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12/13/12 Camera-ready version of our CoNEXT 2012 paper, Defending against large-scale crawls in online social networks, is now available.
10/30/12 Camera-ready version of our CIKM 2012 paper, Predicting Emerging Social Conventions in Online Social Networks, is now available.
08/27/12 Our WOSN 2012 paper titled, Inferring Who-is-Who in the Twitter Social Network, has been selected for publication in the CCR issue dedicated to SIGCOMM 2012 proceedings. Congrats Naveen, Saptarshi, Fabricio, and Niloy!
06/06/12 Camera-ready version of our Usenix Security 2012 paper, Policy-Sealed Data: A New Abstraction for Building Trusted Cloud Services, is now available.
06/07/12 Our paper titled, The Emergence of Conventions in Online Social Networks, received a Best paper award at ICWSM 2012. Congrats Farshad, Mia, and Winter!
Click here for older news posts.

I am broadly interested in the areas of networking and distributed systems. My research is motivated by the growing complexity (scale, heterogeneity, and distributed control) of today's networked systems. My projects focus either on understanding how well existing systems work in practice or on building new systems. We use a combination of measurement, analysis, design, and implementation methodologies to achieve our goals.

• Online Social Networks: Online social networking sites like Facebook and Twitter have become extremely popular for finding and connecting to friends and for sharing and retrieving content. Our broad research agenda includes (a) understanding the structure and evolution of social network graphs, (b) understanding how content and information propagates through social networks, (c) leveraging social networks for building better information sharing systems (i.e., better search results and content recommendations as well as filtering unwanted communication and content), and (d) building scalable infrastructures for supporting social networking sites and their workloads.


• Internet Access Networks: Broadband acess network infrastructures, such as cable, DSL, and cellular networks, are being widely deployed. Yet we have very little knowledge about the real world access ISP deployments and we do not understand how well systems or protocols perform over these networks. We attempt to make ISP deployments more transparent by (a) conducting large-scale measurement studies of broadband ISP deployments, (b) designing tools and testbeds that enable researchers to evaluate the performance of systems and protocols in broadband network environments, and (c) designing measurement systems that enable end users to detect middleboxes (e.g., traffic shapers) deployed by their ISPs.


• Trusted Cloud Computing: Customers adopting cloud computing today worry about the security risks associated with outsourcing their private data and computation to cloud providers. We are investigating ways to leverage trusted computing technology in cloud infrastructures to improve customer trust in cloud services.

In the past, I have worked on peer-to-peer systems and overlay routing systems.

Graduate Students: I work with many fantastic graduate students at MPI-SWS.

• Juhi Kulshrestha
• Mainack Mondal
• Nuno Santos (Co-advised with Rodrigo Rodrigues)
• Bimal Viswanath
• Muhammad Bilal Zafar

If you are interested in graduate studies at MPI-SWS, follow this link.

Former Students:

• Farshad Kooti, masters student, is a Ph.D. student at USC
• Massimiliano Marcon, Ph.D. student, is a Software Engineer at SAP
• Marcel Dischinger, Ph.D. student, is a Senior Software Engineer at Barracuda Networks
• Meeyoung Cha, postdoctoral researcher, is an Assistant Professor at KAIST
• Alan Mislove, Ph.D. student (coadvised with Peter Druschel), is an Assistant Professor at Northeastern University
• Alexey Reznichenko, masters student, is Ph.D. student at MPI-SWS
• Malveeka Tewari, undergraduate student, is a Ph.D. student at UCSD

For a complete list of my publications in chronological order, follow this link.

