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 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.

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)

Windows tool to find out which port an app is trying to use?

I am guessing that netstat shows apps and their ports that already have a connection and it doesn’t show or can’t show an app that is trying to open a connection.

If I have an app that’s trying to connect to the net but is blocked by a firewall, how do I know which port it’s trying to use?

5 Answers 5

You can use TCPView from Microsoft/Sysinternals.

If you find it difficult to capture the port opening with that utility, than the best bet is to install and run Wireshark to get a network trace (assume you aren’t talking about a local software-based firewall.

Windows tool to find out which port an app is trying to use?

NirSoft’s CurrPorts — network monitoring software that displays the list of all currently opened TCP/IP and UDP ports on your local computer. For each port in the list, information about the process that opened the port is also displayed, including the process name, full path of the process, version information of the process (product name, file description, and so on), the time that the process was created, and the user that created it.

CurrPorts allows you to close unwanted TCP connections, kill the process that opened the ports, and save the TCP/UDP ports information to HTML file , XML file, or to tab-delimited text file. CurrPorts also automatically mark with pink color suspicious TCP/UDP ports owned by unidentified applications (Applications without version information and icons)

How to determine which program uses or blocks specific Transmission Control Protocol ports in Windows Server 2003

This step-by-step article discusses how to determine which program uses or blocks specific Transmission Control Protocol (TCP) ports.

For a Microsoft Windows XP version of this article, see 281336.

Original product version: В Windows Server 2003
Original KB number: В 323352

Summary

The Netstat.exe utility has a new switch, the -o switch, that can display the process identifier (ID) that is associated with each connection. This information can be used to determine which process (program) listens on a particular port. For example, the netstat -ano command can produce the following output:

If you use Task Manager, you can match the process ID that is listed to a process name (program). With this feature, you can find the specific port that a program currently uses. Because a program already uses this specific port, another program is prevented from using that same port.

How to match the process ID to a program

To match the process ID to a program, follow these steps:

1. Press Ctrl+Alt+Delete, and then click Task Manager.
2. Click the Processes tab.
3. If you don’t have a PID column, click View >Select Columns, and then click to select the PID (Process Identifier) check box.
4. Click the column header that is labeled «PID» to sort the process by PIDs. You should be able to easily find the process ID and match it to the program that is listed in Task Manager.

How to obtain additional information about the Netstat.exe utility

To obtain additional information about the Netstat.exe utility, follow these steps:

1. Click Start >Run.
2. In the Open box, type cmd, and then click OK.
3. At a command prompt, typenetstat /?.

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