Disabling the virbr0 NAT Interface

Taken from Linux KVM: Disable virbr0 NAT Interface

 If you accidentally install the KVM components and you do not wish to use the interface, you will notice when you do ifconfig, you will see the "virbro"

virbr0    Link encap:Ethernet  HWaddr 00:00:00:00:00:00
          inet addr:192.168.1.1  Bcast:192.168.122.255  Mask:255.255.255.0
          inet6 addr: fe80::202:c9ff:fee5:70b0/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6885 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:17192337 (16.3 MiB)  TX bytes::1107966 (1.0 MiB)

If you use the follow command

# virsh net-list

Name                 State      Autostart
-----------------------------------------
default              active     yes

# virsh net-destroy default
# virsh net-undefine default
# service libvirtd restart