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Flow measurement evolved into the primary method for measuring the composition of Internet traffic. Cisco's NetFlow is a widely deployed flow measurement solution that uses a configurable static sampling rate to control processor and memory usage on the router and the amount of reporting flow records generated. But during flooding attacks the memory and network bandwidth consumed by flow records can increase beyond what is available. In this paper, we propose an entropy based flow aggregation algorithm, which not only alleviates the problem in memory and export bandwidth, but also maximizes the accuracy of legitimate flows. Relying on information-theoretic techniques, the algorithm efficiently identifies the clusters of attack flows in real time and aggregates those large number of short attack flows to a few metaflows. Finally, we evaluate our system using real trace files from the Internet. [ABSTRACT FROM AUTHOR]

We study cooperative caching technique for supporting data access in ad hoc networks. Two protocols that are based on the notion of zone are proposed. The IXP protocol is push-based in the sense that a mobile node would broadcast an index message to the nodes in its zone to advertise a caching event. A data requester can fetch a needed item from a nearby node if it knows that it has cached the data. The second protocol, called DPIP, is explicitly pull-based with implicit index pushing property. A data requester may broadcast a special request message to the nodes in its zone asking them to help satisfy its demand. However, this is done only if its own caching information does not result in a successful fetch. Performance study shows that the proposed protocols can significantly improve system performance when compared to existing caching schemes. [ABSTRACT FROM AUTHOR]