Analysis of network traffic is becoming increasingly important, not just for determining network characteristics and anticipating requirements, but also for security analysis. Several tool sets have been developed to perform analysis of flow-level network traffic, however none have had security as the primary goal of the analysis, nor has performance been a key consideration.

In this paper we present a suite of tools for network traffic collection and analysis based on Cisco NetFlow. The two primary design considerations were performance and the ability to build richer models of traffic for security analysis. Thus the data structures and code have been optimized for use on very large networks with a large number of flows. Data filter rates are approximately 80 million records in less than 1.5 minutes on a Sun 4800.