Recent publications grouped by research topic: Online Social Networks | Internet Access Networks | Trusted Cloud Computing | Miscellaneous

Online Social Networks:

Measurement and Analysis Studies:

• Predicting Emerging Social Conventions in Online Social Networks,
  by Farshad Kooti, Winter Mason, Krishna P. Gummadi, and Meeyoung Cha
  Proceedings of the 21st ACM International Conference on Information and Knowledge Management (CIKM), Maui, Hawaii, October 2012.
  (.pdf, 512 KB)
  
• The Emergence of Conventions in Online Social Networks,
  by Farshad Kooti, Meeyoung Cha, Krishna P. Gummadi, and Winter Mason
  Proceedings of the 6th International AAAI Conference on Weblogs and Social Media (ICWSM), Dublin, Ireland, June 2012. (Best paper)
  (.pdf, 432 KB)
  
• Geographic Dissection of the Twitter Network,
  by Juhi Kulshrestha, Farshad Kooti, Ashkan Nikravesh, and Krishna P. Gummadi
  Proceedings of the 6th International AAAI Conference on Weblogs and Social Media (ICWSM), Dublin, Ireland, June 2012.
  (.pdf, 279 KB)
  
• The world of connections and information flow in Twitter,
  by Meeyoung Cha, Fabricio Benevenuto, Hamed Haddadi, and Krishna P. Gummadi
  IEEE Transactions on Systems, Man and Cybernetics -- Part A, 2012.
  (.pdf, 997 KB)
  
• Delayed Information Cascades in Flickr: Measurement, Analysis and Modeling,
  by Meeyoung Cha, Fabricio Benevenuto, Young-Yeol Ahn, and Krishna P. Gummadi
  Elsevier Computer Networks, 2012.
  (.pdf, 515 KB)
  
• On Word-of-Mouth Based Discovery of the Web,
  by Tiago Rodrigues, Fabricio Benevenuto, Meeyoung Cha, Krishna P. Gummadi, and Virgilio Almeida
  Proceedings of the 11th Usenix/ACM Internet Measurement Conference (IMC), Berlin, Germany, November 2011.
  (.pdf, 535 KB)
  
• Analyzing Facebook privacy settings: User expectations vs. reality,
  by Yabing Liu, Krishna P. Gummadi, Balachander Krishnamurthy, and Alan Mislove
  Proceedings of the 11th Usenix/ACM Internet Measurement Conference (IMC), Berlin, Germany, November 2011.
  (.pdf, 549 KB)
  
• Media landscape in Twitter: A World of New Conventions and Political Diversity,
  by Jisun An, Meeyoung Cha, Krishna P. Gummadi, and Jon Crowcroft
  Proceedings of the 5th International AAAI Conference on Weblogs and Social Media (ICWSM), Barcelona, Spain, July 2011.
  (.pdf, 394 KB)
  
• Sharing Social Content from Home: A Measurement-driven Feasibility Analysis,
  by Massimiliano Marcon, Bimal Viswanath, Meeyoung Cha, and Krishna P. Gummadi
  Proceedings of the 21st International Workshop on Network and Operating Systems Support for Digital Audio and Video (NOSSDAV), Vancouver, Canada, June 2011.
  (.pdf, 311 KB)
  
• Measuring User Influence in Twitter: The Million Follower Fallacy,
  by Meeyoung Cha, Hamed Haddadi, Fabricio Benevenuto, and Krishna P. Gummadi
  Proceedings of the 4th International AAAI Conference on Weblogs and Social Media (ICWSM), Washington, DC, May 2010.
  (.pdf, 205 KB)
  
• On the Evolution of User Interaction in Facebook,
  by Bimal Viswanath, Alan Mislove, Meeyoung Cha, and Krishna P. Gummadi
  Proceedings of the 2nd ACM SIGCOMM Workshop On Social Networks (WOSN), Barcelona, Spain, August 2009.
  (.pdf, 108 KB)
  
• A Measurement-driven Analysis of Information Propagation in the Flickr Social Network,
  by Meeyoung Cha, Alan Mislove, and Krishna P. Gummadi
  Proceedings of the 18th International World Wide Web Conference (WWW), Madrid, Spain, April 2009.
  (.pdf, 868 KB)
  
• Characterizing Social Cascades in the Flickr Social Network,
  by Meeyoung Cha, Alan Mislove, Ben Adams, and Krishna P. Gummadi
  Proceedings of the 1st ACM SIGCOMM Workshop On Social Networks (WOSN), Seattle, WA, August 2008.
  (.pdf, 410KB)
  
