Finding the Windows Process That's Using a Particular TCP or UDP Port

Identifying Active Processes on Network Ports

When managing network connections and system security, it is critical to understand which processes are listening on specific TCP or UDP ports. This knowledge is useful in detecting network problems, blocking unwanted access, and improving network performance.

In Windows, numerous tools and commands can be used to identify these processes. Understanding and efficiently using these tools can help you maintain a safe and functional network environment. This article will walk you through the procedures needed to determine which process is listening on a specific port.

Understanding the Method of Identifying Listening Ports

The offered scripts are intended to determine which process is listening on a specific TCP or UDP port on a Windows system. The first script uses the Windows Command Prompt. The netstat -ano command displays a list of all active TCP connections, including their process IDs. The findstr command is used to filter the output and isolate the desired port number. After identifying the correct PID, use the tasklist /FI "PID eq PID_NUMBER" command to display detailed information about the process, such as its name and other attributes. This technology gives a simple way to link network activity to individual processes, making it important for troubleshooting and security audit.

The second script makes use of PowerShell, which allows for more advanced and versatile programming. The Get-NetTCPConnection cmdlet retrieves information about TCP connections, including the owning process for a specific port. Similarly, the Get-NetUDPEndpoint cmdlet is utilized for UDP ports. The received process ID is then supplied to the Get-Process cmdlet to get full process details. This PowerShell approach is extremely efficient and smoothly integrates with other Windows administration tools, making it an effective alternative for network managers. The third script uses Python's psutil package, which is cross-platform and extremely versatile. The psutil.net_connections method produces a list of all socket connections on the system, which the script iterates through to locate the provided port. Once detected, it utilizes the psutil.Process method to build a process object for the identified PID, and then obtains and shows the process name and ID. This Python script is very beneficial for people who want to script in a cross-platform environment or need to automate processes that span multiple operating systems.

REM Open Command Prompt as Administrator
netstat -ano | findstr :PORT
REM Replace PORT with the port number you want to check
REM This will display the list of processes using the specified port
REM Note the PID (Process ID) from the results
tasklist /FI "PID eq PID_NUMBER"
REM Replace PID_NUMBER with the noted Process ID
REM This will display the details of the process using the specified port
REM Example: tasklist /FI "PID eq 1234"

Get-Process -Id (Get-NetTCPConnection -LocalPort PORT).OwningProcess
REM Replace PORT with the port number you want to check
REM This command retrieves the process information
Get-Process -Id (Get-NetUDPEndpoint -LocalPort PORT).OwningProcess
REM For UDP ports, replace PORT with the port number
REM This command retrieves the process information for UDP connections
# Example for TCP port 80:
Get-Process -Id (Get-NetTCPConnection -LocalPort 80).OwningProcess
# Example for UDP port 53:
Get-Process -Id (Get-NetUDPEndpoint -LocalPort 53).OwningProcess

import psutil
import socket
def check_port(port):
    for conn in psutil.net_connections(kind='inet'):
        if conn.laddr.port == port:
            process = psutil.Process(conn.pid)
            return process.name(), process.pid
    return None
port = 80  # Replace with your port number
result = check_port(port)
if result:
    print(f"Process {result[0]} with PID {result[1]} is using port {port}")
else:
    print(f"No process is using port {port}")

Advanced techniques for monitoring network ports on Windows.

Another key part of determining which process is listening on a certain TCP or UDP port in Windows is to use advanced monitoring and logging tools. Tools such as Wireshark, a network protocol analyzer, provide detailed information on network traffic. Wireshark collects packets in real time, allowing you to filter and analyze data to determine which processes use specific ports. This is very important for troubleshooting network issues and ensuring that unauthorized apps do not access sensitive ports. Furthermore, Windows' built-in Resource Monitor offers a graphical interface for viewing network activities of processes, including the ports they use. This tool is accessible via the Task Manager's Performance tab.

Incorporating these advanced technologies into your network management procedures can dramatically improve your system's monitoring and security capabilities. For example, utilizing Wireshark in conjunction with PowerShell scripts allows you to cross-reference real-time network data with process information, resulting in a more comprehensive view of network activities. Setting up automated alarms and logging with tools such as the Windows Event Viewer can also help you track changes in port usage over time, alerting you to potential security concerns or system misconfigurations. These procedures are critical for maintaining a safe and efficient network environment, especially in enterprise settings where network traffic is complicated and broad.

Advanced techniques for monitoring network ports on Windows.

Another key part of determining which process is listening on a certain TCP or UDP port in Windows is to use advanced monitoring and logging tools. Tools such as Wireshark, a network protocol analyzer, provide detailed information on network traffic. Wireshark collects packets in real time, allowing you to filter and analyze data to determine which processes use specific ports. This is very important for troubleshooting network issues and ensuring that unauthorized apps do not access sensitive ports. Furthermore, Windows' built-in Resource Monitor offers a graphical interface for viewing network activities of processes, including the ports they use. This tool is accessible via the Task Manager's Performance tab.

Incorporating these advanced technologies into your network management procedures can dramatically improve your system's monitoring and security capabilities. For example, utilizing Wireshark in conjunction with PowerShell scripts allows you to cross-reference real-time network data with process information, resulting in a more comprehensive view of network activities. Setting up automated alarms and logging with tools such as the Windows Event Viewer can also help you track changes in port usage over time, alerting you to potential security concerns or system misconfigurations. These procedures are critical for maintaining a safe and efficient network environment, especially in enterprise settings where network traffic is complicated and broad.