Re: [TLS] Captive portals, "access administratively disabled" and alert messages

Martin Thomson <martin.thomson@gmail.com> Tue, 02 January 2018 21:56 UTC

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From: Martin Thomson <martin.thomson@gmail.com>
Date: Wed, 3 Jan 2018 08:56:11 +1100
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To: Stephen Farrell <stephen.farrell@cs.tcd.ie>
Cc: =?UTF-8?Q?Mateusz_Jo=C5=84czyk?= <mat.jonczyk@o2.pl>, Eric Rescorla <ekr@rtfm.com>, tls@ietf.org
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Subject: Re: [TLS] Captive portals, "access administratively disabled" and alert messages
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On Wed, Jan 3, 2018 at 7:18 AM, Stephen Farrell
<stephen.farrell@cs.tcd.ie> wrote:
> [...] the capport wg - I'd guess folks
> there are more aware of the full range of cases that may need
> handling and of how to try interpose the portal web page stuff
> before other applications see the n/w as active (or whatever it
> is they're doing with HTTP:-).

As chair of capport, this is definitely something for that group.  The
current approach we are taking there avoids having user equipment
attempt to connect to anything at all, which avoids this class of
problem.  If you look at modern devices, they all probe a network
before making the interface available to applications, and most of
what we would be doing exists at that probing phase.

We are additionally considering a network-based signal for those cases
where the attempt is made anyway, but I don't think that is firm yet.

Captive portal cases are separate to those related to selective
blocking of names or destinations, which is essentially a censorship
mechanism.  We've been careful to avoid creating mechanisms to support
that sort of discrimination.