qemu-tap.sh

#!/bin/sh
#
# (c)2015 Christian Kujau <lists@nerdbynature.de>
#
# Based on:
# > How do I bridge a connection from Wi-Fi to TAP on Mac OS X? (for the emulator QEMU)
# > https://superuser.com/a/766251
#
INTERFACE="en1"

# set to echo/sudo
DEBUG="sudo"

# See how we were called
case $(basename "$0") in
	qemu-ifup)
	# Needed for the symlink
	umask 0022
	${DEBUG} ln -sf /dev/tap0 /dev/tap
	${DEBUG} sysctl -w net.inet.ip.forwarding=1
	${DEBUG} sysctl -w net.link.ether.inet.proxyall=1
	${DEBUG} sysctl -w net.inet.ip.fw.enable=1
	${DEBUG} ifconfig bridge0 create
	${DEBUG} ifconfig bridge0 addm ${INTERFACE} addm tap0
	${DEBUG} ifconfig bridge0 up
	${DEBUG} natd -interface en1
	${DEBUG} ipfw add divert natd ip from any to any via ${INTERFACE}
	;;

	qemu-ifdown)
	${DEBUG} ipfw del 00100
	${DEBUG} ipfw del "$(sudo ipfw list | grep "ip from any to any via ${INTERFACE}" | sed -e 's/ .*//g')"
	${DEBUG} killall -9 natd
	${DEBUG} sysctl -w net.inet.ip.forwarding=0
	${DEBUG} sysctl -w net.link.ether.inet.proxyall=0
	${DEBUG} sysctl -w net.inet.ip.fw.enable=1
	${DEBUG} ifconfig bridge0 deletem ${INTERFACE} deletem tap0
	${DEBUG} ifconfig bridge0 down
	${DEBUG} ifconfig bridge0 destroy
	;;

	*)
	echo "$0: call me as qemu-ifup or qemu-ifdown!"
	exit 1
	;;
esac