In this section, we will first discuss how to get the hashes from an operating system, and then look at the salting and stretching procedures that make Linux hashes much stronger. We will then discuss the specific hashing algorithm used by modern versions of Linux, and finally look at cracking hashes with wordlists and Python.

Here, we have created three users to test the software in much the same way as we did earlier on Windows. John and Paul have the same password and Ringo has a different password:

You get the hashes from the /etc/shadow file, from which we will print out the last three records. So, you will see John, Paul, and Ringo, and after each username comes $6, which indicates that it is a type 6 of password, which is the most modern and secure form. Then there is a long, random string of characters that goes up to the next dollar sign, and then an even longer random string of characters, which is the password hash itself.

The first thing you can see is the...