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File Transfer Protocol (FTP)
FTP defined by RFC 959 is used to transfer files between systems either on a LAN or a remote network. This is beneficial to users who would like to simply upload, download, or even remove files from a remote system. FTP provides user authentication: a username and password combination as an extra layer of security.
Unlike some protocols, FTP uses two ports, port 20 is used for Data (data transfer) and port 21 is for Control (parsing of commands):
If you're interested in setting up your own FTP server, check out an open source application called FileZilla ( www.filezilla-project.org), which provides both an FTP client and and FTP server applications.