In one of the courses I am busy with there was a requirement to create a password file to use during a brute force attempt – and the hints given were that the password is 5 characters and that it uses only q,w,e.
So from a shell on a Kali machine type the following:
crunch 5 5 qwe > pass.txt
The first 5 means a minimum of 5 characters, the second 5 means the maximum amount of characters, the three letters are what needs to be used in the password file, and lastly we > send the standard output to a file called pass.txt.
This can of course also be done using Burpsuite with the following options: