In this chapter, you got to use three new tools for password cracking, and also learned how to add a new item to the main menu. Johnny, and his progenitor, John the Ripper, are the most popular tools you can find on Kali, for cracking hashes on the local machine, so you will probably choose one of these two tools when you are testing your users' password decisions.
Hydra has many more options than basic John-based tools, but with the improved power comes increased complexity. Hydra is designed to attack specific devices over the wire, but as you discovered, the attack surface is very small and the tool is very noisy.
You have also learned that Hydra can use the GPU instead of the CPU, giving you even faster cracking times.
In the next chapter, we will learn about the ancient and broken protocols, NetBIOS and LLMR, and how to exploit and gain access to Windows systems...