FTP¶

FTP (File Transfer Protocol) is one of the protocols in the TCP/IP protocol suite. The FTP protocol consists of two components: the FTP server and the FTP client. The FTP server is used to store files, and users can use an FTP client to access resources on the FTP server via the FTP protocol. When developing websites, the FTP protocol is typically used to upload web pages or programs to the Web server. Additionally, because FTP has very high transfer efficiency, it is generally used for transferring large files over the network.

By default, the FTP protocol uses TCP ports 20 and 21, where 20 is used for data transfer and 21 is used for control information transfer. However, whether port 20 is used for data transfer depends on the transfer mode used by FTP. If active mode is used, then the data transfer port is 20; if passive mode is used, the specific port to be used is negotiated between the server and the client.