Re: [Openvpn-users] Problem with Openvpn 2.0.5 weird kernel/tun interaction

[Evan Harris <eharris@xxxxxxxxxxxxx>]

Haven't seen any replies on this in over a month, so reposting it.  Is there 
any additional information I can provide?

Thanks.

Evan

On Wed, 22 Mar 2006, Evan Harris wrote:

> I'm seeing a wierd problem with openvpn 2.0.5 (using static keys) and what it 
> is sending to the tun interface (linux kernel 2.4.30).  It looks like after a 
> while of runtime, openvpn just goes off the deep end and sends a bunch of 
> strangly sized packets over a second or two to the output interface even 
> though there were no packets sent to the tun interface.  After this burst of 
> packets, the tun interface (or openvpn's reads from it) appear to stop 
> working until the tunnel is reset.
>
> I initially started looking into this problem because I was seeing inactivity 
> timeout restarts of the tunnel, when there was no reason for that to happen. 
> Since I had the restart timeout set to 60 seconds, there would be sporadic 
> periods of 60 seconds where the tunnel didn't work, followed by an inactivity 
> timeout, and then all was well again until the next time it happened.
>
> This problem seems to be very repeatable in my configuration, though it takes 
> various amounts of time for it to happen.  Usually, it will happen beteen 
> 5-30 minutes after a restart.
>
> I've attached a log of one occurrance of this problem to this message, sorry 
> it is so long.  I did cut a little out of the middle of the log to get past 
> the mailing list's size restrictions.  The log is with openvpn running in the 
> background (not as a daemon) with logging set to level 8, and a tcpdump 
> running on the output interface in the same terminal.  The only traffic on 
> the tunnel is the openvpn pings from either end, there was no traffic at all 
> on the tun interface.
>
> To give context, the log shows a few ping exchanges while the tunnel is still 
> working, followed by the packet flurry, followed by the tunnel reset by the 
> inactivity timeout kicking in.
>
> The other end of the tunnel is an older openvpn 2.0, but I don't think that 
> should matter, because the strangeness is all happening on the 2.0.5 side, 
> and there is no other traffic other than the pings.
>
> Any pointers as to what I can do to troubleshoot further or resolve this 
> issue would be greatly appreciated.
>
> Thanks.
>
> Evan

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