File Transfer Protocol

FTP allows a client to connect to, browse, send, and retrieve files to, and from, a server. FTP is useful to know about from a security perspective, because it enables means of discovering information that may not be as heavily monitored or hardened as other network services.

When using TCP, FTP usually operates on port 21. FTP is considered a fully session-oriented protocol, because once a connection is established the client can continue to interact with the server until the session is terminated.

UDP has an FTP counterpart, which runs on port 69, called TFTP. Unlike FTP, TFTP simply allows the one-off transfer or retrieval of files.

Relevant Note(s): Network Protocols