Michael B. Greenwald

Adjunct Assistant Professor
I have moved to Bell Laboratories, in the Computer Sciences Research Center. Please see my webpage there for more up-to-date information. In particular, do not use the contact information on this web page.
Computer and Information Science
University of Pennsylvania
Distributed Systems Laboratory

Contact Information
Office Hours
Michael B. Greenwald Computer & Information Science University of Pennsylvania <greenwald@cis.upenn.edu>
One of the nice things about working at Penn, in a building that is part of the Moore School complex, is the connection to the history of the Eniac. We work in the same building in which the Eniac was built. Part of the Eniac is still in a display case on the first floor (unfortunately not easily accessible).
(Click on the picture to go to an online Eniac museum exhibit.)

Some projects I am currently affiliated with: DOS Prevention (ContessaNS), Harmony, AHBHA (pronounced "Abba") (Adaptive Hop-by-hop Aggregate congestion control), Strongman, cing (Network Tomography/Measurement), GK (Summarizing large sets of streaming data), Canon (consistent security in heterogeneous distributed systems), POSSE, DOS Prevention, TRANSMIT, ABIDE
(This list is almost always incomplete).

Recent Publications

(No longer being updated)

  • N. Foster, M. Greenwald, Christian Kirkegaard, B.C. Pierce, and A. Schmitt, "Exploiting Schemas in Data Synchronization", in Journal of Computer and System Sciences, Vol 73, Issue 4, pp. 669-689, June 2007, PDF

  • J.N. Foster, M. Greenwald, J.T. Moore, B.C. Pierce, and A. Schmitt, "Combinators for Bi-Directional Tree Transformations: A Linguistic Approach to the View Update Problem", in the ACM Transactions on Programming Languages and Systems (TOPLAS), Vol. 29, no. 3, May 2007, PDF

  • M.B. Greenwald, S. Khanna, S.S. Venkatesh, "How Much Bandwidth Can Attack Bots Commandeer?", in Information Theory and Applications Workshop, 2007, pp. 188-196, La Jolla, CA, Jan. 29 2007-Feb. 2 2007 PDF

  • M. Greenwald, S. Khanna, K. Kunal, B.C. Pierce, and A. Schmitt, "Agreeing to Agree: Conflict Resolution for Optimistically Replicated Data", in Proceedings of 20th Int'l Symposium on Distributed Computing (DISC '06), Stockholm, Sweden, September 18--20, 2006. PDF (Longer version available as Technical Report MS-CIS-06-10, University of Pennsylvania, August 2006.).

  • K. Anagnostakis, M. Greenwald, S.Ioannidis, and A.Keromytis, "Robust Reactions to Potential Day-Zero Worms through Cooperation and Validation", in Proceedings of ISC 2006: The 9th Information Security Conference, August 30 -- September 2, 2006 Samos, Greece, LNCS 4176 (Springer), pp. 427--442 PDF

  • M. Greenwald and S. Khanna, "Quantiles and Equidepth Histograms over Streams", Chapter 2 of Part II of "Data Stream Management: Processing High-Speed Data Streams", ed. M. Garofalakis, J. Gehrke, and R. Rastogi, (Springer, ISBN 978-3-540-28607-3), to appear in 2005. PDF version

  • Micah Sherr, M. Greenwald, C. Gunter, S. Khanna, and S.Venkatesh, "Mitigating DoS Attack through Selective Bin Verification", in Proceedings of 1st IEEE ICNP Workshop on Secure Network Protocols (NPSec '05), pp. 7-12, Boston, MA, November 6, 2005.PDF

  • N. Foster, M. Greenwald, Christian Kirkegaard, B.C. Pierce, A. Schmitt, "Exploiting Schemas in Data Synchronization", in Proceedings of 10th Intl Symposium on Database Programming Languages (DBPL 2005), pp. 42-57, Springer, LNCS 3774, ISSN 0302-9743, Trondheim, Norway, August 28-29, 2005 PDF

