Multiple internet gateways, with port routing

[EdmunTimberlane]

I know this can be done, but I am not quite sure how to do it. I have a box with three interfaces: eth0, eth1, & eth2. eth0 & eth1 are internet links, and eth2 is the LAN. I would like all internet traffic to go out over eth0, except for traffic running on specific ports (such as 80). I would like the specified port traffic to be routed out over eth1. I also want to make sure the return traffic comes back to the same IP.

[EdmunTimberlane]

Would this work?

INTERNET1="eth0"
INTERNET2="eth1"
LAN="eth2"

iptables -t nat -A PREROUTING -i $LAN -p tcp --dport 80 -j REDIRECT --to $INTERNET2