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Full-Text Articles in Physical Sciences and Mathematics
Detecting The Presence Of Electronic Devices In Smart Homes Using Harmonic Radar, Beatrice Perez, Gregory Mazzaro, Timothy J. Pierson, David Kotz
Detecting The Presence Of Electronic Devices In Smart Homes Using Harmonic Radar, Beatrice Perez, Gregory Mazzaro, Timothy J. Pierson, David Kotz
Dartmouth Scholarship
Data about users is collected constantly by phones, cameras, Internet websites, and others. The advent of so-called ‘Smart Things' now enable ever-more sensitive data to be collected inside that most private of spaces: the home. The first step in helping users regain control of their information (inside their home) is to alert them to the presence of potentially unwanted electronics. In this paper, we present a system that could help homeowners (or home dwellers) find electronic devices in their living space. Specifically, we demonstrate the use of harmonic radars (sometimes called nonlinear junction detectors), which have also been used in …
Spice: Secure Proximity-Based Infrastructure For Close Encounters, Aarathi Prasad, Xiaohui Liang, David Kotz
Spice: Secure Proximity-Based Infrastructure For Close Encounters, Aarathi Prasad, Xiaohui Liang, David Kotz
Dartmouth Scholarship
We present a crowdsourcing system that extends the capabilities of location-based applications and allows users to connect and exchange information with users in spatial and temporal proximity. We define this incident of spatio-temporal proximity as a \em close encounter. Typically, location-based application users store their information on a server, and trust the server to provide access only to authorized users, not misuse the data or disclose their location history. Our system, called SPICE, addresses these privacy issues by leveraging Wi-Fi access points to connect users and encrypt their information before it is exchanged, so only users in close encounters have …
Demo: Wanda, Securely Introducing Mobile Devices, Timothy J. Pierson, Xiaohui Liang, Ronald Peterson, David Kotz
Demo: Wanda, Securely Introducing Mobile Devices, Timothy J. Pierson, Xiaohui Liang, Ronald Peterson, David Kotz
Dartmouth Scholarship
Nearly every setting is increasingly populated with wireless and mobile devices – whether appliances in a home, medical devices in a health clinic, sensors in an industrial setting, or devices in an office or school. There are three fundamental operations when bringing a new device into any of these settings: (1) to configure the device to join the wireless local-area network, (2) to partner the device with other nearby devices so they can work together, and (3) to configure the device so it connects to the relevant individual or organizational account in the cloud. The challenge is to accomplish all …
Location Privacy For Mobile Crowd Sensing Through Population Mapping, Minho Shin, Cory Cornelius, Apu Kapadia, Nikos Triandopoulos, David Kotz
Location Privacy For Mobile Crowd Sensing Through Population Mapping, Minho Shin, Cory Cornelius, Apu Kapadia, Nikos Triandopoulos, David Kotz
Dartmouth Scholarship
Opportunistic sensing allows applications to “task” mobile devices to measure context in a target region. For example, one could leverage sensor-equipped vehicles to measure traffic or pollution levels on a particular street or users' mobile phones to locate (Bluetooth-enabled) objects in their vicinity. In most proposed applications, context reports include the time and location of the event, putting the privacy of users at increased risk: even if identifying information has been removed from a report, the accompanying time and location can reveal sufficient information to de-anonymize the user whose device sent the report. We propose and evaluate a novel spatiotemporal …
Data Citation Practices In The Crawdad Wireless Network Data Archive, Tristan Henderson, David Kotz
Data Citation Practices In The Crawdad Wireless Network Data Archive, Tristan Henderson, David Kotz
Dartmouth Scholarship
CRAWDAD (Community Resource for Archiving Wireless Data At Dartmouth) is a popular research data archive for wireless network data, archiving over 100 datasets used by over 6,500 users. In this paper we examine citation behaviour amongst 1,281 papers that use CRAWDAD datasets. We find that (in general) paper authors cite datasets in a manner that is sufficient for providing credit to dataset authors and also provides access to the datasets that were used. Only 11.5% of papers did not do so; common problems included (1) citing the canonical papers rather than the dataset, (2) describing the dataset using unclear identifiers, …
