Iptables configuration doubt!!!!!

Hello,

Anyone help me in this regard..

We are having more than 7 ISP's and i have planned to put proxy server in my office with one server. I am using CENTOS 5.1 with squid and IPTABLES. the problem is i can able to configure the firewall transparent mode. But if i have created the alias in ethernet eth1:0 eth1:1 like this i can't able to set up the rule ip segment should go on this gateway and another ip segment should go on that gateway


can you please help me in this regards.....