#!/bin/bash
# Internet Sharing Script
# George Smart, M1GEO - Nov 2009
echo "IPv4 Port Forwarding Script"
echo "George Smart, M1GEO"

if [ $# -ne 3 ]; then
	echo "Usage:	$0 <source device> <output device> <output ip address>"
	echo "eg:	$0 wlan0 eth0 10.0.0.1"
	echo "		bridges wireless to wired"
	exit -1
else
	INPUT="$1"
	OUTPUT="$2"
	NETADD="$3"
	echo "Source:	$INPUT"
	echo "Output:	$OUTPUT"
	echo "IP Add:	$NETADD"

	# DO IT!
	sudo ifconfig eth0 $NETADD up
	sudo iptables -A FORWARD -i $INPUT -o $OUTPUT -s $NETADD/24 -m conntrack --ctstate NEW -j ACCEPT
	sudo iptables -A FORWARD -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
	sudo iptables -A POSTROUTING -t nat -j MASQUERADE
	sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
	sudo sysctl net.ipv4.conf.default.forwarding=1 2>&1 > /dev/null
	sudo sysctl net.ipv4.conf.all.forwarding=1 2>&1 > /dev/null

	echo "Done..."
fi