FTP Work Concept

FTP Work Concept

FTP uses the Transmission Control Protocol (TCP) protocol for data communications between clients and servers, so that between the two components a communication session will be established before data transfer begins. Before making a connection, the TCP port number 21 on the server side will "listen" the connection attempts of an FTP client and will then be used as a control port to (1) create a connection between client and server, (2) to allow clients To send an FTP command to the server and also (3) return the server response to the command. Once a control connection has been established, the server will begin to open TCP port number 20 to establish a new connection with the client to transfer the actual data that is being exchanged during download and upload. So port 21 for giving command and port 20 for file data transfer process.