Opened 3 years ago

Closed 2 years ago

#1244 closed Feature Wish (fixed)

client-connect script blockes openvon server

Reported by: cfasnacht Owned by: plaisthos
Priority: major Milestone: release 2.5
Component: Generic / unclassified Version: OpenVPN 2.4.3 (Community Ed)
Severity: Not set (select this one, unless your'e a OpenVPN developer) Keywords: Openvpn Server blocked blocked client-connect


I had an issue with Openvpn server. We call a dns update script in which the curl takes 5 seconds, during the execution of this script all traffic on the openvpn server is blocked, or not processed.
I see this when I run a nload tun0. There is absolutly no traffic during the execution of the script. This leads to arround 3% Ping loss, UDP packages errors and UDP buffer errors.
If I have an open ssh connection over the VPN server the session hangs for the 5 seconds.

Openvpn software version: OpenVPN 2.4.3 x86_64-redhat-linux-gnu [SSL (mbed TLS)] [LZO] [LZ4] [EPOLL] [MH/PKTINFO] [AEAD] built on Jun 4 2018

I use a client-connect script : /etc/openvpn/

This script then calls a DNS update script:
# /etc/openvpn/

In this script we execute a curl on Infoblox that takes 5 seconds until it returns an answer.
# /etc/openvpn/

curl https://example....

In my opinion this is very severe, because most users would not even have notices this because the client-connect script would not have taken forever. They would just have package loss or session lag. I would not have found this if the execution of the script would have been just 1 or 2 seconds.
This work arround once noticed, is quite easy just add a & at the end of the

Change History (2)

comment:1 Changed 3 years ago by Gert Döring

Milestone: release 2.4.3release 2.5
Owner: set to plaisthos
Status: newassigned
Type: Bug / DefectFeature Wish

This is the way it is today and has been since ever.

A patch set to be able to do client-connect asynchronously is being worked on, but will not hit 2.4 (as this is fairly intrusive).

For the time being, this can be worked around by using a auth-user-pass-verify plugin that does deferred (async) authentication, creating the necessary files for the client-connect phase while at it.

comment:2 Changed 2 years ago by Gert Döring

Resolution: fixed
Status: assignedclosed

The patchset has been merged into "git master" a few weeks ago.

@cfasnacht: for your use case, you already found the workaround - just for this into the background. For other use cases, where you want feedback "has this worked? shall we block the user on failure?" this can now also be done.

I am closing this ticket as the workaround for the "easy case" has been properly documented now (here), and the necessary code for the "complicated case" has been written, tested and merged.

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