David,

This is a very good observation - and one that we have had to consider in our 
implementation. The source of the captive status needs to be reliable and quick 
enough to achieve the flow described in section 6 (Example Interaction):

"Once the user satisfies the requirements for external network access, the 
client SHOULD query the API server again to verify that it is no longer 
captive.”.

For us, the API saying the user is online but the enforcement device still 
blocking them would be a major support headache, but could be caused by a 
number of different scenarios. This sentence was key in making us seek a robust 
solution to that possibility.

Thanks,

Steve


> On 3 Jul 2020, at 17:23, David Bird <dbird=40google....@dmarc.ietf.org> wrote:
> 
> Thanks Steve, I have no doubt that some operators will implement this very 
> well! :-) 
> 
> Indeed, the login flow is the same through the Portal via API (assuming you 
> figure out the "unique device identity" question).. and I'm sure you'll have 
> the API server fully integrated with your AAA so that all sorts of logout 
> events are handled (e.g. NAS restart, idle timeout, etc).
> 
> In the long-tale of public access, I believe users will experience a wide 
> range of networks, with various levels of integration. My concern is more 
> that users learn (or even told by venue staff) to disable CAPPORT support if 
> they find it often "wrong" (e.g. there is a CAPPORT API but no NAS 
> enforcement; API says you are logged in, but NAS is dropping/redirecting; 
> etc)... 
> 
> [I personally believe we missed an opportunity to make a more robust protocol 
> by directly involving the NAS (for notification of captivity), providing a 
> single source of truth...]
> 
> On Fri, Jul 3, 2020 at 7:13 AM Steve Haskew <st...@boaz.org.uk 
> <mailto:st...@boaz.org.uk>> wrote:
> Hi David, Tommy, all,
> 
> Just to add the the discussion, from the perspective of a network operator! 
> We are just implementing and going to be testing this very soon. We don’t see 
> any issues in terms of policy application, because the final step to log the 
> user in will be the same with either approach. Actually, this provides a 
> really nice route for us to resolve the ever-increasing issue of the ugliness 
> of forcing redirects, especially with the decreasing use of plain HTTP (and 
> therefore causing SSL warnings). We can only hope that other vendors roll 
> this out soon too! I see it as a big step forward.
> 
> However, the challenge for us that is linked revolves around identity. MAC 
> Randomisation (also coming in iOS 14)  is great for privacy, but in the short 
> term is poor for user experience on any form of guest wifi, particularly for 
> longer stays (e.g. hotel, vs cafe). We’ve actually seen a deterioration of 
> support for Hotspot2.0/Passpoint, in that installation of a profile from 
> within the Captive Network Assistant on iOS no longer works.
> 
> It feels like the dichotomy of privacy vs user experience here has no 
> practical solutions - could this be something that the wider WG has 
> previously considered, and is it within the remit of the group to look at?
> 
> Thanks,
> 
> Steve Haskew
> 
> 
>> On 3 Jul 2020, at 14:23, David Bird <dbird=40google....@dmarc.ietf.org 
>> <mailto:dbird=40google....@dmarc.ietf.org>> wrote:
>> 
>> Thanks Tommy,
>> 
>> Might you have screenshots of the user experience ? I'd be interested to see 
>> it....
>> 
>> Agreed, adopting the new CAPPORT spec is very easy to setup (just a DHCP 
>> server config change at the access point, and an API/Portal server on the 
>> Internet). The complexity for network operators comes when fully integrating 
>> this new "application" method of captive portaling with existing "network" 
>> (NAS/redirect) methods. The complexity is in ensuring the NAS and API are 
>> enforcing the same policies, for all kinds of users (roaming, paid, free, 
>> etc) ... if the network operator doesn't do this well, or at all, then the 
>> complexity is shifted to client device support, answering questions like 
>> "Why does the WiFi at airport X not work only for new devices?". For this 
>> reason, I believe you will eventually start probing for redirects again... 
>> 
>> You may trust the API, but you may also want to verify.... :)  
>> 
>> 
>> On Thu, Jul 2, 2020 at 7:24 AM Tommy Pauly <tpa...@apple.com 
>> <mailto:tpa...@apple.com>> wrote:
>> Hi David,
>> 
>> One point I wanted to clarify: the iOS and macOS betas support for CAPPORT 
>> discovery and APIs still goes through the standard and existing UI flow for 
>> captive portals. The times in which the captive portal UI is shown is 
>> limited, for example to times when the user is in WiFi settings. Thus, while 
>> adoption should indeed be easy and only require adding a small bit of 
>> infrastructure in order to provide a flow that doesn’t require redirects, 
>> the set of circumstances in which a network can display content to the user 
>> is not increased.
>> 
>> Thanks,
>> Tommy
>> 
>>> On Jul 1, 2020, at 5:27 PM, David Bird <db...@google.com 
>>> <mailto:db...@google.com>> wrote:
>>> 
>>> 
>>> That's pretty cool! 
>>> 
>>> This will give new opportunities in monetizing WiFi for new iOS and macOS 
>>> devices with only a DHCP server change and an API server!
>>> 
>>> On Wed, Jul 1, 2020 at 4:22 PM Erik Kline <ek.i...@gmail.com 
>>> <mailto:ek.i...@gmail.com>> wrote:
>>> +1
>>> 
>>> Out of curiosity, does the implementation handle the 7710bis options'
>>> urn:ietf:params:capport:unrestricted value?
>>> 
>>> On Mon, Jun 22, 2020 at 5:00 PM Martin Thomson <m...@lowentropy.net 
>>> <mailto:m...@lowentropy.net>> wrote:
>>> >
>>> > Tommy, this is great!  Thanks for all your work here, it's good to see 
>>> > this turn into something concrete.
>>> >
>>> > On Tue, Jun 23, 2020, at 07:30, Tommy Pauly wrote:
>>> > > Hello CAPPORT,
>>> > >
>>> > > I wanted to highlight an announcement we’ve made for the betas of iOS
>>> > > and macOS released today:
>>> > >
>>> > > How to modernize your captive network
>>> > > <https://developer.apple.com/news/?id=q78sq5rv 
>>> > > <https://developer.apple.com/news/?id=q78sq5rv>>
>>> > >
>>> > > The betas for iOS and macOS support both draft-ietf-capport-rfc7710bis
>>> > > and draft-ietf-capport-api by default. This doesn’t change the user
>>> > > experience of logging onto captive networks, but the system will
>>> > > request the DHCP options and handle the RA option, and will prefer
>>> > > using the Captive Portal API Server interaction over having a probe
>>> > > that is intercepted.
>>> > >
>>> > > If you have a portal system that is already implementing the CAPPORT
>>> > > features, please test out these betas and let us know if you see any
>>> > > issues! And if you have a captive portal solution, we’d encourage you
>>> > > to start supporting this soon.
>>> > >
>>> > > Best,
>>> > > Tommy
>>> > > _______________________________________________
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>>> > > https://www.ietf.org/mailman/listinfo/captive-portals 
>>> > > <https://www.ietf.org/mailman/listinfo/captive-portals>
>>> > >
>>> >
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>>> 
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