How to check ports on windows

Certain apps and processes in Windows 10 can cause problems if you’re not properly connected to the internet. Firewalls can cause these connection issues when they cannot determine whether incoming and outgoing connections pose a threat. Work around this issue and open ports for incoming and outgoing connections. We will know to check whether a TCP port is open or closed on the Windows operating system.

Basically, many times we need to check the port status when any of the below issues results in closing the port.

1. They may not be properly working.
2. External IP addresses that are in use may be set to private IPs.
3. Firewall rules may block the network.

There are several ways to check open TCP/IP ports in Windows. Here are a few options:

Using Telnet Client:

Step 1: Check whether the telnet client feature is ON or not. In order to check, open the Turn Windows feature on or off settings from the search bar. OR press the ‘window’ key and type ‘windows’ features. Then press on “Turn Windows features on or off”.

A new prompt will be opened. Search for “Telnet Client” and check the box in front of ‘telnet Client’.

Step 2: Open the command prompt. Press the ‘windows’ key and type ‘cmd’. Press “Command Prompt”.

Step 3: On the command prompt, type the command “telnet + IP address or hostname + port number” and check the status of the provided TCP port.

Step 4: If only the blinking cursor is visible, then the port is open.

Step 5: If you get the message “connection failed” then the port is closed.

Using built-in netstat command-line utility:

Step 1: Open the command prompt. 

Step 2: Run the following command:

netstat -an

Using TcpView

Another option is to use the TcpView utility from Microsoft’s Sysinternals suite of tools. This utility provides a more user-friendly interface for viewing active TCP/IP connections, along with additional information such as the process ID and process name for each connection. Steps to be followed:

Step 1: Download the TcpView utility from the Microsoft Sysinternals website. You can find the download link on the TcpView page of the Sysinternals website.

Step 2: Extract the downloaded file and run the TcpView.exe file to launch the TcpView utility. This will open the TcpView window, which shows a list of all active TCP/IP connections on your machine.

Step 3: Open the tcpview.exe (application).

By default, TcpView will display the following columns in the list of connections:

Protocol: Shows the protocol being used for the connection (TCP or UDP)

Local Address: Shows the local address and port being used for the connection

Remote Address: Shows the remote address and port being connected to

State: Shows the current state of the connection (e.g. Established, Listen, etc.)

You can use the “Local Address” and “Remote Address” columns to see which ports are being used by which applications. For example, if you see a connection with a local address of “127.0.0.1:80”, this means that the local application is using port 80 for outgoing connections.

Windows PowerShell

You can also use Windows PowerShell to check open TCP/IP ports. To do this, use the Get-NetTCPConnection cmdlet, which allows you to view a list of active TCP/IP connections and the local and remote addresses and ports being used. For example, you can run the following command to view a list of all active TCP/IP connections:

Get-NetTCPConnection | 
Select-Object LocalAddress,
LocalPort, RemoteAddress, RemotePort

Nmap

To install Nmap in the Windows command line, follow these steps:

Step 1: Download the latest version of Nmap from the Nmap website. You can find the download link on the Nmap download page: 

https://nmap.org/download.html

Step 2: Extract the downloaded file to a location on your computer. This will create a new folder containing the Nmap files.

Step 3: Open a command prompt and navigate to the directory where you extracted the Nmap files. For example, if you extracted the files to the C:nmap directory, you would run the following command:

cd C:nmap

Step 4: Once you are in the Nmap directory, you can install Nmap by running the nmap.exe file. To do this, run the following command:

nmap.exe -V

This will display the version number of Nmap, indicating that it has been installed successfully.

Step 5: To use nmap to scan for open TCP/IP ports, run the “nmap -sT” command, followed by the IP address or hostname of the machine you want to scan.

nmap -sT localhost

This will scan the specified host or IP address and display the results. You can also use the -h option to view a list of available options and arguments for the nmap command. Overall, installing Nmap in the Windows command line is a straightforward process. You can download the latest version of Nmap from the Nmap website, extract the files, and then run the nmap.exe file to install it. Once it is installed, you can use the nmap command to scan hosts and IP addresses and view the results.

Is this article up to date?

In this how to check if port is open article, we will try to answer all the how-to questions we receive on our website.

We will add a new question from time to time base on new how to questions that users will ask.

For general question, we will try to answer it for the Windows operation system, assuming it can be asking for Windows, Linux, MAC or Mobile device.

Here is a common question regarding how to check a port is open:

• how to check 443 port open or not?
• how to check if port 443 is open?
• how to check if port 9675 is open?
• how to check port 443 is open?
• how to test port 443 is open?
• how to check if port 25 is open?
• how to check if the port 47827 open?

To check if a port is open or not on your local computer you will have to use a tool.

Using our own Open Port Viewer tool:

You can download our Open Port Viewer tool and run it (right click and run as administrator).

Open Port Viewer is an easy to use GUI tool to get the current list of used ports on your system.

In the list of ports that you will see, please check if you can see the port you are searching.

Using netstat command line tool:

Another option is to use the netstat command line tool.

To do so, please open cmd as administrator:

1. Press the Windows button
2. Type cmd
3. Right click on Command Prompt.
4. Select Run as administrator.

In the command prompt type the following:

netstat -an | find “PORT NUMBER TO FIND”

example to check for 443 with netstat:

netstat -an | find “443”

If you see the port number on the left side (red location on the blow image) the port is open.

Read more information about netstat on our netstat command article.

Using telnet command line tool:

Telnet is also a command line tool, to use it you may have to enable it first, on Windows 10.

This is how you enable telnet on windows 10:

1. Open Turn Windows Feature on or off
   1. Press the Windows Button + R
   1. On the Run dialog type: OptionalFeatures
   1. Press enter or Click OK.
2. Fin Telnet client in the list.
3. Mark V near it.
4. Press Ok

Open the command prompt as administrator (look above how to open cmd as administrator).

Type the following:

telnet localhost <PORT NUMBER>

example to check for 443 with telnet:

telnet localhost 443

If you get the following error, the port is close:

Connecting To localhost…Could not open a connection to the host, on port 443: Connect failed

Using putty tool:

To check if the port is open using putty tool, you need to download putty from the internet first.

Putty can open a terminal, like telnet or SSH to connect to a remote host, like the telnet command.

We will use it to connect a local port.

Downloading putty from putty website – Putty

When the site is open scroll down to the Alternative binary files section.

Select the 32-bit or 64-bit version of the tool, and download it to your computer.

Once it finishes downloading open it.

• Set hostname – localhost
• Set Port – The port number
• Select telnet
• Press open

Example of using putty to check port 443:

If you see the following message the port is close:

In this article, we show you 4 tools that you can use to check if port is open or not.

The above tools are designed to run on Windows operation system and you might need to be an administrator to use them.

Hope it helps.