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Smartphone magnetometer readings exhibit high linear correlation when two phones coexist within a short distance. Thus, the detected coexistence can serve as a proxy for close human contact events, and one can conceive using it as a possible automatic tool to modernize the contact tracing in infectious disease epidemics. This paper investigates how good a diagnostic test it would be, by evaluating the discriminative and predictive power of the smartphone magnetometer-based contact detection in multiple measures. Based on the sensitivity, specificity, likelihood ratios, and diagnostic odds ratios, we find that the decision made by the smartphone magnetometer-based test can be accurate in telling contacts from no contacts. Furthermore, through the evaluation process, we determine the appropriate range of compared trace segment sizes and the correlation cutoff values that we should use in such diagnostic tests. INDEX TERMS Mobile sensing, human contact tracing, smartphone magnetometer, infectious disease epidemic, diagnostic test.

There exists a way that attackers can identify software defined networks (SDNs). Knowing the vulnerabilities of a SDN, the attackers can mount a saturation attack on the SDN controller with the aim of incapacitating the entire SDN. Therefore, the controller should have an architecture to weather out such an attack while continuing operation. A scheduling-based architecture is proposed for the SDN controller that leads to effective attack confinement and network protection during denial of service (DoS) attacks.Introduction: There exists a way that attackers can identify networks that employ software defined networks (SDNs) for control [1]. To incapacitate an identified SDN, the attackers could mount a saturation attack towards the SDN controller simply by sending a large volume of new flows, e.g. from a botnet to a known server in the given SDN [2]. Since every new flow should be handled by the controller for flow entry creation on the traversed switches, the SDN controller can be overwhelmed by flow creation type denial of service (DoS) attacks. A flooded controller will show poor responsiveness to the flow requests from other unaffected flow switches, so that they too will be indirectly rendered less capable of handling new flows.Although provisioning large resource for the controller is one way to cope with the aforementioned DoS attacks, a more systematic approach is desired. Unfortunately, there is a dearth of even the most rudimentary work on how to design the SDN controller for continued operation under the aforementioned attack scenario. Although there is a body of literature on SDN security, most of it is focused on mitigating attacks at flow switches where the attack traffic actually flows [3]. Therefore, in this Letter, we discuss an architecture that helps the controller weather out the DoS attacks targeted at it independently of the attack mitigation measures working in the switches on the actual attack flow paths. Specifically, we propose a scheduling-based scheme that contains most of the attack traffic at attack ingress switches so that the SDN network as a whole can continue normal operation.

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