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Intermediate 16 min readModule: Module 2: Network Security & TCP/IP Protocols

Network Defense: TCP Handshake, DNS & Firewalls

Understand network packet flow, TCP 3-way handshake (SYN, SYN-ACK, ACK), and packet filtering firewalls.

What You Will Learn in This Lesson

  • The TCP 3-Way Handshake mechanism and SYN Flood DDoS attacks
  • DNS resolution, DNS Spoofing, and DNSSEC protection
  • Stateful packet inspection firewalls and network segmentation

Introduction & Core Concept

Network security involves policies, processes, and practices adopted to prevent, detect and monitor unauthorized access, misuse, modification, or denial of a computer network.
WHY DOES THIS MATTER IN THE REAL WORLD?

Understanding TCP packet headers allows security engineers to detect port scanning, spoofing, and DDoS attacks.

TCP 3-Way Handshake Flow

text
text
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Client ------------ [SYN: Synchronize Sequence] -----------> Server
Client <----------- [SYN-ACK: Acknowledge & Sync] ---------- Server
Client ------------ [ACK: Connection Established] ---------> Server

Line-by-Line Technical Breakdown

1SYN cookies defend servers against SYN flood denial-of-service attacks.

Try It Yourself (Interactive Editor)

Modify the code in real-time and click Run to test live browser output and console logs.

Intelligent Code Runner & Live Sandbox[TEXT]
TEXT SOURCE EDITOR
Interactive Live Code

Industry Best Practices & Professional Standards

  • Close all unused server ports and segment networks with strict firewall rules.

Lesson Summary & Core Takeaways

  • Network protocols require defensive configuration to repel automated scans and flood attacks.