Portmon ^hot^

Under the Options menu, select Show Hex to see raw data packets, which is essential for reverse-engineering.

You can capture port activity from other computers over a network using the Sysinternals Portmon remote connection feature. portmon

: Allows users to narrow down specific data packets or port events. Under the Options menu, select Show Hex to

In the pantheon of legendary software utilities, few command the quiet respect of Portmon. Developed by Mark Russinovich and Bryce Cogswell as part of the Sysinternals suite, Portmon was a tool with a deceptively simple purpose: to capture and display all data passing through a system’s serial and parallel ports. In an era before USB dominated the peripheral landscape, Portmon was not just a utility; it was an essential stethoscope for diagnosing the pulse of communication between a computer and the outside world. In the pantheon of legendary software utilities, few

The classic Sysinternals Portmon has not been updated in many years. Because it relies on a legacy kernel driver, it frequently encounters "Access Denied" or "Unable to start driver" errors on modern operating systems like Windows 10 or Windows 11. These OS versions have stricter security policies regarding kernel-mode driver signing, often preventing unsigned or legacy drivers like Portmon's from loading.

Portmon is used to observe how software interacts with hardware ports. It is essentially a "sniffer" for I/O requests. Common scenarios include:

Write a to simulate serial traffic for testing.