Kali Linux: what it is, what it is for, and how to install it

Kali Linux is an open-source operating system based on Debian, maintained by OffSec (Offensive Security) and used in penetration testing, security auditing, and digital forensics. The successor to BackTrack, it bundles hundreds of pre-installed security tools and is distributed for free.

• What is Kali Linux?
• Why is Kali Linux popular among ethical hackers?
• What tools come pre-installed in Kali Linux?
• Kali Linux in the programmer's daily life
• How to install Kali Linux?

What is Kali Linux?

Kali Linux is a Linux distribution specialized in information security: instead of serving as a general-purpose system, it is born configured to perform penetration tests, security audits, and forensic analysis in authorized environments.

According to the official project history, Kali Linux 1.0 ("Moto") was released on March 13, 2013 by Offensive Security, on the base of Debian 7 (Wheezy). It replaced BackTrack Linux — whose last major version, BackTrack 5 "Revolution" from 2011, was still built on Ubuntu. After Kali 2.0 "Sana", from August 2015, the project adopted on January 16, 2016 the rolling release model based on Debian Testing: the system is updated continuously, without requiring reinstallation at each version.

Another pillar of the project is zero cost. The official Kali documentation states that the system "is completely free of charge and always will be", with an open Git tree for anyone to inspect or modify the code.

Why is Kali Linux popular among ethical hackers?

Kali Linux dominates the ethical hacking field because it eliminates the work of building a testing environment from scratch: the essential tools come already installed, integrated, and maintained by the OffSec team. Three factors explain this preference:

1. Ready-to-use tool arsenal: the official documentation describes Kali as a system with hundreds of tools, configurations, and scripts geared toward security tasks, dispensing with lengthy manual installations.
2. Images for practically any platform: there are official builds for desktop, virtual machines, live USB, containers, mobile phones (Kali NetHunter), and boards like the Raspberry Pi.
3. Active community and comprehensive documentation: forums, tutorials, and OffSec's own documentation resolve most questions, which lowers the barrier to entry for those starting out.

This combination made Kali Linux the de facto standard in offensive security courses, certifications, and labs worldwide.

What tools come pre-installed in Kali Linux?

Kali Linux includes hundreds of security tools organized by category, and the official tool catalog documents each one. The best-known ones cover the entire cycle of a pentest:

In practice, few people use all categories: a web security analyst will live inside Burp Suite, while an infrastructure auditor will spend more time with Nmap and Metasploit.

Kali Linux in the programmer's daily life

Kali Linux is also useful for those who develop software, not just for security specialists. Programmers use the system mainly in three ways:

1. Secure software development: testing your own application with Kali's tools reveals vulnerabilities — such as SQL injections or exposed endpoints — before a real attacker exploits them.
2. Penetration testing and auditing: development teams assess the robustness of their networks and APIs in controlled environments, simulating attacks with formal authorization.
3. Learning and experimentation: running Kali in a virtual machine creates a safe lab to study ethical hacking techniques without risks to the main system.

To get the most out of Kali Linux, it is worth mastering the fundamental terminal commands first, since most of the tools run from the command line. Here at CodeCrush, we recommend this path — terminal first, security tools later — for those who want to move from development to offensive security.

How to install Kali Linux?

The simplest way to install Kali Linux is to download an official image and burn it to a bootable USB stick or import it into a virtual machine (VM). The step-by-step for installing on a dedicated computer is:

1. Download the ISO image from the official Kali Linux site, choosing the appropriate variant (Installer, VM, Live, or mobile).
2. Burn the image to a USB stick with Rufus or another image burner of your choice.
3. Boot the computer from the USB stick (USB boot) and select the "Graphical Install" option.
4. Follow the wizard to set the language, disk partitioning, and user.
5. Update the system after the first boot with sudo apt update && sudo apt full-upgrade.

For those who don't want to dedicate a machine to Kali, there are official alternatives: ready-made images for VirtualBox and VMware, WSL (Windows Subsystem for Linux), Docker containers, and Raspberry Pi builds. If you are still deciding which system to use day to day, see our comparison between Windows, Linux, and macOS before choosing.

Conclusion

Kali Linux is not — and doesn't try to be — a system for everyday use: it is a specialized toolbox, and that is exactly what makes it valuable. For those who work or want to work with offensive security, it is the shortest path between theory and practice; for programmers, it is a cheap way to test their own applications as an attacker would. Start in a virtual machine, master the terminal, use the tools only in authorized environments, and Kali will stop being "the movie hackers' system" and become a real part of your workflow.