Day 151: Security Hardening — Locking Down Your Production System

Yesterday (Day 150), we deployed our production application. Today we harden it. Here’s the agenda:

• Security Control Layer — rate limiting, IP allowlisting, request validation

• Firewall Rules — UFW-based network-level access restrictions

• Intrusion Detection — Fail2ban watching live logs and banning attackers

• Security Monitoring Dashboard — real-time React UI showing threat events, ban logs, and system posture

By end of lesson, you’ll have a live dashboard that detects, blocks, and visualizes attacks happening in real time.

Week 21: Deploy → Week 22: Harden → Week 23: Tune → Week 24: Scale
          Day 150          Day 151         Day 152
       [Application]   [Security]      [Performance]
       [Deployment ]   [Hardening]     [Tuning     ]

Security hardening sits between deployment and performance tuning intentionally. You don’t tune what isn’t secured — attackers will exploit any performance shortcuts.