  • G. Agha, C. Gunter, M.B. Greenwald, S. Khanna, J. Meseguer, K. Sen, and P. Thati. "Formal Modeling and Analysis of DoS Using Probabilistic Rewrite Theories," in Workshop on Foundations of Computer Security (FCS'05) (LICS'05 Affiliated) pp. 91-102, Chicago, IL, June 30-July 1, 2005 PDF

  • J. N. Foster, M.B. Greenwald, C. Kirkegaard, B.C. Pierce, and A. Schmitt. "Schema-Directed Data Synchronization". Technical Report MS-CIS-05-02, University of Pennsylvania, March 2005. (Supersedes MS-CIS-03-42.) PDF

  • K. G. Anagnostakis, M. B. Greenwald, S. Ioannidis, D. Li, and J. M. Smith, ``Flexible Network Monitoring with FLAME'', Computer Networks Vol. 50, No. 14, 5 October 2006, pages 2548-2563 (Elsevier Science)

  • N. Foster, M. B. Greenwald, J. T. Moore, B. C. Pierce, and A. Schmitt, ``Combinators for Bi-directional Tree Transformations: A linguistic approach to the View Update Problem'', Proceedings of POPL 2005, pp. 233-246, Long Beach, CA, January 12-14, 2005. This paper (PDF) is based on a tech report, University of Pennsylvania CIS Dept. Technical Report, MS-CIS-04-15, July, 2004. The full version of the report is 75 pages: PDF, but some readers may prefer a quick overview, presented in a short version of the tech report: PDF. The paper won the Most Influential POPL Paper Award in 2015, for the year 2005.

  • J. M. Smith, M. B. Greenwald, S. Ioannidis, A. D. Keromytis, B. Laurie, D. Maughan, D. Rahn, and J. L. Wright. ``Experiences Enhancing Open Source Security in the POSSE Project'' In Free/Open Source Software Development, Stefan Koch (editor), pp. 240 - 255. Idea Group Publishing, July, 2004. ISBN-10: 1591403693. Also re-published in Global Information Technologies: Concepts, Methodologies, Tools, and Applications, Felix B. Tan (editor), pp. 1587 - 1598. Idea Group Publishing, 2007. PDF

  • M. B. Greenwald and S. Khanna, ``Power-Conserving Computation of Order-Statistics over Sensor Networks'', in the 23rd ACM Symposium on Principles of Database Systems (PODS 2004), pp. 275-285, Paris, France, June 13--18, 2004. Postscript, PDF, Slides

  • K. Anagnostakis and M.B. Greenwald, "A Hybrid Direct-Indirect Estimator of Network Internal Delays", Short paper, in Proceedings of SIGMETRICS 2004, pp. 426-427, New York, NY, June 12-16, 2004 gzip'd Postscript, PDF

  • K. Anagnostakis and M.B. Greenwald, "Exchange-based Incentive Mechanisms for Peer-to-Peer File Sharing", in The 24th IEEE International Conference on Distributed Computing (ICDCS 2004), Tokyo, Japan, pp. 524-533, Tokyo, Japan, March 23-26, 2004 gzip'd Postscript, gzip'd PDF

  • B. C. Pierce, A. Schmitt, and M. B. Greenwald, ``Bringing Harmony to Optimism: An experiment in synchronizing Heterogeneous tree-structured data'', University of Pennsylvania CIS Dept. Technical Report, MS-CIS-03-42, March, 2004. PDF.

