Aircrack

Link: https://github.com/aircrack-ng/aircrack-ng

Aircrack is listed as one of the Kali Top 10 programs.

It can be used to capture wifi handshakes, which contain the information needed to brute-force the wifi passsword. It can also be used to do the brute-forcing of handshakes itself. When used in conjunction with other specialized tools for generating password permutations based on patterns, like John the Ripper, this becomes a powerful password-cracking tool in addition to a wireless-sniffing tool.

Aircrack/WEP Cracking - This is a great introductory exercise to using aircrack. Cracking a WEP network should only take a few minutes.

Aircrack/WPA Cracking - While more challenging than cracking a WEP network, this can also go very quickly if a weak password is used.

Aircrack/Packet Injection Testing - Before doing packet injection, you may want to run some of these tests.

Some notes on using Aircrack with John the Ripper: Aircrack and John the Ripper

The big dumb undocumented but extremely useful flag: -l [filename] will log any cracked passwords to a file. Don't forget to use this flag!! Otherwise, all that time you spent brute-forcing the password will be lost if you accidentally close your terminal window (oops)