Linux Security Modules (LSMs) are kernel modules that implement mandatory access control to enhance Linux system security by providing fine-grained access control over various resources. AppArmor, one of the most popular LSMs, offers mandatory access control by enforcing security policies through profiles, which are sets of rules that restrict what applications or processes can do. These profiles can be generated using tools like aa-genprof and can operate in either enforce or complain mode, with the former applying restrictions and the latter logging violations without enforcement. Despite its utility, AppArmor has limitations, such as the potential security risks associated with its powerful SYS_ADMIN capability and the complexity of its domain-specific language for writing profiles. The article also illustrates practical applications of AppArmor by demonstrating how to create profiles to restrict file and network access, highlighting both the flexibility and constraints of using AppArmor for system security.