Windows check if port is free

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:

Netstat–an

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.

netstat –ano

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.

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.

A Port basically serves as an interface between your computer and the internet or other computers in the network. Every communication over the web is exchanged using these ports so they are the essential part of the entire internet communication model.

Every IP address has a total of 65,535 ports and it’s either a UDP port or a TCP port. Open port in a computer refers to a port that is configured to accept the connections and a port which rejects connections is obviously a closed port.

While open ports are necessary for internet communication, they can be dangerous if the service listening on the port has bad security rules and is misconfigured. Such open ports are vulnerable to attacks.

In this post today, we will learn how to check which ports are being used in your machine, how to test if a Firewall is blocking a Port, and also learn how to check which process or service is using the open port.

Open Command Prompt, type the following, and hit Enter to view the Ports used along with the Process Identifiers (PIDs):

netstat -ano

This will display the ports on your PC. It will display the details in 5 columns-

1. Protocols,
2. Local Address,
3. Foreign Address,
4. State, and
5. PID (Process Identifier).

The port numbers here are displayed under the Local Adress column, for example, if the Local Adress is 0.0.0.0:5040, 5040 here is the port number.

Under the State tab, you can check whether a port is open or not.

• LISTENING means that it just waits and it is ready to send an answer whenever a client program requests it. The connection becomes open when a client connects to that port and a conversation begins.
• ESTABLISHED means that the connection has been established.
• TIME_WAIT means it’s waiting for a reply or connection. this often happens when a port is activated and the connection has not yet. been established
• CLOSE_WAIT means that the other side of the connection has closed the connection.

This is how you check what all ports are open in your Windows 10.

You can also view the Ports used along with the Process Names by running this command:

netstat -ab

Read: How to use Port Query Tool (PortQry.exe).

Check which process or service is using the open port

Now when we know what all ports are open in our system, we can also check which service is using which open port. To check that, go to the PID (Process ID) tab.

Let’s take the example of our first open port in the list, port 135, and its PID is 1192.

Now open the Task Manager by hitting Ctrl+Alt+Delete. Go to the Services tab and check for PID 1192.

Under the Description tab, you will see which app/program is using that port. End that particular task if you want to close that connection.

Alternatively, you can also find this using this command:

takslist|findstr "1192"

This will display the program using the selected port.

If you are looking for an easy way, you can also use some third-party software to check what all ports are open in your Windows 10. There is quite a few such freeware available on the web which tell what all websites your computer is connecting to and what all ports are open in your PC. One of such freeware is CurrPorts.

Read: How to Block or Open a Port in Windows Firewall.

How to test if Firewall is blocking a Port

CurrPorts is a simple and portable freeware to check open ports that comes in a zip file and takes no time to download on your PC. Since it is portable software, you do not need to install it. Simply download it, extract all the files and run it. Make sure you download the correct version as per your machine’s configuration.

CurrPorts is a network monitoring software that displays the entire list of all open ports of your PC. Apart from the port number and its State, the freeware also shows detailed information about the processes using the open ports, the complete path of the process, file description, product name, file version, date and time it was created, and much more.

Once you download CurrPorts and run it, the main overview has it all. It displays the entire thing in one single window. You can check all the currently opened TCP and UDP ports and the program using that particular port in a single window. Check the screenshot below. You can select one or more processes at a time, check their ports and kill them if they seem to be unwanted. It also allows you to save the port information to an HTML/XML/Text file.

Furthermore, CurrPorts also lets you kill the process from the same window. Simply select the processes you want to kill, right-click and select ‘Kill processes of selected ports’ from the dropdown menu.

Another benefit of using CurrPorts is that it marks the suspicious TCP/UDP ports owned by the unidentified applications. So you can directly kill them and save your PC from a possible attack.

Certainly, using this freeware is an easier option as compared to the Command Prompt option mentioned above. You can download the software from the official website Nirsoft.net. Please note that there is a separate download link for x64 versions of Windows. This utility works fine with almost every version of Windows. It is a standalone executable utility so doesn’t require any installation.

NETSTAT will tell you if the port is listening but it will not tell you if the port is open to the outside world. What I mean by this is that NETSTAT may show that the 0.0.0.0 is LISTENING on port 3306 but a firewall may still be blocking that port which is preventing outside connections; so it isn’t sufficient to rely on NETSTAT alone.

The best way to check if a port is blocked is to do a port scan from the client machine.

There are many ways to do a port scan but since you mentioned being on Windows then I will suggest the Microsoft command line utility PortQry and the Graphical version PortQryUI

To test all open ports:

portqry.exe -n #.#.#.#   

To test a specific port:

portqry.exe -n #.#.#.# -e #

For example to test the Web interface of a router at 192.168.1.1:

portqry.exe -n 192.168.1.1 -e 80

Which returns:

TCP port 80 (http service): LISTENING

Where as testing on a local machine with no HTTPD running returns:

TCP port 80 (http service): NOT LISTENING

Using a PortScan utility you will get one of 3 results.

• Listening means the server is listening on the specified port
• Filtered means it received a TCP acknowledgement packet with the Reset flag set which likely indicates a firewall or software issue
• Not Listening means it didn’t receive a response at all

telnet is another command line option that is usually installed on the OS by default. This command line utility can be used a quick way to see if a port responds to a network request.

To use telnet you would simply issue the following command from a command prompt:

telnet localhost 3306

The command above should give you a quick indication if the port 3306 on the localhost is responding.

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 check open ports on Windows and see which applications are using which ports.

Check Port Usage With 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 check port status on Windows.

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.

List Open Ports Using the Command Prompt

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 open 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.

Install TCPView to Check Open Ports

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.