Network Security

Firewalls, IDS/IPS, VPNs, network segmentation, and traffic analysis.

Overview

Network security protects data in transit and network infrastructure.

Key Concepts

• Firewalls — Traffic filtering and control
• IDS/IPS — Intrusion detection and prevention
• VPNs — Encrypted remote access
• Segmentation — Network isolation
• Traffic Analysis — Monitoring and detection

Firewall Types

Packet Filtering

• Examines packet headers
• Rules based on IP, port, protocol
• Fast but limited inspection

Stateful Inspection

• Tracks connection states
• Context-aware filtering
• More secure than packet filtering

Next-Generation (NGFW)

• Deep packet inspection
• Application awareness
• Threat intelligence integration

Network Segmentation

Internet
    │
┌───┴───┐
│  DMZ  │ ← Public-facing services
└───┬───┘
    │
┌───┴───┐
│  FW   │
└───┬───┘
    │
┌───┴───────┐
│ Internal  │ ← Workstations
│ Network   │
└───────────┘

VPN Technologies

IDS/IPS Signatures

# Snort rule example
alert tcp $EXTERNAL_NET any -> $HOME_NET 80 (
  msg:"SQL Injection Attempt";
  content:"SELECT"; nocase;
  content:"FROM"; nocase;
  classtype:web-application-attack;
  sid:1000001;
)

Practice

Configure firewall rules to protect a web server and analyze network traffic.