Kali Linux

Kali Linux is an open-source, Debian-based Linux distribution purpose-built for penetration testing, security auditing, digital forensics, and reverse engineering. It is developed and maintained by Offensive Security (branded OffSec), the training and certification company founded by Mati Aharoni.

Origins: WHAX, Auditor, and BackTrack

Kali's lineage traces back through BackTrack Linux, which itself was formed in 2006 by merging two earlier security-focused live distributions: WHAX (a Slax-based distribution created by Mati Aharoni, evolved from the Knoppix-based Whoppix) and the Auditor Security Collection, a Knoppix-based live CD built by Max Moser that bundled roughly 300 security tools. BackTrack's first stable release shipped on May 26, 2006, on a Slackware base. The distribution later moved to an Ubuntu base with BackTrack 4 (final release January 9, 2010), followed by BackTrack 5 (May 10, 2011) and its final iteration, BackTrack 5 R3, on August 13, 2012.

The 2013 Rebuild on Debian

In March 2013, Offensive Security discontinued BackTrack and released its replacement, Kali Linux, as a complete rewrite built on the testing branch of Debian rather than Ubuntu. Version 1.0.0, code-named "moto," was released on March 13, 2013. The rebuild was led by Mati Aharoni and Devon Kearns of Offensive Security, and it reorganized the distribution around Debian's packaging standards, Filesystem Hierarchy Standard compliance, and a rolling-release update model rather than periodic full-image releases.

Offensive Security Stewardship

Offensive Security has continued to steward Kali as its core platform, distributing it free of charge under the GNU General Public License v3.0 with development tracked openly in Git repositories. The project is currently led by Jim O'Gorman, OffSec's Chief Content and Strategy Officer, with a development team that has included longtime BackTrack contributor Ben Wilson and Debian specialists such as Raphaël Hertzog and Arnaud Rebillout, reflecting Kali's close ties to the upstream Debian project.

Evolution and Features

Since 2013, Kali has shipped with a custom kernel patched for wireless injection testing, GPG-signed packages, multilingual support, and broad hardware support including ARM devices such as the Raspberry Pi. Notable later changes include switching the default desktop environment from GNOME to Xfce in the 2019.4 release (November 2019) and changing the default shell from Bash to ZSH in the 2020.3 release (August 2020). Offensive Security has also extended the platform beyond traditional offense-only tooling, releasing Kali NetHunter as an Android-based mobile penetration testing platform and Kali Purple in 2023 as a defensive-security variant structured around the NIST Cybersecurity Framework. Kali Linux gained additional mainstream visibility through its use as a prop and reference point in the television series Mr. Robot.

Timeline

• 2006-05-26BackTrack Linux, formed by merging the WHAX and Auditor Security Collection distributions, ships its first stable release on a Slackware base.
• 2010-01-09BackTrack 4 final release switches the distribution's base from Slackware to Ubuntu.
• 2011-05-10BackTrack 5 is released.
• 2012-08-13BackTrack 5 R3, the final BackTrack release, is published.
• 2013-03-13Offensive Security releases Kali Linux 1.0.0 ("moto"), a complete rebuild of BackTrack on a Debian base, led by Mati Aharoni and Devon Kearns.
• 2019-11Kali Linux 2019.4 switches the default desktop environment from GNOME to Xfce.
• 2020-08Kali Linux 2020.3 changes the default shell from Bash to ZSH.
• 2023Offensive Security releases Kali Purple, a defensive-security-oriented variant structured around the NIST Cybersecurity Framework.