Ports blocked under Windows

Sometimes when you want to install a service or launch a program (ie. apache or glassfish) on your Windows PC the port required by that program is already in use. Windows gives you no further information on the issue other than "in use".


2 answers

Netstat and Task Manager

Windows offers a small program which by default is already located in the classpath.
Launch the Windows Command Line by pressing Windowsbutton+R and typing "cmd".
Then type "netstat -ano" which will bring up a list of all active connections on your machine with the process ids being located in the right most column.
Once you find out which PID is blocking your port, launch the Windows Task Manager and switch to the Processes tab. If the PID is not already displayed you can select View->Select Columns.. and then place a checkmark next to PID.
Find the PID of your port-blocking process in the Task Manager and in the same row look up the process name.


find blocked ports with "Process Explorer"

Process Explorer is a nice tool originally developed by Symantec. It provides more in-depth information to running processes.
It shows used resources, open registry handles, open ports etc etc.
Finding out which port is blocked by which program is just a matter displaying the used port, and let PE tell you,
what program uses that port at the moment.