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 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.

How to check if port is open on windows

The knowledge of how to check for open ports is important especially when you own a windows device. Here is an article about how to check if port is open on the windows operating system.

This can be done using any of the available port checker tools online. There are freeware tools for Microsoft Windows which can be used to check if a port is open.

These free utilities are quite effective at scanning for open ports.

How to Check For Open Ports in Windows

When troubleshooting network connectivity issues, there are ways to check for open (or listening) ports. In this article, we will look at the port check tools available in order of their popularity.

1. NetStat.exe

The netstat.exe is a popular Windows command line located in the Windows ‘System32’ folder. It is very effective for checking for open ports or if a port is in use by a particular host.

The netstat command line to be used in checking for open ports in a local host should be entered in the command prompt (cmd.exe) as follows:

This displays the results across four columns with protocol type, IP address, foreign address and the state as the headings respectively.

The column of significant interest is the content of the second column in the command prompt display.

The “o” parameter can be added to the netstat command to show the application process ID (PID). A process ID column appears in the result as a fifth column.

Open Tasklist.exe to help identify the application using the open (listening) port from the command prompt.

2. TCPView.exe

The second on our list is TCPView.exe which is similar to the netstat.exe command. The difference between the two methods of checking for open ports is that TCPView.exe gives a detailed representation in a graphical format or graphical user interface (GUI).

By opting to use TCPView, you get to scan for which ports are open.

Also, as its extended benefit, it enables you to check both the local and remote TCP connection, the protocols that are being used as well as the processes involved.

TCPView can be downloaded from Microsoft SysInternals website and runs as a standalone application without any need to install.

3. PortQry.exe

An alternative method to check for open (listening) ports is the PortQry.exe Windows command.

It can be downloaded by visiting Microsoft Download’s Center and just like the TCPView command; it also runs as a standalone application.

The use of the PortQry.exe command line allows checking for open ports available on the local or remote host.

It works by downloading and extracting the executable file from the Download’s Center and opening a command prompt.

On the command prompt, enter portqry.exe and the parameter identifying the folder which contains the executable file.

It should be noted that the results obtained from running the portqry.exe are similar to that of the netstat.exe command except that it also shows the port statistics stating the number of port mappings and ports in each state.

4. OpenPortViewer.exe

Open Port Viewer is our home develop a free tool design for Windows 10 that can show you a list open port in windows, it is like the netstat command line tool but with GUI. It supports IP v4 and V6, it can resolve the remote IP to the domain name and show network statistics.

How To Check If Port Is Open

It is very important to know the ports that are open on your computer because some ports are associated with special services and these ports have to be open for your computer to run properly. It is also important to check if port is open and which ports are open.

To check if port is open, you should enter “netstat -a” in the command line and it will return with a list of open ports.

Open port and hacking:

Apart from the ports that are used for special services, all other ports should be closed because the more open ports you have on your system, the more vulnerable it will be to hacking.

This is because ports are the doors through which access to your computer can be gained.

Firewalls are the only locks that prevent access. Knowing the ports that are open is a step towards safeguarding your computer.

The special ports that should be open and their uses have been outlined below. All other ports should be closed or filter.

Here are the ports:

Port 7:

This port is also referred to as Ping and Echo. It is used to retrieve the IP address of your computer and its gateway. This is done by typing ipconfig in the command prompt. It is also used for troubleshooting. This is done by typing ping and the number of your gateway. You will get a response after.

Port 21:

This is known as the FTP. This is used to either upload or download files to or from a server when websites are being updated.

Port 25:

This port is called SMTP. It works with applications like Thunderbird, Pegasus and the popular Microsoft Outlook to send emails. Gmail, Yahoo mail and Hotmail do not need this port because they are webmail.

Port 53:

This port is also known as DNS. This port helps to convert URL to the IP address of the website. Here is how it works. The computer does not understand the website you type on your web browser and you cannot cram the IP address of websites. So when you type the website, it is converted to the appropriate IP address for your computer through the process known as DNS. The computer now loads the page based on the IP address. Without DNS, you will have to be typing IP address and not the website. Imagine how difficult it will be.

