karsten's blog

Attending the Google Summer of Code Mentor Summit feels like the perfect time to finally write the wrap up of this year's Google Summer of Code. So, what did we learn in our third year of participation?

We had 5 students funded by Google to work on Tor over this summer, plus 1 more for The Electronic Frontier Foundation. We had to pick these 6 out of 32 applications, which was a pretty hard process for us. In retrospect, there were at least 2 more students that we'd really have wanted to work on Tor but that we were not able to pick. Fortunately, they stuck with the project anyway, writing a neat relay monitor and helping reimplement Tor in Java for mobile devices. read more »

Two weeks ago we posted early measurements about the growth of Tor usage in Iran. Since then we have improved our math, and used more data sources. This work is part of our metrics project, where we're learning about the Tor network to improve its availability and performance while keeping our users safe. read more »

In the past few days the Tor network is seeing a lot of new users coming from Iran. At the same time we have heard from many people who want to support the Tor network by setting up more relays and bridges. Now we wanted to know, are these just promises, or did the network really grow? Here are the results: read more »

On this year's HotPETs workshop (August 5-7 in Seattle, WA, USA) I'm going to present some results on Measuring the Tor Network from Public Directory Information. The main idea is to observe trends in the Tor network without having to measure any data other than public directory information. These data are there anyway as they are required for clients to make good path selection decisions and build circuits. The results of this paper reveal problems in the current Tor network that need to be addressed, e.g., by lowering requirements for assigning certain flags, facilitating the upgrade process, improving support for dynamic IP addresses, possibly calculating bandwidth capacity more reliably, and clarifying legal issues for running relays in view of data retention laws. The next step in understanding the problems of the Tor network requires an extension of network measurements to improve performance and blocking-resistance of Tor.

The Tor network has grown to more than one thousand relays and millions of casual users over the past few years. We are proud of our network's popularity, but with growth has come increasing performance problems and attempts by some countries to block access to the Tor network. In order to address these problems, we need to learn more about the Tor network. In this post, I describe the current state of network measurements in Tor and some proposed additions to help us understand the network better. read more »

Great news! We have been accepted as a mentoring organization for Google Summer of Code 2009 together with The Electronic Frontier Foundation. Yay!

This will be our third Google Summer of Code after 2007 and 2008. In our first year we had four students working on making relays work better (and not crash) on Windows, on a library and tool to try alternative path selection algorithms, on a fuzzing library to look for parsing problems, and on scalability and privacy for hidden services. In our second year we had seven students. One of our successful students of the 2008 program wrote a nice blog post reviewing how GSoC went for him, for the other students, and for the project in general. read more »

During the past eight months we have been trying pretty hard to improve hidden service performance. This work was part of the project to Speed Up Tor Hidden Services, generously funded by the NLnet Foundation. As of today, we know that we have succeeded in our attempts -- well, or not? read more »