Tor is unfair &amp;#x2014; And what to do about it

Tschorsch, Florian; Scheuermann, Björn

doi:10.1109/lcn.2011.6115503

Cited by 15 publications

(22 citation statements)

References 10 publications

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“…Although the concept of fairness and in particular the max-min fairness have been studied in the literature of computer networks in general (e.g., in [2,13,14,20]), one finds considerably less papers in the context of peer-to-peer networks, and in particular in BitTorrent-like systems.…”

Section: Related Workmentioning

confidence: 99%

Modeling max–min fair bandwidth allocation in BitTorrent communities

Antal

Vinkó

2016

Comput Optim Appl

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This paper gives an exact mathematical programming model and algorithm of the max-min fairness bandwidth allocation problem in multi-swarm peer-to-peer content sharing community. The proposed iterative method involves solution of LP and MILP problems of large scale. Based on real-world data traces, numerical experiments demonstrate that the new algorithm is computationally faster than an earlier developed one for larger problem sizes, and it provides better numerical stability. Moreover, even if its execution is stopped after some initial steps it still grants feasible solution with good approximation to max-min fairness.

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Section: Related Workmentioning

confidence: 99%

Modeling max–min fair bandwidth allocation in BitTorrent communities

Antal

Vinkó

2016

Comput Optim Appl

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“…Of course, in practice, the distribution will not be perfectly fair; in fact, there are certain known artifacts with respect to intercircuit fairness [43]. But Tor relays include mechanisms which will still result in bandwidth allocations to circuits that are not arbitrarily unfair: there is a round-robin scheduler which picks cells from circuit queues for transmission.…”

Section: Adaptive Circuit Killingmentioning

confidence: 99%

“…An attacker needs a lower rate and thus fewer resources either if the queues of benign circuits become longer (higher value of Q) or if the distribution of relay bandwidth to the circuits becomes less fair (smaller value of α). Approaches that bound the queue lengths based on per-link feedback [10], or improve transmission scheduling in Tor [43] would therefore complement this defense strategy.…”

Section: Adaptive Circuit Killingmentioning

confidence: 99%

The Sniper Attack: Anonymously Deanonymizing and Disabling the Tor Network

Jansen¹,

Tschorsch²,

Johnson³

et al. 2014

Proceedings 2014 Network and Distributed System Security Symposium

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Abstract-Tor is a distributed onion-routing network used for achieving anonymity and resisting censorship online. Because of Tor's growing popularity, it is attracting increasingly larger threats against which it was not securely designed. In this paper, we present the Sniper Attack, an extremely low cost but highly destructive denial of service attack against Tor that an adversary may use to anonymously disable arbitrary Tor relays. The attack utilizes valid protocol messages to boundlessly consume memory by exploiting Tor's end-to-end reliable data transport. We design and evaluate a prototype of the attack to show its feasibility and efficiency: our experiments show that an adversary may consume a victim relay's memory by as much as 2187 KiB/s while using at most only 92 KiB/s of upstream bandwidth. We extend our experimental results to estimate the threat against the live Tor network and find that a strategic adversary could disable all of the top 20 exit relays in only 29 minutes, thereby reducing Tor's bandwidth capacity by 35 percent. We also show how the attack enables the deanonymization of hidden services through selective denial of service by forcing them to choose guard nodes in control of the adversary. Finally, we discuss defenses against the Sniper Attack that provably render the attack ineffective, and suggest defenses against deanonymization by denial-of-service attacks in general that significantly mitigate the threat.

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“…We were not only able to provide answers to a number of fundamental questions how to build anonymous communication systems with good performance, but also contributed a number of specific design improvements to Tor [11]. Likely the largest success in this area was the insight that apparently straightforward application of standard mechanisms for congestion Brought to you by | New York University Bobst Library Technical Services Authenticated Download Date | 7/10/15 6:34 PM control and flow control in such a setting, as it had been done in the Tor protocol from its very beginning, can lead to severe and unexpected security and anonymity problems: this led to the discovery of a severe problem at the heart of the Tor protocol design -and a matching, nonstraightforward remedy, which is meanwhile deployed in Tor [12].…”

Section: Internet Anonymitymentioning

confidence: 99%

Designing networks for challenging applications

Scheuermann¹

2014

It - Information Technology

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Most networks in use today, most prominently the Internet, follow a design philosophy which aims to support a broad range of applications. This comes to a limit when the combination of application and environment poses increasing challenges with respect to scarce resources (like bandwidth, latency or energy). It also fails if the challenges stem from application requirements that are violated by core network protocols, like, for instance, anonymity requirements in a network using unique addresses. This observation motivates an overarching perspective on the design of network protocols in such cases, which takes the interplay between network and application explicitly into consideration -a challenge which is tackled for several application areas in my research group.

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Tor is unfair — And what to do about it

Cited by 15 publications

References 10 publications

Modeling max–min fair bandwidth allocation in BitTorrent communities

Modeling max–min fair bandwidth allocation in BitTorrent communities

The Sniper Attack: Anonymously Deanonymizing and Disabling the Tor Network

Designing networks for challenging applications

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