Wireshark

Wireshark (64-bit)
FreeNetwork packet inspection
Windows
Wireshark
Free32-bit packet analysis
Windows
Wireshark (64-bit) Development Release
FreePerform thorough analysis of your network protocol.
Windows
Wireshark Portable
FreeWireshark: The Industry Standard for Network Protocol Analysis
Windows
WireShark for Linux
FreePerform thorough analysis of your network protocol.
Linux
Wireshark
FreePerform network protocol deep inspection and live capture.
MacWireshark Network Protocol Analyzer
FreeWireshark: Powerful Network Analysis for Experts
Windows
Wireshark (32-bit) Development Release
FreeWireshark: The Premier Network Protocol Analyzer
WindowsWireShark for Linux beta
FreePerform thorough analysis of your network protocol.
Linux
Wireshark Portable Development Release
FreeWireshark: Powerful Network Protocol Analysis Tool
Windows
Wireshark U3 Development Release
FreeWireshark: The Ultimate Network Protocol Analyzer
Windows
Wireshark U3
FreeWireshark: Powerful Network Analysis Tool
Windows