[ Thanks to Lee Schlesinger for this link. ]
BackTrack Linux has established itself as the de facto
suite of choice for security professionals and administrators who
want to find any possible holes in their servers, systems, and
networks.This bootable Linux distro includes a complete set of tools that
can help you not only assess the security of your system but also
aid in uncovering possible break-ins, making it an essential part
of any administrator’s toolkit.