KVM Network Bridge to assign Static IP

I installed Ubuntu server 14.04. and assigned static IP to it... then installed KVM and Virtual machine manager... then created a test virtual machine and it worked fine also with local IP address over NAT.

I have two LAN Card and only one is connected to internet.

What i want is configuration to bridge em2 to guest machines. So, that static ip address work also for guest machines. Right now if i assing static ip to guest machine there is no connectivity.

My ifconfig details is:

ifconfig -a
em1 Link encap:Ethernet HWaddr 0c:c4:7a:4d:96:aa UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Memory:f7100000-f717ffff
em2 Link encap:Ethernet HWaddr 0c:c4:7a:4d:96:ab inet addr:68.168.105.130 Bcast:68.168.105.255 Mask:255.255.255.0 inet6 addr: fe80::ec4:7aff:fe4d:96ab/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:3717 errors:0 dropped:10 overruns:0 frame:0 TX packets:373 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:269655 (269.6 KB) TX bytes:239608 (239.6 KB) Interrupt:20 Memory:f7200000-f7220000
lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:123 errors:0 dropped:0 overruns:0 frame:0 TX packets:123 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:8881 (8.8 KB) TX bytes:8881 (8.8 KB)
virbr0 Link encap:Ethernet HWaddr 52:54:00:23:1c:65 inet addr:192.168.100.1 Bcast:192.168.100.255 Mask:255.255.255.0 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
virbr0-nic Link encap:Ethernet HWaddr 52:54:00:23:1c:65 BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:500 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) 

and /etc/network/interfaces details is:

auto lo
iface lo inet loopback
auto em2
iface em2 inet static address 68.168.105.130 netmask 255.255.255.0 network 68.168.105.0 broadcast 68.168.105.255 gateway 68.168.105.1 # dns-* options are implemented by the resolvconf package, if installed dns-nameservers 8.8.8.8 dns-search dedicated.codero.net 

1 Answer

Step 1: Create the bridge

You probably have bridge-utils installed already, but in case you don't:

sudo apt-get install bridge-utils

In the host and as root, edit /etc/network/interfaces:

auto lo
iface lo inet loopback
auto br0
iface br0 inet static
address 68.168.105.130
netmask 255.255.255.0
network 68.168.105.0
broadcast 68.168.105.255
gateway 68.168.105.1
# dns-* options are implemented by the resolvconf package, if installed
dns-nameservers 8.8.8.8
dns-search dedicated.codero.net
bridge_ports em2
bridge_fd 9
bridge_hello 2
bridge_maxage 12
bridge_stp off

Now you can either re-boot or:

sudo ifup br0

Reference

Step 2: Modify your VM definition to use the bridge

Note: There is probably a way to do this step using virt-manager, however I do not use it and do not know how.

Use virsh edit and change your interface definition lines to use bridging instead of what is currently being used. Here is an example from one of my VMs. Before:

<interface type='network'> <mac address='52:54:00:0d:ed:95'/> <source network='default'/> <model type='virtio'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>

after:

<interface type='bridge'> <mac address='52:54:00:0d:ed:95'/> <source bridge='br0'/> <model type='virtio'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>

Step 3: Specify the static IP address in the guest VM

Now, while running the guest VM, which might have network issues for the moment, edit /etc/network/interfaces and add the static definition for the interface name. For example, and guessing a little for your setup:

auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 68.168.105.101
netmask 255.255.255.0
network 68.168.105.0
broadcast 68.168.105.255
gateway 68.168.105.1
dns-nameservers 8.8.8.8
dns-search dedicated.codero.net 

Notes:

The default editor used by virsh edit is as defined by the $EDITOR environment variable, or vi if it does not exist. add export EDITOR="/bin/nano" to your ~/.bashrc file to set, for example, nano as your default editor.

You MUST use virsh edit do not edit the XML file directly, as virsh edit will do a bunch of checks upon save and exit. From any directory, and for example, do:

virsh edit desk_tt