In the first section of the course, you will learn some important security concepts. We won't get behind the command line of a Linux system in this first section, but it's important that we lay down the foundation of understanding before we start securing and hardening our systems. Next, we move on to physical security. In this section of the course, you'll learn how attackers break into Linux systems when they have physical access and several countermeasures you can use to protect your Linux systems. From there, we'll go into detail on the authentication systems used in Linux. You'll learn about the various account types on a Linux system and how to secure each one. You'll also learn how to enforce strong passwords and manage account and password expirations. In the networking section of the course, you'll learn how to secure network services that run on Linux systems. You'll also learn how the local firewall works in Linux and how to configure it. Next, we'll talk about Linux file system security. We'll cover how permissions work in detail, including special modes, file attributes, and ACL's. You'll also learn what rootkits are, how to detect them, and how to remove them. Finally, I'll leave you with several security resources you can use to continue your security education and stay on top of the latest security issues for your Linux distribution.