Port 80:

This port is known as HTTP. This is the route through which your computer gains access to the internet or to other websites. If this port is closed, you won’t be able to visit other websites.

Port 110:

This port is called POP3 and it works with the same applications as Port 25 above to receive emails. It does not also work with webmail.

Ports 135 to 139:

This is known as NetBios. This gives you the name of any computer on your network.

Port 443:

This port is known as HTTPS, it does the same thing as Port 80 but for secure websites.

In conclusion:

The above freeware utilities are the answer to the how to check for open ports question and they are useful in being able to troubleshoot network connectivity issues if the need arises and form a part of a network auditing toolkit or basic checks for vulnerabilities where necessary.

How to Find Open and Blocked TCP/UDP Ports

Using one of these free scanning tools

There’s a good chance you’ve happened upon this article because an application you’re trying to run is complaining about a “port” being blocked or you’ve read about how leaving certain “ports” open on your network can be a security problem.

Either way, by the end of this piece you’ll not only know what these ports everyone is going on about are, but how to check your computer to find open or closed ports.

What Is a Network Port?

The first thing you should know is that the ports we’re referring to here are virtual. It has nothing to do with the physical network hardware ports on your router, TV, consoles or computers. Ports are simply a way for your network hardware and software to organize information traffic.

Think of reserved lanes on a road. The sidewalk is for pedestrians. There might be a dedicated bike lane. Carpool vehicles and buses have their own lanes too. Ports serve the same function. One port might be used for receiving emails, while another carries file transfer requests, or website traffic.

There are two common types of ports, which need a brief explanation before we move on to checking which ports on your system are open and which aren’t.

What Are TCP & UDP Ports?

The two common types of ports on modern networks are known as TCP and UDP ports. That is Transmission Control Protocol and User Datagram Protocol respectively. So these two port types use different network protocols.

Which you can think of as distinctive sets of rules for how bits of information should be sent and received. Both port types are built on the fundamental Internet Protocol (IP) that makes the internet and home networks, well, work. However, they are suitable for different applications.

The big difference is that when you send information over UDP, the sender doesn’t first have to establish a connection with the receiver before starting the conversation. It’s a bit like sending a letter. You don’t know if the other person received your message and you have no guarantee that you’ll get any feedback.

TCP, on the other hand, is more like making a phone call. The receiver has to “pick up” the connection and there’s a back-and-forth flow of information until someone deliberately hangs up.

UDP messages are generally broadcast over a network to anyone who is listening on the specified UDP port. This makes it perfect for housekeeping type messages that relate to running the network itself. It’s also perfect for voice-over-IP streaming, online video games and streaming broadcasts.

Why? These applications benefit from UDP’s low latency and constant stream of information that doesn’t have to be perfect to be useful. A little corruption in your Skype chat is far less important than low amounts of lag, after all.

TCP is much more common than UDP and absolutely makes sure that all data is received free from errors. Just about everything that doesn’t need the specific advantages of UDP, uses TCP instead.

Which Ports Are Usually Open By Default?

There are a LOT of ports. A port number can be anything from 0 to 65535! That doesn’t mean any application can just pick any port. There are established standards and ranges, which helps us make sense of the noise.

Ports 0-1023 are associated with some of the most important and fundamental network services. This makes sense, since the lower-numbered ports were assigned first. The SMTP protocol for email, for example, is exclusively used by port 25.

Ports 1024-49151 are known as “registered ports” and are assigned to important common services such as OpenVPN on port 1194 or Microsoft SQL on ports 1433 and 1434.

The rest of the port numbers are known as “dynamic” or “private” ports. These ports aren’t reserved and anyone can use them on a network to support a particular service. The only problem crops up when two or more services on the same network are using the same port.

