(Mr. Fei is now the technical director of sniffer China Technical Service Center. He is the only sniffer master (SCM) in China. He has rich experience and classic cases and speaks well. I am a student of teacher Fei, but I can't disclose my unit, because I don't think teacher Fei will allow me to make his lectures public. The following content is written by me according to the class recording. It is basically the original words of teacher Fei. It took me a week to sort it out. Teacher Fei had a lot of books in class. It was very difficult to sort them out. Some people would ask why he didn't share the recordings. The main reason was that there were many experiments in the course. Only recordings did not do much. It would be more convenient for me to sort them into words. When I finished sorting them out, it is estimated that I can publish the books. Who should I pay the copyright fee? Haha, this article has 14976 words, which is easy to understand. It is suitable for beginners to learn. It can save a lot of time to explore.)