My research interests broadly lie in the area of distributed systems with a special emphasis on Peer to Peer and Overlay networks. I like measuring and anayzing such systems. I am also interested in dissecting the security aspects of these systems.

Our paper on BitTorrent leecher attacks has been covered in press.

Here are some of the projects I have been involved in in the last few years.

Measurement and Analysis of BitTorrent Ecosystem
In this research project, we obtained a nearly complete picture of the entire public BitTorrent Ecosystem, studying in-depth the user behavior, the content it provides, and other entities in the ecosystem.  We also developed tools and methodologies for a comprehensive exploration and mapping of the ecosystem.
 
Complemeting our study of the public BitTorrent world, we also considered 800+ private sites to obtain a broad picture of the private BitTorrent world, also called BitTorrent Darknets, obtaining estimates of the user base, content scale. Although the size of each private site is relatively small, we found the aggregate size of the darknet landscape to be surprisingly large.
 
Vulnerability Analysis of BitTorrent
Our work on BitTorrent security involved analyzing the vulnerability of two major components in the BitTorrent ecosystem – BitTorrent leechers and seeds. By developing tools to actively monitor real torrents in the wild, we were able to detect the prevalence of attacks against BitTorrent leechers in targeted torrents. We have found BitTorrent to be quite resilient against leecher attacks – the attacks generally extend the download durations for torrents by a factor less than 1.
 
We also studied the vulnerability of BitTorrent seeds to a potentially devastative attack in which the attacker attempts to prevent the initial seed from distributing the entire file to legitimate users. By fabricating our own attacks using Planetlab nodes, we again discovered that BitTorrent is quite resilient to such attacks.
 
Our work on BitTorrent leecher attacks has also been covered in press.
 
Vulnerability Analysis of P2P Video Streaming
Our research group was the first to expose the vulnerability of P2P video streaming systems to a devastating pollution attack. In the attack, an attacker attempts to degrade the quality of rendered video at the peers of a video stream by mixing decoyed video chunks into the P2P distribution. We demonstrated that with limited attack resources, the attack can be very effective and analyzed a suite of defenses for the attack.
Privacy Leak in Peer Assisted Patch Distribution
Although peer assisted distribution of patches provides high bandwidth and resource savings for patch distribution servers, it bring about a serious privacy leak that allows an attacker to identify the vulnerable machines and exploit the vulnerability when pretending to be a patch distribution peer. We analyzed the effectiveness of two different mechanisms to combat the attackers in such a scenario.
 
Measurement and Analysis of Delays in Tor
Although Tor is the most widely used overlay for providing anonymity, its users often experience very high delays. To take an important step in reducing the delays observed in Tor, we performed an in-depth analysis of delays in the Tor network. We have discovered that delays in overloaded Tor network routers to be the major contributors to delays.