Wireshark is a packet-sniffing application that is used by IT professionals for a diverse set of requirements (including forensics, troubleshooting, and enhancing network performance). You can download it for free from https://www.wireshark.org/download.html, where it is available for the majority of platforms, including Linux, Macintosh, and Windows.
Packet sniffing is also referred to as tapping into the wire, which basically involves reading pieces of information traveling in a communication channel. Considerations such as placement of sniffer, protocols to be analyzed, and communication channel type need to be assessed before capturing network packets.
Wireshark collects network traffic from the wire through the computer's network interface, running in promiscuous mode (if needed), to inspect and display information related to protocols, IP addresses, ports, headers, and packet length. The following diagram is an illustration of how all the elements...