From Map To Dist: The Evolution Of A Large-Scale Wlan Monitoring System, Keren Tan, Chris Mcdonald, Bennet Vance, Chrisil Arackaparambil, Sergey Bratus, David Kotz
From Map To Dist: The Evolution Of A Large-Scale Wlan Monitoring System, Keren Tan, Chris Mcdonald, Bennet Vance, Chrisil Arackaparambil, Sergey Bratus, David Kotz
Dartmouth Scholarship
The edge of the Internet is increasingly becoming wireless. Therefore, monitoring the wireless edge is important to understanding the security and performance aspects of the Internet experience. We have designed and implemented a large-scale WLAN monitoring system, the Distributed Internet Security Testbed (DIST), at Dartmouth College. It is equipped with distributed arrays of “sniffers” that cover 210 diverse campus locations and more than 5,000 users. In this paper, we describe our approach, designs and solutions for addressing the technical challenges that have resulted from efficiency, scalability, security, and management perspectives. We also present extensive evaluation results on a production network, …
Effects Of Network Trace Sampling Methods On Privacy And Utility Metrics, Phillip A. Fazio, Keren Tan, David Kotz
Effects Of Network Trace Sampling Methods On Privacy And Utility Metrics, Phillip A. Fazio, Keren Tan, David Kotz
Dartmouth Scholarship
Researchers choosing to share wireless-network traces with colleagues must first anonymize sensitive information, trading off the removal of information in the interest of identity protection and the preservation of useful data within the trace. While several metrics exist to quantify this privacy-utility tradeoff, they are often computationally expensive. Computing these metrics using a \emphsample\/ of the trace could potentially save precious time. In this paper, we examine several sampling methods to discover their effects on measurement of the privacy-utility tradeoff when anonymizing network traces. We tested the relative accuracy of several packet and flow-sampling methods on existing privacy and utility …
Adapt-Lite: Privacy-Aware, Secure, And Efficient Mhealth Sensing, Shrirang Mare, Jacob Sorber, Minho Shin, Cory Cornelius, David Kotz
Adapt-Lite: Privacy-Aware, Secure, And Efficient Mhealth Sensing, Shrirang Mare, Jacob Sorber, Minho Shin, Cory Cornelius, David Kotz
Dartmouth Scholarship
As healthcare in many countries faces an aging population and rising costs, mobile sensing technologies promise a new opportunity. Using mobile health (mHealth) sensing, which uses medical sensors to collect data about the patients, and mobile phones to act as a gateway between sensors and electronic health record systems, caregivers can continuously monitor the patients and deliver better care. Although some work on mHealth sensing has addressed security, achieving strong security and privacy for low-power sensors remains a challenge. \par We make three contributions. First, we propose Adapt-lite, a set of two techniques that can be applied to existing wireless …
Short Paper: The Netsani Framework For Analysis And Fine-Tuning Of Network Trace Sanitization, Phil Fazio, Keren Tan, Jihwang Yeo, David Kotz
Short Paper: The Netsani Framework For Analysis And Fine-Tuning Of Network Trace Sanitization, Phil Fazio, Keren Tan, Jihwang Yeo, David Kotz
Dartmouth Scholarship
Anonymization is critical prior to sharing wireless-network traces within the research community, to protect both personal and organizational sensitive information from disclosure. One difficulty in anonymization, or more generally, sanitization, is that users lack information about the quality of a sanitization result, such as how much privacy risk a sanitized trace may expose, and how much research utility the sanitized trace may retain. We propose a framework, NetSANI, that allows users to analyze and control the privacy/utility tradeoff in network sanitization. NetSANI can accommodate most of the currently available privacy and utility metrics for network trace sanitization. This framework provides …
Privacy Analysis Of User Association Logs In A Large-Scale Wireless Lan, Keren Tan, Guanhua Yan, Jihwang Yeo, David Kotz
Privacy Analysis Of User Association Logs In A Large-Scale Wireless Lan, Keren Tan, Guanhua Yan, Jihwang Yeo, David Kotz
Dartmouth Scholarship
