Mitigating TCP SYN DDoS Attacks via Trusted Device Whitelisting
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Solution Overview
Problem
Existing threat protection systems in network appliances are unable to effectively combine traditional TCP SYN/ACK cookie methods with the direct server return mode, leading to bottlenecks and increased latency due to the requirement for constant two-way communications.
Innovation Solution
Implementing a system that recognizes trusted network devices by whitelisting them for a predetermined period, allowing direct server return mode by using a TCP reset command to establish and maintain secure connections without constant cookie verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional TCP SYN/ACK cookie methods are used to protect against DOS attacks, then security is improved, but the network appliance becomes a bottleneck and latency increases due to constant two-way communications
Solution Approach 1:
The system performs preliminary validation of the client device during the SYN-ACK phase by checking for the presence of a valid TCP SYN/ACK cookie. Once validated, the client is whitelisted for a predetermined period, allowing subsequent connections to bypass intensive cookie verification. This preliminary action eliminates the need for continuous two-way communications during the established connection phase, reducing latency while maintaining security.
Solution Approach 2:
The system dynamically adjusts the level of security verification based on the connection state. During the initial handshake phase, full TCP SYN/ACK cookie validation is performed. Once the connection is established and the client is whitelisted, the verification level is reduced, allowing direct server return mode to operate without constant appliance intervention. This dynamic adjustment resolves the contradiction between security and latency.
2Reliability
If traditional TCP SYN/ACK cookie methods are used, then security validation is maintained, but direct server return mode cannot be implemented due to requirement for constant two-way communications
Solution Approach 1:
The system performs preliminary security validation using TCP SYN/ACK cookies during the initial handshake phase. Once the client is validated and whitelisted, the security validation is cached, allowing direct server return mode to be implemented for subsequent communications. This preliminary action enables the system to maintain security validation while eliminating the need for constant two-way communications during data transfer.
Solution Approach 2:
The TCP SYN/ACK cookie acts as an intermediary mechanism that enables direct server return mode. By validating the cookie during the handshake phase, the system establishes trust that allows the server to return data directly to the client without constant appliance mediation. The cookie serves as a preliminary authentication token that bridges security requirements with direct communication capabilities.
3Reliability
If constant two-way communications are required for cookie verification, then security is maintained, but data traffic capacity is reduced due to network appliance bottleneck
Solution Approach 1:
The system performs preliminary security validation during the SYN-ACK handshake phase using TCP cookies. Once the client is validated and added to the whitelist, subsequent data traffic can flow directly between the server and client without constant appliance verification. This preliminary action eliminates the bottleneck effect, allowing full data traffic capacity to be utilized while maintaining security through the cached validation state.
Solution Approach 2:
The system implements periodic re-validation by setting a predetermined whitelist expiration period. During this period, validated clients can communicate with high data traffic capacity. The periodic nature of re-validation (rather than continuous verification) maintains security while allowing uninterrupted high-speed data transfer between validation cycles, thus resolving the bottleneck issue.
Data Source
AI summary
Provided are methods and systems for recognizing network devices as trusted. A system for recognizing network devices as trusted may include a network module, a storage device, and a processor. The network module may be configured to receive a request from a network device to establish a data connection between the network device and a server based on a determination that the network device is trusted. The storage device may be configured to store a whitelist associated with a plurality of trusted network devices. The processor may be configured to determine that the network device is trusted. Based on the determination, the processor may associate the network device with the whitelist for a predetermined period of time.