Конфиг iptables:
*nat
-A POSTROUTING -o eth0 -j SNAT --to-source inet_addres
COMMIT
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -i eth0 -p tcp -m tcp --tcp-flags FIN,SYN,ACK SYN -j LOG --log-level 7 --log-tcp-options
-A INPUT -i eth0 -p tcp -m tcp --tcp-flags FIN,SYN,ACK SYN -j REJECT --reject-with icmp-port-unreachable
-A FORWARD -s 192.168.1.0/24 -p icmp -i eth1 -j ACCEPT
-A FORWARD -d 192.168.1.0/24 -p icmp -o eth1 -j ACCEPT
-A FORWARD -s 192.168.1.0/24 -p udp -m udp --dport 53 -i eth1 -j ACCEPT
-A FORWARD -d 192.168.1.0/24 -p udp -m udp --sport 53 -o eth1 -j ACCEPT
-A FORWARD -s 192.168.1.0/24 -p tcp -m multiport --dports 20,21,25,80,110,8080 -i eth1 -j ACCEPT
-A FORWARD -d 192.168.1.0/24 -p tcp -m multiport --sports 20,21,25,80,110,8080 -o eth1 -j ACCEPT
-A FORWARD -s 192.168.1.0/24 -p ! icmp -m state --state INVALID -i eth1 -j DROP
-A FORWARD -d 192.168.1.0/24 -p ! icmp -m state --state INVALID -o eth1 -j DROP
-A FORWARD -o eth0 -j DROP
-A FORWARD -o eth1 -j DROP
COMMIT