How To Check if a Port Is Blocked by Firewall? A Guide

How to Find Out if Your Port is Blocked by a Firewall

How To Check if a Port Is Blocked by Firewall? A Guide

One of the most common network security measures, a firewall is installed to block unauthorized access to and from your internet-connected devices. If you are running into problems when trying to connect with certain websites or online games, it could be that your port is blocked by the firewall. The following article will show you how to check if this is the case!

How To Check if a Port Is Blocked by Firewall?

There are many ways to determine if your port is blocked, or not. We will present you with three methods that can help you check in less than a minute:

  • Use the Command Prompt on Windows;
  • Use Nmap command-line utility for Linux and Mac machines;
  • Check firewall settings online (on router level).

Which Method Should I Choose?

It depends on what kind of operating system you use and how comfortable you feel working with technology like the Command Line Interface (CLI) or Terminal. If none of these suit your needs it’s always possible to contact your service provider for assistance.

What Is a Firewall?

A firewall is a system that controls what traffic can pass through your device and to which network it belongs. They are essential when you want to allow or block certain types of connections, either on the local computer or router level. Firewalls have been in use since the 1980s but modern devices like routers now come with them pre-installed.

How To Use a Port Scanner?

Port Scanner is a free online tool that can be used to determine if your port is open or closed. By using this method you will need an active internet connection and access to the web browser.

This website looks up which ports are in use by querying one of the public domain name servers (DNS) for your current IP address, then it tries connecting with these ports on both UDP and TCP protocols.

There are more than 65,000 ports available from 0 to 65535.

If the port is not blocked you will see the message “open” and a green sign. If it’s closed, instead of seeing open or closed status you will get an error message saying that there was no response (“connection timed out”).

What if I Don’t Know Which Port Number I Should Use?

Most applications rely on common protocols like TCP (Transmission Control Protocol) for communication over the network. This means that any application that uses this protocol uses specific well-known ports to function correctly. You can find these numbers online by searching for service name + Port Number Registry. For example: SMTP + 25 , pop + 110 , ssh + 22 , etc.

Are Open Port Vulnerabilities a Big Deal?

If your ports are blocked, it means that you won’t be able to connect with certain websites or online games. This is because almost all services communicate over specifically dedicated network channels called “ports”.

If a service uses port 80 and this channel happens to be closed, well then it’s not going to work! In other words, the internet wouldn’t function very well if every device used only one port and such a scenario would make life much more difficult for those responsible for maintaining our routers’ security settings.

However, there are some situations where blocking of ports can provide additional protection so in most cases allowing up-to-date firewall software is essential.

Important Things To Keep In Mind When Configuring Your Router for Remote Access

When you allow access to your router through the Internet, there are some things that you need to keep in mind.

  • First of all, make sure that login credentials for the router’s web interface are either hidden or changed! If it’s not then anybody who knows about this could reconfigure your router remotely and cause a lot of problems (not just blocking ports).
  • Second, if your ISP provides technical support over remote connections, be aware that they can have full control over your device and everything connected with it – including port forwarding/blocking privileges.
  • Third, don’t forget to change any default passwords after initially configuring the firewall settings since these are well known by hackers looking for opportunities like this one.

How Often Should I Check My Open Ports?

The answer to this question depends on what kind of network activity you have. If your ports are blocked it is most likely that they will stay closed for a very long time. 

However, if there are changes in the firewall configuration or some new services/applications get added, then it could be a good idea to check back now and then – just to make sure everything still works fine!

How To Unblock Your Ports?

There are two main ways to unblock ports:

  • Configure your router web interface (remotely or locally);
  • Get assistance from your ISP.

If you have no idea what port forwarding is, then there’s a chance that it has been automatically configured by the service provider when they set up your Internet connection. This means that you’ll have to contact them and ask for assistance.

What if My ISP Is Not Able To Unblock Ports?

If your ISP doesn’t provide any useful support and you can’t unblock your ports by yourself, then a good solution would be to get help from an IT specialist. However, this could also cost additional money so it’s something that needs careful consideration before going ahead with it.

Unfortunately, there are situations when the best solution would be to get a new service provider who can help with that (or use an alternative connection). This might seem like something trivial but we all know how frustrating it can become when the Internet connection is slow (or not working at all).


If you let just any person from the outside access your home network then it’s very easy for them to cause problems and even steal some of your personal data. That is why opening up ports without a proper understanding of what needs to be done can lead to serious security issues that are not so easy to resolve.

Therefore, if you want to be able to access ports on your home network from the Internet it’s a good idea for you to make sure that everything is configured properly and change default passwords as soon as this becomes possible.

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