HOWTO - Routing Traffic over Private VPN

[ligand]

Hi Everyone,
Wanted to share a configuration option to help with port forwarding.  My setup:

Interfaces
WAN
VyprVPN
LAN

Thanks to this thread I was able to get Transmission to route out of the VPN interface instead of the WAN interface.  However, Transmission reported that my peer listening port was closed.  I setup port forwarding on the VyprVPN interface to forward inbound traffic to my Transmission host but it didn't work.  After doing a bunch of  tcpdumps, I found that inbound traffic entered the VyprVPN interface but left using the WAN interface. 

I also have an OpenVPN server setup and found a rule in the OpenVPN server rule in that ruleset was affecting my Transmission traffic.   The rule is the one that allows for all traffic to enter OpenVPN (see attachment).  If I disabled the rule then all traffic to and from Transmission went over the VPN.  If the rule was enabled, then I experienced asymmetric routing.  I found that if I unchecked "apply rule immediately" then my routing worked as expected.  :-). Hope this helps.