User association logs collected from a large-scale wireless LAN record where and when a user has used the network. Such information plays an important role in wireless network research. One concern of sharing these data with other researchers, however, is that the logs pose potential privacy risks for the network users. Today, the common practice in sanitizing these data before releasing them to the public is to anonymize users' sensitive information, such as their devices' MAC addresses and their exact association locations. In this work, we aim to study whether such sanitization measures are sufficient to protect user privacy. By …
Social Network Analysis Plugin (Snap) For Mesh Networks, Soumendra Nanda, David Kotz
Social Network Analysis Plugin (Snap) For Mesh Networks, Soumendra Nanda, David Kotz
Dartmouth Scholarship
In a network, bridging nodes are those nodes that from a topological perspective, are strategically located between highly connected regions of nodes. Thus, they have high values of the Bridging Centrality (BC) metric. We recently introduced the Localized Bridging Centrality (LBC) metric, which can identify such nodes via distributed computation, yet has an accuracy equal to that of the centralized BC metric. The LBC and BC metrics are based on the Social Network Analysis (SNA) metric "betweenness centrality". We now introduce a new SNA metric that is more suitable for use in wireless mesh networks: the Localized Load-aware Bridging Centrality …
A Correlation Attack Against User Mobility Privacy In A Large-Scale Wlan Network, Keren Tan, Guanhua Yan, Jihwang Yeo, David Kotz
A Correlation Attack Against User Mobility Privacy In A Large-Scale Wlan Network, Keren Tan, Guanhua Yan, Jihwang Yeo, David Kotz
Dartmouth Scholarship
User association logs collected from real-world wireless LANs have facilitated wireless network research greatly. To protect user privacy, the common practice in sanitizing these data before releasing them to the public is to anonymize users' sensitive information such as the MAC addresses of their devices and their exact association locations. In this work,we demonstrate that these sanitization measures are insufficient in protecting user privacy from a novel type of correlation attack that is based on CRF (Conditional Random Field). In such a correlation attack, the adversary observes the victim's AP (Access Point) association activities for a short period of time …
Saluki: A High-Performance Wi-Fi Sniffing Program, Keren Tan, David Kotz
Saluki: A High-Performance Wi-Fi Sniffing Program, Keren Tan, David Kotz
Dartmouth Scholarship
Building a campus-wide wireless LAN measurement system faces many efficiency, scalability and security challenges. To address these challenges, we developed a distributed Wi-Fi sniffing program called Saluki. Compared to our previous implementation and to other available sniffing programs, Saluki has the following advantages: (1) its small footprint makes it suitable for a resource-constrained Linux platform, such as those in commercial Wi-Fi access points; (2) the frame-capture rate increased more than three-fold over tcpdump with minimal frame loss; (3) all traffic between this sniffer and the back-end server was secured using 128-bit encryption; and (4) the traffic load on the backbone …
On The Reliability Of Wireless Fingerprinting Using Clock Skews, Chrisil Arackaparambil, Sergey Bratus, Anna Shubina, David Kotz
On The Reliability Of Wireless Fingerprinting Using Clock Skews, Chrisil Arackaparambil, Sergey Bratus, Anna Shubina, David Kotz
Dartmouth Scholarship
No abstract provided.
Dartmouth Internet Security Testbed (Dist): Building A Campus-Wide Wireless Testbed, Sergey Bratus, David Kotz, Keren Tan, William Taylor, Anna Shubina, Bennet Vance, Michael E. Locasto
Dartmouth Internet Security Testbed (Dist): Building A Campus-Wide Wireless Testbed, Sergey Bratus, David Kotz, Keren Tan, William Taylor, Anna Shubina, Bennet Vance, Michael E. Locasto
Dartmouth Scholarship
We describe our experiences in deploying a campus-wide wireless security testbed. The testbed gives us the capability to monitor security-related aspects of the 802.11 MAC layer in over 200 diverse campus locations. We describe both the technical and the social challenges of designing, building, and deploying such a system, which, to the best of our knowledge, is the largest such testbed in academia (with the UCSD's Jigsaw infrastructure a close competitor). In this paper we focus on the \em testbed setup, rather than on the experimental data and results.
