#!/bin/sh
#########################################
##### CONFIGURATION                     #
I=/usr/sbin/iptables                    # Path to iptables binary
INTIF="eth0"                            # Internal Interface
INTIP="192.168.0.1"                     # Internal IP Address
EXTIF="eth1"                            # External Interface
EXTIP="10.0.0.100"                      # External IP Address
##### END CONFIGURATION                 #
#########################################
if [ "$1" = "status" ]; then
 echo "[iptables]";$I -t nat -L;$I -n -L;exit;
fi
echo "   Clearing any existing rules and setting default policy.."
$I -P INPUT ACCEPT
$I -F INPUT
$I -P OUTPUT ACCEPT
$I -F OUTPUT
$I -P FORWARD DROP
$I -F FORWARD
$I -t nat -F
$I -t mangle -F
$I -X
if [ "$1" = "stop" ]; then
 echo "Firewall rules deleted...";exit;
fi
echo "   Setting default policies"
$I -A INPUT -i lo -j ACCEPT             # Allow INPUT on local loopback  
$I -A INPUT -i $INTIF -j ACCEPT         # Allow INPUT on LAN
$I -A INPUT -i $EXTIF -j ACCEPT         # Allow INPUT on EXT
$I -A OUTPUT -o lo -j ACCEPT            # Allow OUTPUT on local loopback
$I -A OUTPUT -o $INTIF -j ACCEPT        # Allow OUTPUT on LAN
$I -A OUTPUT -o $EXTIF -j ACCEPT        # Allow OUTPUT on EXT
echo "   Setting NAT/MASQ/FWD policies"
echo "1" > /proc/sys/net/ipv4/ip_forward
$I -A FORWARD -i $EXTIF -o $INTIF -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
$I -A FORWARD -i $INTIF -o $EXTIF -j ACCEPT
$I -t nat -A POSTROUTING -o $EXTIF -j MASQUERADE