Identifying Which Ports Are in Use on a Windows PC

[Product_Support]

Issue

A PC is experiencing communication problems or application startup failures because one or more TCP or UDP ports are already in use.
Users need a reliable method to determine which application or service is occupying specific ports.

Product Line

All product Lines.

Environment

Any Windows operating system

Cause

Multiple applications running on the same PC may require the same network ports.
If port assignments are not managed, this can lead to TCP/UDP conflicts that affect building management software, web servers, databases, or other services.

Resolution

Use Microsoft TCPView to identify all active TCP and UDP ports, including the associated processes and services.

Steps

1. Download TCPView from the official Microsoft Sysinternals site:
   https://technet.microsoft.com/en-us/sysinternals/bb897437.aspx
2. Extract and run TCPView.exe.
3. The interface displays:
   • Active TCP and UDP endpoints
   • Process names and paths
   • Local and remote addresses
   • Connection states

     

4. Sort or filter to identify which application is using a specific port.
5. Close or reconfigure the conflicting application as required.

TCPView documentation on the Microsoft site includes detailed usage instructions.