This paper presents a simple local medium access control protocol, called , for multi-hop wireless networks with a single channel that is provably robust against adaptive adversarial jamming. The wireless network is modeled as a unit disk graph on a set of nodes distributed arbitrarily in the plane. In addition to these nodes, there are adversarial jammers that know the protocol and its entire history and that are allowed to jam the wireless channel at any node for an arbitrary @math -fraction of the time steps, where @math is an arbitrary constant. We assume that the nodes cannot distinguish between jammed transmissions and collisions of regular messages. Nevertheless, we show that achieves an asymptotically optimal throughput if there is a sufficiently dense distribution of nodes.
Traditionally, jamming defense mechanisms operate on the physical layer @cite_5 @cite_42 @cite_40 . Mechanisms have been designed to avoid jamming as well as detect jamming. Spread spectrum technology has been shown to be very effective to avoid jamming as with widely spread signals, it becomes harder to detect the start of a packet quickly enough in order to jam it. Unfortunately, protocols such as IEEE 802.11b use relatively narrow spreading @cite_26 , and some other IEEE 802.11 variants spread signals by even smaller factors @cite_27 . Therefore, a jammer that simultaneously blocks a small number of frequencies renders spread spectrum techniques useless in this case. As jamming strategies can come in many different flavors, detecting jamming activities by simple methods based on signal strength, carrier sensing, or packet delivery ratios has turned out to be quite difficult @cite_8 .
@cite_26 @cite_8 @cite_42 @cite_40 @cite_27 @cite_5
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Wireless networks are built upon a shared medium that makes it easy for adversaries to launch jamming-style attacks. These attacks can be easily accomplished by an adversary emitting radio frequency signals that do not follow an underlying MAC protocol. Jamming attacks can severely interfere with the normal operation of wireless networks and, consequently, mechanisms are needed that can cope with jamming attacks. In this paper, we examine radio interference attacks from both sides of the issue: first, we study the problem of conducting radio interference attacks on wireless networks, and second we examine the critical issue of diagnosing the presence of jamming attacks. Specifically, we propose four different jamming attack models that can be used by an adversary to disable the operation of a wireless network, and evaluate their effectiveness in terms of how each method affects the ability of a wireless node to send and receive packets. We then discuss different measurements that serve as the basis for detecting a jamming attack, and explore scenarios where each measurement by itself is not enough to reliably classify the presence of a jamming attack. In particular, we observe that signal strength and carrier sensing time are unable to conclusively detect the presence of a jammer. Further, we observe that although by using packet delivery ratio we may differentiate between congested and jammed scenarios, we are nonetheless unable to conclude whether poor link utility is due to jamming or the mobility of nodes. The fact that no single measurement is sufficient for reliably classifying the presence of a jammer is an important observation, and necessitates the development of enhanced detection schemes that can remove ambiguity when detecting a jammer. To address this need, we propose two enhanced detection protocols that employ consistency checking. The first scheme employs signal strength measurements as a reactive consistency check for poor packet delivery ratios, while the second scheme employs location information to serve as the consistency check. Throughout our discussions, we examine the feasibility and effectiveness of jamming attacks and detection schemes using the MICA2 Mote platform. It has long been recognized that complete jamming of wireless networks can be realized by generating continuous noise with sufficient power in the vicinity of the wireless network. There are many disadvantages of this approach including high energy requirements and a high probability of detection. The purpose of this paper is to show that similar jamming effectiveness can be achieved with very low energy requirements and low probability of detection. We discuss various measures of performance for jamming and the role of authentication in denial of service attacks. Then we study and simulate, using OPNET 11.5, the effect of periodic jamming on throughput for an 802.11b network. We add intelligence to the jammer by using knowledge of the protocol and exploiting crucial timings and control packets. Intelligent jamming is shown to be more efficient than continuous jamming in terms of signal duration. The next approach is to use a node or two to exploit the backoff timer to create a denial of service attack. Finally, we discuss how these attacks can be applied to networks with protocols such as MILSTD- 188-220D. Jamming is a very effective denial-of-service attack that renders most higher-layer security mechanisms moot - yet it is often ignored in WSN design. We show that an interrupt jamming attack is simple to perpetrate in software using a MICAz mote, is energy efficient and stealthy for the jammer, and completely disrupts communication. Solutions are needed to mitigate this insider threat even if more powerful attackers are not thwarted. We present DEEJAM, a novel MAC-layer protocol for defeating stealthy jammers with IEEE 802.15.4-based hardware, to address this problematic area. It layers four defensive mechanisms to hide communication from a jammer, evade its search, and reduce its impact. Given the difficulty of modeling the physical layer accurately in simulation, we evaluate DEEJAM instead on the MICAz mote. We show the performance of the protocol against successively more complex attacks: interrupt jamming, activity jamming, scan jamming, and pulse jamming. Results show that DEEJAM defeats the otherwise devastating interrupt jammer, and achieves a packet delivery ratio of 88 in the presence of a pulse jammer. To the best of our knowledge, this work is the first to confront multiple types of jamming on common WSN hardware with solutions that are shown empirically to enable continued communication despite an ongoing attack. A typical wireless sensor node has little protection against radio jamming. The situation becomes worse if energy-efficient jamming can be achieved by exploiting knowledge of the data link layer. Encrypting the packets may help prevent the jammer from taking actions based on the content of the packets, but the temporal arrangement of the packets induced by the nature of the protocol might unravel patterns that the jammer can take advantage of even when the packets are encrypted. By looking at the packet interarrival times in three representative MAC protocols, S-MAC, LMAC and B-MAC, we derive several jamming attacks that allow the jammer to jam S-MAC, LMAC and B-MAC energy-efficiently. The jamming attacks are based on realistic assumptions. The algorithms are described in detail and simulated. The effectiveness and efficiency of the attacks are examined. Careful analysis of other protocols belonging to the respective categories of S-MAC, LMAC and B-MAC reveal that those protocols are, to some extent, also susceptible to our attacks. The result of this investigation provides new insights into the security considerations of MAC protocols.