[tor-talk] Fw: Your feedback to Startpage

[Aaron Gibson <aagbsn@xxxxxxxx>]

Per discussion with some randoms in #nottor, I emailed startpage to
clarify how their rate limiting is applied to Tor. Here's the response
I received below.

--Aaron

Begin forwarded message:

Date: Fri, 24 Jan 2014 14:24:52 -0700
From: support@xxxxxxxxxxxxx
To: aagbsn@xxxxxxxx
Subject: Your feedback to Startpage


Dear Aaron,

At Ixquick and StartPage, we feel sympathetic to the Tor project. Tor
fulfills an important role in keeping the Internet private - especially
in the world after Snowden.

StartPage and Ixquick are anonymous search engine that have all sorts
of costs to cover; search results, servers, bandwidth.  We are showing
sponsored ads on the top of the page to balance those costs.

By nature, Tor traffic generates close to zero revenue - while the
claim on servers and bandwidth is large. Therefore we simply cannot
accommodate all Tor traffic unrestricted.

The answer to your question can be found in our support article:
https://support.startpage.com/index.php?/Knowledgebase/Article/View/188/0/how-does-startpage-prevent-scraping-and-abuse-without-recording-ip-addresses.
The article text is quoted below:

How does StartPage prevent scraping and abuse without recording IP
addresses?

In order to prevent our service from being "scraped" or excessively
queried by automatic programs or bots - with resulting server slow-down
and extra costs to our organization - our engineers have devised
intelligent methods to filter out those unwanted visitors.

We do not know the real IP address until somebody turns abusive.  This
is one of our strongest privacy features.

An abusive source is one that sends large amount of queries in a short
span of time. The IP addresses are saved in a one-way encrypted form in
in-memory hash under normal usage condition. We keep track of the
number of requests being made. In other words, instead of keeping track
that a user with IP 12.34.56.78 has performed some number of searches,
StartPage encrypts this using a one-way hash to a random string such as
"D87ab420475rn3ner65", for example, that can't be reversed to find the
IP address.

When the number of requests from a source crosses pre-defined
thresholds that we deem to be abusive, the source is added to a block
list. For all others, the in-memory hash is cleared, so no record
remains of even the one-way-encrypted hashes. We use a similar approach
for IP ranges.

The IPs of the Tor exit nodes can be retrieved from the Internet. Those
IPs can be rate limited without storing the IPs according the above
description.

Again, thank you for contacting us. Your feedback helps us continue to
keep making StartPage even better. And since you appreciate what we do,
please tell your friends about StartPage so we can help keep the
Internet free and private.

Best regards,
Deborah H.
StartPage.com

http://www.facebook.com/startpagesearch
http://twitter.com/startpagesearch
________________________________________________________________________________

Your question to Startpage was:
    01-18-2014  -  Request for clarification of how startpage
implements autoquery rate limiting without logging users IP addresses
Several Tor community members are curious how startpage can claim
"Since January 2009 we do not record our users' IP addresses
anymore" (https://startpage.com/eng/protect-privacy.html) yet has
implemented rate limiting from Tor exit nodes, presumably due to abuse.
Could you please clarify how this is implemented?

Thanks in advance for transparency,

--Aaron


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