Deamon: Energy-Efficient Sensor Monitoring, Minho Shin, Patrick Tsang, David Kotz, Cory Cornelius
Deamon: Energy-Efficient Sensor Monitoring, Minho Shin, Patrick Tsang, David Kotz, Cory Cornelius
Dartmouth Scholarship
In people-centric opportunistic sensing, people offer their mobile nodes (such as smart phones) as platforms for collecting sensor data. A sensing application distributes sensing `tasks,' which specify what sensor data to collect and under what conditions to report the data back to the application. To perform a task, mobile nodes may use on-board sensors, a body-area network of personal sensors, or sensors from neighboring nodes that volunteer to contribute their sensing resources. In all three cases, continuous sensor monitoring can drain a node's battery. \par We propose DEAMON (Distributed Energy-Aware MONitoring), an energy-efficient distributed algorithm for long-term sensor monitoring. Our …
The Changing Usage Of A Mature Campus-Wide Wireless Network, Tristan Henderson, David Kotz, Ilya Abyzov
The Changing Usage Of A Mature Campus-Wide Wireless Network, Tristan Henderson, David Kotz, Ilya Abyzov
Dartmouth Scholarship
Wireless Local Area Networks (WLANs) are now commonplace on many academic and corporate campuses. As "Wi-Fi" technology becomes ubiquitous, it is increasingly important to understand trends in the usage of these networks. This paper analyzes an extensive network trace from a mature 802.11 WLAN, including more than 550 access points and 7000 users over seventeen weeks. We employ several measurement techniques, including syslog messages, telephone records, SNMP polling and tcpdump packet captures. This is the largest WLAN study to date, and the first to look at a mature WLAN. We compare this trace to a trace taken after the network's …
Streaming Estimation Of Information-Theoretic Metrics For Anomaly Detection (Extended Abstract), Sergey Bratus, Joshua Brody, David Kotz, Anna Shubina
Streaming Estimation Of Information-Theoretic Metrics For Anomaly Detection (Extended Abstract), Sergey Bratus, Joshua Brody, David Kotz, Anna Shubina
Dartmouth Scholarship
Information-theoretic metrics hold great promise for modeling traffic and detecting anomalies if only they could be computed in an efficient, scalable ways. Recent advances in streaming estimation algorithms give hope that such computations can be made practical. We describe our work in progress that aims to use streaming algorithms on 802.11a/b/g link layer (and above) features and feature pairs to detect anomalies.
Workshop Report — Crawdad Workshop 2007, Jihwang Yeo, David Kotz, Tristan Henderson
Workshop Report — Crawdad Workshop 2007, Jihwang Yeo, David Kotz, Tristan Henderson
Dartmouth Scholarship
Wireless network researchers are hungry for data about how real users, applications, and devices use real networks under real network conditions. CRAWDAD, the Community Resource for Archiving Wireless Data at Dartmouth, is an NSF-funded project that is building a wireless network data archive for the research community. We host wireless data, and provide tools and documents to make it easy to collect and use wireless network data. We hope that this resource will help researchers to identify and evaluate real and interesting problems in mobile and pervasive computing. This report outlines the CRAWDAD project and summarizes the third CRAWDAD workshop, …
Detecting 802.11 Mac Layer Spoofing Using Received Signal Strength, Yong Sheng, Keren Tan, Guanling Chen, David Kotz, Andrew T. Campbell
Detecting 802.11 Mac Layer Spoofing Using Received Signal Strength, Yong Sheng, Keren Tan, Guanling Chen, David Kotz, Andrew T. Campbell
Dartmouth Scholarship
MAC addresses can be easily spoofed in 802.11 wireless LANs. An adversary can exploit this vulnerability to launch a large number of attacks. For example, an attacker may masquerade as a legitimate access point to disrupt network services or to advertise false services, tricking nearby wireless stations. On the other hand, the received signal strength (RSS) is a measurement that is hard to forge arbitrarily and it is highly correlated to the transmitter's location. Assuming the attacker and the victim are separated by a reasonable distance, RSS can be used to differentiate them to detect MAC spoofing, as recently proposed …
