Security analysis of the micro transport protocol with a misbehaving receiver

BitTorrent is the most widely used Peer-to-Peer (P2P) protocol and it comprises the largest share of traffic in Europe. To make BitTorrent more Internet Service Provider (ISP) friendly, BitTorrent Inc. invented the Micro Transport Protocol (uTP). It is based on UDP with a novel congestion control called Low Extra Delay Background Transport (LEDBAT). This protocol assumes that the receiver always gives correct feedback, since otherwise this deteriorates throughput or yields to corrupted data. We show through experimental investigation that a misbehaving uTP receiver, which is not interested in data integrity, can increase the bandwidth of the sender by up to five times. This can cause a congestion collapse and steal large share of a victim’s bandwidth. We present three attacks, which increase the bandwidth usage significantly. We have tested these attacks in a real world environment and show its severity both in terms of number of packets and total traffic generated. We also present a countermeasure for protecting against the attacks and evaluate the performance of that defence strategy

Stealing bandwidth from BitTorrent seeders

BitTorrent continues to comprise the largest fraction of Internet traffic. While significant progress has been made in understanding the BitTorrent choking mechanism, its security vulnerabilities have not been investigated thoroughly. This paper presents an experimental analysis of bandwidth attacks against different choking algorithms in the BitTorrent seed state. We reveal a simple exploit that allows malicious peers to receive a considerably higher download rate than contributing leechers, therefore introducing significant efficiency degradations for benign peers. We show the damage caused by the proposed attack in two different environments: a lab testbed comprising 32 peers and a PlanetLab testbed with 300 peers. Our results show that 3 malicious peers can degrade the download rate up to 414.99% for all peers. Combined with a Sybil attack that consists of as many attackers as leechers, it is possible to degrade the download rate by more than 1000%. We propose a novel choking algorithm which is immune against bandwidth attacks and a countermeasure against the revealed attack

Evaluation and improvement of CDS-based topology control for wireless sensor networks

The connected dominating set (CDS) principle has emerged as the predominant method for energy-efficient discovery and clustering of power-/location-unaware WSN nodes. While many CDS discovery protocols have been proposed recently, a one-to-one comparative evaluation of these protocols has not been performed on judicious metrics. In this paper, we perform a simulation-based evaluation of three prominent CDS based protocols (CDS Rule K, EECDS and A3) on the basis of message and energy overhead, residual energy, number of unconnected nodes, and convergence time. Our analysis shows that the protocols’ performances vary significantly with different maintenance techniques and none of the existing protocols can outperform the others on all metrics. Based on this result, we identify some performance-improving guidelines for CDS-based topology discovery and utilize them to propose a new protocol, clique-based CDS discovery (CCDS). We show that CCDS provides considerably better performance than existing protocols in most operational scenarios

Poly: A Reliable and Energy Efficient Topology Control Protocol for Wireless Sensor Networks

Energy efficiency and reliability are the two important requirements for mission-critical wireless sensor networks. In the context of sensor topology control for routing and dissemination, Connected Dominating Set (CDS) based techniques proposed in prior literature provide the most promising efficiency and reliability. In a CDS-based topology control technique, a backbone – comprising a set of highly connected nodes – is formed which allows communication between any arbitrary pair of nodes in the network. In this paper, we show that formation of a polygon in the network provides a reliable and energy-efficient topology. Based on this observation, we propose Poly, a novel topology construction protocol based on the idea of polygons. We compare the performance of Poly with three prominent CDS-based topology construction protocols namely CDS-Rule K, Energy-efficient CDS (EECDS) and A3. Our simulation results demonstrate that Poly performs consistently better in terms of message overhead and other selected metrics. We also model the reliability of Poly and compare it with other CDS-based techniques to show that it achieves better connectivity under highly dynamic network topologies

Study on Static Electrification of Palm Fatty Acid Ester (PFAE) Oil Using Mini Static Tester (Archive)

Palm fatty acid ester (PFAE) oil is an alternative insulating liquid of power transformer that has good biodegradable properties. As a part of insulating system of power transformer, PFAE should also has a low risk in term of static electrification that may degrade electrical strength of solid insulation due to charge accumulation at its surface during oil circulating. Charge potential value could describe the possibility of insulating oil in involving on charge accumulation at the surface of solid insulation. This can be calculated from charge density through electrostatic charge tendency (ECT) and volume resistivity. This study using mini-static-tester to measure ECT since it is easy to reproduce the specimen and suitable for standardization. Since PFAE has higher polarity than mineral oil, PFAE has larger charges than mineral oil. Even though static charges are estimated to generate on the pressboard surface easily, generated charges are estimated to escape from pressboard surface because of its lower resistivity. Variation of charge density and volume resistivity of several types (i.e. PFAE and mineral) and conditions (i.e. with-additives, non-additives, unused, and aged) of oil will influence to its charge potentia

Comparing apples and oranges: assessment of the relative video quality in the presence of different types of distortions

<p>Abstract</p> <p>Video quality assessment is essential for the performance analysis of visual communication applications. Objective metrics can be used for estimating the relative quality differences, but they typically give reliable results only if the compared videos contain similar types of quality distortion. However, video compression typically produces different kinds of visual artifacts than transmission errors. In this article, we focus on a novel subjective quality assessment method that is suitable for comparing different types of quality distortions. The proposed method has been used to evaluate how well different objective quality metrics estimate the relative subjective quality levels for content with different types of quality distortions. Our conclusion is that none of the studied objective metrics works reliably for assessing the co-impact of compression artifacts and transmission errors on the subjective quality. Nevertheless, we have observed that the objective metrics' tendency to either over- or underestimate the perceived impact of transmission errors has a high correlation with the spatial and temporal activity levels of the content. Therefore, our results can be useful for improving the performance of objective metrics in the presence of both source and channel distortions.</p