![]() ![]() IANA states that this range should be between 49152 through 65535, but most likely, you'll see your application using a port just above 1024 - the area that used to be the dynamic port number area. Typically, in a packet trace of active mode FTP, you'll see the data channel originating from server port 20 to a dynamic client port number. This is illustrated in this active FTP diagram. ![]() Upon receipt of the PORT command, the server establishes a new TCP connection to the client using that TCP port value. In some FTP implementations port 20 is used for data, but that is the exception rather than the rule.Īn FTP client sends a PORT command to the FTP server to identify what port the client will be listening on for the data channel connection. The PORT command is sent by an FTP client to establish a secondary connection (address and port) for data to travel over. This is where the PORT command comes into play. What is the FTP PORT command?įTP communications use two TCP port number values: one for commands - port 21 by default - and one for data transfer. ![]() Let's look at how FTP works and the purpose of the PORT command. Individual control and data channels are used to separate control commands from large file transfers. Even though port 20 is assigned to the FTP data channel, most FTP data sessions don't use port 20, unfortunately. ![]()
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