Ok greatings and here we go. ---- eth0 | Linux Box | eth1 ----- eth0 = 200.1.1.10 eth1 = 192.168.101.1 ok on eth0 I have comon internet connection with a public IP, know on eth1 I have a NAT that I created like this: ...../ipv4/ip_forward=1 iptables -t nat -A POSTROUTING -s 192.168.101.2 -o eth1 -j SNAT --to 200.1.1.10 iptables -t nat -A POSTROUTING -s 192.168.101.3 -o eth1 -j SNAT --to 200.1.1.10 iptables -t nat -A POSTROUTING -s 192.168.101.4 -o eth1 -j SNAT --to 200.1.1.10 that works ok, now I do some pings from a NATed machine lets say 192.168.101.4 and I get: ping 192.168.101.1 OK! ping 200.1.1.10 OK! ping 200.51.12.18 FAIL! (ping a DNS known IP) I imagine that eth0 thoes not forward ti eth1 and viceversa. This is a problem with ip route or something? where can I look to solve this problem? I know it must be a small configuration, but I can''t find it I need a little push, thanks here is "ip route show" and "ip neigh show" from the linux box # ./ip route show 200.x.x.128/29 dev eth0 proto kernel scope link src 200.x.x.131 192.168.101.0/24 dev eth1 proto kernel scope link src 192.168.101.1 127.0.0.0/8 dev lo scope link default via 200.x.x.129 dev eth0 # ./ip neigh show 200.x.x.130 dev eth0 lladdr 00:06:29:d5:7a:12 nud stale 192.168.101.4 dev eth1 lladdr 00:00:f8:98:c2:8e nud stale 200.x.x.129 dev eth0 lladdr 00:30:80:22:37:da nud stale thanks