-cut /etc/defaults/rc.conf-
### Jail Configuration #######################################
##############################################################
jail_enable="NO"        # Set to NO to disable starting of any jails
jail_list=""            # Space separated list of names of jails
jail_set_hostname_allow="YES" # Allow root user in a jail to change its hostname
jail_socket_unixiproute_only="YES" # Route only TCP/IP within a jail
jail_sysvipc_allow="NO" # Allow SystemV IPC use from within a jail
#
# To use rc's built-in jail infrastructure create entries for
# each jail, specified in jail_list, with the following variables.
# NOTE: replace 'example' with the jail's name.
#
#jail_example_rootdir="/usr/jail/default"       # Jail's root directory
#jail_example_hostname="default.domain.com"     # Jail's hostname
#jail_example_ip="192.168.0.10"                 # Jail's IP number
#jail_example_exec_start="/bin/sh /etc/rc"              # command to execute in
#jail_example_exec_stop="/bin/sh /etc/rc.shutdown"      # command to execute in
#jail_example_devfs_enable="NO"                 # mount devfs in the jail
#jail_example_fdescfs_enable="NO"               # mount fdescfs in the jail
#jail_example_procfs_enable="NO"                # mount procfs in jail
#jail_example_mount_enable="NO"                 # mount/umount jail's fs
#jail_example_devfs_ruleset="ruleset_name"      # devfs ruleset to apply to jail
#jail_example_fstab=""                          # fstab(5) for mount/umount
#jail_example_flags="-l -U root"                # flags for jail(8)
-cut-

p.s. есть еще наработки аудита jail'a