Ubuntu is a complete, free operating system that emphasizes ease of use, community, and support while enhancing speed, power, and flexibility.
BackBox is a Linux distribution based on Ubuntu. It has been developed to perform penetration tests and security assessments.
BackTrack is a Linux-based penetration testing arsenal that aids security professionals in the ability to perform assessments in a purely native environment dedicated to hacking.
Ubuntu Privacy Remix is a modified Live-CD based on Ubuntu Linux.
Ubuntu 10.10, codenamed "Maverick Meerkat", is now available for download. Ubuntu 10.10 introduces an array of online and offline applications to Ubuntu Desktop Edition with a particular focus on the personal cloud.