How Can I Tell What is Listening on a TCP/IP Port in Windows?
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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 what application has the port locked, but
we’ll walk through the built-in way using the command line and Task
Manager, and then a great freeware application that does it all in one
utility.
Use 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 -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 4708.
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.
Use CurrPorts to View What is Listening :
If
you aren’t really the command-line type, or you’d rather just use a
simple utility to do it all in one step, you can use the excellent
freeware CurrPorts utility by NirSoft, one of our favorite freeware
authors.
Just open up the utility, and you can see everything—processes, ports, remote ports, the full path to the process.
If you double-click on any of the items, you’ll see every single detail.
You can also use CurrPorts to directly kill the process if you want.pen
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.
Use CurrPorts to View What is Listening :
If
you aren’t really the command-line type, or you’d rather just use a
simple utility to do it all in one step, you can use the excellent
freeware CurrPorts utility by NirSoft, one of our favorite freeware
authors.
Just open up the utility, and you can see everything—processes, ports, remote ports, the full path to the process.
If you double-click on any of the items, you’ll see every single detail.
You can also use CurrPorts to directly kill the process if you want.
