Using the netstat command to find port information¶
To run the netstat command, you will first need to open a Command Prompt as administrator, to do so, please select start, type cmd, right click the resultant cmd.exe and “Run as Administrator” as below
Finding processes running on a port¶
In order to find what process is running on a specific port in Windows, you need to utilise the
netstatcommand
In the Command Prompt, type netstat -ano | find ":Required port number", for example, if you wish to find out what process is listening on port 25, you would type netstat -ano | find ":25" and hit Enter
The Command Prompt will now display any processes listening on port 25 as below
At the right hand side of the result, you will see a number, this number is a PID (Process Identifier), this number is assigned to a specific process on your server.
To find out what process is assigned the displayed PID, right click on the task bar, and select “Task Manager”, once task manager has presented itself, select the “processes tab” and right click on the status title.
This will now display a context box with a number of options as below, please select “PID” from the list.
now search through the list of netstat command, in this example 844,which as you can see below is occupied by the hMailServer application.
This means that port 25 is being occupied by hMailServer, which is as expected.
The netstat command can be extended to count the number of connections on a specific port, you can do this by adding /c to the end of the command. for example
netstat -ano | find ":25"` /c
What port is my service listening on?¶
In order to find out what port a specific service is listening on, you simply use the
netstatcommand again, but in a slightly different way.
In the Command Prompt, type netstat -ano and press enter.
This will present you with a list of all current connections to and from your server as below
Right click on the taskbar, and select task manager, again, select processes, and right click on the title bar, Select “PID” from the resultant list. Find the the PID of the program for which you are trying to find the corresponding port, now review the connections in Command Prompt to find the Correct PID, look to the left of the Command Prompt on the matching line to see which port that specific PID is using.