Access Point FTM Request Filtering for DoS Prevention
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Solution Overview
Problem
Current Fine Timing Measurement (FTM) frameworks in wireless networks are vulnerable to Denial of Service (DoS) attacks and inefficient resource allocation due to unfiltered ranging requests, leading to overloading of access points and disruption of legitimate network functions.
Innovation Solution
Implementing a selective ranging request processing system where access points within a cluster only initiate FTM sessions based on criteria such as client association, time since last FTM burst, and acceptance thresholds, thereby rejecting unauthorized or excessive requests and preventing DoS attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If access points process all ranging requests without filtering, then FTM positioning functionality is maintained, but the access points become overloaded and vulnerable to DoS attacks
Solution Approach 1:
The access point performs preliminary actions by maintaining a state machine that tracks the status of each client device (e.g., associated, disassociated, suspended) before processing ranging requests. This preliminary state tracking allows the AP to quickly determine whether to accept or reject incoming FTM requests without full processing, thereby preventing overload while maintaining legitimate FTM functionality.
Solution Approach 2:
The access point segments the handling of ranging requests by implementing separate state machines for different client devices and tracking individual client states independently. This segmentation allows the AP to selectively process requests from authorized clients while rejecting requests from unauthorized or malicious clients, thereby protecting against DoS attacks without affecting legitimate FTM operations.
2Adaptability or versatility
If the access point accepts all FTM ranging requests, then positioning services are available to all clients, but malicious requests cause denial of service attacks
Solution Approach 1:
The access point implements feedback mechanisms through state machines that track the behavior of each client device over time. When a client sends excessive or malformed FTM requests, the state machine detects this abnormal behavior and transitions the client to a suspended or rejected state, providing feedback that prevents further malicious requests. This feedback loop maintains FTM availability for legitimate clients while blocking DoS attacks.
Solution Approach 2:
The access point applies preliminary anti-action by proactively suspending or rejecting client devices that exhibit suspicious behavior patterns before they can cause significant disruption. The state machine monitors request frequency and validity, and when thresholds are exceeded, the AP preemptively blocks further requests from that client, preventing DoS attacks in advance while maintaining normal FTM operations for authorized clients.
3Adaptability or versatility
If the access point processes excessive ranging requests, then all client positioning needs are met, but computing resources and airtime are wasted
Solution Approach 1:
The access point applies partial action by selectively processing only the necessary subset of FTM ranging requests based on client authorization and behavior validation. Instead of processing all incoming requests, the state machine identifies and processes only legitimate requests from authorized clients, rejecting excessive or malicious requests. This partial processing approach maintains positioning service coverage for valid clients while conserving computing resources and airtime that would otherwise be wasted on malicious requests.
Data Source
AI summary
Examples of techniques for handling fine time measurement ranging requests are described. In an example, an access point (AP) may receive a ranging request for initiating a Fine Timing Measurement (FTM) session. Responsive to determining that the client device is associated with the AP, it is determined that the ranging request is received after a threshold time from expiry of an FTM burst period of the client device. It is determined that the ranging request is within an FTM acceptance threshold of the AP. A number of consecutive unsuccessful FTM bursts between the AP and the client device is determined. In response to determining that the number of consecutive unsuccessful FTM bursts is less than an unsuccessful burst threshold of the AP, the FTM session may be initiated based on the ranging request.