• Growth of the Flickr Social Network,
  by Alan Mislove, Hema Swetha Koppula, Krishna P. Gummadi, Peter Druschel, and Bobby Bhattacharjee
  Proceedings of the 1st ACM SIGCOMM Workshop On Social Networks (WOSN), Seattle, WA, August 2008.
  (.pdf, 186 KB)
  
• Measurement and Analysis of Online Social Networks,
  by Alan Mislove, Massimiliano Marcon, Krishna P. Gummadi, Peter Druschel, and Samrat Bhattacharjee.
  Proceedings of the 7th Usenix/ACM SIGCOMM Internet Measurement Conference (IMC), San Diego, CA, October 2007.
  (.pdf, 533 KB)
  

Systems Design and Implementation:

• Defending against large-scale crawls in online social networks,
  by Mainack Mondal, Bimal Viswanath, Allen Clement, Peter Druschel, Krishna P. Gummadi, Alan Mislove, and Ansley Post
  Proceedings of the 8th International Conference on emerging Networking EXperiments and Technologies (CoNEXT), Nice, France, December 2012.
  (.pdf, 230 KB)
  
• Cognos: Crowdsourcing Search for Topic Experts in Microblogs,
  by Saptarshi Ghosh, Naveen Kumar Sharma, Fabricio Benevenuto, Niloy Ganguly, and Krishna P. Gummadi
  Proceedings of the 35th Annual SIGIR Conference (SIGIR), Portland, Oregon, August 2012.
  (.pdf, 232 KB)
  
• Inferring Who-is-Who in the Twitter Social Network,
  by Naveen Sharma, Saptarshi Ghosh, Fabricio Benevenuto, Niloy Ganguly, and Krishna P. Gummadi
  Proceedings of the 4th ACM SIGCOMM Workshop On Social Networks (WOSN), Helsinki, Finland, August 2012. (Selected for publication in ACM SIGCOMM CCR, August 2012)
  (.pdf, 184KB)
  
• Understanding and Combating Link Farming in the Twitter Social Network,
  by Saptarshi Ghosh, Bimal Viswanath, Farshad Kooti, Naveen Kumar Sharma, Korlam Gautam, Fabricio Benevenuto, Niloy Ganguly, and Krishna P. Gummadi
  Proceedings of the 21st International World Wide Web Conference (WWW), Lyon, France, April 2012.
  (.pdf, 886 KB)
  
• Simplifying Friendlist Management,
  by Yabing Liu, Bimal Viswanath, Mainack Mondal, Krishna P. Gummadi, and Alan Mislove
  Proceedings of the 21st International World Wide Web Conference (WWW), Demo Paper, Lyon, France, April 2012.
  (.pdf, 350 KB)
  
• Canal: Scaling Social Network-based Sybil Tolerance Schemes,
  by Bimal Viswanath, Mainack Mondal, Krishna P. Gummadi, Alan Mislove, and Ansley Post
  Proceedings of the 7th European Conference on Computer Systems (EuroSys), Bern, Switzerland, April 2012.
  (.pdf, 337 KB)
  
• Exploring the design space of social network-based Sybil defenses,
  by Bimal Viswanath, Mainack Mondal, Allen Clement, Peter Druschel, Krishna P. Gummadi, Alan Mislove, and Ansley Post
  Proceedings of the 4th International Conference on Communication Systems and Networks (COMSNETS), Invited Paper, Bangalore, India, January 2012.
  (.pdf, 28 KB)
  
• Addressing the Privacy Management Crisis in Online Social Networks,
  by Krishna P. Gummadi, Alan Mislove, and Balachander Krishnamurthy
  The IAB Workshop on Internet Privacy, Position Paper, Boston, MA, December 2010.
  (.pdf, 19 KB)
  
• An Analysis of Social Network-based Sybil Defenses,
  by Bimal Viswanath, Ansley Post, Krishna P. Gummadi, and Alan Mislove
  Proceedings of the ACM SIGCOMM 2010, New Delhi, India, August 2010.
  (.pdf, 495 KB)
  
