We all know that Linux is one of the most secure modern operating systems available in the market today. However, it is still possible to improve or "harden" its security and this is where Bastille Linux comes in.
The Bastille Hardening program "locks down" an operating system, proactively configuring the system for increased security and decreasing its susceptibility to compromise. Bastille can also assess a system's current state of hardening, granularly reporting on each of the security settings with which it works.
This third-party utility is a must-have for the security-paranoid users among us. It works on Debian, Red Hat (including Fedora Core), Gentoo, Mandrake/Mandriva, Suse and Ubuntu. It is currently being ported to Mac OS X.