I recently upgraded my virtual host node from Fedora 13 to Fedora 15 and alas virt-manager / NetworkManager do not yet configure a bridged network device for use with KVM guests.
You will need to have bridge-utils installed, I found it was included when I installed virt-manager.
yum install bridge-utils
Configure your interfaces by editing the network scripts located in /etc/sysconfig/network-scripts. Take note of the new terminology Fedora is using.
Note: You will lose networking temporarily as you perform the configuration.
1. Disable NetworkManager. Unfortunately NM does not manage bridges and if you do not disable it , NM will over write your configuration.
systemctl stop NetworkManager.service
systemctl disable NetworkManager.service
2. Configure your bridge by adding a file ifcfg-br0 with the contents:
IPADDR=192.168.0.10 # Set your IP address here.
DNS1=192.168.0.2 # Set your DNS server.
IPV6INIT=no # ipv6 is disabled
Or if you prefer to use DHCP:
3. Add your network card to the bridge. Here we will add an interface using a file ifcfg-em0
# change the hardware address to match the hardware address your NIC uses
3. Enable networking
systemctl start network.service
systemctl enable network.service
We can add a single rule to allow network packets to be forwarded to the guests.
iptables -I FORWARD -m physdev --physdev-is-bridged -j ACCEPT
# Save your changes