For the impatient, here is our simple script. We’ll explain it afterwards. This is assuming that you’re on a network with no DHCP server.



sudo brctl addbr br0

sudo ifconfig eth0

sudo brctl addif br0 eth0

sudo ifconfig br0 netmask up

sudo route add -net netmask br0

sudo route add default gw br0

sudo tunctl -b -u john

sudo ifconfig tap0 up

sudo brctl addif br0 tap0


sudo iptables -I RH-Firewall-1-INPUT -i br0 -j ACCEPT

qemu-kvm ~/win2k.img -m 512 -net nic -net tap,ifname=tap0,script=no

via HowTos/KVM – CentOS Wiki.