Sample Forwarding Chain ipchains -A forward -i ppp0 -s 192.168.1.0/24 -d 0.0.0.0/0 -j MASQ There you go... assumes that ppp0 is the external interface and that your local networks is 192.168.1.0/24 Sample Add Delete ipchains -A input -i all -s 203.45.17.88 -d 0.0.0.0 -j DENY -l blocks all incomming traffic from that ip, simply denying it, and kernel log the details ipchains -D input -i all -s 203.45.17.88 -d 0.0.0.0 -j DENY -l