How to check which application is using which port

October 04, 2009

Today I found an easy way to check which application is using which port in my system. Here I’m sharing the steps. These steps are applicable for the Windows Operating System.

Checking which application is using a port:

1. Open the command prompt — startВ В» runВ В» cmd or startВ В» All ProgramsВ В» AccessoriesВ В» Command Prompt.
2. Type netstat -aon | findstr ‘[port_number]’ . Replace the [port_number] with the actual port number that you want to check and hit enter.
3. If the port is being used by any application, then that application’s detail will be shown. The number, which is shown at the last column of the list, is the PID (process ID) of that application. Make note of this.
4. Type tasklist | findstr ‘[PID]’ . Replace the [PID] with the number from the above step and hit enter.
5. You’ll be shown the application name that is using your port number.

Checking which port is being used by a application:

This is exactly the reverse of the above steps.

1. Open the command prompt — startВ В» runВ В» cmd or startВ В» All ProgramsВ В» AccessoriesВ В» Command Prompt.
2. Type tasklist | findstr ‘[application_name]’ . Replace the [application_name] with the application that you want to check (for example, apache) and hit enter.
3. Make note of the PID (second column) from the details shown.
4. Type netstat -aon | findstr ‘[PID]’ . Replace the [PID] from the above step and hit enter.
5. You’ll be shown the application detail and the corresponding port to which it is listening.

How to find out which ports are used by a program?

I try to figure out which ports a specific program uses if they send data to the internet. Is there a tool which is able to find this out? Or do I have to do package inspection by using wireshark?

Background: I try to create a priority rule on my fritz!box 7490 router, so that some computer games are seen as real-time applications and there are as less lags as possible e.g. if someone in the network decides to watch videos on youtube while I am playing online.

3 Answers 3

Determine PID of your program

Check ports in third column of output from

• there is a space before PID to rule out inappropriate matches potentially coming from other columns (a little trick)
• /n keeps addresses in numeric form (without resolving) what causes the command to finish without delays (it should suffice for what you need)

If you are using windows you can use the free utility «Process Explorer» for this — among many other things. You have to run it in Administrator mode though.

If you are wanting to optimize something like a game or netflix streaming, then you don’t need to worry about the port on your computer — that is the client, and is (somewhat) randomly chosen from the higher range of ports. What you want is to find out what port(s) the service you are connecting to is provided on, and optimize connections to those ports from your machine (possibly by MAC address? or local lan ip)

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:

Content Manager at Make Tech Easier. Enjoys Android, Windows, and tinkering with retro console emulation to breaking point.

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.

FileCloud Blog

How to find what application is listening on a TCP/IP port in windows using netstat?

Whenever an application wants to make itself accessible over the network, it claims a TCP/IP port, which means that port can’t be used by anything else. So if you need to use an in-use port, how do you tell what application is holding it?

There’s a number of ways to tell which application has the port locked, here we will use a windows built-in way using the command line and Task Manager.

Using Built-In Tools to See What is Listening on a Port

The first step is to use a command-line tool to see what ports are in use, and use a special flag that tells us which port is assigned to each Windows process identifier number. Then we can use that number to look up exactly which process it is.

Open up a command prompt and type in the following—you may have to open in Administrator mode to see all processes:

netstat -ab | more

This will immediately show you a list, although it’s maybe a little complicated. You’ll see the process name in the list, and you can search for it.

You can also use this other method, which takes an extra step, but makes it easier to locate the actual process:

netstat -aon | more

If you look on the right-hand side, you’ll see where I’ve highlighted the list of PIDs, or Process Identifiers. Find the one that’s bound to the port that you’re trying to troubleshoot—for this example, you’ll see that 0.0.0.0:80, or port 80, is in use by PID 1184.

Now you can simply open up Task Manager—you might have to use the option to Show Processes for All Users, and then you’ll be able to find the PID in the list. Once you’re there, you can use the End Process, Open File Location, or Go to Service(s) options to control the process or stop it.

Alternatively you can even use resource monitor to stop any process that is running. To open resource monitor type resmon.exe in run. This will bring up the resource monitor window.

There would be situations were some other process is running at port 80. To stop anything running in port 80 the following command can be used from command prompt.