All our subscribers arrive at the gateway via PPTP tunnels, and have statically assigned IP addresses. Internet connection from the gateway is via two dsl modems. I'd like to route one group of subscribers out through modem A and another group through modem B.
The PPTP network is 172.16.4.0/24. If I split this into /26 subnets can I use Mangle to route-mark packets from the 172.16.4.0/26 network for Modem A and packets from the 172.16.4.64/26 network for Modem B? ie. does the route-mark survive the termination of the tunnel? Would it be better to use packet marking, or connection marking?
What's the correct chain to use, prerouting or forward?
With what address are the packets forwarded out of the gateway to the modem - that of the PPtP server (172.16.4.1), the router's interface to the modem, or the IP of the originating source? For accounting purposes it's necessary that all responses pass back through the tunnel.
Thanks for reading.