The anonymous reviewers and Amin Vahdat, our shepherd provided us with invaluable feedback which helped substantially towards improving the quality of the paper. Tom Anderson, Anand Desai, Nick Feamster, Mark Handley, Chris Karlof, Ratul Mahajan, Satomi Okazaki, Vern Paxson, Adrian Perrig, Jennifer Rexford, Dawn Song, Doug Tygar and David Wagner provided several technical comments on this work. Krishna Gummadi and Konstantina Papagianakki provided us with valuable data for empirically evaluating our Listen algorithm. Several students in Berkeley read earlier drafts of this paper and provided useful feedback. The authors would like to thank them all.