Hydra is a very powerful and efficient password cracking tool that is part of the default Kali Linux installation. Hydra is capable of cracking passwords for various protocols such as FTP, SSH, HTTP, and so on. Hydra can be launched from the Terminal as shown in the following image:

hydra -l user -P passlist.txt ftp://192.168.25.129

The preceding command would launch a password cracking attack against the FTP server running on IP address 192.168.25.129 and try out all passwords from the word-list passlist.txt.