Security (SELinux & Firewall)

SELinux enforcement, booleans, file contexts, port labels, and firewalld zones/services/ports. Roughly 15% of the EX200 exam.

SELinux contexts, booleans & ports

Enforcing vs permissive, semanage fcontext for file contexts, setsebool for toggles, semanage port for ports, and restorecon/chcon for relabeling.

Manage firewalld zones at the navigation layer: query and change the default zone, list active zones, and toggle IPv4 masquerade for NAT.

Configure firewalld with firewall-cmd — zones, adding services/ports, --permanent vs runtime, and rich rules for source-based access.

Generate SSH key pairs, deploy public keys with ssh-copy-id, and configure sshd for key-only authentication.