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Re: [GSoC] Improving Snakes on a Tor

Hi there John - glad to have you working with Tor! We're really anxious to see where you go with this project since, as exemplified by the recent incident with PrivacyNow [0], we're currently pretty miserable about noticing and flagging bad exits.

Unfortunately our definition of a bad exit is pretty vague [1]:
  "BadExit" if the router is believed to be useless as an exit node
    (because its ISP censors it, because it is behind a restrictive
    proxy, or for some similar reason).

An easy place to start would be to solicit input on or-talk for a better definition and enumerable attributes we can look for. Some obvious starting ones would be ssl stripping, certificate tampering (checking for differences like the Perspectives addon [2]), and bad DNS responses. I'd imagine Scott Bennett would be glad to jump in with some more ideas. :)

Also, have you thought about setting up a site or blog where people can check how things are coming along? Here's what I did when doing GSoC with the SIP Communicator project: http://www.atagar.com/misc/gsocBlog/

Again, glad to have you and looking forward to working with you this summer! -Damian

[0] http://archives.seul.org/or/talk/Apr-2010/msg00120.html
[1] http://gitweb.torproject.org/tor.git?a=blob_plain;hb=HEAD;f=doc/spec/dir-spec.txt
[2] http://www.cs.cmu.edu/~perspectives/index.html

On Fri, Apr 30, 2010 at 9:15 PM, John M. Schanck <jms07@xxxxxxxxxxxxx> wrote:
Hi or-talk,
My name is John Schanck, I'm a third year CS student at Hampshire College,
and I'll be working with Tor this summer through Google Summer of Code.
First, let me say how excited I am to have this opportunity - I've been
following the Tor project for several years now and can think of no better
place to devote my efforts. Many thanks to those of you who read my
proposal, especially Mike Perry who has graciously agreed to mentor the
project, and Damian and Erinn who have also offered up some of their time.

I'm going to be working on improving the Snakes on a Tor (SoaT) exit
scanner. For those of you not familiar with it, SoaT aims to detect
malicious, misconfigured, or heavily censored exit nodes by comparing the
results of queries fetched across those exits to results obtained without
Tor. It's an ambitious project, originally developed by Mike Perry and
crafted into its current form by Aleksei Gorney during GSoC 2008, so my
goals are modest. I'm going to begin by stabilizing the existing codebase,
and then work on minimizing the number of false positives generated by the
current filters. If time permits I'll also begin designing new filters to
handle adversaries not yet accounted for.

If you'd like to talk about the project (or just say hello), you can find
me on OFTC under the nickname 'susurrusus'.

Cheers,
John

PS. Congratulations to the other accepted students, I look forward to
meeting you and hearing about your projects :).

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