Security

In the context of CompTIA Linux+, security is a critical domain involving the implementation of defense-in-depth strategies to protect system integrity and data. It begins with **User and Group Management**, where administrators enforce the principle of least privilege using standard file permissions (`chmod`, `chown`), Access Control Lists (ACLs), and special permission bits (SUID, SGID, Sticky Bit). Additionally, Pluggable Authentication Modules (PAM) are configured to enforce strong password policies and manage authentication boundaries. A major focus is placed on **Mandatory Access Control (MAC)** systems, specifically **SELinux** and **AppArmor**. These tools confine applications and processes to specific resources, preventing compromised services from affecting the wider system. Network security is maintained through host-based firewalls, requiring proficiency in `firewalld`, `ufw`, and legacy `iptables` to filter traffic and manage zones. **SSH Hardening** is vital for secure remote administration. This involves modifying `/etc/ssh/sshd_config` to disable root login, change default ports, and enforce key-based authentication (PKI) while disabling password-based access. Data security also covers storage encryption using **LUKS** and file encryption via GPG. Finally, the curriculum emphasizes auditing and logging; administrators must utilize `systemd-journald`, `rsyslog`, and the Linux Audit Daemon (`auditd`) to monitor logs, track security events, and detect unauthorized access attempts, ensuring compliance with security standards. In the context of CompTIA Linux+, security is a critical domain involving the implementation of defense-in-depth strategies to protect system integrity and data. It begins with **User and Group Management**, where administrators enforce the principle of least privilege using standard file permissio…