Re: Question about error code 451 and internet censorship

[Stephane Bortzmeyer <[e-mail]>]

On Fri, Feb 19, 2016 at 07:10:55AM +0000,
 Philippe-Joseph Salazar <[e-mail]> wrote 
 a message of 612 lines which said:

>  I am an academic researcher, currently preparing a book on the
>  Islamic State for publication at Yale UP.

Hello. Apart from the specific case of HTTP status code 451, I'm not
sure it is the best place to ask. May be the IRTF research group HRPC
(Human Rights and Protocol Considerations)
<https://www.irtf.org/mailman/listinfo/hrpc>

> I have the following question: when a site is blocked due to
> censorship by a non-dictatorial state (ie not one of those that IETF
> lists in relevant documents, and I am thinking here of French state
> of emergency censorship), what error code is supposed to come up?

The IETF does not mandate how to censor :-) Various countries
(dictatorial or not) use different techniques. In France, the most
common one is forcing DNS resolvers to lie (see a technical survey of
DNS lying in Europe in
<https://labs.ripe.net/Members/stephane_bortzmeyer/dns-censorship-dns-lies-seen-by-atlas-probes/>)
and therefore to redirect to an official Web site (see it at
<http://interieur2.eu.org/>). This official server does not return a
451 but a plain 200 (funny, if you use wget, you'll get a 403, unless
you use --user-agent).

> Or, can you kindly direct me to documents on your site that may help
> me find out what current policy or good practice is in regard of
> sites censored by Western agencies?

I'm not aware of a comprehensive survey. There is an attempt
<https://datatracker.ietf.org/doc/draft-hall-censorship-tech/> but it
seems to move slowly. There are some very good country-specific
surveys such as for Greece
<https://www.usenix.org/conference/foci15/workshop-program/presentation/ververis>