[Wylug-help] Linux gateway not a gatewat

[Steven Dodd]

On 11/11/2011 10:54, Gary Stainburn wrote:
> I have a number of issues with this setup. Firstly, it seems to stop working
> during the night, but I have no idea why.
>
> The VPN stays up, and I can connect to the remote gateway over the VPN.
>  From the remote gateway I can access both the internet and my network.
> However, the computers behind the gateway lose access to my network and also
> sometimes lose access to the internet.
> Rebooting the Linux boxes at both ends of the VPN seems to get it working
> again but I have no idea why.
>
> I'll check the net channel values etc. next time it fails.
>
Reason I asked about the the per-device forwarding settings is that the 
general ip_forwarding setting only applies to interfaces that were 
present at the time it is set to 1.  I was wondering if the VPN had come 
up after forwarding was enabled - but clearly not.

Is the VPN set to automatically restart if it drops?  So rather than it 
staying up it's dropping and coming back up and in the process the 
forwarding flag on ppp0 is lost?  Not sure how plausible that is though. 
  But checking the file /proc/sys/net/ipv4/conf/ppp0/forwarding when 
you're having problems would answer that.

Otherwise, as Christopher MacLean suggested, use tcpdump to see if 
traffic from the clients is or is not actually going out on ppp0 - you 
never know it might be the other end of the tunnel that has the problem.

-Steve.