IP Binding for Linux script

########################################################################
# This script will get your VPN IP address from tun0 and then bind     #
# your LAN to your VPN address using iptables. Uncomment the right LAN #
# for what you are using. If you have a static IP enter that.          #
# The iptables are flushed so VPN ips can be changed                   #
# Onryo aka Erik Adler                                                 #
########################################################################

#!/bin/bash

#Set variables
IPT=/sbin/iptables
VPN=$(/sbin/ifconfig tun0 | awk '/inet addr/ {print substr($2, 6)}')
LAN1=192.168.0.0/16
## LAN2=10.0.0.0/8
## LAN3=172.16.0.0/12

#Flush all rules
$IPT -F
$IPT -X
$IPT -t nat -F
$IPT -t nat -X
$IPT -t mangle -F
$IPT -t mangle -X
$IPT -P INPUT ACCEPT
$IPT -P FORWARD ACCEPT
$IPT -P OUTPUT ACCEPT

echo "You are locked to VPN" $VPN

#Default policies and define chains
$IPT -P OUTPUT DROP
$IPT -P INPUT DROP
$IPT -P FORWARD DROP

#Allow input from LAN and tun0 ONLY
$IPT -A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
$IPT -A INPUT -i lo -j ACCEPT
$IPT -A INPUT -i tun0 -m conntrack --ctstate NEW -j ACCEPT
$IPT -A INPUT -s $LAN1 -m conntrack --ctstate NEW -j ACCEPT
## $IPT -A INPUT -s $LAN2 -m conntrack --ctstate NEW -j ACCEPT
## $IPT -A INPUT -s $LAN3 -m conntrack --ctstate NEW -j ACCEPT
$IPT -A INPUT -j DROP

#Allow output from lo and tun0 ONLY
$IPT -A OUTPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
$IPT -A OUTPUT -o lo -j ACCEPT
$IPT -A OUTPUT -o tun0 -m conntrack --ctstate NEW -j ACCEPT
$IPT -A OUTPUT -d $VPN -m conntrack --ctstate NEW -j ACCEPT
$IPT -A OUTPUT -j DROP
exit 0