How to Ensure FTP Port 21 is Open for Smooth File Transfers

Having trouble connecting to your FTP server? It might be due to port 21. Let’s explore how to check if this crucial port is open.

Understanding FTP and Port 21

FTP, or File Transfer Protocol, is a method that allows the transfer of files over the internet or within a local network. To function correctly, FTP uses two ports: port 21 for command and control, and port 20 for data transfer. If port 21 is blocked, the FTP client cannot communicate with the server, leading to connection issues.

Unfortunately, due to security concerns, some routers and firewalls block port 21. Hackers often target FTP servers through this port, so ensuring it’s open and secure is essential for smooth file transfers.

Checking If FTP Port 21 is Open

To determine if port 21 is open, you will need access to your system console. Here’s a step-by-step guide:

Open your system console. This process differs slightly based on your operating system. For Windows, you can use the Command Prompt, while Linux and macOS users can utilize the Terminal.
Type the following command, replacing yourdomain.com with your actual domain name: telnet yourdomain.com 21
If the port is open, you will see a response such as 220 FTP Server ready. This indicates the server is ready to accept commands.
If you do not receive the 220 response, it suggests that port 21 is blocked. In this case, contact your Internet Service Provider (ISP) to open the port.

How to Enable Telnet Client on Windows

Since you will be using the Telnet command to check port 21, ensure that the Telnet Client is enabled on your system. Here’s how to enable it on Windows:

Press the Windows + R keys simultaneously to open the Run dialog box.
Type control and press Enter to open the Control Panel.
Navigate to Programs → Programs and Features.
In the left panel, click on Turn Windows features on or off.
In the dialog box that appears, check the Telnet Client box and click OK.

Why Is Port 21 Important?

Port 21 is crucial because it handles the command and control messages in FTP transactions. Without it, the FTP cannot initiate file transfers. If you experience issues with FTP connections, checking port 21 should be your first troubleshooting step.

Common FTP Connection Issues and Fixes

Error 421 – Too Many Connections: This error indicates that the server has reached its connection limit. Consider closing unnecessary connections or increasing the limit in your server settings.
ECONNREFUSED Error: If you encounter this error, ensure that your FTP server is running and that your firewall settings are not blocking the connection.

For more advanced troubleshooting, you may need to look into your FTP server settings or consult with your hosting provider.

If you’re looking for reliable hosting solutions, consider Hostinger. With excellent customer support and robust server solutions, they can help you manage your FTP settings and more.

Conclusion

Ensuring that FTP port 21 is open is vital for maintaining effective file transfers. By following the steps outlined in this guide, you can verify your port’s status and troubleshoot common FTP issues. For further assistance or questions, feel free to leave a comment below.

Edgaras G. brings his expertise as a server administrator at Hostinger, ensuring top-notch server performance. When not at work, he enjoys skiing and exploring new destinations.

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Feb 17, 2025
Edgaras G.
2min Read
Having issues connecting to your FTP account? If that’s the case, it’s worth checking whether port 21 is the culprit behind the connection failure. In this guide, we’ll show you how to check if your FTP port 21 is open.

How to Check If Port 21 Is Open?

Before we begin, this tutorial will require access to your system console. You can find more information on how to access the system console on Windows, Linux, and macOS in this article. Here’s how to check whether or not there’s a blockage in FTP port 21:

Open the system console, then enter the following line. Make sure to change the domain name accordingly. This same command applies to all operating systems. telnet yourdomain.com 21
If the FTP port 21 is not blocked, the 220 response will appear. Please note that this message may vary: 220 FTP Server ready.
If the 220 response doesn’t appear, that means the FTP port 21 is blocked. If that’s the case, we recommend you to contact your ISP to open the port.

telnet yourdomain.com 21

220 FTP Server ready.

Enabling Telnet Client

Since we’re be using a Telnet command to check the connection, you need to ensure that your operating system has Telnet Client enabled. 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. In this example, we’ll be showing how to enable Telnet Client on Windows:

Press the Window + R keys together, then enter control to open up your Control Panel.
Navigate to Programs → Programs and Features. On the left panel, select Turn Windows features on or off.
In the new dialog box, check the Telnet Client box and click OK.

What Is FTP Port 21?

FTP is an internet protocol that allows computers within the network to exchange files in bulk. In order to work correctly, 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. If you happen to have an FTP connection issue, it’s essential to verify whether or not there’s a blockage in port 21.

Conclusion

Some routers and firewalls block FTP port 21 due to security reasons, so it’s essential to check the port’s connection before performing the File Transfer Protocol. You might also want to check out our articles on solving FTP issues like solving error 421 – too many connections and ECONNREFUSED. We hope you found this tutorial helpful. If you have any more questions, don’t hesitate to leave a comment down below.

Edgaras G.
Edgaras is a veteran server administrator at <a href=”https://hostinger.com?REFERRALCODE=1CRYPTO99″ rel=”sponsored noopener” target=”_blank”>Hostinger</a>. 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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