What are Control Connection and Data Connection used in FTP protocol?

FTP protocol uses two independent connections to perform communication tasks:

1. Control Connection - Control Connection is used for the FTP client to send commands to the FTP server, and receive replies from the server.

When a FTP client connects to a FTP server, a control connection will be established immediately using the TCP protocol. The client then uses the control connection to send FTP commands to the server. For example, USER to provide user name, PASS to provide password, CWD to change directory, or QUIT to end the session.

2. Data Connection - Data Connection is used for the FTP client to upload or download data with the FTP server.

When the FTP client wants to exchange data with the FTP server, like upload or download a file, it will work with the server to establish a new temporary data connection using the UDP protocol in passive mode or activate mode.

Here is diagram showing the two types of connections used in FTP protocol:

 

⇒ What FTP Commands Require Data Connections

⇐ What Is FTP (File Transfer Protocol)?

⇑ Understanding FTP (File Transfer Protocol)

⇑⇑ FTP - Frequently Asked Questions