what is virbr0

The virbr0, or "Virtual Bridge 0" interface is used for NAT (Network Address Translation). It is provided by the libvirt library, and virtual environments sometimes use it to connect to the outside network.

$ ifconfig

Sample outputs:

virbr0    Link encap:Ethernet  HWaddr 00:00:00:00:00:00  

          inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0

          inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:0 errors:0 dropped:0 overruns:0 frame:0

          TX packets:39 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0 

          RX bytes:0 (0.0 b)  TX bytes:7921 (7.7 KiB)

  

Remove that bridge vrbr0 will make it come back.

$ sudo ifconfig virbr0 down

$ sudo brctl delbr virbr0

Now start the 'default' network using virsh command.

$ sudo virsh net-start default

This will automatically re-create the virbr0 bridge.

references:

https://gist.github.com/abelardojarab/e10ed30ab69bf9636929e17e3446bc2a