[metrics-team] Measuring web servers' discrimination against Tor users

[David Fifield]

This paper will be of interest to metrics team members.

https://www.benthamsgaze.org/2016/02/23/do-you-see-what-i-see/
https://www.cl.cam.ac.uk/~sk766/publications/ndss16_tor_differential.pdf

It measures blocking (including e.g. captchas) of Tor exit nodes by web
servers, in three ways:
 1. All-IPv4 port scans run directly from a few Tor exit IP addresses.
 2. Alexa 1k homepage downloads through every Tor exit.
 3. Historical OONI comparisons of Tor and non-Tor downloads.
It finds blocking at both the network/transport layers and at the
application layer.