Refocusing In 802.11 Wireless Measurement, Udayan Deshpande, Chris Mcdonald, David Kotz
Refocusing In 802.11 Wireless Measurement, Udayan Deshpande, Chris Mcdonald, David Kotz
Dartmouth Scholarship
The edge of the Internet is increasingly wireless. To understand the Internet, one must understand the edge, and yet the measurement of wireless networks poses many new challenges. IEEE 802.11 networks support multiple wireless channels and any monitoring technique involves capturing traffic on each of these channels to gather a representative sample of frames from the network. We call this procedure \emphchannel sampling, in which each sniffer visits each channel periodically, resulting in a sample of the traffic on each of the channels. \par This sampling approach may be sufficient, for example, for a system administrator or anomaly detection module …
Active Behavioral Fingerprinting Of Wireless Devices, Sergey Bratus, Cory Cornelius, David Kotz, Dan Peebles
Active Behavioral Fingerprinting Of Wireless Devices, Sergey Bratus, Cory Cornelius, David Kotz, Dan Peebles
Dartmouth Scholarship
We propose a simple active method for discovering facts about the chipset, the firmware or the driver of an 802.11 wireless device by observing its responses (or lack thereof) to a series of crafted non-standard or malformed 802.11 frames. We demonstrate that such responses can differ significantly enough to distinguish between a number of popular chipsets and drivers. We expect to significantly expand the number of recognized device types through community contributions of signature data for the proposed open fingerprinting framework. Our method complements known fingerprinting approaches, and can be used to interrogate and spot devices that may be spoofing …
Evaluating Opportunistic Routing Protocols With Large Realistic Contact Traces, Libo Song, David Kotz
Evaluating Opportunistic Routing Protocols With Large Realistic Contact Traces, Libo Song, David Kotz
Dartmouth Scholarship
Traditional mobile ad hoc network (MANET) routing protocols assume that contemporaneous end-to-end communication paths exist between data senders and receivers. In some mobile ad hoc networks with a sparse node population, an end-to-end communication path may break frequently or may not exist at any time. Many routing protocols have been proposed in the literature to address the problem, but few were evaluated in a realistic “opportunistic” network setting. We use simulation and contact traces (derived from logs in a production network) to evaluate and compare five existing protocols: direct-delivery, epidemic, random, PRoPHET, and Link-State, as well as our own proposed …
Periodic Properties Of User Mobility And Access-Point Popularity, Minkyong Kim, David Kotz
Periodic Properties Of User Mobility And Access-Point Popularity, Minkyong Kim, David Kotz
Dartmouth Scholarship
Understanding user mobility and its effect on access points (APs) is important in designing location-aware systems and wireless networks. Although various studies of wireless networks have provided useful insights, it is hard to apply them to other situations. Here we present a general methodology for extracting mobility information from wireless network traces, and for classifying mobile users and APs. We used the Fourier transform to reveal important periods and chose the two strongest periods to serve as parameters to a classification system based on Bayes' theory. Analysis of 1-month traces shows that while a daily pattern is common among both …
Workshop Report — Crawdad Workshop 2006, Jihwang Yeo, Tristan Henderson, David Kotz
Workshop Report — Crawdad Workshop 2006, Jihwang Yeo, Tristan Henderson, David Kotz
Dartmouth Scholarship
Wireless network researchers are seriously starved for data about how real users, applications, and devices use real networks under real network conditions. CRAWDAD, the Community Resource for Archiving Wireless Data at Dartmouth, is an NSF-funded project that is building a wireless network data archive for the research community. We host wireless data, and provide tools and documents to make it easy to collect and use wireless network data. We hope that this resource will help researchers to identify and evaluate real and interesting problems in mobile and pervasive computing. This report outlines the CRAWDAD project and summarizes the second CRAWDAD …
