On fast and accurate detection of unauthorized wireless access points using clock skews

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Publication Type thesis
School or College College of Engineering
Department Computing (School of)
Author Jana, Suman
Title On fast and accurate detection of unauthorized wireless access points using clock skews
Date 2009-05-06
Description We explore the use of clock skew of a wireless local area network access point (AP) as its fingerprint to detect unauthorized APs quickly and accurately. The main goal behind using clock skews is to overcome one of the major limitations of existing solutions - the inability to effectively detect Medium Access Control (MAC) address spoofing. We calculate the clock skew of an AP from the IEEE 802.11 Time Synchronization Function (TSF) timestamps sent out in the beacon/probe response frames. We use two different methods for this purpose - one based on linear programming and the other based on least square fit. We supplement these methods with a heuristic for differentiating original packets from those sent by the fake APs. We collect TSF timestamp data from several APs in three different residential settings. Using our measurement data as well as data obtained from a large conference setting, we find that clock skews remain consistent over time for the same AP but vary significantly across APs. Furthermore, we improve the resolution of received timestamp of the frames and show that with this enhancement our methodology can find clock skews very quickly, using 50-100 packets in most of the cases. We also discuss and quantify the impact of various external factors including temperature variation, virtualization, clock source selection and NTP synchronization on clock skews. Our results indicate that the use of clock skews appears to be an efficient and robust method for detecting fake APs in wireless local area networks.
Type Text
Publisher University of Utah
Subject Wireless LANs; Medium Access Control
Dissertation Institution University of Utah
Dissertation Name MS
Language eng
Relation is Version of Digital reproduction of "On fast and accurate detection of unauthorized wireless access points using clock skews" J. Willard Marriott Library Special Collections TK7.5 2009 .J36
Rights Management © Suman Jana
Format Medium application/pdf
Format Extent 357,122 bytes
Identifier us-etd2,121623
Source Original: University of Utah J. Willard Marriott Library Special Collections
Conversion Specifications Original scanned on Epson GT-30000 as 400 dpi to pdf using ABBYY FineReader 9.0 Professional Edition.
ARK ark:/87278/s6zk5x8q
Setname ir_etd
Date Created 2012-04-23
Date Modified 2012-05-16
ID 193546
Reference URL https://collections.lib.utah.edu/ark:/87278/s6zk5x8q