Operating System Fingerprinting via DHCP Analysis

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Solution Overview

Problem

Existing methods for determining information about client devices, particularly their operating systems, are limited by requiring active approaches that may be restricted for security reasons, making it difficult to identify and differentiate between various operating systems effectively.

Innovation Solution

A system and process that utilize a fingerprint database to analyze DHCP message features, such as field values and options, to determine the operating system of a client device, allowing for accurate identification and authentication decisions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If active approaches are used to determine client device information, then information can be obtained, but security restrictions limit the ability to send requests to clients

Engineering Contradiction:

Improveclient device informationVSAvoidsecurity restrictions

Core Design Contradiction:

Loss of informationVSEase of operation

Solution Approach 1:

Instead of actively sending requests to clients to obtain information, the patent inverts the approach by having clients send DHCP messages and the server passively analyzing these messages to extract operating system information. This eliminates the need for clients to initiate connections while still achieving information gathering.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent uses DHCP messages as an intermediary carrier to transmit operating system identification information. Rather than direct active probing, the DHCP protocol serves as a mediator that naturally carries client information that can be analyzed by the server without requiring additional active requests.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If generic authentication processes are used, then all devices can be authenticated, but targeted security measures cannot be applied

Engineering Contradiction:

Improvetargeted authenticationVSAvoiddevice identification accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies different authentication and security policies to different operating systems by identifying specific OS types through DHCP message analysis. Each OS receives tailored authentication treatment based on its identified characteristics, enabling localized security policies rather than uniform generic authentication.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If DHCP message features are analyzed to identify operating systems, then accurate identification is achieved, but additional processing complexity is introduced

Engineering Contradiction:

Improveoperating system identification accuracyVSAvoidfingerprint database processing

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent pre-processes and stores operating system identification patterns in a fingerprint database during system setup. This preliminary action allows the actual DHCP message analysis to simply match against pre-defined patterns rather than performing complex real-time analysis, reducing processing complexity during operation.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9213736B2Operating system fingerprinting

Publication Date: 2015.12.15 INFOBLOX INC

AI summary

Determining operating system data is disclosed, including receiving a message associated with a network protocol, extracting a set of one or more features from the message, and determining operating system data at least in part by matching one or more features of the message with one or more features of a fingerprint associated with an operating system. An exact match of the features is not required to determine operating system data.