# mkdir -p /jails/vj1
# cd /usr/src
# make buildworld
# make installworld DESTDIR=/jails/vj1
# make distribution DESTDIR=/jails/vj1
# mount -t devfs devfs /jails/vj1/dev
# vi /etc/rc.conf 

jail_enable="YES"
jail_list="vj1"
jail_interface="em0"
jail_vj1_rootdir="/jails/vj1"
jail_vj1_hostname="vj1"
jail_vj1_ip="192.168.1.173"
jail_vj1_devfs_enable="YES"
jail_vj1_parameters="allow.raw_sockets allow.sysvipc" 

# service jail start

List virtual machines.

# jls

Stop/start virtual machines.

# service jail stop vj1
# service jail start vj1 

Go to shell of virtual machine.

# jexec 2 tcsh