How do I find out which process is listening on a TCP or UDP port on Windows?

To identify which process is using a specific TCP or UDP port on Windows, follow these steps using built-in tools:

Method 1: Command Prompt/PowerShell (Built-in Tools)

1. List all ports and their associated PIDs:

   netstat -ano

• -a: Displays all connections and listening ports.
• -n: Shows addresses and ports numerically.
• -o: Includes the Process ID (PID).

1. Filter for your specific port (e.g., port 80):

   netstat -ano | findstr ":80"

• Replace 80 with your port number.
• Look for the PID in the last column.

1. Find the process name from the PID:

   tasklist /FI "PID eq 1234"

• Replace 1234 with the PID from the previous step. In PowerShell:

   Get-Process -Id 1234

Method 2: Resource Monitor (GUI)

1. Press Win + R, type resmon, and hit Enter.
2. Go to the Network tab.
3. Under Listening Ports, sort by Port to find your port and its associated process.

Method 3: Sysinternals TCPView (Third-Party Tool)

1. Download TCPView from Microsoft.
2. Run Tcpview.exe (no installation required).
3. Locate your port in the list, which shows:

• Process name
• Protocol (TCP/UDP)
• Local/remote addresses
• Status

Example Workflow

Check port 8080:

1. Find the PID:

   netstat -ano | findstr ":8080"

Output:

   TCP    0.0.0.0:8080           0.0.0.0:0              LISTENING       1234

2. Identify the process:

   tasklist /FI "PID eq 1234"

Output:

   Image Name                     PID Session Name        Session#    Mem Usage
   ========================= ======== ================ =========== ============
   node.exe                      1234 Console                    1     250,000 K

Key Notes

• Run as Administrator: Ensure Command Prompt/PowerShell has elevated privileges to see all processes.
• UDP Ports: Use the same steps for UDP ports (look for UDP in the Proto column).
• Persistent Port Issues: Use TCPView to monitor ports in real-time.