qemu-ifup

#!/bin/sh

#
# script to bring up the tun device in QEMU in bridged mode
# first parameter is name of tap device (e.g. tap0)
#
# some constants specific to the local host ? change to suit your host
#

ETHNAME='eth0'
ETH0IP=10.0.2.15
NETMASK=255.255.0.0
BROADCAST=10.0.2.255
GATEWAY=10.0.2.2

#
# First take eth0 down, then bring it up with IP 0.0.0.0
#
ifconfig $ETHNAME down
ifconfig $ETHNAME 0.0.0.0 promisc up

#
# Bring up the tap device (name specified as first argument, by QEMU)
#
openvpn --mktun --dev $1 -user 'id -un'
ifconfig $1 0.0.0.0 promisc up

#
# create the bridge between eth0 and the tap device
#
brctl addbr br0
brctl addif br0 $ETHNAME
brctl addif br0 $1

#
# only a single bridge so loops are not possible, turn off spanning
# tree protocol
#
brctl stp br0 off

#
# Bring up the bridge with ETH0IP and add the default route
#
ifconfig br0 $ETH0IP netmask $NETMASK broadcast $BROADCAST
route add default gw $GATEWAY

#
# stop firewall ? comment this out if you don't use Firestarter
#
#service firestarter stop