Hans du Plooy wrote: Hi!
This worked fine with two public IPs on the same network, with the same gateway (colo provider gave me two IPs), but I'm not sure how being behind two natting firewalls would impact this. I also don't have physical access to the box, so I've got to do it right first time :-)
Problem is that you can't use two default routes at the same time. And from both NAT engines you'll get "normal" looking internet traffic. Nothing that you can see, except the change dest. IP (your local IP).
So traffic that comes in via eth1 will go out to eth0. I'm doing the same but with one central firewall. Then it's easy, you have to make the firewall route the traffic to the right ISP back out. Well easy... in most cases you have to make seperate SAT (port forwarding) rules for two different internal IP's on the same interface to make that work. But it's doable. What you are trying to do will be a bit tricky I think.
A system can have only one default route, and traffic from the MTA will be addressed to an external IP. Maybe with two NICs and some trickery you can fix something.
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