FrameSeer is an inexpensive network packet capture application for the Apple Macintosh. FrameSeer is a “universal binary” that runs on Mac OS X 10.4.5 (Tiger) or later.
Packet-capture applications go by a variety of names including, sniffing tools or sniffers (after the Network Associates "Sniffer" product), frame grabbers, packet monitors, and protocol analyzers.
Packet-capture tools are essential aids for diagnosing communications problems, investigating network security breaches, and for general network performance monitoring and troubleshooting tasks.
FrameSeer is a native Mac OS X ("Cocoa/Aqua") application and will help you to diagnose network faults with confidence.
FrameSeer can capture traffic on your Ethernet, AirPort, PPPoE (eg aDSL or cable-modem), PPP (eg dial-up modem) and loopback interfaces. FrameSeer can also open tcpdump files captured either on Mac OS X systems or on little-endian systems such as Linux.
My favorite network mapping/debugging tools!