From /etc/vm.conf:

switch "my_switch" {
    interface bridge0
vm "user123" {
    memory 512M
    cdrom "/home/user/install66.iso"
    disk "/home/user/user123.qcow2"
    interface {
       locked lladdr aa:bb:cc:dd:ee:ff
       switch "my_switch"
# vmctl create -s 20G user.qcow2

You will need to add this crontab entry for a user to prevent the networking from timing out:

For openbsd:

@reboot /usr/bin/tmux new -d 'while true; do /sbin/ping -i5; done' \;

For debian:

@reboot /usr/bin/tmux new -d 'while true; do /usr/bin/ping -i5; done' \;
# groupadd vmdusers
# chown root:vmdusers /var/run/vmd.sock