Issue with "register-dns"

[wla]

"register-dns" do:

• C:\Windows\system32\net.exe stop dnscache
• C:\Windows\system32\net.exe start dnscache
• C:\Windows\system32\ipconfig.exe /flushdns
• C:\Windows\system32\ipconfig.exe /registerdns

If the software "opsi" from ​http://uib.de/ is installed, "net.exe stop dnscache" hangs, because the service opsiclientd.exe depends from dnscache service. If we simulate this from a cmd, we saw that a question "did you will continue ..." wait for answer, but this all runs in background.
As result the tunnel is established, but we have in tasklist 2 processes openvpn.exe and 1 net.exe and net1.exe.

I expect the same issue with other services which depends from service dnscache.

I attach a screenshot (the cmd ist manually started to illustrate the issue):

[Gert Döring]

Selva, Samuli, any idea how to tackle this?

[Selva Nair]

I think "net stop dnscache /yes" will get rid of that user prompt about dependent services (not sure /yes is supported on all version of net.exe -- can't find any docs on it).

But, if there are dependent services, net stop will stop those too, but subsequent "net start dnscache" will not restart the dependent service.

I think we should get rid of restarting the dns client service as a part of register-dns. "ipconfig /flushdns" and "ipconfig /registerdns" should be enough to fix the dns registration issues seen on some windows platforms. I've never seen a situation where dns server fails to register without a client service restart. Also, restarting service is too intrusive and takes a while to complete.

[Gert Döring]

Replying to selvanair:

I think we should get rid of restarting the dns client service as a part of register-dns. "ipconfig /flushdns" and "ipconfig /registerdns" should be enough to fix the dns registration issues seen on some windows platforms. I've never seen a situation where dns server fails to register without a client service restart. Also, restarting service is too intrusive and takes a while to complete.

Indeed, this might be the best way forward.

I wonder if we should do this unconditionally ("just get rid of it"), or add a parameter to register-dns - "as is", it would just do /flushdns and /registerdns, but with --register-dns full you get the full blast stuff... or maybe not.

It's not "stone age" stuff, though - James introduced stopping and starting the service in 2010 in commit 75dfe3d7f73279ddefb533f2e3b4a4cce4e9802a (coming from SVN, which is no longer online, meh) - which is about the time when Vista and Win7 were already around...

[Selva Nair]

As restart service needs admin rights and GUI will not have it going forward, we may not want get to rid of it completely. What about

--restart-dns --> restart the dns client service (add /yes to cmdline too?)
--register-dns --> only ipconfig /flushdns and /registerdns

That said, some feedback from regular Windows users may help decide whether we should keep the current way as the default and add a method to disable the service restart.

Wish we knew why James added the service restart part.

Selva

[Samuli Seppänen]

I asked James about this.

[Samuli Seppänen]

An answer from James:

On 29/11/2016 02:16, Samuli Seppänen wrote:
> Hi James,
>
> We recently received a bug report about register-dns not working, because
> an external system service depends on the dnscache service:
>
> <https://community.openvpn.net/openvpn/ticket/775>
>
> As you added the register-dns option, could share some insights on why you
> did it, and why did you implement it as you did?
>
> If possible, respond directly to the Trac ticket .
>
> Thanks!
>
> Samuli 
>
I think it's probably okay to remove the net stop/start dnscache commands
because they are commented out in OpenVPN 3.

James

[wla]

We tested with an up batch script to have only the 2 commands:

ipconfig /flushdns and
ipconfig /registerdns

This works fine (since 1 day).

I think for DNS issues the restart of service dnscache is not required.

[Selva Nair]

So what's the consensus? Shall we just remove 'net stop/start dnscache' or make it optional?

[Gert Döring]

meeting tonight, then decide

[Selva Nair]

At today's IRC meeting it was decided to remove restarting the dns client service as a part of --register-dns.

Patch sent to the list.

[Gert Döring]

commit fb56058a98dcc81b34cffbdc46417d672b8926e1
Author: Selva Nair <selva.nair@…>
Date: Wed Nov 30 16:51:36 2016 -0500

Do not restart dns client service as a part of --register-dns processing

thanks :-)

@wla: there are snapshot installers on ​https://build.openvpn.net/download/snaphots/ - could you grab the latest one and test if it works for you?

[wla]

404 Not Found ?

[wla]

ok, typing error: ​https://build.openvpn.net/downloads/snapshots/ - I will try ...

[wla]

Tested with:

openvpn-install-2.4_beta2-I904-active-setup.exe - 'net stop/start dnscache' still active!

and

openvpn-install-master-20161201154916-1c587a1112.exe - this works !!!

Respect for fastest reaction!

[Gert Döring]

Thanks for testing & confirming all is good now :-)