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Re: [Openvpn-users] Routing problem

  • Subject: Re: [Openvpn-users] Routing problem
  • From: Erich Titl <erich.titl@xxxxxxxx>
  • Date: Fri, 01 Feb 2008 12:43:47 +0000

Hi Lars

Lars Skjærlund wrote:
> Hi list,
> I'm new to OpenVPN and stuck with a routing problem - a trivial
> problem, I hope.
> I'm trying to connect two Linux computers:
> <->
> The first is using a registered IP, the second a private IP. I've
> created a tunnel using more or less default values, with the registered
> IP as the server and the private IP as the client. The server has the IP
>, and the client I can ping both these adresses.
> Unfortunately, I must run an application that will only connect to the
> servers' primary addresses: It's a database application, and when the
> two instances need to communicate, it will connect from to
> or vice versa.
> Because of this, I've setup an extra route pointing to the primary
> interface on the other end, ie. the server has a route directing
> through tun0,

Isn't this the address the tunnel points to? If you route the tunnel 
through itself, this will for sure create problems.

I guess you are heading for some iproute2 magic, e.g. build routes for 
the database trafic only through the tunnel.

I found a little info about this at


  and the client routes
> through it's tun0. When the tunnel comes up, routing tables in both ends
> are updated correctly and I've enabled packet forwarding.
> Still, though, it doesn't work: Using tcpdump, when I ping an IP, I can
> see echo request packets entering tun0, but they are never received on
> the other end. The behaviour is identical in both ends.

Not a real surprise. I am surprised your routes are not crashing the 
tunnel alltogether. What does the log say?

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