Lesson 4: School Firewall & Deep Packet Inspection
A firewall acts like a digital security guard (or bouncer) standing at the school entrance doors. Modern cyber defense doesn't just look at the port number on the outside — it conducts Deep Packet Inspection (DPI) by examining the payload inside!
⏱️ Lesson Time Guide:
• ~20 Mins: Packet Inspector Simulator
• ~20 Mins: Companion Digital Worksheet
• ~20 Mins: Packet Inspector Simulator
• ~20 Mins: Companion Digital Worksheet
Incoming Packets at Firewall Barrier
5 Pending
PASSED
🔬 DEEP PACKET INSPECTOR [X-RAY SCAN]
SCANNING...
Source Host IP Address:
192.168.2.14
Destination Service Door:
Port 80 (HTTP)
Intended Service:
Web Browsing (Online Learning)
Deep Payload Inspection (Raw Content Inside Packet):
GET /bbc_bitesize/ks3_cells_and_microscopes.html
📋 Table 1: School Firewall Policy Guide
Use these established school network rules to evaluate incoming traffic:
| Door / Port | Policy | Purpose / Threat |
|---|---|---|
| 🌐 Web (80) | ALLOW* | Online research & Bitesize (*Check payload for hidden trojans!) |
| ✉️ Email (25) | ALLOW | Teacher & pupil messaging and homework submissions |
| 🗄️ Database (3306) | BLOCK | Confidential grade records. Strangers must never connect! |
| 👾 Trojan (666) | BLOCK | Malicious remote backdoor probe |
| 🤖 Botnet (1337) | BLOCK | Unauthorized hacker command & control communication |
💡 Security Analyst Insight (DPI):
A simple firewall only checks the Port number on the outside. But smart hackers try to smuggle viruses inside Port 80 (Web) because they know schools leave it open! Always inspect the Payload inside!
A simple firewall only checks the Port number on the outside. But smart hackers try to smuggle viruses inside Port 80 (Web) because they know schools leave it open! Always inspect the Payload inside!
DEFENSE SHIFTS PROGRESSION
• Shift 1: Baseline Port Filtering (5 Packets)
• Shift 2: Stealth Trojans & Database Defense (6 Packets)
• Shift 3: Cyber Emergency (The Port 80 Dilemma) (7 Packets)