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NetCheck : Network Diagnoses from Blackbox Traces. Yanyan Zhuang , Eleni Gessiou NYU Poly, University of British Columbia. Motivation. Ping Only reachability Wireshark Applicationor network-specific knowledge Network Config Analysis Detailed network knowledge HW + config ….
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NetCheck: Network Diagnoses from Blackbox Traces YanyanZhuang, EleniGessiou NYU Poly, University of British Columbia
Motivation • Ping • Only reachability • Wireshark • Applicationor network-specific knowledge • Network Config Analysis • Detailed network knowledge • HW + config • …
Goal • Diagnose network problems in large and complex applications • Without modifying the original application
Challenges • Accuracy: ambiguity in order reconstruction • Efficiency: exploring an exponential space of possible orderings • Network complexity: diagnosing issues in real networks
NetCheck Overview • Finding deviations from the model of the network (Deutsch’s Fallacies) • network is reliable, latency is zero, etc.
Rules summary • Example of rule (1): when a client is behind a NAT, (i) the client uses a private IP, (ii) the peer socket address in server’s accept is not the client’s IP
Evaluation • Reproduce reported bugs from bug trackers (Python, Apache, Ruby, Firefox, etc.) • A total of 71 bugs • Correct analysis of 95.7% bugs • Twenty faults observed in practice on a live network(Seattle Testbed) • 90% of cases correctly detected
Runtime performance overhead Best: O(l) Worst: O(nl)
Conclusion • Derives a plausible global traces ordering as a proxy for the ground truth • Uses a model of expected and simple network behavior to identify and diagnose unexpected behavior