It is similar to the previously discussed tool, the only difference being that Hydra works online while John the Ripper works offline. Hydra is, however, more powerful and thus more popular among hackers. It is available for Windows, Linux, and macOSX. The tool is commonly used for fast network login hacking. It uses both dictionary and brute-force attacks to attack login pages.

Brute-force attacks may raise alarms on the target's side if there are some security tools put in place, and thus hackers are extremely careful with the use of the tool.

Hydra has been found to be effective against databases, LDAP, SMB, VNC, and SSH.

The workings of Hydra are quite simple. The attacker gives the tool the login page to any of the target's online systems. The tool then tries all possible combinations for the username and password fields. Hydra stores its combinations offline, making it faster to do the matching process.

The following diagram (Figure 5) shows a screenshot of the installation of Hydra. The installation is being done on a Linux machine, but the process is the same for Windows and Mac. The user is required to type make install during the installation. The setup handles the rest until completion of the installation: