FrameSeer is a Cocoa application, written for Mac OS X, which lets you capture and decode data-communications traffic as it passes across your network.

FrameSeer uses the services of a standard Unix utility called tcpdump, which is installed by the Mac OS X installer as part of the BSD subsystem. FrameSeer provides a graphical user interface to the facilities offered by tcpdump.

FrameSeer can decode traffic captured from the following types of network media:

• Ethernet
• AirPort
• PPP-over-Ethernet (eg aDSL)
• PPP (eg modem)
• The local, or loopback interface

FrameSeer is a multi-document application. Multiple captures can occur simultaneously, on the same or different network interfaces.

FrameSeer reads and writes files in tcpdump-native format. Among other things, this means that tcpdump can be launched manually on a remote system (eg via ssh) and the resulting file can be retrieved and analysed using FrameSeer.

At this stage, the major focus is upon decoding IPv4 packets. Future versions may expand to include IPv6.