• You are who you know: Inferring user profiles in Online Social Networks,
  by Alan Mislove, Bimal Viswanath, Krishna P. Gummadi, and Peter Druschel
  Proceedings of the 3rd ACM International Conference on Web Search and Data Mining (WSDM), New York, NY, February 2010.
  (.pdf, 181 KB)
  
• Ostra: Leveraging Trust to Thwart Unwanted Communication,
  by Alan Mislove, Ansley Post, Peter Druschel, and Krishna P. Gummadi.
  Proceedings of the 5th Usenix Symposium on Networked Systems Design and Implementation (NSDI), San Francisco, CA, April 2008.
  (.pdf, 372 KB)
  
• Exploiting Social Interactions in Mobile Systems,
  by Andrew G. Miklas, Kiran K. Gollu, Kelvin K.W. Chan, Stefan Saroiu, Krishna P. Gummadi, and Eyal de Lara.
  Proceedings of the 9th International Conference on Ubiquitous Computing (UbiComp), Innsbruck, Austria, September 2007.
  (.pdf, 885 KB)
  
• Exploiting Social Networks for Internet Search,
  by Alan Mislove, Krishna P. Gummadi, and Peter Druschel.
  Proceedings of the 5th ACM Workshop on Hot Topics in Networks (HotNets), Irvine, CA, November 2006.
  (.pdf, 140 KB)
  

Internet Access Networks:

Measurement and Analysis Studies:

• Detecting BitTorrent Blocking,
  by Marcel Dischinger, Alan Mislove, Andreas Haeberlen, and Krishna P. Gummadi
  Proceedings of the 8th Usenix/ACM SIGCOMM Internet Measurement Conference (IMC), Vouliagmeni, Greece, October 2008.
  (.pdf, 470 KB)
  
• Characterizing Residential Broadband Networks,
  by Marcel Dischinger, Andreas Haeberlen, Krishna P. Gummadi, and Stefan Saroiu.
  Proceedings of the 7th Usenix/ACM SIGCOMM Internet Measurement Conference (IMC), San Diego, CA, October 2007.
  (.pdf, 735 KB)
  
• Monarch: A Tool to Emulate Transport Protocols over the Internet at Large,
  by Andreas Haeberlen, Marcel Dischinger, Krishna P. Gummadi, and Stefan Saroiu.
  Proceedings of the 6th Usenix/ACM SIGCOMM Internet Measurement Conference (IMC), Rio De Janeiro, Brazil, October 2006.
  (.pdf, 951 KB), (.ps, 10.8 MB)
  

Systems Design and Implementation:

• Measurement Lab: Overview and an Invitation to the Research Community,
  by Constantine Dovrolis, Krishna P. Gummadi, Aleksandar Kuzmanovic, and Sascha D. Meinrath
  Proceedings of ACM SIGCOMM Computer Communication Review (CCR), Editorial Section, July 2010.
  (.pdf, 77 KB)
  
• Glasnost: Enabling End Users to Detect Traffic Differentiation,
  by Marcel Dischinger, Massimiliano Marcon, Saikat Guha, Krishna P. Gummadi, Ratul Mahajan, and Stefan Saroiu
  Proceedings of the 7th Usenix Symposium on Networked Systems Design and Implementation (NSDI), San Jose, CA, April 2010.
  (.pdf, 667 KB)
  
• SatelliteLab: Adding Heterogeneity to Planetary-Scale Testbeds,
  by Marcel Dischinger, Andreas Haeberlen, Ivan Beschastnikh, Krishna P. Gummadi, and Stefan Saroiu
  Proceedings of the ACM SIGCOMM 2008, Seattle, WA, August 2008.
  (.pdf, 340 KB)
  

Trusted Cloud Computing:

• Policy-Sealed Data: A New Abstraction for Building Trusted Cloud Services,
  by Nuno Santos, Rodrigo Rodrigues, Krishna P. Gummadi, and Stefan Saroiu
  Proceedings of the 21st Usenix Security Symposium, Bellevue, WA, August 2012.
  (.pdf, 295 KB)
  
