If you are using FreeBSD jails, or are planning to use (just make sure it’s the right solution as there are some caveats), you should look into ezjail, a powerful set of jail management scripts. It can really help save time and do things better: more secure jails, less space usage, easier upgrades, etc…

Install from ports (that was easy and predictable)

cd /usr/ports/sysutils/ezjail/ 
make install clean

Then, configure ezjail behaviour at /usr/local/etc/ezjail.conf, the most important thing is to setup the ezjail directory, where all the jails will be written to (moving afterwards is a pain in the ass), so consider your partitions and backups plan when setting this up.

Next thing is to build world and make basejail. Just one command:

ezjail-admin update -b

If you don’t have src, this is the error you will get:
Error: Your source tree in /usr/src seems to be incomplete (Makefile is missing).

Very easy to get src, type ‘sysinstall’ go to Configure, Distributions, src, All (everything gets selected), Exit, Exit, FTP, select a FTP site, YES, and there a couple of minutes later (your mileage may vary) /usr/src is populated with everything you need. Then exit sysintall and repeat the command above.

If you have already a built world (ex: from a system upgrade) just need to install it

ezjail-admin update -i

Now, everything is set to to go!

To create a new jail

ezjail-admin create hostname ip-address

With a 100G file-Backed md filesystem

ezjail-admin create -i -s 100G hostname ip-address

To list jails managed by ezjail

ezjail-admin list

List all running jails (in ezjail scope and others) you can fallback to the normal system command


To get a console inside a runing jail

ezjail-admin console hostname

WARNING! You don’t actually get a tty, so some things work strange, for instance: ssh and sftp to remote machines, mysql imports showing password as you type, etc… if something works strange, to be safe better log in through ssh, you have been warned.

Start/stop all jails

/usr/local/etc/rc.d/ezjail.sh start 
/usr/local/etc/rc.d/ezjail.sh stop

Star/stop one jail

/usr/local/etc/rc.d/ezjail.sh start hostname 
/usr/local/etc/rc.d/ezjail.sh stop hostname

To check the jail status, if it is running or not use the jls command


To start automatic at boot just set the ezjail_enable in /etc/rc.conf. It will run all jails in ezjail scope, except if you specify some jail not to boot automatically:

ezjail-admin config -r norun hostname

of course if you change your mind, you can simply revert it

ezjail-admin config -r norun hostname

About the ports, as i am very happy with the current setup, and it seemed a waste of space to have duplicate ports tree in the same machine… first i simply monted null_fs my existing ports tree of the main host into /ezjail_dir/basejail/usr/ports but i couldn’t access it from within the jails… probably double mount_null problem, as the basejail dir is also null mounted, so i add it to the fstab of each jail. Just look and edit /etc/fstab.jailname and:

/usr/ports /usr/jails/jaildir/usr/ports nullfs ro 0 0

Also tweak main host and jails /etc/make.conf to avoid any interference with ports building, files and indexes.


Don’t forget to look into /usr/local/etc/ezjail/ directory, where all the configs for each jail live in separate files. I find it much easier to change or setup things like cpusets and multiple ip here than thru ezjail-admin command.

With a multi core CPU, you can to set a jail cpu affinity to use one particular core, just go to the /usr/local/etc/ezjail directory, then find and open your jail configuration file, should be something like jailhostname_com. Edit the line  export jail_iedp_pt_cpuset=”” and set the core you want to assign the jail to.

To get the number of cpu/cores just type as root

sysctl hw.model hw.ncpu

At last, if you want to delete a jail simply type (and say goodbye)

ezjail-admin delete -w hostname

If you are using file based disks (md disks) and need to check them just stop the jail (if it is running). Attach the disk, use fsck, and detach it:

mdconfig -a -f file.img
fsck -t UFS /dev/mdxx
mdconfig -d -u xx

(replace the xx by the number outputed in the first command).

Updating the jails OS copy after a freebsd-update upgrade is also very easy. You must take note the original OS version and the target upgrade version. So upgrading from 10.0 to 10.1 you must always keep this information.


First in the main host do the freebsd-update upgrade operations

# freebsd-update upgrade -r 10.1-RELEASE

Nnormally includes automatic file adds/edits/deletes, manual rebooting and running freebsd-update install afterwards to finish.

# freebsd-version

The main host is at 10.1, but your jails are out of sync in 10.0, again with ezjail it’s a breeze to fix this, just issue this command (note the -s parameter is the original OS version):

# ezjail-admin update -U -s10.0-RELEASE

There you go, a very simple guide to ezjail jails management, as always feel free to ask any questions or add up some knowledge. Also, try and make yourself comfortable before stepping into production, and remember if all goes terrible bad you are on your own.