WiFiProfiler: Cooperative Diagnosis in Wireless LANs .

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Category: General / Misc
2. Remote Woes. Clients frequently ask why:
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WiFiProfiler: Cooperative Diagnosis in Wireless LANs Ranveer Chandra, Venkat Padmanabhan, Ming Zhang Microsoft Research

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Wireless Woes Users frequently ask why: "My machine says: remote association inaccessible" "I get poor execution on remote" "My remote card continues attempting to confirm" "Is it just me?"

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Wireless Woes Users regularly ask why: "My machine says: remote association inaccessible" "I get poor execution on remote" "My remote card continues attempting to verify" "Is it just me?" Many spots have no/negligible system administrator Hotspots: bistros, air terminals Transient systems: gatherings, IETF gatherings

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Prior Work: Operator View Infrastructure-based checking (Aruba, DAIR) Focuses on administrator point of view (e.g., rebel APs) Monitoring at customers (e.g., [Adya 2004]) Fault finding utilizing framework bolster Also concentrates on administrator viewpoint Correlate customer perceptions at AP (MOJO) Detect PHY level oddities

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WiFiProfiler Goal: User View Enable customers to analyze arrange disappointments without requiring administrator/foundation bolster: Reduce client dissatisfaction Reduce stack on administrator, when there is one Help clients help themselves

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State of the Art: Local Diagnosis Wireless Connection Manager, WZC Reasonable identification, Poor conclusion Bad NIC MAC Filtering Bad WEP Key Cannot Associate Bad AP

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WiFiProfiler Based on two key perceptions: Clients shape Information Plane with companions Even when customer can\'t interface with AP Extent of issue demonstrates cause Diagnose blames by relating companions\' wellbeing

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WiFiProfiler Overview Healthy Client Req. Wellbeing Health Info. (WEP key data) Dissatisfied Machine (Cannot associate with WEP-empowered AP) Create Information Plane Access Point Health Info. (WEP key information) Req. Wellbeing Diagnose Problem: Same WEP key? Sound Client Diagnose scope of issues crosswise over layers!

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Faults and Some Causes Location No AP Detected H/w or s/w No Association Security DHCP Server No IP Address Firewall/intermediary End-to-End Failure WAN Disconnect WAN blockage Poor Performance Wireless issue

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Outline Introduction WiFiProfiler Overview WiFiProfiler Design Evaluation Summary

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WiFiProfiler Design Goals Transparency: Minimal client affect/inclusion Deployability: Work with off-the-rack cards and unmodified drivers Scalability: Work with an expansive number of customers Security: Prevent bargain of customers and AP

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WiFiProfiler Architecture Sensing : What is checked? Correspondence : How is it shared? Determination : How are flaws analyzed?

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Sensing Monitor strength of customer\'s availability Static information (e.g., NIC sort) Dynamic data (e.g., assoc. achievement/disappointment) Sensed Info Some Causes Fault NIC Model, Make, Driver form H/w or s/w No Association Auth/Encryption setting, key data Security

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Sensed Information User-level administration (daemon) surveys different layers Wireless: NIC, BSSID, RSSI, Beacon Loss, 1-path hash of key, Interface Queue IP: IP Address, DHCP, DNS Transport: Failed associations, Server Ports Application: Web intermediary settings Snapshot got once consistently Summarized data < 1200 bytes

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Communication 802.11 NICs can associate with just a single system at once Challenges: Discovery: How does H realize that D needs assistance? Parallelism: How does H send bundles to D? Req. Wellbeing H D Sensed Info Establishing the Information Plane

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Discovery D starts impromptu system with particular SSID Special SSID arrange indicates ask for help H gets guide notwithstanding when related to AP SSID: Help: D H Port: 5000

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Parallelism utilizing VirtualWiFi Details: Infocom \'04 Approach: Virtualize card, cradle bundles, switch b/w systems Application Layer User-level Kernel-level TCP/IP, Network Stack VirtualWiFi Layer Virtual Interface 1 Virtual Interface 2 Virtual Interface 3 Wireless Card

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Communication Protocol WiFiProfiler utilizes 2 (virtual) connectors: Primary connector actuated in typical utilize Helper connector devoted for WiFiProfiler Activated just when required SSID: Help: D H Primary VNIC Port: 5000 Helper VNIC Scalability and Security talks in paper

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Diagnosis Initiated by client Correlate associates\' data and surmise likely cause Rule-based procedures rather than discovery Suggest ventures for issue determination Change setup settings e.g. nearby DNS server, web intermediary, WEP scratch Change area, contact administrator Diagnose blames crosswise over layers of system stack

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Diagnosing Association Failure If another companion has effectively connected with the AP: Similar card Associated? Is Sec. config Same? Is BLR much higher? YES NO YES NO Bad Sec. setting (Fix it) Bad flag (change area) MAC Filtering (contact administrator) S/w or H/w config (change NIC or redesign driver)

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Diagnosis Features Inherent vulnerability at times Need information from AP to affirm MAC sifting Conflicting data from associates Used to dispense with branches in finding methodology, e.g. NIC sort Vulnerability to counterfeit data from assailants Use data from expansive number of associates Susceptible to Sybil assault

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Outline Introduction WiFiProfiler Architecture Sensing Communication Diagnosis Evaluation Summary

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Evaluation Sensing: Low overhead (utilized < 1% CPU on 1.33 GHz portable workstation) Communication utilizing VirtualWiFi: Healthy customers spend < 2 sec sending information Sick customers get data inside 30 seconds Much of the deferral in disclosure (examining delays)

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Little Impact on Healthy Clients Extra 0.5 to 3 seconds!

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Effectiveness of WiFiProfiler Relevant analysis at all customers inside 30 seconds!

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WiFiProfiler Summary Enables helpful conclusion in WLANs Without framework bolster, low overhead Working framework on Windows XP Future work: Security: Privacy, Sybil Attacks, Passive Mode Long-term Profiling

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