How to Check for Ports in Use in Windows 10
At any one time, there’s a whole bunch of information being sent between your Windows 10 PC and the endless void of the Internet. This is done using a process whereby network-dependent processes seek out TCP and UDP ports, which they use to communicate with the Internet. First, your data gets sent to remote ports at the destination or website your processes are trying to connect to, then it gets received at local ports back on your PC.
Most of the time, Windows 10 knows how to manage ports and ensure that traffic is being directed through the right ports so that those processes can connect with what they need to. But sometimes two processes may be assigned to one port, or maybe you just want to get a better picture of your network traffic and what’s going in and out.
That’s why wrote this guide that shows you how to get an overview of your ports and see which applications are using which ports.
Use Nirsoft CurrPorts
NirSoft is one of the best indie software developers, giving us great utilities, like PassView and WirelessKeyView. While some people will prefer checking their ports without installing third-party software (in which case, scroll down to the CMD method), CurrPorts is easily the fastest and most convenient way to view your ports.
Once you’ve installed CurrPorts, just open it to see a list of all your ports currently in use. If you’re looking for local ports in use, just click the “Local Port” column at the top to order the list by port number (handy if you’re looking for a specific one). You can do the same thing with remote ports, too.
If you want to really find specific ports, click the “Advanced Filters” icon at the top and enter your string in the format they suggest. It should look something like the below image.
Hit OK when you’re ready, and the list will filter down to your queries.
Command Prompt Method
The integrated – though not necessarily the simplest – way to check open ports is to use the trusty command prompt.
Click the Start button, type cmd , then right-click “Command Prompt” when it shows up in the search results. Click “Run as administrator.”
Once you’re in the elevated command prompt, enter the following command:
This will steadily bring up a list of ports that is probably quite long, along with the Windows processes that are using them. (You can press Ctrl + A , then Ctrl + C to copy all information to the clipboard.) On the average PC, there will be two main local IP addresses that contain ports on your PC.
The first, in our case, is “127.0.0.1.” This IP address is otherwise known as “localhost” or a “loopback address,” and any process listening to ports here is communicating internally on your local network without using any network interface. The actual port is the number you see after the colon. (See image below.)
The bulk of your processes will probably be listening to ports prefixed with “192.168.xxx.xxx,” which is your IP address. This means the processes you see listed here are listening for communications from remote Internet locations (such as websites). Again, the port number is the number after the colon.
TCPView
If you don’t mind installing a third-party app and want to have more control over what’s going on with all your ports, you can use a lightweight app called TCPView. This immediately brings up a list of processes and their associated ports.
What make this better than the command prompt is that you can actively see the ports opening, closing and sending packets. Just look for the green, red and yellow highlights. You can also reorder the list by clicking the column headings, making it easier to find the process you want or two separate processes vying for the same port.
If you do find a process or connection you want to close, just right-click that process. You can then select “End process,” which is exactly the same function as the one in Windows task manager. Or you can click “Close Connection” to leave the process open but stop it from listening on a given port.
If you’re having some trouble in Windows 10, then see whether a Windows update may be causing it. We also have a handy guide for managing the health of your hard drive in Windows 10.
Related:
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How do I check whether an open port is TCP or HTTP?
Specifically, I have a Windows server (Windows 7), but the netstat -an command only shows whether ports are TCP or UDP. I thought these were the only kinds of ports, but node.js seems to distinguish between HTTP ports and TCP ports (example at bottom of linked page). I’m currently using node.js in a program that will run on my server, and it opens HTTP ports by default. These appear as TCP ports under netstat -an .
Is there a command line trick for distinguishing whether an open port on this server is HTTP or TCP? I make requests to my Information Technology office about ports that I need on this server, and they need to know whether these ports will be TCP, UDP, etc.
If necessary to use a remote client, I have a Mac that can do the job.
2 Answers 2
All HTTP traffic is transmitted over TCP Ports. I think what may be causing some confusion is that the first node.js example uses the http module and the second example uses the net module.
The http module is built on top of the net module (which handles the TCP layer underlying HTTP).
Only one process can bind to a port. If you’re having difficulties connecting, shut down any other applications that may be using the same port, such as your Java Hello World server. Run netstat -an to make sure you don’t see the port listed that you’re trying to listen on in you node.js TCP server (port 1337) in the example. If nothing is listening on the port, fire up your node.js TCP server and run netstat -an again to make sure it’s actually listening on the intended port.
Another suggestion — temporarily turn off the software firewall then use the telnet client on the local server to attempt to connect to the port using the command telnet 127.0.0.1 1337 (replace 1337 with your port) from the command prompt. This will eliminate any network devices such as firewalls between the client (telnet in this case) and the server. If the screen goes blank, you’ve connected. If you get the message Could not open connection to the host, on port then it’s still not listening on the TCP Port. If you can connect locally from Telnet but you cannot connect remotely then there is something blocking your connection.
Find the PID of a process that uses a port on Windows
My service crash on startup with the classic:
How can I find the process for killing it?
7 Answers 7
Just open a command shell and type (saying your port is 123456):
You will see everything you need.
The headers are:
Find the PID of a process that uses a port on Windows (e.g. port: «9999»)
-a Displays all connections and listening ports.
-o Displays the owning process ID associated with each connection.
-n Displays addresses and port numbers in numerical form.
Then kill the process by PID
/F — Specifies to forcefully terminate the process(es).
Note: You may need an extra permission (run from administrator) to kill some certain processes
Command:
Output:
Now cut the process ID, «10396», using the for command in Windows.
Command:
Output:
If you want to cut the 4th number of the value means «LISTENING» then command in Windows.
Command:
Output:
If you want to do this programmatically you can use some of the options given to you as follows in a PowerShell script:
However; be aware that the more accurate you can be the more precise your PID result will be. If you know which host the port is supposed to be on you can narrow it down a lot. netstat -aon | findstr «0.0.0.0:9999» will only return one application and most llikely the correct one. Only searching on the port number may cause you to return processes that only happens to have 9999 in it, like this:
The most likely candidate usually ends up first, but if the process has ended before you run your script you may end up with PID 12331 instead and killing the wrong process.
