Secure the system. Prove the controls. Pass the exam.Volume 1 built the mental model. Volume 2 built the muscle. The Security & Identity volume builds the wall. This is a hands-on treatment of the XK0–006 Security domain (18%) and the identity-management skills that thread through it: authentication, authorization, mandatory access control, remote-access hardening, network filtering, cryptography, auditing, and compliance.Every chapter follows the series pattern: conceptual explanation, worked examples, hands-on labs, and exam-shaped review questions. The labs assume a two-VM environment — a Red Hat-family system and a Debian-family system — so you practice SELinux and AppArmor on real hosts, not in theory.Security work is unforgiving of shortcuts. A misconfigured firewall, an unvalidated sshd_config, or a forgotten SELinux context can lock you out of the system you are supposed to be securing. This volume drills the validation steps as carefully as the configuration steps, because the exam grades whether you hardened a system without breaking it.
