13,775 research outputs found
Evaluating Connection Resilience for the Overlay Network Kademlia
Kademlia is a decentralized overlay network, up to now mainly used for highly
scalable file sharing applications. Due to its distributed nature, it is free
from single points of failure. Communication can happen over redundant network
paths, which makes information distribution with Kademlia resilient against
failing nodes and attacks. This makes it applicable to more scenarios than
Internet file sharing. In this paper, we simulate Kademlia networks with
varying parameters and analyze the number of node-disjoint paths in the
network, and thereby the network connectivity. A high network connectivity is
required for communication and system-wide adaptation even when some nodes or
communication channels fail or get compromised by an attacker. With our
results, we show the influence of these parameters on the connectivity and,
therefore, the resilience against failing nodes and communication channels.Comment: 12 pages, 14 figures, accepted to ICDCS2017. arXiv admin note:
substantial text overlap with arXiv:1605.0800
X-Vine: Secure and Pseudonymous Routing Using Social Networks
Distributed hash tables suffer from several security and privacy
vulnerabilities, including the problem of Sybil attacks. Existing social
network-based solutions to mitigate the Sybil attacks in DHT routing have a
high state requirement and do not provide an adequate level of privacy. For
instance, such techniques require a user to reveal their social network
contacts. We design X-Vine, a protection mechanism for distributed hash tables
that operates entirely by communicating over social network links. As with
traditional peer-to-peer systems, X-Vine provides robustness, scalability, and
a platform for innovation. The use of social network links for communication
helps protect participant privacy and adds a new dimension of trust absent from
previous designs. X-Vine is resilient to denial of service via Sybil attacks,
and in fact is the first Sybil defense that requires only a logarithmic amount
of state per node, making it suitable for large-scale and dynamic settings.
X-Vine also helps protect the privacy of users social network contacts and
keeps their IP addresses hidden from those outside of their social circle,
providing a basis for pseudonymous communication. We first evaluate our design
with analysis and simulations, using several real world large-scale social
networking topologies. We show that the constraints of X-Vine allow the
insertion of only a logarithmic number of Sybil identities per attack edge; we
show this mitigates the impact of malicious attacks while not affecting the
performance of honest nodes. Moreover, our algorithms are efficient, maintain
low stretch, and avoid hot spots in the network. We validate our design with a
PlanetLab implementation and a Facebook plugin.Comment: 15 page
Backward Compatible Multi-Path Routing
This project studies the behaviour of multipath routing compared to single path routing in order to demonstrate the different benefits that multipath offers. For this purpose, it have been implemented routers that have 2 routing tables with the capability of storing in one these routing tables the primary next hop for a destination through the shortest path which is calculated by the Open Shortest Path First (OSPF) algorithm, as well as storing a secondary next hop calculated by the Ideal Multipath Routing Expedient (IMRE) algorithm in order to have different paths for the same destination. Besides matching on the destination address, the routers select between the primary and secondary tables based on the Time To Live (TTL) field of the IP header. The end-system can change the forwarding path immediately upon it senses the degradation of the current path by sending the packets with a different TTL value, without waiting for the slow convergence of OSPF to the changed topology. This multipath behaviour is measured for 3 different use cases. First use case measures the throughput and transmission time when transmitting a file in an ideal scenario where there are no other transmissions at the same time. Second use case performs the measurements for the same transmission as before but when there is a transmission that makes 2 links of the shortest path to be overloaded in order to check the load balancing capability of multipath routing. Finally, the third use case studies the behaviour of multipath routing when there is a failure in a link during the transmission and checks its failure resilience characteristic. Furthermore, I have studied the paths provided by the IMRE algorithm with a specific TTL match rule. I have demonstrated that in this architecture some TTLs might result in loops, hence, the set of available TTLs for the end-system has to be selected with care
Architectural Considerations for a Self-Configuring Routing Scheme for Spontaneous Networks
Decoupling the permanent identifier of a node from the node's
topology-dependent address is a promising approach toward completely scalable
self-organizing networks. A group of proposals that have adopted such an
approach use the same structure to: address nodes, perform routing, and
implement location service. In this way, the consistency of the routing
protocol relies on the coherent sharing of the addressing space among all nodes
in the network. Such proposals use a logical tree-like structure where routes
in this space correspond to routes in the physical level. The advantage of
tree-like spaces is that it allows for simple address assignment and
management. Nevertheless, it has low route selection flexibility, which results
in low routing performance and poor resilience to failures. In this paper, we
propose to increase the number of paths using incomplete hypercubes. The design
of more complex structures, like multi-dimensional Cartesian spaces, improves
the resilience and routing performance due to the flexibility in route
selection. We present a framework for using hypercubes to implement indirect
routing. This framework allows to give a solution adapted to the dynamics of
the network, providing a proactive and reactive routing protocols, our major
contributions. We show that, contrary to traditional approaches, our proposal
supports more dynamic networks and is more robust to node failures
Comprehending Kademlia Routing - A Theoretical Framework for the Hop Count Distribution
The family of Kademlia-type systems represents the most efficient and most
widely deployed class of internet-scale distributed systems. Its success has
caused plenty of large scale measurements and simulation studies, and several
improvements have been introduced. Its character of parallel and
non-deterministic lookups, however, so far has prevented any concise formal
analysis. This paper introduces the first comprehensive formal model of the
routing of the entire family of systems that is validated against previous
measurements. It sheds light on the overall hop distribution and lookup delays
of the different variations of the original protocol. It additionally shows
that several of the recent improvements to the protocol in fact have been
counter-productive and identifies preferable designs with regard to routing
overhead and resilience.Comment: 12 pages, 6 figure
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