Network Security

The digital city's road system — how data travels.

• How Data Travels Across a NetworkPackets, hops, and the invisible roads of the internet.Free
• IP Addressing and SubnetsEvery device needs an address — here's how the addressing system works.
• ARP and Layer 2 FundamentalsHow devices find each other on the same local network.
• DNS: The Internet's Phone Book (and a Hacker's Playground)How name resolution works — and why attackers love abusing it.

Gates, guards, and walls — where the internet meets your network.

• Firewalls and Next-Generation FirewallsThe first line of defense — and what modern firewalls actually do.Free
• IDS and IPS: Detection vs. PreventionWatching the road vs. stopping the car.
• DMZ Architecture and Network ZonesDesigning the battlefield — zones, trust levels, and traffic flows.

Reading the road — what packets reveal about attacker behavior.

• Packet Capture and Wireshark FundamentalsThe network analyst's microscope.Free
• NetFlow Analysis and Traffic BaselinesReading the map, not the territory — metadata at scale.
• Detecting Anomalies in Network TrafficWhat's normal? What's not? How do analysts tell the difference?

From alert to action — containing network-based attacks.

• Isolation and Containment TechniquesStop the bleeding before you stitch the wound.Free
• Incident Response Playbooks and RunbooksScripted chaos — having a plan before the alarm goes off.
• Post-Incident Review and Threat HuntingWhat the attacker left behind — and how to find the next one before they act.