Why the "dir" command hangs when using the FTP command-line tool on Windows?

when you run the "dir" command with the FTP command-line tool on Windows and your computer is configured with a firewall, the "dir" will hang, and you will get no directory listing.

This is because the FTP command-line tool is using a data connection in active mode, which requires the FTP server to make an incoming UDP connection request back to your computer to deliver the directory listing.

If your computer's firewall setting rejects the incoming UDP connection request, the FTP command-line tool will never receive the directory listing.

Here is good example, where the FTP command-line tool hands on the "dir" command:

C:\fyicenter>ftp space.mit.edu
Connected to space.mit.edu.
220-space.mit.edu NcFTPd Server (free educational license) ready.
220-
220- This server is operated by the MIT Center for Space Research.
220- Only anonymous FTP access is allowed to this server.  Use the
220- login Name `ftp', and use your e-mail address for the password.
220-
User (space.mit.edu:(none)): anonymous
331 Guest login ok, send your complete e-mail address as password.
Password:
230 Logged in anonymously.

ftp> dir
200 Command okay.
150 Opening ASCII mode data connection for file list.
Ctrl-C
Aborting any active data connections... 
425 Can't open data connection.

You can press Ctrl-C to break out from this situation.

To solve this problem, you need to open the firewall on your computer as shown in the next tutorial.

⇒ Firewall for FTP Command-Line Tool on Windows

⇐ Start of FTP Command-Line Tool on Windows

⇑ Using FTP Command Tool on Windows

⇑⇑ FTP - Frequently Asked Questions