Thanks. We'll continue with the explicit login link, then.

Chris

On 23 Jul, 2012, at 10:57 , Russ Allbery wrote:

> Chris Beer <[email protected]> writes:
> 
>> In DLSS, we're working on an application that allows public access to
>> some material, but WebAuthed users may receive additional access based
>> on SUnet ID or workgroups. We've successfully added WebAuth to our
>> application. When we require WebAuth across the whole application,
>> everything works as expected (users are prompted by webauth as-needed,
>> the application receives the WebAuth credentials, etc). When we use
>> WebAuthOptional to let anonymous/public users into the website, our
>> application does not receive the WebAuth information from users who
>> signed in to WebAuth through a different website.
> 
> Correct.  WebAuth authentication is per web site, so your site has no way
> (by design) of knowing whether the user is signed on to a different site.
> 
>> Has anyone else run into this problem before? Is there a work-around we
>> should use (a .stanford.edu cookie that could tell us the user is
>> WebAuth-able, a graceful way to 'try' WebAuth without interrupting the
>> user, etc)? In the meantime, we're requiring the user to explicitly
>> sign-in to the application, but it would be nice to make this a seamless
>> SSO process.
> 
> I'm afraid that you have to ask the user to explicitly sign in.  I'm
> reluctant to add a domain cookie saying that the user has single sign-on
> cookies because this won't reliably work.  If, for example, the user
> authenticated with Negotiate-Auth, they will never have single sign-on
> cookies, but they'll still be able to authenticate to any new site without
> a password.
> 
> This model (where you're logged in unauthenticated by default and can
> click on login to authenticate as yourself) is a very common pattern that
> I think users already expect, so I don't think you're really missing that
> much by not being able to know in advance if the user can sign in without
> a password.  (Personally, as a user, I actually prefer having an explicit
> login link.)
> 
> -- 
> Russ Allbery <[email protected]>
> Technical Lead, ITS Infrastructure Delivery Group, Stanford University


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