Vittorio Bertola <[email protected]> writes:
> > Il 10 agosto 2019 20:57 Wes Hardaker <[email protected]> ha scritto:
> >
> > 4) Now that this has had multiple implementations (though they'll need
> > to change after the packet format and code changes [that they
> > requested]), this is likely ready for last call after passing through
> > the document for nits and addressing any last comments raised.
>
> Given some recent discussions on the ADD list, I think that it could
> make sense to add a third error code for DNS filtering. Currently, the
> draft has these two:
Hi Vittorio,
I've included responses and actions to your suggestions below.
10 Sep 4 Vittorio Bertola
=========================
10.1 DONE Add another blocked error
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Given some recent discussions on the ADD list, I think that it could
make sense to add a third error code for DNS filtering. Currently, the
draft has these two:
4.16. Extended DNS Error Code 15 - Blocked
The resolver attempted to perfom a DNS query but the domain is
blacklisted due to a security policy implemented on the server being
directly talked to.
4.17. Extended DNS Error Code 16 - Censored
The resolver attempted to perfom a DNS query but the domain was
blacklisted by a security policy imposed upon the server being talked
to. Note that how the imposed policy is applied is irrelevant (in-
band DNS somehow, court order, etc).
There is however a third case, which is "blocked by user request". The
three cases differ on who made the decision to filter, i.e.:
- code 15 is for when the recursor blocks stuff that its own operator
dislikes;
- code 16 is for when the recursor blocks stuff that public
authorities dislike;
- the third code would be for when the recursor blocks stuff that the
user (the entity that acquired the service) dislikes, e.g. for
parental control, destinations not suitable for work, etc.
+ Response: I think the idea of a "you requested we block this" makes
sense, so I'll add that one
10.2 WONTDO you requested blocking
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
There was also some discussion on whether these error codes could be
accompanied by a URL that the client device can use to display a
human-readable explanation to the user, which would be a cleaner
solution than the current practice of giving to the client a positive
response, but with the IP address of a local web server instead of the
original one (a practice that doesn't work well with HTTPS anyway).
This has many security caveats, and could only work with an
authenticated, trusted resolver (which is anyway true of the above
error codes in themselves, since an adversarial recursor could just
lie on the reason for blocking or even on the fact that it is actually
blocking something). It is really too early to say whether this could
work or whether it would actually be implemented, and also, on
transports other than DoH, I'm not sure if applications could ever
access this information. Still, perhaps a note on whether EXTRA-TEXT
could bear structured information for certain error codes, and how
this mechanism could be later defined, could be useful.
+ Response: I don't think we want to get into how log messages should
be delivered. If an implementation wants to put a URL in the
additional information, that certainly would make sense. But the
Web does not equal the internet, and figuring out how to do it for
everything is not easily possible.
--
Wes Hardaker
USC/ISI
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