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 Check Open Ports In Windows

To know which port is open in window can be done easily. So you can check open port in windows by doing this. All you need is a program that displaces all TCP and UDP connections and their respective states.

And all windows computers have such program—Netstat. Even when you do not supply, it does it by default. The only exceptions are ports in listening mode (you can also use it to know the port that are in listening mode too)

Using Netstat on the server itself to check for open ports in windows

So, a program can open a port and there is no client connected to it. And Netstat can also help you figure out which port are in listening mode—like I have said earlier. How it does that? Simple.

Common port numbers are translated into the protocol usually associated with them by Netstat. For instance it converts IP addresses to their DNS names and also it translated port 25 to smtp.

You may want to see the port or IP address numbers. If you want to do that, you should use n-switch. The process identifier (PID) or even the executable will not be identified. It is Netstat default setting.

On the other hand, you can see the service within the executable that opened the port by using the b-switch. When you use it that is what it tells Netstat to do.

And there is the o-switch which you can use to show the same PID for a process. You should know that Task Manager does the same thing too.

Using Telnet from outside to check open ports in windows

You should know too that telnet is not a default option in window Vista or 7 and so it is not recognized as an external command or internal for that matter. It is also not recognized as an operable program or batch file too.

But here is what to do: Go to ‘Start’ on your windows, click it and go to’ Control Panel’. It will display options.
Click on ‘Programs’ (it is usually below in the option displayed). And you should locate ‘Turn Windows Features on or off’. Click it and wait for it to load. You will see this at the top; ‘’ To turn a feature on, select its box. To turn it off, clear its check box. A filled box means that only part of the feature is turned on’’.

In the displayed list below, scroll down and select ‘Telnet Client’. And then click ‘Ok’. That is it.

And that is how you check for open ports from within or from outside in windows. Pretty straight forward, right? It sure is.

How to Determine What Ports are Being Used in Windows 10

Last year we suffered the BitCoin miner virus which locked our computer and levied a ransom. And yet, the main reason for the spread of the virus was that the unused ports did not close. So, to guard against happening again, we have to determine what ports are being used in windows and then turn it off.

What is a Port?

When it comes to port, it’s necessary to talk about IP as well. Let me draw an analogy to describe the relationship between the Port and IP. Once upon a time, if you want to send a letter to your friend in a faraway place, you need to write down your address and his address on the envelope. The envelope is amount to the data package while both addresses are amount to IP. When the postman sends the letter to your friend’s house, and if your friend opens the door to get it, now the door is equal to the port. If your friend doesn’t open the door, that is to say, the port closed. After that, the letter will be sent back to you. In network technology, ports divide into two classes. One is a physical port, such as USB port. The second is the logical port, which generally refers to the port in the TCP/IP protocol. These port will cause some virus and harm your PC. As a result, there is necessary to check if the port is open.

Determine What Ports are Being Used in Windows 10

Step 1: Hit Windows + R to invoke Run dialog and type cmd to open Command Prompt.

Step 2: Type netstat -ano to list states of all ports.

Alternatively, type telnet

to check if port is open.

Step 3: Locate to the target port and view the corresponding PID in the final column. For example, the PID of port 2179 is 3800.

Step 4: Input tasklist|findstr “3800” and hit Enter on the keyboard to view which service takes up the port.

Step 5: To end up this service, run taskkill /f /t /im vmms.exe.

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Scanning Open Ports in Windows: A Quick Guide (Part 2)

This post has been reviewed and the information is still relevant as of June 2018.

In early 2012, I wrote an article called Scanning Open Ports in Windows: A Quick Guide that covered how to use NetStat.exe, Tasklist.exe, TCPView.exe and PortQry.exe and Scanning Open Ports in Windows: Part 3 that covered how to use NMAP to view open ports and troubleshoot client or server side application network connectivity issues. This article is a continuation of that and discusses three more free tools you can use to check for open ports – Telnet, CurrPorts.exe and TCPEye.exe.
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Telnet

To get started, one tool I thought would be worthy of a brief mention is Telnet. Using the telnet command you can quickly test if a specific port is open on a host in your network. To do this:

1. Open a command prompt window
2. Type telnethostnameport_number or telnetip_address port_number

Replace hostname or ip_address with the name or IP address of the machine you wish to connect to, and port_number with the port number you want to test. You will see a blank screen if the connection was successful (indicating that the specified port is open).

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Note: On Windows Vista/7/8, Telnet is disabled by default. To enable it:

1. Go to the Control Panel >Programs and Features >Turn Windows features on or off
2. Check Telnet Server and Telnet Client
3. Click OK to have the features installed.

CurrPorts

Another handy tool to add to your collection is CurrPorts. CurrPorts runs as a standalone application that displays all open TCP and UDP ports on your local computer and detailed information about which process opened those ports. Using this tool, you can also:

1. Close unwanted TCP connections (when run under an admin account)
2. Kill the process that opened the port
3. Export the TCP/UDP port information to a file
4. Filter the information that is displayed to show or hide TCP/UDP ports, ports that are listening, established, closed, and even flag ports that are not associated with a known application.

To open CurrPorts, simply extract the ZIP file and run CurrPorts.exe. It will immediately list information about all currently open ports. Use the Options menu to filter out which port information you wish to view.

The image below shows what a suspicious connection might look like if you were investigating a local machine. In this example, I created a small console application in C# to simulate client/server network connectivity that connects to port 6996 on the local IP address. You can use the “Remote IP Country” column on the far right of the window to give you a quick indication of where the remote server is located.

Note: In the real-world, a malicious process (e.g. botnet) would have a different remote address (for the purposes of this example the client and server processes are running on the same machine).

Whatever it is that you are investigating, look at the process name and port number together to determine if something seems out of the ordinary. Alternatively, if you are looking for a specific open port, sort the “Local Port” or “Remote Port” column and search for the port number in question.

The status bar at the bottom of the CurrPorts window shows the total amount of ports in use and the number of established remote connections.

TCPEye

Finally, similar to CurrPorts is an application called TCPEye. TCPEye also displays a list of all currently opened TCP/UDP ports on your local computer and shows detailed information about the process that opened the port. Like CurrPorts, TCPEye also allows you to:

1. View which country the remote server is located
2. Close unwanted TCP connections
3. Save TCP/UDP port information into an HTML, XML or CSV file.

One standout feature in TCPEye is that if you notice a suspicious process (e.g. one that is connected to an open port and a remote address), you can right click on it and select “Check with VirusTotal” for the process information to be uploaded and analysed by VirusTotal (as shown in the image below).

One thing to note about TCPEye is that it does not run as a standalone application and will require installation first.

Do you know of any other free or open source tools you use to check for open ports? If so, we’d love to hear from you.

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Get immediate results. Identify where you’re vulnerable with your first scan on your first day of a 30-day trial. Take the necessary steps to fix all issues.