Well here goes my network configuration. I have two computers. 1st has two ifs: eth0 192.168.2.91 eth1 172.16.1.1 2nd has one if: eth0 172.16.1.2 On 192.168.2.0/24 subnet I have a 192.168.2.254 router (I can't admin it) which provides NAT for the 192.168.2.0 subnet. I want to make NAT for my 2nd comp on the 1st one. I do the following on the 1st comp: #/sbin/iptables -A POSTROUTING -t nat -s 192.168.1.0/24 -j SNAT --to-source 192.168.2.91 #/sbin/iptables -A FORWARD -i eth0 -o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT #/sbin/iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT The 2nd comp has default router set to 172.16.1.1. Everything goes fine but nothing works. I can see with tcpdump all incoming packets from eth1 but I can't see any outgoing from eth0 corresponding to them. What should I do?