Re: Strange VPN problems

[Dan Williams <dcbw redhat com>]

On Thu, 2008-11-06 at 18:24 +0000, Rick Jones wrote:
> --On Thursday, November 06, 2008 16:49:29 +0000 Rick Jones
> <rick activeservice co uk> wrote:
> 
> ¦ I take your point. In fact for my purpose I should really have a
> gateway route just to 192.168.7.* via the VPN server. Can this kind of
> routing policy be configured in NM?
> ¦ 
> ¦ However, there's still a strange problem with these routes. If the
> default route to the MB gateway on ppp0 is not present, then nothing
> will go over the VPN on ppp1, not even the echo packets. Successful
> echo depends _only_ on the existence of this route. Other
> communication over the VPN depends on both this _and_ an explicit
> route to the VPN server on ppp1.
> ¦ 
> ¦ I've tried all kinds of route permutations, and it won't work if the
> original MB default route is not there. It doesn't seem to make a lot
> of sense, but that's what's happening. Maybe you can figure it out?
> 
> Cracked it!
> 
> There must be at minimum a gateway route to the VPN host via ppp0,
> since pptp is using that to carry the VPN packets. By adding just that
> route, everything then works. The routing table ends up as:
> 
> 82.153.174.82   10.44.200.0     255.255.255.255
> UGH   0      0        0 ppp0
> 10.44.200.0     0.0.0.0         255.255.255.255
> UH    0      0        0 ppp0
> 0.0.0.0         0.0.0.0         0.0.0.0         U     0      0        0 ppp1
> 
> The first line is the route I manually added. 82.153.174.82 is the
> public address of my server, 10.44.200.0 is the MB gateway for the
> current session. If the original default route via the MB gateway is
> removed, then it must be replaced by this.

This is how it should already work with recent VPN and PPTP fixes; I
fixed a few PPTP things the other day.  If it doesn't do this with
latest SVN then it's a bug.

> It would be nice to be able to set a policy of which addresses go via
> the VPN, but it's not critical so long as this routing fix is made.

You do this from the Routes dialog in the IPv4 tab of the connection
editor

Dan