linux firewall + load balance ISP connections

view full story

http://serverfault.com – I'm trying to get a linux Mint computer with 4 NIC's to act as a load balance server. The idea is that we have three internet connections, and we want to use all of them so we can share usage of 50 computers across all the lines. I've managed to get balancing happening on the server itself using ip route defaults etc, but I want a iptables solution (so unlike ip route's it wont be cached since all of the ppl are facebookers) Where I seem to be stuck; I've got all the NIC's setup with static address information (see below) and I've tested the connections. They are working. I don't know how (HowTos)