Ethereal – Monitor Packets in Realtime

This one requires a good understanding of networking in order to use; Ethereal is a free and powerful network analyzer that has the ability to monitor packets in realtime. It can show you the packet source, the destination, the protocol its running on and a brief description of what it is. It can then break it down further and show you the packet in HEX. This can be useful for computer technicians who are trying to troubleshoot networks or find suspicious activity on a computer like hacking, viruses, trojans or spyware phoning home. Ethereal can run on Unix, Linux and Windows based computers.

Screenshot:

(heavily censored)

Downloads:

Download from Official Site – 12.4mb