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Towards Improved Overlay Simulation Using Realistic Topologies
Gert Pfeifer, Ryan C. Spring, and Christof Fetzer
Proceeding of the 8th IEEE International Symposium on Network Computing and Architectures, NCA 2009, Cambridge/MA, USA
Date: July 9-11, 2009
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Simulation of distributed applications and overlay networks is challenging. Often the results generated in simulation do not match experimental results. Distributed testbeds like Planet-Lab help to bridge the gap, but they do not offer enough nodes to do an Internet scale evaluation. In this paper we use a tool called TopDNS for generating realistic topologies for simulations, using the Planet-Lab to collect measurement data.We show, that simulation results may differ significantly from earlier results using synthesized topologies. We provide a data analysis to explain the observed results and to provide a better understanding of latency between hosts in certain DNS name spaces.
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Experiences Building Internet-based Topologies with GNP
Gert Pfeifer and Christof Fetzer
Proceeding of the IEEE International Workshop on Quantitative Evaluation of large-scale Systems and Technologies, Bradford, UK
Date: May 26-29, 2009
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Building realistic Internet topologies is an important step towards predicting the behavior of new distributed applications and protocols. We are creating topologies that predict the distances between identifiable nodes in the Internet as it is today. These nodes are not anonymous average Internet nodes, but are known by name and network address. We are using a landmark and network coordinate based approach and evaluate the characteristics of the topologies found. We provide hints, how to select important parameters for such topology generators.
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Reducible Complexity in DNS
Gert Pfeifer, André Martin and Christof Fetzer
Proceeding of the IADIS International Conference WWW/Internet 2008, Freiburg, Germany
Date: 13 October 2008
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DNS is one of the most important components of the Internet infrastructure. Unfortunately, it is known to be difficult to implement, and available implementations are difficult to configure correctly. DNS performance and availability often suffer from poor configuration which leads to unavailability or erroneous behavior of distributed systems that depend on DNS. The data structures of DNS are historically grown. Some are no longer needed, some have changed their semantics. However, they have to be maintained by implementations. We measure the extent and configuration issues in DNS data and propose simplifications to DNS data types and semantics that would allow building more dependable implementations. New DNS implementations could also reduce complexity by ignoring certain functionality of DNS that are not needed or that can be implemented in other ways.
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Talk at the 1st German Hadoop Meeting: Experiences with Hadoop
Gert Pfeifer and André Martin
Date: 24 June 2008
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Exploiting Host Name Locality for Reduced Stretch P2P Routing
Gert Pfeifer, Christof Fetzer, and Thomas Hohnstein
Proceeding of the 6th IEEE International Symposium on Network Computing and Architectures (IEEE NCA 2007)
Date: 12-14 July 2007
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Structured P2P networks are a promising alternative for engineering new distributed services and for replacing existing distributed services like DNS. Providing competitive performance with traditional distributed services is however very difficult because existing services like DNS are highly tuned using a combination of caching and localized communication. Typically, P2P systems use randomized host IDs which destroys any locality that might have been inherent in the IP addresses or the names of the hosts. In this way, P2P communication can result in a high stretch. We propose a locality preserving structured P2P system that supports efficient local communication and low stretch. While this system was optimized for resolving domain names, it will also provide a low stretch to other applications and it can be combined with existing replication schemes to optimize the response times even further.
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Rearchitecting DNS
Gert Pfeifer, Christof Fetzer, and Martin Steuer
Proceeding of the 6th International Workshop on
Innovative Internet Community Systems (I2CS 2006)
Date: 26-28 June 2006
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The Domain Name System (DNS) has been the naming service of the Internet for more than 2\
0 years.
It is the foundation of virtually all other distributed service.The deficiencies of DNS with respect to performance, availability, and\
reliability are well known.
We want to systematically improve DNS by (1) measuring DNS performance, (2) evaluating past proposals, and (3) try to come up with a n\
ew architecture for DNS.SEDNS is a system in which we investigate various design ideas to speed up DNS requests and improve availabili\
ty, reliability, and security.
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Enhancing DNS Security using the SSL Trust Infrastructure
Christof Fetzer, Gert Pfeifer, and Trevor Jim
Proceeding of the IEEE International Workshop on Object-oriented Real-time Dependable Systems (WORDS 2005), pages 13-20, ISBN 0-76952347-1, ISSN 1530-1443
Date: 2-4 February 2005
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The main functionality of the Domain Name System (DNS) is to translate symbolicnames into IP addresses. Due to the criticality of DNS for the proper functioning of the Internet, many improvements have been proposed for DNS in terms of security and dependability. However, the current secure DNS (DNSSEC) standard has still several problems that need further consideration. For example, online updates and denial of service attacks are not sufficiently addressed. These problems are serious obstacles that might prevent DNSSEC from replacing the traditional DNS. In this paper we discuss several of these technical and economic problems. To address these issues, we propose a simple extension to the existing DNS. It is SSL based and individual domains can decide independently of each other if and when to adopt the extensions.We show how to implement these extensions with the help of a simple proxy DNS server.
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Dependable Distributed Computing using Free Databases
Christof Fetzer and Trevor Jim
2nd International Service Availability Symposium, Berlin
Date: 25-26 April 2005
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Designing and programming dependable distributed applications is very difficult. Databases provide features like transactions and replication that can help in the implementation of dependable applications. There are in particular various free databases that make it economically feasible to run a database on each computer in a system. Hence, one can partition database tables across multiple hosts to harness the processing power and disks of multiple machines. We describe a system that simplifies partitioning tables across multiple hosts. DOSE exposes the partitions to the programmer rather than giving the illusion of a single table. Our focus is on providing a simple implementation that works for freely-available databases, on automatic tuning of the partitions for best performance, and on applying the fault tolerance mechanisms of the databases to build dependable distributed systems. We show how we use this system to implement a distributed work queue.
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Using SSL for Secure Domain Name System (DNS) Transactions
Christof Fetzer, Gert Pfeifer, and Trevor Jim
Proceeding of the XXX. Seminary ASR'05 Instruments and Control, ISBN 80-248-0774-2
Date: 28-29 April 2005
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The main functionality of the Domain Name System (DNS) is to translate symbolic names into IP addresses.
Since there is a growing demand for trustworthiness in the Internet many research articles consider DNS security issues.
The reason is, that DNS is a vital service for nearly all distributed applications based on the TCP/IP protocol suite.
This article examines different possibilities to protect DNS transactions and shows an interesting alternative to the existing solutions.
This is necessary since all existing approaches show significant flaws in terms of manageability, usability, scalability, versatility, and realizability.
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