Port 21 ftp

FTP, running at TCP port 21, is one of the oldest protocols on the net.

FSP (UDP)

FSP (File Service Protocol) is an FTP-like UDP-based file transfer service.

FSP

Hardening the FTP service-How to configure your FTP service in order to avoid hacks. Exploiting an FTP service-How hackers/crackers break into FTP services. Trojan: DarkFTP