Network Operations and Internet Security @ UChicago

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New Measurement/Policy Brief: Mobile and Fixed Broadband in South Africa

How do mobile and fixed broadband stack up in South Africa?

Unlike in more developed nations, where fixed-line broadband connectivity is the predominant form of broadband access, in South Africa, mobile broadband is predominant. Mobile broadband connectivity is also both cheaper and faster than fixed-line connectivity.   Unfortunately, our study using a BISmark testbed deployment in South Africa shows that wireless is inherently less stable than fixed broadband technologies such as XDSL and fibre and the implications of not having ubiquitous, reliable always-on high-speed connectivity for the economy and global competitiveness are serious.

For a detailed description about the methods applied for measuring broadband performance, download the policy paper draft that we co-authored with Research ICT Africa for comments on investigating broadband performance in South Africa 2013. (Comments welcome!)

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Feamster Gives Talk on Coursera SDN MOOC Experience

Professor Feamster gave a talk at the University of Cape Town on his experiences with designing and running the first-ever university-level course on Software Defined Networking, which was also a Coursera Massive Open Online Course (MOOC).

In the talk, Nick offers several insights and thoughts about MOOCs, including why certain aspects of teaching a large MOOC are, in fact, easier than teaching a small classroom course.

Slides from the talk are available here: A ReMOOCable Experience: Teaching Networking to the Masses from Nick Feamster

Update: See the interview with Nick in TechTarget on his experiences preparing the SDN MOOC.

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Home Networking and DNS Security Papers Accepted to Internet Measurement Conference

Project BISmark

Our research group has had three long papers accepted at the ACM SIGCOMM Internet Measurement Conference this October in Berlin, Germany.  Two of the papers are on studying the performance and usage of home networks.  A third paper is on the security of the Internet’s domain name system.  The draft abstracts of the papers are below.  We are very well represented (seven students, and one alum, Nazanin, who is now at Cisco).

There were only 25 long papers accepted at IMC, so we are very well-represented in the program.

Congrats to Sarthak, Srikanth, Shuang, Mi Seon, Sam, Joon, Bharath, and Nazanin!

Peeking Behind the NAT: An Empirical Study of Home Networks
Sarthak Grover (Georgia Institute of Technology)
Mi Seon Park (Georgia Institute of Technology)
Srikanth Sundaresan (Georgia Institute of Technology)
Sam Burnett (Georgia Institute of Technology)
Hyojoon Kim (Georgia Institute of Technology)
Bharath Ravi (Georgia Institute of Technology)
Nick Feamster (Georgia Institute of Technology)

We present the first empirical study of home network availability, infrastructure, and usage, using data collected from home networks around the world. In each home, we deploy a router with custom firmware to collect information about the availability of home broadband network connectivity, the home network infrastructure (including the wireless connectivity in each home network and the number of devices connected to the network), and how people in each home network use the network. Outages are more frequent and longer in developing countries—sometimes due to the network, and in other cases because they simply turn their home router off. We also find that some portions of the wireless spectrum are extremely crowded, that diurnal patterns are more pronounced during the week, and that most traffic in home networks is exchanged over a few connections to a small number of domains. Our study is both a preliminary view into many home networks and an illustration of how measurements from a home router can yield significant information about home networks.

Measuring and Mitigating Web Performance Bottlenecks in Broadband Access Networks
Srikanth Sundaresan (Georgia Institute of Technology)
Nick Feamster (Georgia Institute of Technology)
Renata Teixeira (CNRS/UPMC Sorbonne Universites)
Nazanin Magharei (Cisco Systems)

We measure Web performance bottlenecks in home broadband access networks and evaluate ways to mitigate these bottlenecks with caching in home networks. We first measure Web performance bottlenecks to nine popular Web sites from more than 5,000 broadband access networks and demonstrate that when the downstream throughput of the access link exceeds about 16 Mbits/s, latency is the main bottleneck for Web page load time. Next, we use a router-based Web measurement tool, Mirage, to deconstruct Web page load time into its constituent components (DNS lookup, TCP connection setup, object download) and show that simple latency optimizations can yield significant improvements in overall page load times. We then present a case for placing a cache in the home network and deploy three common optimizations: DNS caching, TCP connection caching, and content caching. We show that just caching DNS and TCP connections can can yield significant improvements in page load time, and even user’s browser is already performing similar independent optimizations. Finally, we use traces from real homes to demonstrate how popularity-based prefetching of DNS and TCP connections in a home-router cache can achieve faster page load times in home networks.