  • K. G. Anagnostakis and M. B. Greenwald, ``A Hybrid Approach to Estimating per-link Network Queuing Delays'', University of Pennsylvania CIS Dept. Technical Report, CIS TR MS-CIS-02-31, December, 2003, (supersedes earlier version of October, 2002). PDF, Postscript

  • A. Keromytis, K. G. Anagnostakis, S. Ioannidis, M. Greenwald, and J. M. Smith, "Managing Access Control in Large Scale Heterogeneous Networks", in Proceedings of the NATO Consultation, Command and Control (C3) Interoperable Networks for Secure Communication (INSC '03) Symposium, The Hague, Netherlands, November 4-6, 2003, PDF,

  • K. Anagnostakis, M.B. Greenwald, S. Ioannidis, A.D. Keromytis, and D. Li, "A Cooperative Immunization System for an Untrusting Internet", in Proceedings of ICON 2003: The 11th IEEE International Conference on Networks, September 28 - October 1, 2003 Sydney, NSW, Australia gzip'd Postscript, gzip'd PDF

  • M. B. Greenwald, J. T. Moore, B. C. Pierce, and A. Schmitt, ``A Language for Bi-Directional Tree Transformations'', University of Pennsylvania CIS Dept. Technical Report, MS-CIS-03-08, August, 2003. Full version: gzipped PDF, gzip'd Postscript. Short version (workshop): PDF.

  • A. D. Keromytis, S. Ioannidis, M. Greenwald, and J. M. Smith, ``The STRONGMAN Architecture'', in The Third DARPA Information Survivability Conference and Exposition (DISCEX III), pp. 178-188, IEEE Press. Washington, D.C. April 22-24, 2003 (gzip'd Postscript)

  • K.G. Anagnostakis, M. B. Greenwald, and R.S. Ryger, ``cing: Measuring Network-Internal Delays using only Existing Infrastructure'', in Proceedings of the 22nd Annual Joint Conference of IEEE Computer and Communication Societies (Infocom 2003), San Francisco, CA, April 1-3, 2003. gzip'd Postscript, gzip'd PDF. (Long version (CIS-TR-02-21): gzip'd Postscript, PDF.)

  • M.B. Greenwald, C. A. Gunter, B. Knutsson, A. Scedrov, J. M. Smith, and S. Zdancewic, "Computer Security is Not a Science (but it should be)", in the Large-Scale Network Security Workshop, Landsdowne, VA, March 13-14, 2003. PDF.
  • K. Anagnostakis, M. Greenwald, S. Ioannidis, and S. Miltchev, ``Open Packet Monitoring on FLAME: Safety, Performance,and Applications'', in Proceedings of IFIP (IWAN 2002) Fourth Annual International Working Conference on Active Networks, Springer Lecture Notes in Computer Science, Vol. 2546, pp. 120-131, Zurich, Switzerland, December 4-6, 2002. gzip'd Postscript, gzip'd PDF

  • K.G.Anagnostakis, M. B. Greenwald, and R. S. Ryger, ``On the Sensitivity of Network Simulation to Topology'', Proceedings of the Tenth IEEE/ACM Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunications Systems (MASCOTS 2002), pp. 117-126, Fort Worth, Texas, October 12-16, 2002. gzip'd Postscript, PDF, Powerpoint slides. An earlier draft is available as University of Pennsylvania CIS Dept. Technical Report, MS-CIS-02-15, May 2002 (gzip'd Postscript).

  • K.G. Anagnostakis and M.B. Greenwald, ``Direct Measurement Versus Indirect Inference for Determining Network-Internal Delays'', (Best Student Paper Award Performance 2002), Rome, Italy. Performance Evaluation, Elsevier Science, vol. 49/1-4, September, 2002, pp. 165-176, gzip'd PDF file, gzip'd Postscript of final draft.

  • M. Greenwald, ``Two-Handed Emulation: How to build Non-Blocking implementations of Complex Data-Structures using DCAS'', Proceedings of the 21st ACM Symposium on Principles of Distributed Computing,, pp. 260--269, Monterey, CA, July 21-24, 2002.gzip'd Postscript, . PDF.

