#!/bin/sh

LAN="eth2"
WAN="eth1"


# Delete all existing rules.
iptables -F
iptables -t nat -F
iptables -t mangle -F
iptables -X

# Always accept loopback traffic
iptables -A INPUT -i lo -j ACCEPT

# Allow established connections, and those not coming from the outside
iptables -A INPUT -m state --state ESTABLISHED -j ACCEPT
iptables -A INPUT -m state --state RELATED -j ACCEPT
iptables -A INPUT -m state --state NEW -i $WAN -j ACCEPT
iptables -A FORWARD -i $LAN -o $WAN -m state --state ESTABLISHED,RELATED -j ACCEPT

# Allow outgoing connections from the LAN side.
iptables -A FORWARD -i $LAN -o $WAN -j ACCEPT

# Masquerade.
iptables -t nat -A POSTROUTING -o $WAN -j MASQUERADE

# Don't forward from the outside to the inside.
iptables -A FORWARD -i $WAN -o $LAN -j REJECT

# Enable routing.
#Do it in /etc/sysctl.conf, noob!
#echo 1 > /proc/sys/net/ipv4/ip_forward

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth2
192.168.0.0     0.0.0.0         255.255.255.0   U     0      0        0 eth1
0.0.0.0         192.168.0.1     0.0.0.0         UG    0      0        0 eth1