This book provides a comprehensive overview of the security challenges and solutions in the field of the industrial internet. Specifically, starting from the reference security framework of the industrial internet and regarding it as a complex giant system, this book deeply analyzes security issues from the perspectives of opponent observation, object protection, and defense organization.Specifically, the book provides a practical learning roadmap, following the step-by-step principle and offering readers guidance on carrying out security risk assessments and creating security defenses for Industrial Internet systems from the perspective of actual practice, presenting a range of real-world cases. After completing this book, readers will have a more comprehensive, in-depth, and accurate understanding of Industrial Internet security, including industrial control system security and cyber security.This book can not only serve as a tutorial for undergraduates and graduate students of cyberspace security, automation, computer science, and related majors but also as a valuable reference guide for practitioners in the security field.Furthermore, it offers systematic and technical assistance for researchers and developers in related areas.