#!/bin/bash
#Copyright 2002 William Stearns <wstearns@pobox.com>
#Released under the GPL

#Note: This is NOT complete.  You will almost certainly need to
#customize it; this is provided as a starting point only.  At an
#absolute minimum, you need to fix the IP addresses below.

#FIXME - make safe for multiple uml_switches?

#Edit these:
#IP address of the host as seen by the outside world
HostIP=66.59.109.137

#Allocated real IP address subnet
UMLRealNet=66.59.111.160
UMLRealNetMask=255.255.255.224

UMLFakeNet=172.28.0.0/16
UMLFakeNetGW=172.28.0.1
UMLFakeNetBC=172.28.255.255
UMLFakeNetMask=255.255.0.0


status () {
	echo "$*"
}


while [ -n "$1" ]; do
	case "$1" in
	[Ss][Tt][Oo][Pp])
		Action='stop'
		;;
	[Ss][Tt][Aa][Rr][Tt])
		Action='start'
		;;
	tap*)
		Device="$1"
		;;
	esac
	shift
done

if [ -z "$Action" ]; then
	Action='start'
fi


case "$Action" in
start)
	status Loading tun support
	modprobe tun

	status Setting up tap device
	TapDevice=`tunctl -b -u 0`
	HostEth='eth1'

	case "$TapDevice" in
	tap[0-9]|tap[0-9][0-9]|tap[0-9][0-9][0-9]|tap[0-9][0-9][0-9][0-9])
		echo Tap device "$TapDevice"
		;;
	*)
		echo Unknown tap device "$TapDevice", exiting
		exit
		;;
	esac

	status Assigning IP addresses to tap device
	ifconfig "$TapDevice" $HostIP netmask 255.255.255.255 up
	ifconfig "$TapDevice:0" $UMLFakeNetGW netmask $UMLFakeNetMask broadcast $UMLFakeNetBC up

	status Setting up firewall, port forwarding, masquerading
	#Put any rules you need here.
	#iptables -A POSTROUTING -t nat -o $HostEth -s $UMLFakeNet -j MASQUERADE
	#For example, to forward specific ports back to one of the reserved addresses
	#iptables -A PREROUTING -t nat -p tcp -d $HostIP --dport 1111 -j DNAT --to 172.28.0.99:22
	#iptables -A PREROUTING -t nat -p udp -d $HostIP --dport 27015 -j DNAT --to 172.28.0.2:27015

	status '(re)starting uml_switch'
	killall -TERM uml_switch ; sleep 1 ; killall -9 uml_switch

	chmod 777 /tmp/uml.ctl

	screen -S uml_switch -t uml_switch -d -m bash -c "uml_switch -tap \"$TapDevice\" ; sleep 360000"

	sleep 2

	chmod 777 /tmp/uml.ctl
	chmod 666 /dev/net/tun

	status Configuring IP forwarding and proxy_arp
	echo 1 > /proc/sys/net/ipv4/ip_forward
	echo 1 > /proc/sys/net/ipv4/conf/$TapDevice/proxy_arp

	route del -net $UMLRealNet netmask $UMLRealNetMask 2>/dev/null
	route add -net $UMLRealNet netmask $UMLRealNetMask dev $TapDevice
	status Adding routes to new address block
	for LastOctet in `seq 160 190` ; do
		arp -Ds 66.59.111.$LastOctet $HostEth pub
	done
	;;
stop)
	echo stop not implemented.
	;;
esac

status 'Done!'