Reducing Efficiency of Connectivity-Splitting Attack on Newscast via Limited Gossip

Newscast is aPeer-to-Peer, nature-inspired gossip-based data exchange protocol used for information dissemination and membership management in large-scale, agent-based distributed systems. The model follows a probabilistic scheme able to keep a self-organised, small-world equilibrium featuring a complex, spatially structured and dynamically changing environment. Newscast gained popularity since the early 2000s thanks to its inherent resilience to node volatility as the protocol exhibits strong self-healing properties. However, the original design proved to be surprisingly fragile in a byzantine environment subjected to cheating faults. Indeed, a set of recent studies emphasized the hard-wired vulnerabilities of the protocol, leading to an efficient implementation of a malicious client, where a few naive cheaters are able to break the network connectivity in a very short time. Extending these previous works, we propose in this paper a modification of the seminal protocol with embedded counter-measures, improving the resilience of the scheme against malicious acts without significantly affecting the original Newscast’s proper- ties nor its inherent performance. Concrete experiments were performed to support these claims, using a framework implementing all the solutions discussed in this work

Measuring the Fog, Gently

The availability of suitable monitoring tools and techniques will be crucial to orchestrate multi-service applications in a context- and QoS-aware manner over new Fog infrastructures. In this paper, we propose FogMon, a lightweight distributed prototype monitoring tool, which measures data about hardware resources (viz., CPU, RAM, HDD) at the available Fog nodes, end-to-end network QoS (viz., latency and bandwidth) between those nodes, and detects connected IoT devices. FogMon is organised into a peer-to-peer architecture and it shows a very limited footprint on both hardware and bandwidth. The usage of FogMon on a real testbed is presented

Third and fifth harmonic responses in viscous liquids

International audienceWe review the works devoted to third and fifth harmonic susceptibilities in glasses, namely χ (3) 3 and χ (5) 5. We explain why these nonlinear responses are especially well adapted to test whether or not some amorphous correlations develop upon cooling. We show that the experimental frequency and temperature dependences of χ (3) 3 and of χ (5) 5 have anomalous features, since their behavior is qualitatively different to that of an ideal gas, which is the high-temperature limit of a fluid. Most of the works have interpreted this anomalous behavior as reflecting the growth, upon cooling, of amorphously ordered domains, as predicted by the general framework of Bouchaud and Biroli (BB). We explain why most—if not all—of the challenging interpretations can be recast in a way which is consistent with that of Bouchaud and Biroli. Finally, the comparison of the anomalous features of χ (5) 5 and of χ (3) 3 shows that the amorphously ordered domains are compact, i.e., the fractal dimension d f is close to the dimension d of space. This suggests that the glass transition of molecular liquids corresponds to a new universality class of critical phenomena