Proxy Detection via Response Time Analysis

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Solution Overview

Problem

Current methods are inadequate for determining the presence and characteristics of proxies in communication paths between clients and servers, which affects security, speed, and reliability.

Innovation Solution

A method involving transmitting messages to a request source address and assessing responses, including measuring elapsed time, to determine if a proxy is present and its location, using techniques such as sending requests on non-standard ports and recording error response times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a proxy is present between client and server, then security and reliability may be improved, but communication speed and directness deteriorate

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidcommunication speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The patent uses an intermediary detection mechanism where the server sends a test request back to the client's source address. By measuring the response time and analyzing whether the response comes from the expected source, the system can detect the presence of a proxy intermediary without blocking communication. This allows the system to identify security-relevant information while maintaining normal communication speed.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of information

If proxy detection methods are implemented, then knowledge of proxy presence is improved, but system complexity increases

Engineering Contradiction:
Improveproxy detection informationVSAvoiddetection system complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The detection mechanism leverages the existing communication protocol and the server's own resources to perform detection. The server sends a test request using standard protocols (HTTP, HTTPS, SMTP, etc.) and analyzes the response from the client's source address. This self-service approach eliminates the need for complex dedicated detection hardware or additional protocol overhead, reducing system complexity while providing accurate proxy detection.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If multiple detection techniques are used, then detection accuracy is improved, but measurement time increases

Engineering Contradiction:
Improveproxy detection accuracyVSAvoiddetection time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent employs a lightweight detection approach that uses a single test request rather than multiple complex detection techniques. The server sends one test request to the client's source address and analyzes the response characteristics (response time, source address matching) to determine proxy presence. This partial action approach provides sufficient detection accuracy without the time overhead of multiple comprehensive detection methods.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP1872241B1System and method for detecting a proxy between a client and a server
Publication Date: 2019.01.02 DELL EMC
  • EP1872241B1 patent drawingFigure 1A~1B
  • EP1872241B1 patent drawingFigure 2~3
  • EP1872241B1 patent drawingFigure 4

AI summary

A method and system for determining whether a proxy is present in a communication link between a client (100) and a server (108), and if so, certain characteristics of the proxy (106).