CS Department Seminar: Prof. Justin Cappos, NYU-Poly

NetCheck: Network Diagnoses from Blackbox Traces

Monday, December 2, 2013 ( 2:00 pm to 3:00 pm )

Location: Babbio Center 221

Title: NetCheck: Network Diagnoses from Blackbox Traces


This talk introduces NetCheck, a tool to diagnose network problems in large and
complex applications. NetCheck uses traces from existing blackbox tracing mechanisms, such as strace, to diagnosis network problems in real world applications. NetCheck can diagnose faults without any specific information about the underlying network or application. NetCheck does this by (1) totally ordering the distributed set of input traces, and by (2) utilizing a network model to identify points in the totally ordered execution where the traces deviated from the behavior a programmer is likely to expect. The key insight in this work is to perform network problem diagnosis by understanding how the programmer expects the network to operate and look for differences in the observed behavior.

Our evaluation demonstrates that NetCheck is able to accurately diagnose failures without relying on any application- or network-specific information. For instance, NetCheck correctly identified the existence of NAT devices, simultaneous network disconnection/reconnection, and platform portability issues. In a more targeted evaluation, we have found that NetCheck correctly detects over 95% of the network problems reported in bug trackers of projects like Python, Apache, and Ruby. When applied to traces of faults observed by a network administrator in a live network, NetCheck identified the primary cause of the fault in 90% of the cases. NetCheck performs diagnosis efficiently and can process a GB-long trace in about 2 minutes


Justin Cappos is an assistant professor at NYU Poly. Justin's research interests generally fall broadly in the area of systems security. He focuses on understanding high-impact, large-scale problems by building and deploying systems. His dissertation work on package management has been adopted by popular Linux package managers, enhancing the security of millions of Linux servers worldwide. Prof Cappos's TUF security system is being integrated into production use on Ruby and Python, leading to deployment on nearly a billion devices. In his first two years at NYU Poly, he has received numerous grants and awards including five NSF grants for over $5M USD. He performs regular media outreach and was chosen as one of Popular Science's "Brilliant 10" researchers under age 40 for his work on the Seattle testbed. His Seattle testbed is the world's largest academic testbed with thousands of installs, developers, and users.

For more information, please contact:
Georgios Portokalidis
Assistant Professor
Lieb Room 213