  • M. Greenwald, ``Brief Announcement: How to wait when you are not going to block'', Proceedings of the 21st ACM Symposium on Principles of Distributed Computing,, pp. 256, Monterey, CA, July 21--24, 2002, gzip'd Postscript.

  • M. Greenwald, ``Quantitative Modeling of Contention in Distributed Algorithms'', University of Pennsylvania CIS Dept. Technical Report, MS-CIS-02-10, April 2002.

  • K. Anagnostakis, S. Ioannidis, S. Miltchev, J. Ioannidis, M. Greenwald, and J.M. Smith, ``Safety and Performance in an Open Packet Monitoring Architecture'', University of Pennsylvania CIS Dept. Technical Report, MS-CIS-02-07, April 2002.gzip'd Postscript.

  • K. G. Anagnostakis, S. Ioannidis, S. Miltchev, J. Ioannidis, M. Greenwald, and J. M. Smith, ``Efficient Packet Monitoring for Network Management'', in Proceedings of the 8th IFIP/IEEE Network Operations and Management Symposium (NOMS 2002), pp. 423-436, April, 2002. gzip'd Postscript, gzip'd PDF.

  • K.G. Anagnostakis and M. B. Greenwald, ``On the Feasibility of Network Delay Tomography without Infrastructure Support'', University of Pennsylvania CIS Dept. Technical Report, MS-CIS-01-35, December 2001.gzip'd Postscript.

  • R. Alur, M. Greenwald. ``Coherency of Shared Memory in Ad-hoc Networks'', University of Pennsylvania CIS Dept. Technical Report, MS-CIS-01-29, September 2001.gzip'd Postscript.

  • M. Greenwald, S. Khanna. ``Space-Efficient Online Computation of Quantile Summaries'', Proceedings of the 2001 ACM SIGMOD Intl. Conference on Management of Data, pp. 58--66, Santa Barbara, CA, May 21--24, 2001. Compressed PDF, Compressed Postscript, Slides.

  • A. D. Keromytis, S. Ioannidis, M. Greenwald, and J. M. Smith, ``Scalable Security Mechanisms for the Internet", University of Pennsylvania CIS Dept. Technical Report, MS-CIS-01-05, January 2001.gzip'd Postscript.

  • J. Shi, N. Badler, M. Greenwald. ``Joining a Real-Time Simulation: Parallel Finite-State Machines and Hierarchical Action Level Methods for Mitigating Lag Time'', Proceedings of the 9th Conference on Computer Generated Forces and Behavioral Representation, Orlando, FL, May 16-18, 2000. Word format

  • M. Greenwald. Non-blocking Synchronization and System Design. Ph.D. Thesis (postscript), (or pdf), July 1999. Also available as Stanford University Technical Report STAN-CS-TR-99-1624 by http or ftp).

  • J. Stone, M. Greenwald, C. Partridge, and J. Hughes. Performance of Checksums and CRCs over Real Data. IEEE/ACM Transactions on Networking, Oct. 1998, vol 6, no. 3, pp. 529-543, compressed PostScript, PDF.

  • M. Greenwald and D.R. Cheriton. The Synergy Between Non-blocking Synchronization and Operating System Structure, Proceedings of the Second Symposium on Operating System Design and Implementation. USENIX, Seattle, October, 1996, pp 123-136. compressed PostScript, compressed PDF, Hypertext, slides, or abstract.

  • M. Greenwald. Practical Algorithms for Self Scaling Histograms or Better than Average Data Collection, Proceedings of Performance '96 IFIP, Lausanne, October, 1996, and in Performance Evaluation Volumes 27&28, October 1996, North-Holland, pp 19-40. slides or abstract. (Copyright is held by Elsevier Science B.V. ; copies may be obtained by ordering publication number 0166-5316(96)00043-0).
    A slightly earlier, and slightly more extended, draft is available as a Postscript file.

  • M.B. Greenwald, S.K. Singhal, J.R. Stone, and D.R. Cheriton. Designing an Academic Firewall. In OnTheInternet, Vol. 2, No 3, May/June 1996, pp 24-33.

