Try the Linux Firewalls Using iptables tutorial on peter's site. Helped the members of my staff greatly.
I would like to setup a router for an experiment and the router just needs to route packets between two lans. I tried using NATting using private IP addresses, for both the LANs , but lots of packets are being dropped at the router. Hence I am trying to use public IPs (Assuming I do have some at my disposal). My setup is lan1 <---> (eth1) router (eth0) <---> lan2 , also I am using iptables for routing. I absolutely couldnt find any article which would explain me how to go about setting up as mentioned above. Also say, I am using the public IP addresses 130.138.6.xx for lan1 and eth1 (internal) is 220.127.116.11 and eth0 (external) is configured to be 18.104.22.168. I would like to know if this setup is possible in the first place? Any help in this direction would be of great help and thanks a zillion in advance to all.