This chapter introduced you to the amazing world of Kali Linux, which is a Live DVD Linux distribution that has been specially developed to help you in the penetration testing process. Kali is the successor of BackTrack, a famous Linux distribution focused on the purpose of penetration testing.

The chapter started with a brief description of Kali Linux's history. Next, it moved on to see what functionalities Kali Linux has to offer. When looking at the vast array of tools in the latest version of Kali Linux, we can see that there is functionality for a wide variety of security tasks. These include digital forensics, wireless security assessments, reverse engineering software, hacking hardware, and penetration testing.

There was also discussion on the variety of ways that Kali Linux can be deployed. There is the ability to deploy Kali Linux using a live DVD or USB, installing it as a virtual machine and finally, using it as the primary operating system on a stand-alone system.

To ensure that penetration testing can be conducted, Kali Linux requires the networking connections be configured. Kali Linux makes use of a wired connection through the computer's ethernet connection or shared connections with the virtual machine host. In addition, Kali Linux can also be configured with a wireless connection using an external antenna. We also discussed how to use several features in the VirtualBox machine to make it easier to work with the virtual machine; for example, installing additional tools, configuring shared folders, exporting the virtual machine for a backup purpose or to share it with other people, and taking a snapshot to back up the virtual machine temporarily.

As with any other software, Kali Linux also needs to be updated, whether we only update the software applications or the Linux kernel included in the distribution.

You may need to test your penetration testing skills; unfortunately, you don't have permission to do this to other servers as it is considered illegal in several countries. To help you with this, there are several intentionally vulnerable systems that can be installed and used on your own machine. In this chapter, we looked into Metasploitable 2 from Rapid7.

We also discussed several network services included with the latest Kali Linux, such as HTTP, MySQL, and SSH. We started by giving you a brief introduction to each service and then we continued with how to manage the service; for example, how to start or stop the service.

At the end of the chapter, we looked at installing additional information security tools that are not included in the latest Kali Linux version by default, such as the Nessus network scanner and Cisco password cracker.

In the next chapter, we will introduce you to several penetration testing methodologies.