Network Address Translation - Traversal

NAT-T is a technique used to help data packets move through network devices that use NAT. NAT is like a translator that changes the addresses in data packets as they move through a network. However, this can cause issues for certain types of data traffic, like IPsec VPNs, which rely on specific address information to work correctly.

NAT-T solves this problem by wrapping the data packets in another layer, using a common format that NAT devices can handle more easily. This allows the packets to pass through the NAT devices without losing important information, ensuring that secure communications like VPNs can function properly even when NAT is involved.

<aside> <img src="/icons/preview_purple.svg" alt="/icons/preview_purple.svg" width="40px" /> Helpful Video

https://www.youtube.com/watch?v=sbL8f2GSq3w

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NAT-T (NAT Traversal) Cheat Sheet for CISSP

• Purpose: Allows IPsec traffic to pass through NAT devices by encapsulating IPsec packets in UDP.
• Default Port: UDP port 4500 is used for encapsulated IPsec packets.
• Why Needed: NAT modifies IP headers, which can break IPsec's integrity checks. NAT-T helps maintain these checks by encapsulating the original packets.
• How It Works:
  • Encapsulation: IPsec packets are wrapped in a UDP header, making them appear as standard UDP traffic to NAT devices.
  • Negotiation: During the VPN setup, devices negotiate the use of NAT-T via the Internet Key Exchange (IKE) protocol.
• Use Cases: Essential for remote VPN clients connecting from behind NAT routers or firewalls.
• Benefits:
  • Ensures compatibility of IPsec VPNs with NAT environments.
  • Maintains end-to-end security by preserving IPsec's original encryption and integrity.
• CISSP Focus: Understand how NAT-T resolves incompatibilities between NAT and IPsec, ensuring secure VPN connections in complex network environments.