I have a redhat 6.1 machine that currently does NAT using IPCHAINS and IP Masquerade between two networks. It is the gateway for the internal network
eth0 (internal net) 172.20.1.15 netmask 255.255.255.0
eth1 (external net) 172.16.131.254 netmask 255.255.248.0
I need to add a ADSL connection so the internal network can access the internet and would like to do so by adding another NIC to this machine. I will be using a single fixed IP address.
eth2 (the internet) 2x4.25x.2xx.x netmask 255.255.255.0
I have all three NIC's up and running. Looking aroung the web all the examples for 3 way systems I find are based on the DMZ concept which is not what I am looking for. I want the internal network (eth0)to be able to access both the external network (eth1) and the internet (eth2) primarily for http and mail. I DON'T want any unsolicited stuff coming into the internal network from either eth1 or eth2. I also don't want the external net (eth1) to be able to access the internet (eth2) or to be subjected to unsolicited stuff from the internet (eth2)