I'm kind of wondering why libvirt defaults to 192.168.122.0/24 by
default. It is a piece of address space which is relatively likely to
conflict with address space used in the environment surrounding the
machine. Since libvirtd is on by default if installed, this is
particularly problematic.
I would like to suggest either one of the following as default address
space, unless the user has explicitly configured otherwise:
192.0.2.0/24 - reserved as "test and example network"
198.18.0.0/15 - reserved as "benchmark test network"
See RFC 3330 and RFC 2544 for the definitions of these networks. Both
of them are "should not appear on the public Internet" address blocks,
and much less likely than the RFC 1918 address block (10.0.0.0/8,
172.16.0.0/12, and 192.168.0.0/16) to be encountered "in the wild" by a
user.
-hpa