(In terms of hacker attack and defense, it has always been "one foot high, the devil is one foot high". There is no book that can analyze all the attack methods of hackers. This book only describes the most common hacker attack methods. Therefore, this book is an introductory book for hacker attack and defense and network security, suitable for primary computer users to read and reference. The content of many chapters in this book is directly practiced by the user with a personal computer connected to the Internet, so as to achieve the consistency of theoretical learning and practical operation. In addition, this book also involves some basic knowledge of network, suitable for readers who are interested in network knowledge.)