His main active research projects are network intrusion detection in the context of Bro, a high-performance network intrusion detection system he developed; network measurement and analysis; and the threat of botnets and the underground economy that they fuel. He has served as program chair or co-chair for USENIX Security, ACM SIGCOMM, ACM HotNets, and the IEEE Symposium on Security and Privacy. He is an ACM Fellow and recipient of the 2008 ACM Grace Murray Hopper Award for his work on Internet measurement.