Evaluating Next Cell Predictors With Extensive Wi-Fi Mobility Data, Libo Song, David Kotz, Ravi Jain, Xiaoning He
Evaluating Next Cell Predictors With Extensive Wi-Fi Mobility Data, Libo Song, David Kotz, Ravi Jain, Xiaoning He
Dartmouth Scholarship
Location is an important feature for many applications, and wireless networks can better serve their clients by anticipating client mobility. As a result, many location predictors have been proposed in the literature, though few have been evaluated with empirical evidence. This paper reports on the results of the first extensive empirical evaluation of location predictors, using a two-year trace of the mobility patterns of over 6,000 users on Dartmouth's campus-wide Wi-Fi wireless network. The surprising results provide critical evidence for anyone designing or using mobility predictors. \par We implemented and compared the prediction accuracy of several location predictors drawn from …
Mobicom Poster Abstract: Bandwidth Reservation Using Wlan Handoff Prediction, Libo Song, Udayan Deshpande, Ulaş C. Kozat, David Kotz, Ravi Jain
Mobicom Poster Abstract: Bandwidth Reservation Using Wlan Handoff Prediction, Libo Song, Udayan Deshpande, Ulaş C. Kozat, David Kotz, Ravi Jain
Dartmouth Scholarship
Many network services may be improved or enabled by successful predictions of users' future mobility. The success of predictions depend on how much accuracy can be achieved on real data and on the sensitivity of particular applications to this achievable accuracy. We investigate these issues for the case of advanced bandwidth reservation using real WLAN traces collected on the Dartmouth College campus.
Risks Of Using Ap Locations Discovered Through War Driving, Minkyong Kim, Jeffrey J. Fielding, David Kotz
Risks Of Using Ap Locations Discovered Through War Driving, Minkyong Kim, Jeffrey J. Fielding, David Kotz
Dartmouth Scholarship
Many pervasive-computing applications depend on knowledge of user location. Because most current location-sensing techniques work only either indoors or outdoors, researchers have started using 802.11 beacon frames from access points (APs) to provide broader coverage. To use 802.11 beacons, they need to know AP locations. Because the actual locations are often unavailable, they use estimated locations from \em war driving. But these estimated locations may be different from actual locations. In this paper, we analyzed the errors in these estimates and the effect of these errors on other applications that depend on them. We found that the estimated AP locations …
Channel Sampling Strategies For Monitoring Wireless Networks, Udayan Deshpande, Tristan Henderson, David Kotz
Channel Sampling Strategies For Monitoring Wireless Networks, Udayan Deshpande, Tristan Henderson, David Kotz
Dartmouth Scholarship
Monitoring the activity on an IEEE 802.11 network is useful for many applications, such as network management, optimizing deployment, or detecting network attacks. Deploying wireless sniffers to monitor every access point in an enterprise network, however, may be expensive or impractical. Moreover, some applications may require the deployment of multiple sniffers to monitor the numerous channels in an 802.11 network. In this paper, we explore sampling strategies for monitoring multiple channels in 802.11b/g networks. We describe a simple sampling strategy, where each channel is observed for an equal, predetermined length of time, and consider applications where such a strategy might …
Extracting A Mobility Model From Real User Traces, Minkyong Kim, David Kotz, Songkuk Kim
Extracting A Mobility Model From Real User Traces, Minkyong Kim, David Kotz, Songkuk Kim
Dartmouth Scholarship
Understanding user mobility is critical for simulations of mobile devices in a wireless network, but current mobility models often do not reflect real user movements. In this paper, we provide a foundation for such work by exploring mobility characteristics in traces of mobile users. We present a method to estimate the physical location of users from a large trace of mobile devices associating with access points in a wireless network. Using this method, we extracted tracks of always-on Wi-Fi devices from a 13-month trace. We discovered that the speed and pause time each follow a log-normal distribution and that the …