Kali Linux: the attacker machine

What Kali is

Kali Linux is a version of Linux built and maintained for penetration testing and security work. Instead of installing dozens of tools one by one, you get them ready to use. It is free and made by Offensive Security. You will usually run it as a VM in your lab.

Kali is just a tool; it does nothing illegal by itself. The same rules apply: only test machines you are allowed to test. Having Kali installed is normal for a learner or professional.

Getting around the terminal

Most testing happens in the terminal, a text window where you type commands. Here are the few you need at the start. (The prompt ends with $ for a normal user or # for the root/administrator user.)

pwd            # print working directory: where am I?
ls -la         # list files here, including hidden ones
cd /opt        # change directory to /opt
cat notes.txt  # show a file's contents
nano notes.txt # edit a file in a simple editor
ip addr        # show this machine's IP addresses

Updating Kali

Keep Kali up to date so its tools and the system have the latest fixes. On a Debian-based system like Kali you use the apt package manager.

sudo apt update        # refresh the list of available packages
sudo apt full-upgrade  # install the newest versions

Finding your lab's addresses

To attack a target you need its IP address (its number on the network). Run ip addr on both the attacker and the target. On a host-only network they will usually share the first three numbers, for example 192.168.56.x.

Alternatives

Kali is not the only option. Parrot Security OS is similar. You can also add security tools to an ordinary Ubuntu. For this course, any of them is fine; the tools and ideas are the same.