Use Netstat Application to See Listening Ports in Windows
Whenever an application wants to make itself accessible over the network, it claims a TCP/IP port, which means that port can’t be used by anything else. So if you need to use an in-use port, how do you tell what application is holding it?
There’s a number of ways to tell which application has the port locked, here we will use a windows built-in way using the command line and Task Manager.
Using Built-In Tools to See What is Listening on a Port
The first step is to use a command-line tool to see what ports are in use, and use a special flag that tells us which port is assigned to each Windows process identifier number. Then we can use that number to look up exactly which process it is.
Open up a command prompt and type in the following—you may have to open in Administrator mode to see all processes:
netstat -ab | more
This will immediately show you a list, although it’s maybe a little complicated. You’ll see the process name in the list, and you can search for it.
You can also use this other method, which takes an extra step, but makes it easier to locate the actual process:
netstat -aon | more
If you look on the right-hand side, you’ll see where I’ve highlighted the list of PIDs, or Process Identifiers. Find the one that’s bound to the port that you’re trying to troubleshoot—for this example, you’ll see that 0.0.0.0:80, or port 80, is in use by PID 1184.
Now you can simply open up Task Manager—you might have to use the option to Show Processes for All Users, and then you’ll be able to find the PID in the list. Once you’re there, you can use the End Process, Open File Location, or Go to Service(s) options to control the process or stop it.
Alternatively you can even use resource monitor to stop any process that is running. To open resource monitor type resmon.exe in run. This will bring up the resource monitor window.
There would be situations were some other process is running at port 80. To stop anything running in port 80 the following command can be used from command prompt.
net stop http /y
Frequently Asked Questions (FAQs)
What application is listening on a TCP IP port in Windows?
Netstat is a diagnostic tool that creates a list of open ports that the machine is listening to, as well as the ports it is currently connected to on other machines. In Netstat, stat stands for state or statistics, which tells you the current network status of every TCP connection.
How do I find out what application is using a TCP port?
You can use Netstat -b -a -o.
This tool provides a list of all open ports and their associated processes. The -o shows the process id, which you can look up in your task manager or processes tab. To end that process, simply enter taskkill /PID xxxx.
How can I tell if a server is listening on a port?
On the server itself, use Netstat -an to check to see which ports are listening. From outside the server, telnet host port can be used to check connections. A refused connection means nothing is running, whereas an accepted connection means something is running. Timeout implies a firewall is blocking access.
How do I find out what application is using port 8080?
Open the diagnostic tool, netstat -ano. This tool will list the PID (Process Identifier) that is listening to port 80. Open the Task Manager’s Processes tab. Select “View” and “Select Columns” menu. Activate the PID column to see the name of the process listening on port 80.
Is Port 8080 http or https?
Port 8080 is a non-standard, high number port that is popular as an alternative port for HTTP servers, most often application servers. Port 8443 is a default alternative port for HTTPS servers. It can also be used as an alternative port for any protocol like ssh, FTP, NTP, BOOTP, etc.
Why is port 8080 default?
Historically, only authorized system administrators were able to establish and operate a web server on port 80, since this was within the first 1023-port privileged region. When non-administrators wished to run their own web servers, they often chose port 8080 to host a secondary or alternate web server.