How to list open ports and application using them in windows?

Question

I have trouble identifying the application using port 25 on my Windows-10 system. Any useful hints to list used ports and using applications without 3rd party applications ?

Answer 1

Without the use of any external software. Open a command prompt:

1. netstat -abn

OR

2. netstat -a -n -p tcp -o

Within Task Manager -> Processes/Details Tab

You can match the PID against the result of the second netstat command above, you can then find the image name/end the process etc if required.

There's also plenty of third party applications that can simplify the process and make the information easier to read, simple Google search if you want to find them.

Answer 2

A GUI solution would be to use the Ressource Monitor of Windows. You can start it by pressing START and entering this command: Perfmon /Res

Then you can click on the Network tab to view all network connections, listening ports, etc.

Here is a screenshot how it looks like:

Answer 3

Open a command shell and run

netstat -a -n -p tcp -o

No need to run as administrator.

The last column is the PID. You can look up this PID in the task manager. Be sure to activate "show processes of all users" there.

See the documentation for netstat.

Answer 4

netstat -n from the command line will show you a list of IP addresses and open ports on your computer. A web search would probably be best in determining what is running on a particular port, but here's a few resources you could check open ports against:

• https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers
• http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xml

EDIT: user544199's netstat arguments looks to put out some more useful information than mine. I would use that.