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28 Απρ 2024 · The command channel is used to transfer the commands and responses from client to server and server to client. FTP uses the same approach as TELNET or SMTP to communicate across the control connection. It uses the NVT ASCII character set for communication. It uses port number 21.
16 Αυγ 2022 · FTP uses control and data channels, each using a separate TCP port. Port 21 is for the control channel, and port 20 is for the data channel. Learn how these two channels are used.
9 Φεβ 2024 · While port 21 is for sending commands to an FTP server, port 20 transfers files during active mode FTP sessions. As data sent over these ports are unencrypted, consider using one of the more secure versions of the protocol.
FTP communications use two port number values – one for commands (port 21 by default) and one for data transfer (this is where the PORT command comes into play). The PORT command is sent by an FTP client to establish a secondary connection (address and port) for data to travel over.
after client RETR, server connects from port 20 to client port sent via client PORT command OR PASV command can be used to tell server to wait for client connection
FTP client contacts FTP server at port 21, specifying TCP as transport protocol. Client obtains authorization over control connection. Client browses remote directory by sending commands over control connection. When server receives a command for a file transfer, the server opens a TCP data connection to client.
5 Μαρ 2024 · FTP uses port 21 for control connections and port 20 for data connections. FTPS uses port 990 for control connections and port 989 for data connections under implicit security. When using explicit security, FTPS can also use port 21. Learn more about securing an FTP or SFTP server on our blog.
