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How can I list all open TCP ports and their associated applications?



I get a "port already in use" error message. How can I see which application is already using the respective port?

error general networking port software tcp udp

Created on Feb 10, 2010 10:24:20 AM by  Daniel Zobel [Product Manager]

Last change on Feb 10, 2010 12:24:31 PM by  Daniel Zobel [Product Manager]

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FPort: Lists open TCP ports and their associated applications

Many have had this problem: One installs a new internet application on a server but when it is started you get a message like "port already in use". Now it's time for a port mapper, an application that lists open TCP ports and their associated applications

FPort reports all open TCP/IP and UDP ports and maps them to the owning application. This is the same information you would see using the 'netstat -an' command, but it also maps those ports to running processes with the PID, process name and path. FPort can be used to quickly identify unknown open ports and their associated applications.

FPort officially supports Windows NT4, Windows 2000 and Windows XP.

Download it here (Freeware):

As an alternative, execute the following command in the command line tool: netstat -an -b

Created on Feb 10, 2010 10:27:43 AM by  Daniel Zobel [Product Manager]

Last change on May 21, 2014 3:02:57 PM by  Gerald Schoch [Paessler Support]

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.