RHEL6+KVM Guest OS bridge with Host nics

1.首先要把很難用的NetworkManager服務停掉，換回熟悉的network

# chkconfig NetworkManager off
# chkconfig network on
# service NetworkManager stop
# service network start

2.Host實體介面的ifcfg-*，擺脫NetworkManger的控制

ifcfg-eth*

   NM_CONTROLLED=no

3.我們用eth0示範bridge功能，在此bridge的device將取名為br0，先修改eth0的設定

BOOTPROTO=none 

BRIDGE=br0

#eth0本來的ip設給br0

4.新增ifcfg-br0設定如下

DEVICE=br0
TYPE=Bridge
BOOTPROTO=static
ONBOOT=yes
DELAY=0

IPADDR=192.168.1.x

5.防火牆設定值修改

# iptables -I FORWARD -m physdev --physdev-is-bridged -j ACCEPT
# service iptables save
# service iptables restart

6.重載libvirt設定

service libvirtd reload

7.最後可以看一下bridge的設定有沒有生效

# brctl show
bridge name     bridge id               STP enabled     interfaces
br0             8000.000e0cb30550       no              eth0

8.再來修改guest os的網路設定，就會看到新建的bridge interface了
http://www.techotopia.com/index.php/Creating_an_RHEL_6_KVM_Networked_Bridge_Interface
9.官方文件有說 另一個內建的virbr0是拿來做NAT的，請大家不要亂搞它XD

Ref: Redhat Docs