Understanding the Domain Registration Behavior of Spammers
Shuang Hao (Georgia Institute of Technology)
Matthew Thomas (Verisign, Inc.)
Vern Paxson (ICSI & UC Berkeley)
Nick Feamster (Georgia Institute of Technology)
Christian Kreibich (ICSI)
Chris Grier (ICSI)
Scott Hollenbeck (Verisign, Inc.)

Spammers register tremendous number of domains to evade blacklisting and takedown efforts. Current techniques to detect such domains rely on crawling spam URLs or monitoring lookup traffic. Such detection triggers after the spammers have already launched their campaigns, and thus these countermeasures may only come into play after the spammer has already reaped significant benefits from the dissemination of large volumes of spam. In this paper we examine the registration process of such domains, with a particular eye towards features that might indicate directly at registration time that a given domain likely has a malicious purpose. Our assessment includes exploring the characteristics of registrars, domain life cycles, registration bursts, and naming patterns. By investigating zone changes from the .com TLD over a 5-month period, we discover that spammers employ bulk registration, often re-use domains previously registered by others, and tend to register and host their domains over a small set of registrars. Our findings suggest a number of steps that registries and/or registrars could employ to crimp the ease with which miscreants acquire domains in bulk, thus potentially increasing their costs and reducing their agility for large-scale attacks.

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Internet2 Innovation Award on SDN Internet Exchanges

Congratulations to Muhammad Shahbaz and Arpit Gupta, winners of a new Internet2 Internet Innovation award.

Internet2 recently announced the winners of its 2013 Innovative Application Awards program. Each finalist was awarded a $10K grant to support their work building applications using Software Defined Networking (SDN) that solve the challenges faced by research, education and business networks. We are excited to recognize that two of the eight winning proposals were written by current Georgia Tech PhD students.
Muhammad Shahbaz and Arpit Gupta are working with their advisor Nick Feamster and Russ Clark, Ron Hutchins and others to build a working, commercial Internet exchange in Atlanta based on SDN technology that will finally address some of the shortcomings of BGP.
 Shahbaz and Arpit are working with Russ Clark, Ron Hutchins, and others from ColoATL to build an Internet exchange downtown at 55 Marietta Street based on SDN technology.  A preliminary deployment is already in place, and Arpit and Shahbaz are spending the summer building an SDN controller for the exchange and several new interdomain routing applications.  We’re finally giving BGP a run for its money!
Read the full press release here.

SDX March 2013

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Prof. Feamster offers SDN Course on Coursera

Nick Feamster is teaching a course on SDN on Coursera this summer.

About the Course

This course introduces software defined networking, an emerging paradigm in computer networking that allows a logically centralized software program to control the behavior of an entire network.

Separating a network’s control logic from the underlying physical routers and switches that forward traffic allows network operators to write high-level control programs that specify the behavior of an entire network, in contrast to conventional networks, whereby network operators must codify functionality in terms of low-level device configuration.

Logically centralized network control makes it possible for operators to specify more complex tasks that involve integrating many disjoint network functions (e.g., security, resource control, prioritization) into a single control framework, allowing network operators to create more sophisticated policies, and making network configurations easier to configure, manage, troubleshoot, and debug.

The course starts on June 24 and runs for six weeks.

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Mobile Broadband Performance Study Kicks Off in South Africa

  • Have you ever wondered what speeds you’re getting on your mobile device?
  • Do you want to know which applications are eating up your data plan?
  • Do you want to contribute to a data set about the quality of mobile Internet speeds in South Africa?
  • Do you have an Android phone?

If you’ve answered yes to these questions, sign up for our study now!

Research ICT Africa is conducting a study in collaboration with Georgia Institute of Technology to measure the quality of broadband services in South Africa.

Am I eligible for the study?

You’re eligible for the study if you have an Android phone.

What do I have to do if I sign up?

Download and install My Speed Test by GTNoise our speed test on your Android phone. Go here to install the app:
Otherwise, scan the QR code above!

What do I get out of it?

Your data will help us learn about mobile speeds in South Africa.

 You also have a chance of winning a Samsung Galaxy S3 mini 8GB! However, only those conducting at least 3 speed tests per month until July 2013 will be elegible to win the Smart Phone. The more tests you run per month, the greater chance you have of winning the phone. Please be aware that each test can use 5-10 MB of data and running the 3 tests on the same day in the morning (between 7am-2pm) in the arternoon (between 2pm and 7pm) and in the evening (between 7pm and 7am) is preferable.

Where can I get more information?
If you’re interested and want more details, please contact us on

Download the FAQ on the mobile broadband quality of service study.