  • M.B. Greenwald, S.K. Singhal, J.R. Stone, and D.R. Cheriton. Designing an Academic Firewall: Policy, Practice, and Experience With SURF. In Proceedings of the 1996 Internet Society Symposium on Network and Distributed System Security, San Diego, CA, February 1996. pp 79-92. Internet Society / IEEE Computer Society. compressed PostScript, PDF, Hypertext, or abstract. Also available as Technical Report STAN-CS-TR-95-1558. Department of Computer Science, Stanford University (December 1995).

    Selected past publications and talks


    University of Pennsylvania

    TCOM512, Application and Transport Protocols, Fall 2001, Fall 2002
    TCOM500, Networking: Technology, Protocols & Practice, Fall 2000
    CSE 480, Distributed Systems, Spring 2000, Spring 2001, Spring 2003
    CIS 501, Computer Architecture, Spring 1999, Fall 1999,
    CIS 700, Fall 1998, Special Topics in Distributed Systems and Concurrent Programming: Non-blocking Synchronization

    Stanford University

    CS244a, Spring 94, Summer 93, Computer Networking
    CS340 & 341 (TA'd), Spring 90, Distributed Systems (and Lab)

    Office Hours

    Spring Semester, 2004: Wed 11am-12noon, or by appointment.

    Theses supervised

    Thomas Langan, ``Enforcement of Cooperative Security Policies on a Heterogeneous Distributed Environment'', Masters thesis, August 2002.
    Marcus Haebler, ``Implementing Secure Connections between Security Domains with Varying Degrees of Trust'', Masters thesis, December, 2001.
    Jianping Shi, ``Techniques for Mitigating Lag-time when Joining Interest Groups in Real-Time Simulations'', Ph.D. Thesis, December 2000. (co-supervised with N. Badler).
    Kostas Anagnostakis "Exchange mechanisms and cooperative distributed system design", Ph.D. Thesis, 2005, Postscript, PDF.

    Current Ph.D. students

    Peifang Zheng
    Kostas Anagnostakis
    Peng Li

    Class library of histograms from Performance paper.

    Samoil Samak and I worked on a VNC Viewer for Windows CE, while experimenting with using a palmtop as an alternative to a tablet, for input. An old, unsupported, beta version of Samoil's implementation is still available for historical purposes.

    Here is my version of ttcp (The original ttcp is described by Mike Muus, one of its authors). My version includes timestamps and sequence numbers per udp packet for measuring individual packet latencies and patterns of loss, upper bounds on the transmission rates, independent control of transmission and reception to allow testing across firewalls.

    Bibliography of references on non-blocking synchronization. This is incomplete and not always formatted correctly. Please view it as "in progress". I'm updating it and correcting problems incrementally.

    An older bibliography maintained by John Valois contains bibtex references on concurrent objects, lock-free data structures, mutual exclusion, wait-free synchronization, efficient spinlocks, and other related topics. It might also be of interest.

    My thesis on "Non-Blocking Synchronization and System Design" may be of interest if you are really interested in details. (Also available as a Stanford Technical Report STAN-CS-TR-99-1624 as pdf or postscript. You can use ftp if http doesn't work.)


    C.V. (usually out of date!)

    Alona Rivka Bach (b. 4/93)
    Yaron Bryce Greenwald (b. 12/94), in November 1998.

    Click here for older pictures of Alona and Yaron and Meka.
    Click here for pictures of the extended family (the Bach cousins when there were only 11 of them).
    Meka Tamir Greenwald at 2 weeks old (b. 2/15/98) with his older siblings. ("Meka" is pronounced "Mee-kuh") His Hebrew name is Tamir Avraham Greenwald.

    Michael B. Greenwald Computer & Information Science University of Pennsylvania Phone: Fax: <greenwald@cis.upenn.edu>