Like tcpdump, tcpflow gives you the ability to view the text contents of network packets in real time. Tcpdump, however, is more suited to capturing packets and protocol information. Tcpflow is more suited toward viewing the actual data flow between two hosts. While tcpdump displays output to the console by default, tcpflow writes output to a file by default, and you must use the -c option if you want to see the tcpflow output on the console.

This recipe describes how to use tcpflow in pfSense.