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Do you need to know what TCP/IP ports are in use on your Windows 8 PC? Then read this tutorial!

Each and every applications need to occupy an available port or socket when the application wants to be connected to the internet. The application uses that occupied port to communicate and transfer data over internet until the application are terminated. Some applications have dedicated ports, like HTTP (Hyper Text Transfer protocol) uses port 80, FTP (File Transfer Protocol) uses port 21, Telnet has dedicated port 23, SMTP (Simple Mail Transfer Protocol) uses port 25 etc. Some applications do not have any dedicated ports. When they want to connect to internet they occupy any random available port.

To know which application is using what port, follow these steps.

Use the command line and Task Manager to check the ports

1. Open the Task Manager.You can open Task Manger either by right clicking on the taskbar or by pressing Alt, Ctrl and Delete simultaneously. Now click on the File Tab and then select New Task (Run).

2. Then the Run window will appear. Check the box below to "Create this task with administrative privileges” . Write cmd into the input area and press Enter.

Now, the command prompt will appear having administrative privilege. You will see Administrator is written in the bar. It indicates you have the administrative privilege.

3. Now, simply type this command line

netstat -aon | more

and hit Enter.

4. Now you can see a table where the Local Address column will show you the port address and PID column will show the Process Identifier number of the process or application which is listening (using) the particular port. For an example from that table shown in the figure we can tell that Local Address 0.0.0.0:80 or port 80 is being used (Listening) by the process having the PID 1592.

This PID is unique for each and every process.

5. Now, open Task Manager and navigate to Services tab, there you can see the PIDs of all running programs. We can see that Apache 2.2 application holds the PID 1592 and the application is currently running. So we can conclude that port 80
is being uses by Apache 2.2. Now, you can terminate this program or process to release the port.

Thus you can easily identify which port is listening to which program and what are the available ports