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Overview of Network Security Elements

Apr 21, 2025

Cybersecurity Architecture Series: Network Security

Introduction

  • Previous topics: Identity Management and Endpoint Security
  • Current focus: Network Security
  • Elements of Network Security:
    • Firewalls
    • Segmentation
    • Virtual Private Networks (VPNs)
    • Secure Access Service Edge (SASE)

Firewalls

  • Concept Origin: Analogous to physical firewalls preventing the spread of fire.
  • Function: Create isolation and protection from dangerous events in networks.
  • Basic Architecture:
    • Internet-facing firewall
    • Internal-facing firewall
    • Packet Filtering: Filters based on source address, destination address, and port.
    • Allows standard (port 80) and encrypted (SSL/TLS) web traffic.
    • Prevents spoofing and direct access to sensitive areas like databases.

Stateful Packet Inspection

  • Inspects not just packets but their context and payload.
  • Allows for more sophisticated security than simple packet filtering.

Proxies

  • Acts as a middleman for inspecting traffic.
  • Can be used for security and privacy.

Network Address Translation (NAT)

  • Translates internal IP addresses to a routable address.
  • Provides a layer of protection by preventing direct outside access to internal devices.

Segmentation

  • Bastion Host: Not recommended; exposes a web server directly to the Internet.
  • Tri-homed Network: Uses a single firewall with three interfaces for different zones.
  • Basic DMZ: Two firewalls creating a red (untrusted), yellow (semi-trusted), and green (trusted) zone.
    • Advantage: Defense in depth.
  • Multi-tiered DMZ: Adds more firewalls for granular security and further defense in depth.

Virtual Private Networks (VPNs)

  • Purpose: Secure channel over an untrusted network.
  • Encryption: Provides confidentiality by encrypting data.
  • Types of VPNs:
    • Application Layer: Secure Shell (SSH)
    • Transport Layer: TLS/SSL
    • Network Layer: IPsec
    • Data Link Layer: Point-to-Point Tunneling Protocol (P2PTP) and Layer 2 Tunneling Protocol (L2TP)
  • Trends: Movement towards application-specific VPNs for more control and granularity.

Secure Access Service Edge (SASE)

  • Definition: Network security plus WAN, delivered from the cloud.
  • Components:
    • Network security: Firewalls, secure web gateways, DLP
    • WAN: Software-defined WAN
    • Cloud: Scalability and agility
  • Integration: Combines security and networking into a single cloud-delivered service.

Conclusion

  • Covered: Network Security elements - Firewalls, Segmentation, VPNs, SASE
  • Topics not covered: 5G, Wi-Fi, and their network security aspects.
  • Upcoming topics: Application Security

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