78 research outputs found
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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
On the Impact of Practical P2P Incentive Mechanisms on User Behavior
In this paper we report on the results of a large-scale measurement
study of two popular peer-topeer systems, namely BitTorrent and eMule,
that use practical and lightweight incentive mechanisms to encourage
cooperation between users. We focus on identifying the strategic
behavior of users in response to those incentive mechanisms. Our results
illustrate a gap between what system designers and researchers expect
from users in reaction to an incentive mechanism, and how users react to
those incentives. In particular, we observe that the majority of
BitTorrent users appear to cooperate well, despite the existence of
known ways to tamper with the incentive mechanism, users engaging in
behavior that could be regarded as cheating comprised only around 10% of
BitTorrent’s population. That is, although we know that users can
easily cheat, they actually do not currently appear to cheat at a large
enough scale. In the eMule system, we identify several distinct classes
of users based on their behavior. A large fraction of users appears to
perceive cooperation as a good strategy, and openly share all the files
they obtained. Other users engage in more subtle strategic choices, by
actively optimizing the number and types of files they share in order to
improve their standing in eMule’s waiting queues; they tend to
remove files for which downloading is complete and keep a limited total
volume of files shared
An Analysis of incentives mechanisms and evaluation on BitTorrent
Since the first peer-to-peer communities appeared, their number of users has increased considerably owing to the benefits they offer compared to their alternative architectures in the sharing and distribution of multimedia content. However, due to its distributed nature, they can suffer an important problem of misuse: free-riding. Free-riding consists on users consuming resources without contributing to the system. Such behaviour not only is not fair for the rest of the users, but also threatens the success of this type of nets. With the motivation to avoid free-riding, the mechanisms of incentives were born. They provide the system with a method to motivate the nodes and make them share their resources with the other users. In one word, they provide the net with the needed fairness to achieve a good performance for all users. This thesis is organised in two main parts. In the first part there is a comprehensive study of the state of the art regarding the incentive mechanisms, resulting in a classification depending on the characteristics of the studied algorithms. That study provides the reader with a first sight of the strengths and weaknesses of each algorithm. In the second part there is a test scenario based in the virtualization of machines that was useful to evaluate empirically some of the studied algorithms. Finally, a series of experiments were carried out in order to compare some characteristics of these algorithms and thus verify or deny the conclusions resulted in the study of the state of the art
Study of Peer-to-Peer Network Based Cybercrime Investigation: Application on Botnet Technologies
The scalable, low overhead attributes of Peer-to-Peer (P2P) Internet
protocols and networks lend themselves well to being exploited by criminals to
execute a large range of cybercrimes. The types of crimes aided by P2P
technology include copyright infringement, sharing of illicit images of
children, fraud, hacking/cracking, denial of service attacks and virus/malware
propagation through the use of a variety of worms, botnets, malware, viruses
and P2P file sharing. This project is focused on study of active P2P nodes
along with the analysis of the undocumented communication methods employed in
many of these large unstructured networks. This is achieved through the design
and implementation of an efficient P2P monitoring and crawling toolset. The
requirement for investigating P2P based systems is not limited to the more
obvious cybercrimes listed above, as many legitimate P2P based applications may
also be pertinent to a digital forensic investigation, e.g, voice over IP,
instant messaging, etc. Investigating these networks has become increasingly
difficult due to the broad range of network topologies and the ever increasing
and evolving range of P2P based applications. In this work we introduce the
Universal P2P Network Investigation Framework (UP2PNIF), a framework which
enables significantly faster and less labour intensive investigation of newly
discovered P2P networks through the exploitation of the commonalities in P2P
network functionality. In combination with a reference database of known
network characteristics, it is envisioned that any known P2P network can be
instantly investigated using the framework, which can intelligently determine
the best investigation methodology and greatly expedite the evidence gathering
process. A proof of concept tool was developed for conducting investigations on
the BitTorrent network.Comment: This is a thesis submitted in fulfilment of a PhD in Digital
Forensics and Cybercrime Investigation in the School of Computer Science,
University College Dublin in October 201
Experimental Assessment of BitTorrent Completion Time in Heterogeneous TCP/uTP swarms
BitTorrent, one of the most widespread used P2P application for file-sharing,
recently got rid of TCP by introducing an application-level congestion control
protocol named uTP. The aim of this new protocol is to efficiently use the
available link capacity, while minimizing its interference with the rest of
user traffic (e.g., Web, VoIP and gaming) sharing the same access bottleneck.
In this paper we perform an experimental study of the impact of uTP on the
torrent completion time, the metric that better captures the user experience.
We run BitTorrent applications in a flash crowd scenario over a dedicated
cluster platform, under both homogeneous and heterogeneous swarm population.
Experiments show that an all-uTP swarms have shorter torrent download time with
respect to all-TCP swarms. Interestingly, at the same time, we observe that
even shorter completion times can be achieved under careful mixtures of TCP and
uTP traffic.Comment: 14 pages, under submissio
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