Free network protocols software for windows

Network Monitor is a protocol analyzer. It allows you to capture network traffic, view and analyze it. This version is a complete overhaul of the previous Network Monitor 2.x version.
Instructions
Network Monitor can co-exist with older versions of Network Monitor. NM3 installs in %program files%Microsoft Network Monitor 3.0, so there is no conflict.
For Microsoft Vista, Microsoft has a new driver that supports new features available in the NDIS 6.0 driver. If you are using tools that rely on Network Monitor 2.x NPPTools, these tools will no longer work.
Capturing on Vista requires NM3, as Netmon2.x does not capture properly on Vista. If during installation, you opt to use Microsoft Update to receive critical updates, then the installer will configure your system to receive these updates. If this configuration fails (because, for example, your Automatic Update settings are managed by a network administrator), the installation will continue without informing you. To ensure you have successfully signed up for Microsoft update, go here. If the configuration was successful, the site will provide information about available updates. If not, the site allows you to sign up for Microsoft Update directly.
Warning: Capturing with the NM3 GUI with conversations enabled can use up considerable amount of memory. This may cause a machine to become unresponsive. If you need to capture data for long periods of time, please use the included command line utility, NMCap, and the /DisableConversations switch.
System requirements:
- It is suggested that you have a CPU of 1GHz or greater, 1G or greater of Memory and 25 Megs of available Hard Disk space, plus room for capture files.