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

David Fifield david at bamsoftware.com
Wed Feb 24 06:31:11 UTC 2016

This paper will be of interest to metrics team members.


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.

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