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Tcptrace is a tool to analyze TCP (and now, also UDP) sessions captured with TcpDump. It provides a lot of different kinds of statistics and information, a lot of which is useful in diagnosing problems with TCP sessions. It also supports various graphing options.
While the standalone version of tcptrace is rarely used these days, the basic approach and much of its functionality lives on as part of toolsets such as WireShark.
Example usage
This shows the sessions in a tcpdump log:
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