thedesignandimplementationofanextgeneration.pdf

The Design and Implementation of a Next Generation Name Service for the InternetVenugopalan RamasubramanianEmin G¨ un SirerDept. of Computer Science, Cornell University, Ithaca, NY 14853 {ramasv,egs}@cs.cornell.eduABSTRACTName services are critical for mapping logical resource names to physical resources in large-scale distributed systems. The Domain Name System (DNS) used on the Internet, however, is slow, vulnerable to denial of service attacks, and does not support fast updates.These problems stem fundamentally from the structure of the legacy DNS. This paper describes the design and implementation of the Cooperative Domain Name System (CoDoNS), a novel name service, which provides high lookup performance through pro- active caching, resilience to denial of service attacks through automatic load-balancing, and fast propagation of updates. CoDoNS derives its scalability, decentralization, self-organi- zation, and failure resilience from peer-to-peer overlays, while it achieves high performance using the Beehive replication framework. Cryptographic delegation, instead of host-based physical delegation, limits potential malfeasance by names- pace operators and creates a competitive market for names- pace management.Backwards compatibility with existing protocols and wire formats enables CoDoNS to serve as a backup for legacy DNS, as well as a complete replacement. Performance measurements from a real-life deployment of the system in PlanetLab shows that CoDoNS provides fastlookups, automatically reconfigures around faults without man- ual involvement and thwarts distributed denial of service at- tacks by promptly redistributing load across nodes.Categories and Subject Descriptors: C.2.4 [Computer- Communication Networks]: Domain Name SystemGeneral Terms: Design, Performance, Reliability.Keywords: DNS, peer to peer, proactive caching.1.INTRODUCTION Translation of names to network addresses is an essen- tial predecessor to communication in networked systems. The Domain Name System (DNS) performs this transla- tion on the Internet and constitutes a critical component ofPermission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies arenot made or distributed for profit or commercial advantage and that copiesbear this notice and the full citation on the first page. To copy otherwise, torepublish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. SIGCOMM’04, Aug. 30–Sept. 3, 20034, Portland, Oregon, USA. Copyright 2004 ACM 1-58113-862-8/04/0008 ...$5.00.the Internet infrastructure. While the DNS has sustained the growth of the Internet through static, hierarchical par- titioning of the namespace and wide-spread caching, recent increases in malicious behavior, explosion in client popu-lation, and the need for fast reconfiguration pose difficult problems. The existing DNS architecture is fundamentally unsuitable for addressing these issues. The foremost problem with DNS is that it is suscepti- ble to denial of service (DoS) attacks.This vulnerability stems from limited redundancy in nameservers, which pro- vide name-address mappings and whose overload, failure or compromise can lead to low performance, failed lookups and misdirected clients. Approximately 80% of the domain names are served by just two nameservers, and a surprising 0.8% by only one. At the network level, all servers for 32% of the domain names are connected to the Internet through a single gateway, and can thus be compromised by a single failure. The top levels of the hierarchy are served by a rel- atively small number of servers, which serve as easy targets for denial of service attacks [4]. A recent DoS attack [28] on the DNS crippled nine of the thirteen root servers at that time, while another recent DoS attack on Microsoft’s DNSservers severely affected the availability of Microsoft’s web services for several hours [38]. DNS nameservers are easy targets for malicious agents, partly because approximately20% of nameserver implementations contain security flaws that can be exploited to take over the nameservers. Second, name-address translation in the DNS incurs long delays. Recent studies [41, 16, 18] have shown that DNS lookup time contributes more than one second for up to 30% of web object retrievals. The explosive growth of thenamespace has decreased the effectiveness of DNS caching. The skewed distribution of names under popular domains,such as .com, has flattened the name hierarchy and increased load imbalance. The use of short timeouts for popular map- pings, as is commonly employed by content distribution net- works, further reduces DNS cache hit rates. Further, manualconfiguration errors, such as lame delegations [29, 27], can introduce latent performance problems. Finally, widespread caching of mappings in the DNS pro- hibits fast propagation of unanticipated changes. Since the DNS does not keep track of the lo。