Portmon is a classic legacy utility from the Microsoft Sysinternals suite designed to monitor, log, and analyze all serial (COM) and parallel (LPT) port activity on a system. Engineers, embedded developers, and IT administrators rely on it to reverse-engineer hardware protocols, debug peripheral communication issues, and verify driver stability. System Requirements and Modern Workarounds Before deploying Portmon, you must verify your operating system architecture. Native Compatibility : Portmon natively supports 32-bit (x86) legacy Windows versions including Windows 95, 98, NT, 2000, XP, and Server 2003. The 64-Bit Limitation : Portmon relies on a legacy NT4 driver model. It will not run natively on modern 64-bit (x64) versions of Windows 10 or Windows 11. Modern Workarounds : To use Portmon today, you must run it inside a 32-bit Windows XP/7 Virtual Machine (such as VirtualBox) with COM port passthrough enabled, or switch to modern alternative sniffers like the Electronic Team Serial Port Monitor or Device Monitoring Studio . Step-by-Step Guide: Configuring and Running Portmon Portmon - Sysinternals - Microsoft Learn
Using Portmon: A Comprehensive Guide Introduction Portmon is a popular, open-source network traffic capture and analysis tool. It allows users to capture, analyze, and visualize network traffic on a specific port or range of ports. In this guide, we will walk you through the steps to use Portmon effectively. Downloading and Installing Portmon
Visit the Portmon GitHub repository and download the latest release for your operating system. Follow the installation instructions for your platform:
Windows: Run the installer and follow the prompts. macOS (with Homebrew): Run brew install portmon . Linux: Run sudo apt-get install portmon (Ubuntu-based distributions) or equivalent. how to use portmon
Launching Portmon
Launch Portmon from the command line or terminal:
Windows: Open a Command Prompt and navigate to the Portmon installation directory. Run portmon.exe . macOS/Linux: Run portmon in the terminal. Portmon is a classic legacy utility from the
Alternatively, you can launch Portmon from its graphical user interface (GUI).
Configuring Portmon
Select the interface: Choose the network interface you want to capture traffic from (e.g., Ethernet, Wi-Fi). Set the port range: Specify the port or range of ports you want to capture traffic on. You can use the following options: Modern Workarounds : To use Portmon today, you
Single port: Enter a single port number (e.g., 80 for HTTP). Port range: Enter a range of ports (e.g., 1-1024 for common services). Multiple ports: Enter a comma-separated list of ports (e.g., 80,443,8080 ).
Choose the capture mode: Select one of the following modes: