FreeNAS Temperature Report is a small server program that provides temperature readings for your FreeNAS unit. Install this program in a jail on your FreeNAS, then use your web browser and go to http://jail_ip to see your temperature readings.
Installation instructions: http://sourceforge.net/p/freenas-tempreport/wiki/Install/
Jail Chroot Project is an attempt of write a tool that builds a chrooted environment. The main goal of Jail is to be as simple as possible, and highly portable. The most difficult step when building a chrooted environment is to set up the right libraries