• Towards Trusted Cloud Computing,
  by Nuno Santos, Krishna P. Gummadi, and Rodrigo Rodrigues
  Proceedings of the Workshop On Hot Topics in Cloud Computing (HotCloud), San Diego, CA, June 2009.
  (.pdf, 513 KB)
  

Miscellaneous:

• The Local and Global Effects of Traffic Shaping in the Internet,
  by Massimiliano Marcon, Marcel Dischinger, Krishna P. Gummadi, and Amin Vahdat
  Proceedings of the 3rd International Conference on Communication Systems and Networks (COMSNETS), Bangalore, India, January 2011.
  (.pdf, 319 KB)
  
• Pretty Good Packet Authentication,
  by Andreas Haeberlen, Rodrigo Rodrigues, Krishna P. Gummadi, and Peter Druschel
  Proceedings of the 4th Workshop on Hot Topics in System Dependability (HotDep), San Diego, CA, December 2008.
  (.pdf, 138 KB)
  

Some of our research projects and findings have been covered in the mainstream media and popular blogs.

Online Social Networks:

• The Echo of Digital Tweets (MaxPlanck Research, Germany)
• Fishing in the trivial (Deutschlandfunk, German Public Radio in German)
Understanding and combating link farming in the Twitter social network (WWW 2012):
• Who's to blame for Twitter spam? Obama, Gaga, and you (GigaOM)
Media landscape in Twitter (ICWSM 2011):
• How Twitter Could Unleash World Peace (Businessweek)
Measuring user influence in Twitter (ICWSM 2010):
• The Million Follower Fallacy: Audience Size Doesn't Prove Influence on Twitter (ReadWriteWeb and The New York Times)
• On Twitter, Followers Don't Equal Influence (Harvard Business Review)
• Size Doesn't Matter: Why Ebert Beats Oprah on Twitter (TheWrap)
• Live phone interview with Fabricio Benevenuto (MTV News in Brazil)
• TV interview with Meeyoung Cha (Science TV in Korea)
• KAIST president highlights Meeyoung Cha and her research (Seoul SinMun in Korea)
Inferring user profiles in online social networks (WSDM 2010):
• Privacy: Facebook's Achilles Heel (CNET News)
• On Facebook, You Are Who You Know (Miller-McCune)
• On Social Networks, You are Who You Know (Slashdot)
Exploiting social networks for Internet search (HotNets 2006):
• Web searches benefit from some human help (New Scientist)
• Suchen im Netz der Nutzer (MIT Technology Review, Germany)
• Web hits from my PeerSpective (New Scientist)

Internet Access Networks:

Glasnost project (NSDI 2010, IMC 2008):
• Käufliche Vorfahrt auf der Datenautobahn (Deutschlandfunk, German Public Radio in German)
• Putting the Brakes on Web-Surfing Speeds (The New York Times)
• Study: Cox, Comcast Internet subscribers blocked (Associated Press)
• Study Shows Comcast and Cox Slow P2P Traffic (The New York Times)
• Elude Your ISP's BitTorrent Blockade (PCWorld)
• Cox, Comcast biggest BitTorrent blockers in the world (Ars Technica)
• Glasnost im Internet (MaxPlanck Research, Germany)
• Israeli ISPs Caught Interfering with P2P Traffic (Slashdot)
• Test If Your ISP Is Shaping your Download Speed (The Consumerist)

Trusted Cloud Computing:

Towards Trusted Cloud Computing (HotCloud 2009):
• 5 cool cloud computing projects (CIO)

For a complete list of my activities in chronological order, follow this link.

Some upcoming and recent conferences that I am involved with:

• Program Chair/Co-Chair: IMC 2013, WWW 2013 -- Security, Privacy, Trust, and Abuse Track
• Program Committee: NSDI 2013, IMC 2012, WOSN 2012, SIGCOMM 2012, and WSDM 2012

Max Planck Institute for Software Systems
Campus E1 5, Room: 434
D-66123 Saarbruecken, Germany

Tel: +49 681 9325-670
Fax: +49 681 9325-299
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