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Session Initiation Protocol (SIP) is widely used as a signaling protocol to support voice and video communication in addition to other multimedia applications. However, it is vulnerable to several types of attacks because of its open nature and lack of a clear defense line against the increasing spectrum of security threats. Among these threats, flooding attack, known by its destructive impact, targets both of SIP User Agent Server (UAS) and User Agent Client (UAC), leading to a denial of service in Voice over IP applications. In particular, INVITE message is considered as one of the major root causes of flooding attacks in SIP. This is due to the fact that an attacker may send numerous INVITE requests without waiting for responses from the UAS or the proxy in order to exhaust their respective resources. Most of the devised solutions to cope with the flooding attack are either difficult to deploy in practice or require significant changes in the SIP servers implementation. Apart from these challenges, flooding attacks are much more diverse in nature, which makes the task of defeating them a real challenge. In this survey, we present a comprehensive study of flooding attack against SIP, by addressing its different variants and analyzing its consequences. We also classify the existing solutions according to the different flooding behaviors they are dealing with, their types, and targets. Moreover, we conduct a thorough investigation of the main strengths and weaknesses of these solutions and deeply analyze the underlying assumptions of each of them for better understanding of their limitations. Finally, we provide some recommendations for enhancing the effectiveness of the surveyed solutions and address some open challenges. [ABSTRACT FROM AUTHOR]

In mobile ad hoc networks (MANETs), the nodes need to cooperate each other to establish multi-hop routes for out-of-range wireless communication. However, some of them may not always behave normally, either behaving selfishly for saving computational resource or maliciously for compromising communication protocols. Regardless of intents, such misbehavior would lead to the degradation of network performance. It is therefore important to design appropriate mechanisms to ensure that network performance could be maintained at an acceptable level in the presence of misbehaving nodes. But the open nature of MANETs makes such designs challenging. Reputation system has been widely recognized as an effective approach, which associates the behavior of nodes with its reputation, which is calculated by specifying and quantifying the observations of interest with respect to predefined performance metrics. More interestingly, the observations can be obtained and integrated from multiple layers, facilitating cross-layer analysis. This paper intends to take a deep look into several well-studied reputation systems and examine their operational characteristics in terms of modeling approaches and redemption techniques, with an objective to identify their capabilities in terms of misbehavior detection coverage and blind spots. Furthermore, such an anatomy allows us to better understand the failure curses of the deployment and operation of reputation systems in MANETs, so as to improve their performance by adopting effective countermeasures.Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Duty cycling is a fundamental approach used in contention-based medium access control (MAC) protocols for wireless sensor networks (WSNs) to reduce power consumption in sensor nodes. Existing duty cycle-based MAC protocols use either scheduling or low-power listening (LPL) to reduce unnecessary energy lost caused by idle listening and overhearing. This paper presents a new asynchronous duty-cycled MAC protocol for WSN. It introduces a novel dual preamble sampling (DPS) approach to efficiently coordinate channel access among nodes. DPS combines LPL with a short-strobed preamble approach to significantly reduce the idle-listening issue in existing asynchronous protocols. We provide detailed analysis of the energy consumption by using well-known energy models and compare our work with B-MAC and X-MAC, two most popular asynchronous duty cycle-based MAC protocols for WSNs. We also present experimental results based on NS-2 simulations. We show that depending on the traffic load and preamble length, the proposed MAC protocol improves energy consumption significantly without degrading network performances in terms of delivery ratio and latency. For example, for a traffic rate of 0.1 packets/s and a preamble length of 0.1 s, the average improvement in energy consumption is about 154%. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents an efficient hybrid medium-access control (HMAC) protocol with an embedded cross-layer optimization solution to provide routing-layer coarse-grained end-to-end quality-of-service (QoS) support for latency-sensitive traffic flows. A novel channel-reservation technique is proposed to significantly reduce the end-to-end delay for delay-sensitive traffic flows by allowing packets to go through multiple hops within a single medium-access control (MAC) frame and by also giving them higher priority channel access to reduce possible queuing delay. Our proposed protocol (HMAC) combines energy-efficient features of the existing contention-based and time-division multiple-access (TDMA)-based MAC protocols and adopts a short frame structure to expedite packet delivery. Simulation results in ns-2 show that HMAC achieves significant performance improvements in energy consumption, latency, and throughput over existing MAC protocols. [ABSTRACT FROM AUTHOR]

The most commonly used medium access mechanism in wireless mesh networks is based on the CSMA/CA protocol. This protocol schedules properly the access to the medium among all the competing nodes. However, in a hostile environment, such as wireless mesh networks (WMNs), selfish or greedy behaving nodes may prefer to decline the proper use of the protocol rules in order to increase their bandwidth shares at the expense of the well-behaving nodes. In this paper, we focus on such misbehavior and in particular on the adaptive greedy misbehavior of a node in the context of WMN environment. In such environment, wireless nodes compete to gain access to the medium and communicate with a mesh router (MR). In this case, a greedy node may violate the protocol rules in order to earn extra bandwidth share upon its neighbors. In order to avoid its detection, this node may adopt different techniques and switch dynamically between each of them. To counter such misbehavior, we propose to use a fuzzy logic-based detection scheme. This scheme, dubbed FLSAC, is implemented in the MR/gateway to monitor the behavior of the attached wireless nodes and report any deviation from the proper use of the protocol. The simulation results of the proposed FLSAC scheme show robustness and its ability to detect and identify quickly any adaptive cheater. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents an analysis framework for estimating spatio-temporal distortion associated with data-gathering algorithms in sensor networks. We assume that the underlying data field being sensed is spatially and temporally correlated and that the sink node performs real-time reconstruction of the field. Unlike existing work, the proposed analysis framework assumes realistic transmission schemes and network/routing parameters, such as congestion and limited transmission range. Our simulations show that, even for a simple collision-free transmission scheme and regular deployment patterns, the distortion analyses yield starkly different results, compared with the analyses performed in the absence of these assumptions. The analytical method presented in this paper could easily be extended to consider the real-time data-reconstruction problem under different transmission schemes, node distributions, and reconstruction methods. [ABSTRACT FROM AUTHOR]

A particularly severe attack on routing protocols in ad hoc networks is the so-called worm- hole attack in which two or more colluding attackers record packets at one location, and tunnel them to another location for replay at that remote location. When this attack targets specifically routing control packets, the nodes that are close to the attackers are shielded from any alternative routes with more than one or two hops to the remote location. All routes are thus directed to the wormhole established by the attackers. In the optimized link state routing protocol, if a wormhole attack is launched during the propagation of link state packets, the wrong link information percolates throughout the network, leading to routing disruption. In this article we devise an efficient method to detect and avoid wormhole attacks in the OLSR protocol. This method first attempts to pinpoint links that may potentially be part of a wormhole tunnel. Then a proper wormhole detection mechanism is applied to suspicious links by means of an exchange of encrypted probing packets between the two supposed neighbors (endpoints of the wormhole). The proposed solution exhibits several advantages, among which are its nonreliance on any time synchronization or location information, and its high detection rate under various scenarios. [ABSTRACT FROM AUTHOR]