Auto Configuration Server IP Spoofing Prevention

The patent introduces the X-Forwarded-For header as an intermediary mechanism that carries the original client IP address through reverse proxies and load balancers. Instead of directly comparing the client's IP address with the public IP address in the Inform message, the system uses the X-Forwarded-For header as a mediator to transport the original IP address information, allowing the comparison to work correctly even when proxies are involved in the communication path.

The patent moves the IP address information from a single dimension (direct client IP comparison) to another dimension by embedding it in the X-Forwarded-For HTTP header. This allows the original client IP address to be preserved and transmitted through multiple network layers (HTTP protocol layer) rather than relying solely on the network layer IP address, enabling the system to handle complex network topologies with proxies and load balancers.

The patent applies preliminary action by establishing the expected relationship between the X-Forwarded-For header and the public IP address before processing the Inform message. The system predetermines what the X-Forwarded-For header should contain based on the known public IP address from the CWMP data model, and then validates the actual header against this expectation. This preliminary validation prevents spoofed headers from being accepted.

The patent implements feedback by creating a closed-loop verification process where the X-Forwarded-For header is cross-checked against the public IP address extracted from the CWMP data model parameters. The system uses the public IP address as feedback to validate whether the X-Forwarded-For header contains the correct original client IP address, and rejects the message if they do not match, thereby detecting and preventing header spoofing attacks.