#!/bin/bash

INTERFACE_1=rl0
INTERFACE_2=rl1

IP_1=0.0.0.0
IP_2=0.0.0.0

NETMASK_1=0xfffffff0
NETMASK_2=0xfffffff0

DROUTE=0.0.0.0

I1_ALIASES=""
I2_ALIASES=""

# IP redirection is setup as [primary outside]:[secoundary outside]:[inside]
IP_REDIRECT=""

# port redirection is setup as [inside]:[port]:[outside]:[port]
PORT_REDIRECT=""

######################
### end user edits ###
######################

setup_nat()
	{
	for IP_ADDY in `echo $IP_REDIRECT`; do
		IP_OUTSIDE=`echo $IP_ADDY | awk -F : '{ print $1 }'`
		IP_INSIDE=`echo $IP_ADDY | awk -F : '{ print $3 }'`
		REDIRECT="$REDIRECT -redirect_address $IP_INSIDE $IP_OUTSIDE"
	done
	for PORT_ADDY in `echo $PORT_REDIRECT`; do
		IP_OUTSIDE=`echo $PORT_ADDY | awk -F : '{ print $3":"$4 }'`
		IP_INSIDE=`echo $PORT_ADDY | awk -F : '{ print $1":"$2 }'`
		REDIRECT="$REDIRECT -redirect_port tcp $IP_INSIDE $IP_OUTSIDE"
	done
	}

interface1()
	{
	ifconfig $INTERFACE_1 $IP_1 netmask $NETMASK_1
	for ALIAS in $I1_ALIASES; do
		ifconfig $INTERFACE_1 alias $ALIAS netmask $NETMASK_1
	done
	}

interface2()
	{
	ifconfig $INTERFACE_2 $IP_2 netmask $NETMASK_2
	for ALIAS in $I2_ALIASES; do
		ifconfig $INTERFACE_2 alias $ALIAS netmask $NETMASK_2
	done
	}

case $1 in
	start)
		interface1; interface2
		ifconfig $INTERFACE_1
		ifconfig $INTERFACE_2
		route add default $DROUTE
		if [ -f /var/run/natd.pid ]; then
			kill -TERM `cat /var/run/natd.pid`
		fi
		setup_nat
		natd -n $INTERFACE_1 $REDIRECT;;
	stop)
		for IP in `ifconfig $INTERFACE_1 | grep "inet"`; do
			ifconfig $INTERFACE_1 delete $IP > /dev/null 2> /dev/null
		done
		for IP in `ifconfig $INTERFACE_2 | grep "inet"`; do
			ifconfig $INTERFACE_2 delete $IP > /dev/null 2> /dev/null
		done;;
	$INTERFACE_1)
		interface1;;
	$INTERFACE_2)
		interface2;;
	*)
		echo
		echo "usage: network_interfaces [start, stop, interface]";;
esac