Jesus Friginal

Towards benchmarking routing protocols in wireless mesh networks

Wireless mesh networks (WMNs) establish a new, quick and low-cost alternative to provide communications when deploying a fixed infrastructure that could result prohibitive in terms of either time or money. During last years, the specification of multi-hop routing protocols for WMNs has been promoted, leading to their recent exploitation in commercial solutions. The selection of routing protocols for integration in WMNs requires the evaluation, comparison and ranking of eligible candidates according to a representative set of meaningful measures. In this context, the development of suitable experimental techniques to balance different features of each protocol is an essential requirement. This paper copes with this challenging task by proposing a benchmarking methodology to experimentally evaluate and compare the behaviour of these protocols. The feasibility of the proposed approach is illustrated through a simple but real (non-simulated) case study and reflects to what extent this methodology can be useful in increasing our knowledge on how real WMNs behave in practice.

An Attack Injection Approach to Evaluate the Robustness of Ad Hoc Networks

Ad hoc networks constitute a quick and cheap alternative to provide communications when deploying a fixed infrastructure could result prohibitive in terms of either time or money. Although the unique properties of ad hoc networks make them very sensitive to malicious faults attacks), most of current research has focused on improving their routing capabilities, thus widening their application domains, and very little attention has been devoted to their dependability. Accordingly, the confident use of this technology requires the development of new techniques and tools to assess the robustness of such networks in presence of attacks. This paper deals with this challenging goal by proposing an attack injection approach based on real ad hoc networks as experimental platform. Experiments show the feasibility of the proposed approach and identify a large number of possibilities to increase our knowledge on how real ad hoc networks behave in practice.

Towards privacy-driven design of a dynamic carpooling system

Dynamic carpooling (also known as instant or ad-hoc ridesharing) is a service that arranges one-time shared rides on very short notice. This type of carpooling generally makes use of three recent technological advances: (i) navigation devices to determine a drivers route and arrange the shared ride; (ii) smartphones for a traveller to request a ride from wherever she happens to be; and (iii) social networks to establish trust between drivers and passengers. However, the mobiquitous environment in which dynamic carpooling is expected to operate raises several privacy issues. Among all the personal identifiable information, learning the location of an individual is one of the greatest threats against her privacy. For instance, the spatio-temporal data of an individual can be used to infer the location of her home and workplace, to trace her movements and habits, to learn information about her centre of interests or even to detect a change from her usual behaviour. Therefore, preserving location privacy is a major issue to be able to leverage the possibilities offered by dynamic carpooling. In this paper we use the principles of privacy-by-design to integrate the privacy aspect in the design of dynamic carpooling, henceforth increasing its public (and political) acceptability and trust.

On Selecting Representative Faultloads to Guide the Evaluation of Ad Hoc Networks

Ad hoc networks are threatened by a wide variety of accidental and malicious faults. This fact limits the practical exploitation of ad hoc networks. In consequence, apart from enforcing the dependability and security aspects of these networks, the provision of approaches to evaluate their behaviour in the presence of faults and attacks is of paramount importance. Accordingly, analysing and determining which threats should be considered for the evaluation of each particular ad hoc network is an essential task for the definition of representative faultloads. Our previous work focused on evaluating the impact of black and grey hole attacks in real networks using attack injection. This paper enriches the faultload of our experimental platform with five new types of accidental and malicious faults. The goal is to provide the basis for guiding the selection of suitable faultloads when assessing the impact of different threats in different types of ad hoc networks, like wireless sensor networks (WSN) and mobile ad hoc networks (MANET), considering the importance of the applicative context in the interpretation of results.

Attack Injection to Support the Evaluation of Ad Hoc Networks

The increasing emergence of mobile computing devices seamlessly providing wireless communication capabilities opens a wide range of new application domains for ad hoc networks. However, the sensitivity of ad hoc routing protocols to malicious faults (attacks) limits in practice their confident use in commercial products. This requires not only practical means to enforce the security of these protocols, but also approaches to evaluate their behaviour in the presence of attacks. Our previous contribution to the evaluation of ad hoc networks has been focused on the definition of an approach for injecting grey hole attacks in real (non-simulated) ad hoc networks. This paper relies on the use of this methodology to evaluate (i) three different implementations of a proactive ad hoc routing protocol, named OLSR, and (ii) two ad hoc routing protocols of different nature, one proactive (OLSR) and one reactive (AODV). Reported results have proven useful to extend the applicability of attack injection methodologies for evaluation beyond the mere assessment of the robustness of ad hoc routing protocols.

Analysis of results in dependability benchmarking: Can we do better?

