pfSense is a free, open source customized distribution of FreeBSD tailored for use as a firewall and router.As on any *NIX machine, the usage of a file manager always helps 

So here is how to install Midnight Commander on the box:

- SSH to the machine

- select option “8″ for Shell

- install Midnight Commander and its dependencies using: pkg_add -r ftp://ftp.freebsd.org/pub/FreeBSD/ports/i386/packages-8-stable/Latest/mc.tbz

- once installed, you can CD to the following directory: usr/local/bin and start Midnight Commander using: ./mc