Wireshark, the new name for Ethereal, is a protocol analyzer, or packet sniffer application, used for network troubleshooting, analysis, software and protocol development, and education. It has all of the standard features of a protocol analyzer. It allows the user to see all traffic being passed over the network (usually an Ethernet network but support is being added for others) by putting the network card into promiscuous mode.

Wireshark is software that understands the structure of different network protocols. Thus it's able to display encapsulation and single fields and interpret their meaning. Wireshark uses Pcap to capture packets, so it can only capture on networks supported by Pcap.

Wireshark (Ethereal) Features

• Data can be captured from the wire from a live network connection or read from a capture file.
• Captured network data can be browsed via a GUI, or via the TTY-mode tshark program.
• Standard three-pane packet browser
• Capture files compressed with gzip can be decompressed on the fly
• Coloring rules can be applied to the packet list, which eases analysis

Updates : Wireshark Updates