How do I find out of my firewall or ISP is blocking port 21?

[Dynaweb]

The default TCP port for FTP connection is port 21. Sometimes the connection gets blocked by a local firewall rule or your Internet Service Provider blocks this port and this will result in FTP connection issues.

Here's how to, depending on your OS, check whether an essential port is being blocked by your PC, LAN or ISP:

Check port 21 on a Windows OS

Click on the Start menu button, usually located on the left low corner of the screen. There is a tab called "Run". You have to click on it, in order to proceed further. You will notice the appearance of a new small window on the screen. In the text field of this window you need to type "cmd" and then press the "Enter" key. Another window will open. It is the so called "MS-DOS prompt" or "command prompt". Just type the following command in the command prompt window and press "Enter":

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telnet hostned.com 21

Check port 21 on an Apple/Mac OS

Each Mac OS is delivered with a preinstalled terminal emulator. The terminal is a tool which allows you to execute commands from the command line. Usually, the terminal is located under your Mac HD -> "Applications" directory -> Utilities sub-directory. When the window opens, you will see a command line with a flashing cursor on it so you can start typing right away. Just type the following command and press "Enter":

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telnet hostned.com 21

Check port 21 on a Linux OS

Open your favorite terminal emulator and execute the following command in order to telnet your website:

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telnet hostned.com 21
Results from the 21 port check

If the test is successful, you should receive a message like this:

220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
220-You are user number 1 of 50 allowed.
220-Local time is now 12:09. Server port: 21.
220-This is a private system - No anonymous login
220-IPv6 connections are also welcome on this server.
220 You will be disconnected after 15 minutes of inactivity.



If the welcome message similar to the one above does not appear, you should first look at your settings for your Firewall in your OS then in your router.  If everything is set properly there, contact your local ISP and ask them to unblock this port at their end.