[tor-dev] [GSoC '16] Exitmap Improvements Project - Status Report #3

Mridul Malpotra mridul.malpotra at gmail.com
Sat Jul 2 15:27:34 UTC 2016

Hi everyone!

For the past week, I have shifted my focus to the main sub-project of
continuous scanning in Exitmap. What we'll be trying to achieve is
having the Exitmap utility running in the background and running the
various modules. This report recounts one week worth of work since my
2nd report was on 26th June.

Work done:
1. Wire-framed the structure of how continuous scanning will work.
Major components that will be focused on are (a) Periodically updating
the network consensus to scan for new or previously invisible exit
nodes for malicious behaviour, (b) A mechanism that keeps a close eye
on some exit nodes while does not care much for nascent exit relays or
well established guard nodes, and (c) Add as much randomization as
possible for these scans to make it more difficult for a malicious
exit relay to distinguish regular traffic from scanner activity.

2. IRC meeting with my primary mentor Philipp Winter (phw) to discuss
some of the features and how will go about implementing them. Some
points arrived at from the discussion:
 a. Need to create an asynchronous element for periodically fetching
consensus data and to integrate the element with the existing Exitmap
 b. Find a way to update the Tor micro-descriptors and use new
consensus for the modules. I still need to find a way to
programmatically force the Tor client to update its consensus at the
moment specified. Damian Johnson (atagar) advised me to use the
FetchDirInfoEarly parameters that helps. If anyone has any more
information about this, it would help a lot. I will be scouring
through the control-spec for the same.
 c. Create an algorithm to give more weightage to some exit nodes from
consensus depending on what the criteria is. We need to come up with a
selection mechanism that selects nodes visible in the say 0-24 hours
time frame but is not a node that has just come or has been around the
Tor network for some time. Some research still needed on this aspect.

Have a great weekend everyone!

Mridul (mtyamantau)
PGP keyID: 0xb716e33ab6d0a653

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