Wireshark

About

Wireshark is a free and open-source packet analyzer. It is used for network troubleshooting, analysis, software and communications protocol development, and education. It allows users to see what's happening on their network at a microscopic level.

This tool is designed for network professionals, administrators, security analysts, and developers who need to inspect data traveling over a network. It supports hundreds of protocols and offers live capture and offline analysis capabilities, along with a rich set of features for filtering and deep inspection.