Re: [TLS] Possible blocking of Encrypted SNI extension in China

David Fifield <david@bamsoftware.com> Thu, 13 August 2020 20:13 UTC

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Date: Thu, 13 Aug 2020 14:13:06 -0600
From: David Fifield <david@bamsoftware.com>
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Subject: Re: [TLS] Possible blocking of Encrypted SNI extension in China
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On Thu, Aug 13, 2020 at 01:04:48PM -0700, Carrick Bartle wrote:
> Weird. Thanks for the update. How are you confirming that it's blocked from inside-out?

I couldn't test it myself, so I am relying on the reports of colleagues
in China. GFW Report is able to test directly from China.

Measurement vantage points in China are tricky to get ahold of. A
possible alternative is to use a reflected measurement system in the
style of Quack, which uses infrastructural echo servers:
https://censorbib.nymity.ch/#VanderSloot2018a
https://www.usenix.org/conference/usenixsecurity18/presentation/vandersloot
https://github.com/net4people/bbs/issues/2
Censored Planet does regular Quack measurements, but I don't think they
are testing ESNI yet: https://censoredplanet.org/data/raw