How to Check if FTP Port 21 is Not Blocked

How to Check if FTP Port 21 is Not Blocked

Having issues connecting to your FTP account? It’s worth checking your port 21! Here, we’ll show you how to check if your FTP port 21 is open. By the end of this article, you’ll know whether or not the port is the culprit behind the connection issue.

Port 21 in File Transfer Protocol

FTP is an internet protocol that allows computers within the network to exchange files in bulk. To work properly, FTP must use two ports: port 21 for command and control, and port 20 for data transport. An FTP client cannot perform the protocol if it fails to connect to the FTP ports.

Unfortunately, some routers and firewalls block this port because hackers often target FTP servers via port 21.

So if you happen to have an FTP connection issue, it’s essential to verify whether or not there’s a blockage in port 21.

How to Check if Port 21 is Open

This tutorial requires access to your system console. This article provides the steps to access system console in Windows, Linux, and macOS.

As we will use the Telnet command to check the connection, you need to ensure that your operating system enables Telnet Client.

Telnet is a client-server protocol that enables remote control over computers.  In this case, it will help us test the connectivity to FTP port 21. If you’re using Windows, here’s how to enable Telnet Client:

  1. Open the Start menu and access Control Panel. Alternatively, press the Window+R key together, then enter control.
  2. Navigate to Programs -> Programs and Features. On the left panel, select Turn Windows features on or off.
  3. When the Windows Features dialog box appears, check the Telnet Client box and click OK.
    This image shows you how to enable Telnet Client on Windows operating system. By doing so, you can use the Telnet command to test the connectivity to port 21.

Here’s how to check whether or not there’s a blockage in FTP port 21:

  1. Open the system console, then enter the following line. Make sure to change the domain name accordingly.
    telnet 21
  2. If the FTP port 21 is not blocked, the 220 response will appear. Please note that the message may vary.
    This image shows you the confirmation message confirming that port 21 is not blocked.
  3. If the 220 response doesn’t appear, it means the FTP port 21 is blocked. In this case, we recommend you to contact your ISP to open the port.


As some routers and firewalls block FTP port 21 due to security reasons, it’s essential to check the port’s connection before performing the File Transfer Protocol. By following our tutorial, we hope you’re able to verify whether or not the FTP port is open.

The Author


Edgaras G. / @edgaras

Edgaras is a veteran server administrator at Hostinger. He makes sure that every server runs at full throttle and has all the latest technological advancements. When he's not working, Edgaras enjoys skiing and exploring the world.

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Gogu Reply

March 22 2018 it "internet special person"?


    Domantas G.

    Replied on March 23 2018

    Hey Gogu, :) No, ISP = Internet Service Provider.

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