*nat
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]

-A POSTROUTING -o eth0 -j SNAT --to YOUR_IP_ADDRESS_FROM_ISP

COMMIT

*filter
:INPUT DROP [6356:381360]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [58:8502]

-A INPUT -i eth1 -p udp -j ACCEPT
-A INPUT -i eth2 -p udp -j ACCEPT

-A INPUT -i eth1 -j ACCEPT

-A INPUT -i eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -i eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT

-A FORWARD -i eth0 -o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i eth1 -j ACCEPT

COMMIT