What Is Kali Linux? Kali Linux & Penetration Testing

In the cybersecurity, information security, and penetration testing world, Kali Linux stands out as one of the leaders. Kali Linux is a special kind of operating system, like Windows or MacOS, but once downloaded, it's designed specifically to test the security of computer systems and investigate cyber crime.

Built around Debian, a popular type of Linux, Kali Linux has become synonymous with penetration testing and security auditing. In this article, we'll explain what Kali Linux is, how it works, its relationship with penetration testing, its pros and cons, and how to install and update it.

What is Kali Linux?

Kali Linux is a specialized Linux distribution meant for penetration testing, digital forensics, and cyber security auditing. Designed and maintained by Offensive Security, it provides around 600 penetration testing tools that allow security professionals and enthusiasts to test the security of computer systems and networks. Its tools include network sniffers, vulnerability scanners, password checkers, and exploitation frameworks.

Kali Linux and penetration testing

Penetration testing, sometimes referred to as ethical hacking, involves simulating real-world cyberattack scenarios. This allows them to identify and address security weaknesses before real bad-actors can exploit them. The stronger and more realistic the penetration test, the stronger the security of the system will be when faced with real threats.

Kali Linux serves as a comprehensive penetration testing platform that provides many different types of testing systems, software applications, and computer networks. It provides the ability to perform many different types of "attacks," including social engineering attacks and network spying.

How does Kali Linux work?

Kali Linux works like any other Linux distribution. However, the main difference is that Kali is optimized for security testing. A Linux distribution, or "distro," includes everything you need to run a computer system using Linux. The main component is the Linux kernel, which is the core of the operating system.

In order to run a Linux operating system, you choose a distribution based on your device and needs. There are many different types of distributions for all types of devices, from phones to routers to personal computers.

The Kali Linux distribution includes a suite of pre-installed penetration tools organized into categories within a menu called the Applications Tab. This tab provides a visual dropdown list of all the tools available.

Advantages of Kali Linux

Using Kali Linux has many advantages. Consider them below.

Free of charge. Kali is completely free to use. Therefore, this means that security and peace of mind are within reach for businesses and organizations of all sizes, without any cost barriers.
Comprehensive. With a huge collection of over 600 penetration tools including Armitage, Metasploit, Wireshark, John the Ripper, and even more, security professionals don't need to use and manually configure multiple tools across different systems.
Provides community support. The community is large and active for both security professionals and enthusiasts alike. Users can benefit from plenty of online resources, forum Q&As, and tutorials.
Regularly updated. The software's development team, Offensive Security, updates the system regularly with new tools and security patches. These updates provide users with access to the latest and greatest in cybersecurity while also addressing any security vulnerabilities that may come up.
Open source for customization. Since it’s open source, Kali allows users to customize their installations to suit specific requirements, enabling them to tailor the distribution to their needs.

Disadvantages of Kali Linux

While there are many advantages, there are also some drawbacks.

Steep learning curve. Since it's a Linux distribution, Kali Linux may be difficult for users new to Linux-based command-line interfaces and security concepts. Also, due to its focus on advanced security testing, beginners with these activities may face a steep learning curve.
Potential for misuse. Kali Linux is a sort of double-edged sword in the cybersecurity world. While the Kali Linux system is meant for ethical hacking and security testing, bad actors can use it to their advantage. Because of this, there's always a risk that or bad actors may misuse it for illegal activities.
Resource-intensive. Running it may require significant system resources, especially for resource-intensive tasks such as password cracking or network scanning.

How to install Kali Linux

Installing Kali Linux is a straightforward step-by-step process. If you want to download and install the software, simply follow the installation instructions below.

Get the Kali Linux download. Visit the Kali Linux website and download the appropriate installation image for your system architecture. When you download a Kali Linux image, be sure to download the SHA256SUMS and SHA256SUMS.gpg files that are next to the downloaded image.
Create bootable media. Use applications like Rufus (for Windows) or Etcher (for Linux and macOS) to burn to a DVD or live USB drive.
Back up the data to external media. Before booting, make sure to save any important data on the device to an external hard drive.
Boot from installation media. Insert the bootable media into your computer and boot from it. Follow the on-screen prompts to initiate the installation process.
Set your device to boot properly. Make sure to set your device to boot from CD/DVD/USB in your BIOS/UEFI. In the UEFI settings, ensure that Secure Boot is disabled. The Kali Linux kernel is not signed and will not be recognized by Secure Boot
Configure the installation. During installation, you'll set various settings such as language, keyboard layout, disk partitioning, and user account details.
Complete the installation. Once the installation is complete, reboot your system and log in to your newly installed Kali Linux environment.

Note that you can also install it using a virtual machine. For more information on how to install, see the Kali Linux installation page.

How to update Kali Linux

Keeping Kali up to date is crucial for maintaining system security and accessing the latest features.

To update Kali, first ensure that /etc/apt/sources.list is properly populated:

kali@kali:~$ cat /etc/apt/sources.list
# See https://www.kali.org/docs/general-use/kali-linux-sources-list-repositories/
deb http://http.kali.org/kali kali-rolling main contrib non-free non-free-firmware

# Additional line for source packages
# deb-src http://http.kali.org/kali kali-rolling main contrib non-free non-free-firmware
kali@kali:~$

After that, run the following commands and press Enter, which will upgrade you to the latest Kali version:

kali@kali:~$ sudo apt update
kali@kali:~$
kali@kali:~$ sudo apt full-upgrade -y
kali@kali:~$

How to change the admin password for Kali Linux

To keep your system secure, make sure to keep a strong password. To update your password, log in and follow these steps.

To update your username, type‌ the following command to ⁢change ‌your username: adduser –home /home/new_username⁢ new_username
To update your password, re-enter your terminal as‍ the ⁤“new_username” you‍ created in the previous‌ step by typing the command: su new_username. Then to reset‍ your ‌password, type the command: passwd⁢ new_password ⁤

Make sure your new password is strong. This means it should contain more than 12 characters and a mix of lowercase and uppercase letters, symbols, and numbers.

Kali Linux is a powerful tool for both security professionals and enthusiasts. It offers a comprehensive platform for conducting penetration testing, digital forensics, and security auditing. While it comes with its advantages and disadvantages, its versatility and breadth in features make it a staple in the cybersecurity arsenal. By understanding its capabilities and keeping it updated, then good guys can equip themselves with the tools to protect computer systems and networks from the bad guys.