tcpflow is a program that captures data transmitted as part of TCP
connections (flows), and stores the data in a way that is convenient
for protocol analysis and debugging. Each TCP flow is stored in its
own file. Thus, the typical TCP flow will be stored in two files,
one for each direction. tcpflow can also process stored 'tcpdump'
packet flows.

tcpflow is similar to 'tcpdump', in that both process packets from the
wire or from a stored file. But it's different in that it reconstructs
the actual data streams and stores each flow in a separate file for
later analysis.

tcpflow understands sequence numbers and will correctly reconstruct
data streams regardless of retransmissions or out-of-order delivery.