The core of the security problem is that most software contains latent bugs, and many of these bug can be exploited by attackers to cause the software to do something undesirable to the victim's computer. To block this threat, one can either use only perfect software (of which there is a shortage :) or use a security system to control what software may and may not do. The problem is that such systems are historically very difficult to use. AppArmor is an application security system that directly attacks the ease of use problem, making it possible for widespread adoption by developers, system administrators, and users. AppArmor provides for security profiles (policies) that specify the the files that a given program may read, write, and execute, and provides tools to quickly and automatically generate these profiles. This presentation will briefly introduce the AppArmor system, and then spend much of the time showing how to best use AppArmor to confine applications and protect systems. AppArmor is pure GPL software, and is available for SUSE, Slackware, Ubuntu, Gentoo, and Red Hat Linux.