Update introduction in apparmor.md

Rewrite introduction to reflect the newly updated guide on AppArmor and
profile development. Briefly mention that DAC and capabilities are not
considered in the guide but considered prerequisites.

Signed-off-by: Andreas Elvstam Cantner <andreas.elvstam@se.bosch.com>

Apply 2 suggestion(s) to 1 file(s)

content/guides/apparmor.md

@@ -14,13 +14,20 @@ aliases = [
 date = "2016-12-12"
 +++
 
-AppArmor is a security layer which enforces access control on the filesystem
-resources applications can access, and the permissions they can access them
-with. It comprises a kernel module and user space profiles for each
-application, which define the resources an application expects to access. For
-more information, see the
-[AppArmor home page](http://wiki.apparmor.net/index.php/Main_Page). Apertis
-uses AppArmor for all applications and services.
+[AppArmor](https://apparmor.net/) is a [Linux Security Module (LSM)](https://en.wikipedia.org/wiki/Linux_Security_Modules)
+implementation, which enforces [Mandatory Access Control (MAC)](https://en.wikipedia.org/wiki/Mandatory_access_control)
+on a system. AppArmor comprises of both a kernel module and user space profiles for each application.
+Apertis uses AppArmor to enforce security polices for applications and services to allow access to resources based on their profiles.
+Depending on the mode the application or service is running, AppArmor can generate audit logs or deny access to system resources in order to track or prevent undesired accesses.
+This guide will introduce AppArmor and explain how such profiles can be developed
+in order to allow an application to run on a system where AppArmor is activated.
+
+Since this guide is focusing on AppArmor and its implementation,
+this guide will not cover details of prerequisites such as the
+[Discretionary Access Control (DAC)](https://en.wikipedia.org/wiki/Discretionary_access_control)
+or [capabilities](https://man7.org/linux/man-pages/man7/capabilities.7.html) that must
+first be considered, in order to grant the user and application permissions or
+access to resources on the system.
 
 # Summary