In Part VI, you learn about concepts and products that keep you safe by restricting users and packets from doing what they want and going where they want. Chapter 17 describes how to make sure end users are allowed to use a network and introduces you to the process of authentication, authorization, and accounting (AAA). Chapter 18 focuses on securing a company's connection to the Internet and preventing both curious and malicious people in the public Internet from doing harm to the devices inside a corporate enterprise network.