While it’s impossible to list every single important port, these common ports are useful to know by heart:

• 20 – FTP (File Transfer Protocol)
• 22 – Secure Shell (SSH)
• 25 – Simple Mail Transfer Protocol (SMTP)
• 53 – Domain Name System (DNS)
• 80 – Hypertext Transfer Protocol (HTTP)
• 110 – Post Office Protocol (POP3)
• 143 – Internet Message Access Protocol (IMAP)
• 443 – HTTP Secure (HTTPS)

Since there are so many thousands of common port numbers, the easiest approach is to remember the ranges. Which will tell you if a given port is reserved or not. Thanks to Google, you can also look up which services use a specific port in no time at all.

Find Open Ports In Windows

Now that we’ve got all the basic knowledge about TCP and UDP ports out of the way, it’s time to get down to the process of finding which ports are open and in use on your computer.

The good news is that Windows has a pretty useful command built into it that will show you what ports are currently being used on your computer by various applications and services.

• The first thing you want to do is open the Start Menu and search for CMD.

• Now, right-click on CMD and Run as Administrator.

• With the Command Prompt open, type:

Netstat -ab

• Don’t worry about a long list of info scrolling by faster than you can read it. You can simply use CTRL+C and CTRL+V to copy and paste the information into Notepad or any other text editor.
• The information in brackets is the name of the program that’s using the port. TCP or UDP refers to the protocol being used on that port. The number consists of an IP address and then the port number after the colon.

Scanning For Blocked Ports

That takes care of finding which ports are being used and by which application, but it doesn’t tell us which ports are being actively blocked by the Windows Firewall.

• Once again, open the Start Menu and search for CMD.
• Right-click on CMD and Run as Administrator.
• With the Command Prompt open, type:

netsh firewall show state

This is a display of blocked and open ports as per the configuration of your Windows Firewall.

You’ll see a note about this command being deprecated, but the new command doesn’t show us the information we want. So for now using the ‘show state’ command is still the fastest and easiest way to get port information.

Just because the Windows Firewall isn’t blocking a port, that doesn’t mean your router or ISP aren’t. So the last thing we want to do is check if any external blocking is happening.

• Open the Start Menu and search for CMD.
• Now, right-click on CMD and Run as Administrator.
• With the Command Prompt open, type:

netstat -ano | findstr -i SYN_SENT

If you don’t get any hits listed, then nothing is being blocked. If some ports are listed, it means they are being blocked. If a port not blocked by Windows shows up here, you may want to check your router or pop an email to your ISP, if switching to a different port isn’t an option.

Useful Apps To Map Out Your Port Status

While the Command Prompt is a good quick and dirty tool, there are more refined third-party applications that can help you get a picture of your port configuration. The two highlighted here are just popular examples.

SolarWinds Free Port Scanner

SolarWinds requires that you submit your name and details in order to download it, but it’s up to you whether you put your real information into the form or not. We tried several free tools before settling on SolarWinds, but it was the only tool that both worked properly under Windows 10 and had an easy interface.

It was also the only one not to trigger a false positive virus flag. One of the big problems with port scanning software is that security companies tend to see them as malware. So most users ignore any virus warning that come with such tools. That’s a problem because you can’t tell the difference between a false positive and a real virus in these apps.

SolarWinds might come with some strings attached, but it actually works as advertised and is easy to use.

CanYouSeeMe

This is, as you can probably tell, a website service rather than an application. It’s a good first port of call to see if external data can get through your local port or not. It auto-detects your IP address and all you have to do is specify which port to test.

It will then tell you if the port is blocked or not and you’ll then have to figure out whether the blockage is on the computer, router or at the service provider level.

Conclusion

For most users, ports aren’t something you need to worry about. They are managed by your operating system, applications and network hardware.

When things go wrong however, it’s good to have the tool in hand that let you find open ports to sniff out suspicious activity or figure out where exactly your precious information is hitting a brick wall.

Sydney Butler is a social scientist and technology fanatic who tries to understand how people and technology coexist. He has two decades of experience as a freelance computer technician and more than a decade as a technologies researcher and instructor. Sydney has been a professional technology writer for more than five years and covers topics such as VR, Gaming, Cyber security and Transhumanism. Read Sydney’s Full Bio