How to check the ports in use in Windows 10

At any given moment, a ton of information is sent between your Windows 10 PC and the Internet. This is done using a process in which network-dependent processes look for TCP and UDP ports through which they communicate with the Internet.

In most cases, Windows 10 knows how to manage ports and ensures that traffic is being diverted through the right ports so that those processes can connect to what they need.

But sometimes two processes can be assigned to a single port, or you want to have a better picture of what network traffic is going into and out of your network.

This article will show you an overview of the ports and find out which applications are using which ports.

Command Prompt method

Perhaps the easiest way to see which port is used by which process is to use a trusted Command Prompt.

Click the Start button , type cmd , then right-click on 'Command Prompt' when it shows up in the search results. Click 'Run as administrator' .

Once you are in Command Prompt with admin rights, enter the following command:

netstat -ab

This will continuously bring up a list of perhaps quite long ports, along with the Windows processes that are using them. (You can press Ctrl + A , then Ctrl + C to copy all the information to the clipboard). On an average PC there will be two main local IP addresses containing ports on the PC.

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The first, in our case, is "127.0.0.1" . This IP address is also known as 'localhost' or 'loopback address' and any processes that listen for ports here communicate internally on the local network without using any network interfaces. The gate is actually the number you see after the colon.

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Most of your processes will probably listen for ports prefixed '192.168.xxx.xxx' , which is your IP address. This means that the processes you see listed here are listening for communications from remote Internet locations (such as web pages). Again, the port number is the number after the colon.

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TCPView

If you don't mind installing a third-party application and want more control over what's going on with all your ports, you can use a lightweight application called TCPView. The tool immediately lists the processes and their related ports.

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What makes this tool better than the Command Prompt is that you can proactively see ports open, close, and send packets. Just pay attention to the green, red, and yellow highlights. You can also reorder the list by clicking on the column header, making it easy to find the process you want, or find two separate processes that compete for the same portal.

If you find a process or connection you want to close, just right-click on it. Then you can choose 'End process' , which is exactly the same function as in Windows task manager. Or you can click 'Close Connection' to let the process open but prevent it from listening on a certain port.

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David Pac

Update 23 March 2021