The virtualization and softwareization of network functions, controls, and applications are promising as they optimize costs and processes while bringing new value to the network infrastructures. However, the centralized reliability management over the complex softwareized network poses both scalability and latency challenges on the failure recovery process. In this paper, we propose a Network Architecture-aware Reliability Management Schemes (NetAware) to efficiently orchestrate different reliability monitoring mechanisms over SDN network architecture and synchronize the control messages among different controllers and applications. NetAware facilitates many common reliability monitoring factors for the registered applications by analyzing both off-line and on-line network architecture information such as network topologies, virtualization, and protocols. NetAware consists of a High Availability Registration Platform (HARP) and a Topology Aware Reliability (TAR) discovery facilities. A prototype is implemented on Cisco's OpenDayLight (ODL).

Software-defined networking (SDN) is a softwarization technology of networks that can optimize processes and operation costs and bring new values to infrastructures. The issue of reliability, however, becomes more complex in SDN due to new and multi-lateral network domains, and poses many critical challenges on the existing network reliability mechanisms in order to achieve the same reliability services. In this paper, we first identify and illustrate reliability challenges in a control path network that lies between a control plane network and a data plane network to connect them through either an in-band SDN or an out-of-band traditional network. We then observe a number of distinctive control path reliability problems. Accordingly, we propose and develop a control path management framework to enhance SDN reliability addressing the observed issues. It includes several control path reliability algorithms that enhance performance, network protocols that simplify management of control path reliability, as well as a novel control message classification and prioritization system that serves as a fundamental approach to improve scalability and then reliability for SDN. Recognizing the control path as a network and understanding its potential and practical reliability problems enable us to provide effective solutions that prior approaches fall short of. We validate our proposed management framework through extensive experiments through a real network system as well as numerical analyses.

As recent smartphone technologies in software and hardware keep on improving, many smartphone users envision to perform various mission critical applications on their smart-phones that were previously accomplished by using PCs. Hence, smartphone authentication has become one of the most critical security issues. Due to the relatively small smartphone form factor, the traditional user id and password typed authentication is considered as an inconvenient and time-taking approach. Taking advantage of various sensor technologies of smartphones, alternative authentication methods such as pattern, gesture, finger print, and face recognition have been actively researched. However, those authentication methods still pose one of speed, reliability, and usability issues. They are especially not suitable for the users in rugged conditions and with physical challenges. In this paper, we evaluate existing alternative smartphone authentication approaches in various usage scenarios to propose ambient light sensor based authentication for smartphones. We have designed and prototyped a challenge-based programmable Fast, Inexpensive, Reliable, and Easy-to-use (FIRE) hardware authentication token. FIRE token uses an onboard LED to transmit passwords via an Optical Wireless Signal (OWS) to the smartphone that captures, and interprets it via its ambient light sensor. FIRE token is a part of the challenge-response technique in the Inverse Dual Signature (IDS) that we designed to facilitate a multi-factor authentication for the mission critical smartphone applications. Our experiments validate that FIRE can authenticate a user on a smartphone in a simple, fast, and reliable way without compromising the security quality and user experience.

As smartphones gain their popularity, vulnerable road users (VRUs) are increasingly distracted by activities with their devices such as listening to music, watching videos, texting or making calls while walking or bicycling on the road. In spite of the development of various high-tech Car-to-Car (C2C) and Car-to-Infrastructure (C2I) communications for enhancing the traffic safety, protecting such VRUs from vehicles still relies heavily on traditional sound warning methods. Furthermore, as smartphones continue to become highly ubiquitous, VRUs are increasingly oblivious to safety related warning sounds. A traffic accident study shows the number of headphone-wearing VRUs involved in roadside accidents has increased by 300% in the last 10 years. Although recently a few Car2Pedestrian-communication methods have been proposed by various car manufacturers, their practical usage is limited, as they mostly require special communication devices to cope with the wide range of mobility, and also assume VRUs' active attention to the communication while walking. We propose a smartphone-based Car2X-communication system, named WiFi-Honk, which can alert the potential collisions to both VRUs and vehicles in order to especially protect the distracted VRUs. WiFi-Honk provides a practical safety means for the distracted VRUs without requiring any special device using WiFi of smartphone. WiFi-Honk removes the WiFi association overhead using the beacon stuffed WiFi communication with the geographic location, speed, and direction information of the smartphone replacing its SSID while operating in WiFi Direct/Hotspot mode, and also provides an efficient collision estimation algorithm to issue appropriate warnings. Our experimental and simulation studies validate that WiFi-Honk can successfully alert VRUs within a sufficient reaction time frame, even in high mobility environments.

