what i am currently trying to do is have my router masquerade multiple external interfaces to multiple internal ethernets.

I have two ppp connections: one over ethernet (dsl), and the other over serial (pots line dialup).

the dsl line is basically for my servers, it looks like this

internet--dsl-->ppp0(eth0)-->router-->eth1-->server switch-->computers

this ethernet works fine, and all iptables rules written for it work fine. (filtering and NATing) new or established packets are taken in, then forwarded along eth1 to the corresponding class c ip on the server network.

however, i would like to run my client/workstation's internet connection from the same router, but using different external interface and internal ethernet.

for example, i would like the pots dialup line interface masqueraded to eth2, so that all computers connected to eth2 use the ip address of the ppp device connected to dialup.

here is how i vision it:

internet--dial_up-->ppp1(/dev/ttyS3)-->router-->eth2-->crossover_cable-->client

could anyone help me in doing so? is it just a matter of some additional iptables entries, or does this run deeper? please help, and cc reply directly to jamesstickland@sympatico.ca