%0 Conference Paper %B IEEE INFOCOM 2009 %D 2009 %T Fighting Spam with the NeighborhoodWatch DHT %A Bender,A. %A Sherwood,R. %A Monner,D. %A Goergen,N. %A Spring, Neil %A Bhattacharjee, Bobby %K Communications Society %K computer crime %K cryptography %K Databases %K IP addresses %K IP networks %K on-line trusted authority %K Peer to peer computing %K peer-to-peer computing %K peer-to-peer distributed hash table %K Postal services %K Relays %K Resilience %K Routing %K Security %K table size routing %K Unsolicited electronic mail %X In this paper, we present DHTBL, an anti-spam blacklist built upon a novel secure distributed hash table (DHT). We show how DHTBL can be used to replace existing DNS-based blacklists (DNSBLs) of IP addresses of mail relays that forward spam. Implementing a blacklist on a DHT improves resilience to DoS attacks and secures message delivery, when compared to DNSBLs. However, due to the sensitive nature of the blacklist, storing the data in a peer-to-peer DHT would invite attackers to infiltrate the system. Typical DHTs can withstand fail-stop failures, but malicious nodes may provide incorrect routing information, refuse to return published items, or simply ignore certain queries. The neighborhoodwatch DHT is resilient to malicious nodes and maintains the O(logiV) bounds on routing table size and expected lookup time. NeighborhoodWatch depends on two assumptions in order to make these guarantees: (1) the existence of an on-line trusted authority that periodically contacts and issues signed certificates to each node, and (2) for every sequence of k + 1 consecutive nodes in the ID space, at least one is alive and non-malicious. We show how NeighborhoodWatch maintains many of its security properties even when the second assumption is violated. Honest nodes in NeighborhoodWatch can detect malicious behavior and expel the responsible nodes from the DHT. %B IEEE INFOCOM 2009 %I IEEE %P 1755 - 1763 %8 2009/04/19/25 %@ 978-1-4244-3512-8 %G eng %R 10.1109/INFCOM.2009.5062095 %0 Journal Article %J Future Generation Computer Systems %D 2008 %T Trade-offs in matching jobs and balancing load for distributed desktop grids %A Kim,Jik-Soo %A Nam,Beomseok %A Keleher,Peter %A Marsh,Michael %A Bhattacharjee, Bobby %A Sussman, Alan %K Desktop grid %K load balancing %K Matchmaking %K peer-to-peer computing %K Resource discovery %X Desktop grids can achieve tremendous computing power at low cost through opportunistic sharing of resources. However, traditional client–server Grid architectures do not deal with all types of failures, and do not always cope well with very dynamic environments. This paper describes the design of a desktop grid implemented over a modified Peer-to-Peer (P2P) architecture. The underlying P2P system is decentralized and inherently adaptable, giving the Grid robustness, scalability, and the ability to cope with dynamic environments, while still efficiently mapping application instances to available resources throughout the system.We use simulation to compare three different types of matching algorithms under differing workloads. Overall, the P2P approach produces significantly lower wait times than prior approaches, while adapting efficiently to the dynamic environment. %B Future Generation Computer Systems %V 24 %P 415 - 424 %8 2008/05// %@ 0167-739X %G eng %U http://www.sciencedirect.com/science/article/pii/S0167739X07001240 %N 5 %R 10.1016/j.future.2007.07.007 %0 Conference Paper %B Parallel and Distributed Processing Symposium, 2006. IPDPS 2006. 20th International %D 2006 %T DiST: fully decentralized indexing for querying distributed multidimensional datasets %A Nam,Beomseok %A Sussman, Alan %K Computer network management %K distributed multidimensional dataset querying %K failure recovery %K fault tolerant computing %K fully decentralized multidimensional indexing %K grid computing %K Indexing %K large scale distributed resource management %K Large-scale systems %K Multidimensional systems %K Network servers %K P2P systems %K Peer to peer computing %K peer-to-peer computing %K peer-to-peer systems %K Publishing %K Query processing %K query routing %K resource allocation %K Resource management %K telecommunication network routing %K wide area networks %X Grid computing and peer-to-peer (P2P) systems are emerging as new paradigms for managing large scale distributed resources across wide area networks. While grid computing focuses on managing heterogeneous resources and relies on centralized managers for resource and data discovery, P2P systems target scalable, decentralized methods for publishing and searching for data. In large distributed systems, a centralized resource manager is a potential performance bottleneck and decentralization can help avoid this bottleneck, as is done in P2P systems. However, the query functionality provided by most existing P2P systems is very rudimentary, and is not directly applicable to grid resource management. In this paper, we propose a fully decentralized multidimensional indexing structure, called DiST, that operates in a fully distributed environment with no centralized control. In DiST, each data server only acquires information about data on other servers from executing and routing queries. We describe the DiST algorithms for maintaining the decentralized network of data servers, including adding and deleting servers, the query routing algorithm, and failure recovery algorithms. We also evaluate the performance of the decentralized scheme against a more structured hierarchical indexing scheme that we have previously shown to perform well in distributed grid environments %B Parallel and Distributed Processing Symposium, 2006. IPDPS 2006. 20th International %I IEEE %8 2006/04// %@ 1-4244-0054-6 %G eng %R 10.1109/IPDPS.2006.1639280