Tools

PORT FTP command

The PORT command is issued by the client to initiate a data connection required to transfer data (such as directory listings or files) between the client and server. The PORT command is used during "active" mode transfers.

First published date

11/29/2018 10:52 PM

Last published date

6/11/2020 5:52 PM

Overview

This article describes the use of the Data Port (PORT) FTP command.

Product section

Serv-U Managed File Transfer & Serv-U FTP Server

Resolution

The Port command is issued by the client to initiate a data connection required to transfer data (such as directory listings or files) between the client and FTP server. This command is used during "active" mode transfers.

When issuing the PORT command, the client will include information on the address and port that the server is to use in order to connect back to the client. Thus, the structure of this command is clearly defined to allow servers to parse this information from the command. The structure of the command is: PORT (h1,h2,h3,h4,p1,p2) 
 

The numbers used for the values of h1-h4 constitute the IP address the server should connect on. The numbers used for the values of p1-p2 are used to calculate the port number. In order to get the decimal value of the port, the following formula is used: (p1 * 256) + p2 = data port.
 

Common responses 


See also