We test CT lab 4.20 on Kali Linux
Kali Linux (formerly known as BackTrack) is a Debian-based distribution with a collection of security and forensics tools.
It features timely security updates, support for the ARM architecture, a choice of four popular desktop environments, and seamless upgrades to newer versions.
Is a new open source distribution that facilitates penetration testing. Whereas BackTrack was built on Ubuntu, Kali is built from scratch and constructed on Debian and is FHS-compliant. Kali also has improved software repositories that are synchronized with the Debian repositories so it makes it easier to keep it updated, apply patches and add new tools. It is also easy to customize your own Kali Linux so that it contains only the packages and features that are required. You can also customize your desktop environment to use Gnome(default), KDE, LXDE, XFCE or whatever you prefer.
More for Kali Linux here
Screens from our CodeTyphon test here