded to other hosts  on
+       the local network.
+       These rules are secure if you use packet authentication, since no incoming
+       packets will arrive on a TUN or TAP virtual device unless they first  pass
+       an HMAC authentication test.
 FAQ
 …
 HOWTO
        For a more comprehensive guide to setting up OpenVPN  in  a  production
        setting, see the OpenVPN HOWTO at http://openvpn.net/howto.html
+       For  a more comprehensive guide to setting up OpenVPN in a production set‐
+       ting, see the OpenVPN HOWTO at http://openvpn.net/howto.html
 PROTOCOL
        For  a  description  of OpenVPN's underlying protocol, see http://open‐
+       For a description  of  OpenVPN's  underlying  protocol,  see  http://open‐
        vpn.net/security.html
 …
        OpenVPN's web site is at http://openvpn.net/
+       Go here to download the latest version of  OpenVPN,  subscribe  to  the
+       mailing lists, read the mailing list archives, or browse the SVN repos‐
+       itory.
+       Go  here to download the latest version of OpenVPN, subscribe to the mail‐
+       ing lists, read the mailing list archives, or browse the SVN repository.
 BUGS
 …
 NOTES
        This product includes software  developed  by  the  OpenSSL  Project  (
+       This  product  includes  software  developed  by  the  OpenSSL  Project  (
        http://www.openssl.org/ )
        For     more     information     on     the     TLS    protocol,    see
+       For      more     information     on     the     TLS     protocol,     see
        http://www.ietf.org/rfc/rfc2246.txt
        For more information on  the  LZO  real-time  compression  library  see
+       For  more  information  on  the  LZO  real-time  compression  library  see
        http://www.oberhumer.com/opensource/lzo/
 COPYRIGHT
        Copyright (C) 2002-2010 OpenVPN Technologies, Inc. This program is free
        software; you can redistribute it and/or modify it under the  terms  of
        the GNU General Public License version 2 as published by the Free Soft‐
        ware Foundation.
+       Copyright  (C)  2002-2010  OpenVPN Technologies, Inc. This program is free
+       software; you can redistribute it and/or modify it under the terms of  the
+       GNU  General  Public  License  version 2 as published by the Free Software
+       Foundation.
 AUTHORS
 …
 November 2008                     openvpn(8)
+November 2008                      openvpn(8)
 }}}
 }}}