SYMPTOMS
When you connect to a File Transfer Protocol (FTP) server using a Windows command-line FTP client and you then issue a
quote list command (or another quote command), the next command you use may return the following error message:
425 Can't open data connection.
CAUSE
When an FTP client passes a command to an FTP server and the client is in active mode, the client also passes a port on which it listens for the response from the server. If the client is sending a command that does not require a data port (such as the
syst command), the client does not set up a data port. The
ls command, also called the list command, requires a data port to return the data. If the server is expecting a data port from the client, and the server does not receive a data port, the server generates the 425 error.
FTP clients can pass commands that they do not interpret to the server. These commands are passed using the following syntax:
Because the client does not interpret the command it is sending, the client sends the command to the server without generating a listen port for the data, and therefore the server cannot open the data port.