To solve the problem I used Perl (feel free to use your favorite language) to open a pcap file and do some analysis. Let us look at finding sessions where the client sent data but the server didn’t send any data in response. To make it easy I’ve included all the steps I took and, where appropriate, the code. Since the point is to illustrate how to use script language like Perl to do the job, the code is greatly simplified. For the convenience of reader, the complete code is listed at the end.