Ncrack is a command-line tool designed for high-speed, large-scale auditing of credentials over the network. It uses a syntax similar to John the Ripper and Nmap, runs on Windows, Linux, MacOS, and BSD Unixes, and supports numerous network protocols including FTP and Telnet, HTTP and HTTPS, MySQL, PostgreSQL, Windows RDP, SMB, SSH, and VNC. Ncrack can perform brute force guessing attacks against a single service, a group of hosts, or a range of IP addresses, giving you a list of found credentials. It is a strong motivation to get those weak passwords fixed.
— Victor R. Garza