How to do it...

To learn about Crunch follow the given steps:

1. Crunch is preinstalled with Kali, and we can launch it with this command:

        crunch -h

2. As we see, it is easy to use to generate a password list of a minimum of two characters and maximum of two characters containing only abcdef, and we can use the following command:

        crunch 2 2 abcdef

We can see that the word list has been generated:

3. To save it in a file, we can use the -o switch. Crunch also has an inbuilt list containing a predefined character set. It can be found at /usr/share/crunch/charset.lst.

4. To use a charset, we use the -f switch:

        crunch 2 2 -f /usr/share/crunch/charset.lst lalpha

The following screenshot shows the output of the preceding command:

5. This will generate a list of a minimum length and maximum length of 2, containing lowercase alphabets. Crunch also has a -t switch, which can be used to create a word list of a specific pattern:
   • @: This will insert lowercase characters
   • ,: This will insert uppercase characters
   • %: This will insert numbers
   • ^: This will insert symbols
6. Switch -b can be used to specify the size of the file you want to create:

7. Let's try to create a list with a specific pattern and of 1 MB in size:

        crunch 10 10 -t @@packt,,% -b 1mib -o START

8. Once it's, done, we will see a list of text files created with the pattern in the same folder:

9. The -z flag can be used to create a word list and save it in a compressed file. The compression is done on the go:

        crunch 10 10 -t @@packt,,% -b 1mib -o START -z gzip

The following screenshot shows the output of the preceding command: