linuxplus/STUDY.md

Lesson 120

• linuxplus-lesson-120.el
• linuxplus-quiz-120.el
• Topic: Firewall ACLs, packet inspection, persistent configuration, stateful firewall behavior, firewall-cmd --runtime-to-permanent, numbered UFW rules, simple UFW SSH blocking, DenyHosts, and Fail2Ban.
• Practice: sudo firewall-cmd --runtime-to-permanent, sudo ufw status numbered, and sudo ufw deny 22/tcp.