Dependability benchmarking has become through the years more and more important in the process of systems evaluation. The increasing need for making systems more dependable in presence of perturbations has contributed to this fact. Nevertheless, even though many studies have focused on different areas related to dependability benchmarking, and some others have focused on the need of providing these benchmarks with good quality measures, there is still a gap in the process of the analysis of results. This paper focuses on providing a first glance at different approaches that may help filling this gap by making explicit the criteria followed in the decision making process.

Mitigating the impact of ambient noise on Wireless Mesh Networks using adaptive link-quality-based packet replication

Wireless Mesh networks (WMN) typically rely on proactive routing protocols to establish optimal communication routes between every pair of system nodes. These protocols integrate link-quality-based mechanisms to minimise the adverse effect of ambient noise on communications. This paper shows the limitations existing in such mechanisms by analysing the impact of ambient noise on three state-of-the-art proactive routing protocols: OLSR, B.A.T.M.A.N and Babel. As will be shown, the lack of context-awareness in their link-quality mechanisms prevents the protocols from adjusting their behaviour according to persistent levels of ambient noise, which may vary along the time. Consequently, they cannot minimise the impact of such noise on the availability of network routes. This issue is very serious for a WMN since the loss communication links may strongly increase the convergence time of the network. An adaptive extension to studied link-quality-based mechanisms is proposed to avoid the loss of communication links in the presence of high levels of ambient noise. The effectiveness of the proposal is experimentally assessed, thus establishing a new method to reduce the impact of ambient noise on WMN.

Resilience-Driven Parameterisation of Ad Hoc Routing Protocols: olsrd as a Case Study

Ad hoc routing protocols are threatened by a variety of accidental and malicious faults that limit their use. Although a number of well-known strategies exist to enhance the performance and resilience of such type of protocols, their final effectiveness strongly relies on the usage of appropriate protocol configuration parameters. This paper investigates how to parameterise ad hoc routing protocols to combine high performance, with acceptable levels of resilience and low consumption of resources. The research places the spotlight on olsrd, an ad hoc proactive routing protocol able to run on real devices and deploy challenge-response authentication, packet signature and fault tolerance strategies at runtime. The reported practical experience is carried out in different ad hoc networking contexts integrating different types of devices, thus checking the influence that mobility of nodes and device resource constraints have on the parameterisation of the different protocol features considered.

An aspect-oriented approach to face neighbour saturation issues in proactive ad hoc routing protocols: olsrd as a case study

Ad hoc networking is gaining momentum in contexts of use requiring the rapid, and low cost, deployment of communication networks. However, many studies show that ad hoc routing protocols are threatened by a variety of accidental and malicious faults that limit their use in practice. This paper explores the feasibility of using Aspect-Oriented Programming (AOP) to develop reusable mechanisms to mitigate the negative effects of a high density of neighbour nodes on the dependability of olsrd, an implementation of the Optimised Link-State Routing protocol (OLSR), one of the most widely-used ad hoc routing protocol implementations existing today. On one hand, aspect orientation has the potential to promote a clear separation between existing functional (protocol-related) capabilities and the non-functional (fault tolerance-related) features of the system. On the other hand, this approach eases the adaptation of fault tolerance mechanisms to evolutions the protocol implementations may suffer along the time.

Coarse-grained resilience benchmarking using logic score of preferences: ad hoc networks as a case study

Ad hoc networks are self-configuring multi-hop wireless networks whose routing protocols are extremely sensitive to the occurrence of accidental and malicious faults. However, the behaviour exhibited by such protocols varies from one to another. This context motivates the importance of using resilience benchmarking strategies to evaluate, compare and select the most suitable routing protocol alternative, among those available, for each application. Experience shows that such selection process is very complex, since requiring the simultaneous consideration a wide set of different performance, resilience, energy consumption and cost measures. This selection can turn into a complex task when the effect of a big number of perturbations (attacks and accidental faults) is considered on a big variety of protocols. The use of general scores, resulting from the aggregation of different measures, provide an interesting way of obtaining a macroscopic view of the behaviour exhibited by evaluated targets. The idea is to reduce the number of candidates, and then use more fine-grained measures in order to compare only the finally retained candidates. This paper works on this idea by proposing the use of the Logic Score Preferences (LSP) technique to combine and aggregate performance, resilience and energy consumption measures into a single global score. The use of this score will be limited to the very first steps of resilience benchmarking, where decision making is hard for benchmark performers due to the number and variety of available measures. The use of the approach is illustrated through a case study where an ad hoc routing protocol, olsrd v. 0.6.0, is evaluated in the presence of accidental faults and attacks. This contribution must not be considered as a replacement of, but rather as a complement to the typical comparison and selection activities deployed during resilience benchmarking.