AMI threats, intrusion detection requirements and deployment recommendations

Abstract—Advanced Metering Infrastructures (AMI) facilitate bidirectional communication between smart meters and utilities, allowing information about consumption, outages, and electricity rates to be shared reliably and efficiently. However, the numerous smart meters being connected through mesh networks open new opportunities for attackers to interfere with communications and compromise utilities ’ assets or steal customers ’ private information. The goal of this paper is to survey the various threats facing AMIs and the common attack techniques used to realize them in order to identify and understand the requirements for a comprehensive intrusion detection solution. The threat analysis leads to an extensive “attack tree ” that captures the attackers’ key objectives (e.g., energy theft) and the individual attack steps (e.g., eavesdropping on the network) that would be involved in achieving them. With reference to the attack tree, we show the type of information that would be required to effectively detect attacks. We also suggest that the widest coverage in monitoring the attacks can be provided by a hybrid sensing infrastructure that uses both a centralized intrusion detection system and embedded meter sensors. I

Experimental evaluation of the usage of ad hoc networks as stubs for multiservice networks

This paper describes an experimental evaluation of a multiservice ad hoc network, aimed to be interconnected with an infrastructure, operator-managed network. This network supports the efficient delivery of services, unicast and multicast, legacy and multimedia, to users connected in the ad hoc network. It contains the following functionalities: routing and delivery of unicast and multicast services; distributed QoS mechanisms to support service differentiation and resource control responsive to node mobility; security, charging, and rewarding mechanisms to ensure the correct behaviour of the users in the ad hoc network. This paper experimentally evaluates the performance of multiple mechanisms, and the influence and performance penalty introduced in the network, with the incremental inclusion of new functionalities. The performance results obtained in the different real scenarios may question the real usage of ad-hoc networks for more than a minimal number of hops with such a large number of functionalities deployed

Isotopic exchange processes in cold plasmas of H2/D2 mixtures

12 páginas, 3 tablas, 10 figuras.-Isotope exchange in low pressure cold plasmas of H2/D2 mixtures has been investigated by means of mass spectrometric measurements of neutrals and ions, and kinetic model calculations. The measurements, which include also electron temperatures and densities, were performed in a stainless steel hollow cathode reactor for three discharge pressures: 1, 2 and 8 Pa, and for mixture compositions ranging from 100% H2 to 100% D2. The data are analyzed in the light of the model calculations, which are in good global agreement with the experiments. Isotope selective effects are found both in the surface recombination and in the gas-phase ionic chemistry. The dissociation of the fuel gas molecules is followed by wall recycling, which regenerates H2 and D2 and produces HD. Atomic recombination at the wall is found to proceed through an Eley–Rideal mechanism, with a preference for reaction of the adsorbed atoms with gas phase D atoms. The best fit probabilities for Eley–Rideal abstraction with H and D are:gER H = 1.5 x 10-3, gER D = 2.0 x 10-3. Concerning ions, at 1 Pa the diatomic species H2+,D2+ and HD+, formed directly by electron impact, prevail in the distributions, and at 8 Pa, the triatomic ions H3+, H2D+, HD2+ and D3+, produced primarily in reactions of diatomic ions with molecules, dominate the plasma composition. In this higher pressure regime, the formation of the mixed ions H2D+ and HD2 + is favoured in comparison with that of H3 + and D3+, as expected on statistical grounds. The model results predict a very small preference, undetectable within the precision of the measurements, for the generation of triatomic ions with a higher degree of deuteration, which is probably a residual influence at room temperature of the marked zero point energy effects (ZPE), relevant for deuterium fractionation in interstellar space. In contrast,ZPE effects are found to be decisive for the observed distribution of monoatomic ions H+ and D+, even at room temperature. The final H+/D+ ratio is determined to a great extent by proton (and deuteron) exchange, which favours the enhancement of H+ and the concomitant decrease of D+.This work has been funded by the MICINN of Spain under projects FIS 2007-61686, FIS2010-16455 and CSD2009-00038. EC acknowledges also funding from the JdC program of the MICINN.Peer reviewe