Software-Defined Network (SDN) enables agile network traffic control and configuration as well as shortens the network function deployment time. Despite the projected benefits of SDN, the abstractions toward the remote and centralized control tend to impose excessive control traffic overhead in order for the controller to acquire the global network visibility as well as to extend the legacy network's inaccurate and unreliable management problems into the control plane. In addition, a complex combination of multiple and heterogeneous management channels further aggravates the scalability problem. In this paper, to address the above management problems. We propose an intelligent management middlebox called Software-defined Unified Monitoring Agent (SUMA). SUMA builds a hybrid SDN architecture by providing intelligent control, management abstraction, and a filtering layer, that eventually will serve as an essential component for the reliable, scalable, and secure SDN deployment. In this paper, we present design, implementation, deployment, and evaluation results of a SUMA.

Despite various high-tech Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communications that have been developed for enhancing traffic safety, protecting vulnerable road users (VRU), such as pedestrians and bicyclists from the vehicles and trains still heavily relies on the traditional sound warning method. Furthermore, as smart devices continue to become highly ubiquitous, the more VRU are shutting out the safety related warning sounds. A traffic accident study shows the number of headphone-wearing VRU involved in roadside accidents has tripled since 2004. Although recently a few Car2Pedestrian communication methods have been proposed by various car makers, their practical usage is still in question. They assume VRUs' active attention to the communication while walking, and also mostly require special communication devices to cope with the wide range of mobility. In this paper, we propose a smartphone based Car2X communication system, named WiFiHonk that can alert of potential collisions to both VRU and vehicles in order to especially protect the distracted VRU. WiFiHonk provides a practical safety means for the distracted VRU without requiring any special device using the WiFi of a smart device. It is novel in that it removes the WiFi association overhead using the beacon stuffed WiFi communication and also provides an efficient collision estimation algorithm to issue appropriate warnings. Our experimental and simulation studies validate that WiFiHonk can successfully alert the VRU within a sufficient reaction time frame.

While many security schemes protect the content of messages in the Distributed Sensing Systems (DSS), the contextual information, such as communication patterns, is left vulnerable and can be utilized by attackers to identify critical information such as the locations of event sources and message sinks. Existing solutions for location anonymity are mostly designed to protect source or sink location anonymity individually against limited eavesdroppers on a small region at a time. However, they can be easily defeated by highly motivated global eavesdroppers that can monitor entire communication events on the DSS. To grapple with these challenges, we propose a mechanism for Preserving Anonymity of Sources and Sinks against Global Eavesdroppers (PASSAGES). PASSAGES uses a small number of stealthy permeability tunnels such as wormholes and message ferries to scatter and hide the communication patterns. Unlike prior schemes, PASSAGES effectively achieves a high anonymity level for both source and sink locations, without incurring extra communication overheads. We quantify the location anonymity level and evaluate the effectiveness of PASSAGES via analysis as well as extensive simulations. We also perform evaluations on the synergistic effect when PASSAGES is combined with other traditional solutions.

The fast growing popularity of smartphones and tablets enables us the use of various intelligent mobile applications. As many of those applications require position information, a smart mobile device provides positioning methods such as GPS, WiFi, or Cell-ID based positioning services. However, those positioning methods have different characteristics of energy efficiency, accuracy, and service availability. In this paper, we present an Energy- Efficient Cooperative and Opportunistic Positioning System (ECOPS) for heterogeneous mobile devices. ECOPS facilitates mobile devices with estimated locations using WiFi in cooperation with a few available GPS broadcasting devices, in order to achieve high energy efficiency and accuracy within available budget constraints. ECOPS estimates the location using heterogeneous positioning services and the combination methods including a received signal strength indicator, 2D trilateration, and available power measurement of mobile devices. The evaluation shows that ECOPS significantly reduces energy consumption and achieves the good accuracy of a location.

Preserving privacy is one of the most challenging yet essential issues in many mission critical WSN applications. As most of the existing privacy solutions additionally inject fake traffic assuming limited local adversary models, they can be easily defeated by highly motivated global attackers that monitor the entire network communications. We propose a scheme against a global adversary model, named Source Traceability Elimination for Privacy (STEP) using heterogeneous links. The STEP uses wormhole pairs (WHPs) to hide the communication of an original source location and scatter it to a remote location. Unlike the existing privacy mechanisms, the STEP provides privacy without incurring any additional communication overhead. We quantify a source location privacy level, evaluate the STEP with various parameters, and discuss its effect when used with other privacy techniques simultaneously.