Hydra (or THC Hydra) is a parallelized network login cracker built into various operating systems like Kali Linux, Parrot and other major penetration testing environments. It was created as a proof of concept tool, for security researchers to demonstrate how easy it can be to crack logins. Hydra works by using different approaches, such as brute-force attacks and dictionary attacks, in order to guess the right username and password combination. Hydra is commonly used by penetration testers together with a set of programmes like crunch, cupp etc, which are used to generate wordlists based on user-defined patterns.