Microsoft Network Monitor is a free, advanced tool for network administrators to capture and analyze network traffic. To make working with a lot of data easier, the program contains dozens of built-in filters (as well as the ability to define your own) thanks to which you can narrow down the data for analysis. The most important novelties in version 3.0 include promiscuous mode, independence of the application from SMS, listening to several interfaces at the same time, IntelliSense for data filtering and NetMon Parser Language (NPL) for easy creation of new protocol decoders.

Since version 3.1, the program allows, among other things, to eavesdrop traffic in wireless networks, analyze traffic inside VPN tunnels under Vista and create new filters in a simpler way than before.