Adaptive demand-driven multicast routing in multi-hop wireless ad hoc networks

The use of on-demand techniques in routing protocols for multihop wireless ad hoc networks has been shown to have significant advantages in terms of reducing the routing protocol’s overhead and improving its ability to react quickly to topology changes in the network. A number of on-demand multicast routing protocols have been proposed, but each also relies on significant periodic (non-on-demand) behavior within portions of the protocol. This paper presents the design and initial evaluation of the Adaptive Demand-Driven Multicast Routing protocol (ADMR), a new ondemand ad hoc network multicast routing protocol that attempts to reduce as much as possible any non-on-demand components within the protocol. Multicast routing state is dynamically established and maintained only for active groups and only in nodes located between multicast senders and receivers. Each multicast data packet is forwarded along the shortest-delay path with multicast forwarding state, from the sender to the receivers, and receivers dynamically adapt to the sending pattern of senders in order to efficiently balance overhead and maintenance of the multicast routing state as nodes in the network move or as wireless transmission conditions in the network change. We describe the operation of the ADMR protocol and present an initial evaluation of its performance based on detailed simulation in ad hoc networks of 50 mobile nodes. We show that ADMR achieves packet delivery ratios within 1 % of a floodingbased protocol, while incurring half to a quarter of the overhead. 1

On-demand multicast routing in ad hoc networks with unidirectional links

Abstract: "Many techniques used by routing protocols for ad hoc networks assume that links in the network can be used equally well in both directions between the two endpoint nodes of the link. However, there are many real-world situations in which wireless links may physically work in only one direction, resulting in degradation of routing performance in the network. In this paper, we present the first study of the effect of unidirectional links on the performance of on-demand multicast routing protocols for ad hoc networks and present mechanisms that enable such protocols to route efficiently over unidirectional links. We evaluate these mechanisms in the context of the Adaptive Demand-Driven Multicast Routing protocol (ADMR), and simulate the extended protocol, ADMR-U, in a wide range of mobile and static network scenarios with unidirectional links. In networks with only bidirectional links, the unidirectional extensions do not get activated and cause no overhead; in networks with unidirectional links, ADMR-U matches or outperforms ADMR in terms of packet delivery ratio, and lowers ADMR's packet overhead.

A performance comparison of on-demand multicast routing protocols for ad hoc networks

Abstract: "In this paper, we present a comparative performance evaluation of three general-purpose on-demand multicast protocols, namely ADMR, MAODV, and ODMRP, focusing on the effects of changes such as increasing number of multicast receivers or sources, application sending pattern, and increasing number of nodes in the network. We use mobile networks composed of 100 or 200 nodes, with both a single active multicast group and multiple active multicast groups in the network, in a wide range of multicast scenarios. Although some simulation results for these protocols have been published before, the three protocols have not been compared, and prior studies have focused on smaller networks using a small set of simulation scenarios, many with only a single active multicast group. We focus here on the effects of the protocol's relative degree of on-demand behavior and their performance in different multicast scenarios.

POP-level and Access-link-level Traffic Dynamics in a Tier-1

Abstract—In this paper, we study traffic demands in an IP bacbkone, identify the routes used by these demands, and evaluate traffic granularity levels that are attractive for improving the poor load balancing that our study reveals. The data used in this study was collected at a major POP in a commercial Tier-1 IP backbone. In the first part of this paper we ask two questions. What is the traffic demand between a pair of POPs in the backbone? How stable is this demand? We develop a methodology that combines packet-level traces from access links in the POP and BGP routing information to build components of POP-to-POP traffic matrices. Our analysis shows that the geographic spread of traffic across egress POPs is far from uniform. In addition, we find that the time of day behaviors for different POPs and different access links also exhibit a high degree of heterogeneity. In the second part of this work, we examine commercial routing practices to assess how these demands are routed through the backbone. We find that traffic between a pair of POPs is engineered to be restricted to a few paths and that this contributes to widely varying link utilization levels. The natural question that follows from these findings is whether or not there is a better way to spread the traffic across backbone paths. We identify traffic aggregates based on destination address prefixes and find that this set of criteria isolates a few aggregates that account for an overwhelmingly large portion of inter-POP traffic. We demonstrate that these aggregates exhibit stability throughout the day on perhour time scales, and thus form a natural basis for splitting traffic over multiple paths to improve load balancing