The bmd-plugin-avahi publishes VM's vnc port using `avahi-publish` command.
Clients can lookup the vnc port by mDNS protocol. If you use MacOS,
open Finder and Network placement folder then you can find the VM name. And
click it to connect to the remove vnc display. Gtk client `bvnc` is also
available in 'avahi-gtk3' package.