[keycloak-dev] Kerberos, login with different user

[Marek Posolda]

On 01/10/15 09:13, Stian Thorgersen wrote:
> I don't like the query param approach as it requires somehow adding 
> the query param to specify what authenticators to skip. This would 
> have to be added to applications themselves and with Keycloak the 
> whole idea is that applications shouldn't have to worry about 
> authentication semantics.
I thing that some applications care about how was user authenticated :-\

For example when application wants to reuse Kerberos credential from the 
SPNEGO authentication to call some other thirdparty kerberos-secured 
service, it needs a way to "force" keycloak to authenticate with 
Kerberos. Hence it can skip other authenticators and leave just Kerberos.

Similar case is, when application wants to reuse Facebook access token - 
in this case application wants to enforce login with Facebook. For this 
case, we already have kc_idp_hint parameter, which also requires support 
on the application side . Isn't it similar to the query parameter 
skip_auth_mechanisms ?

I might be wrong, but maybe some Keycloak users don't care too much 
about SSO. The added value for them is provisioning of users and the 
fact, that they don't need to implement Facebook or Kerberos 
authentication, but Keycloak implements it for them. So they may want 
some control on the application side how is user authenticated.
> We need a generic mechanism to be able to skip any authenticators that 
> automatically log in a user. Currently this is only Kerberos, but in 
> the future we could add more, including an option to automatically 
> route to external IdPs.
For external IdPs, we already have "Authenticate by Default" switch on 
identity providers. We also have kc_idp_hint parameter as I mentioned above.
>
> Ignoring implementation semantics for now, but taking Kerberos as the 
> example authenticator I can see some options (in the example below 
> replace 'Kerberos' with any other authentication method that can 
> automatically login a user):
>
> * If a user that was logged in using Kerberos logs out the user should 
> not just be automatically logged-in again for the current browser 
> session. Instead the user should be displayed with a regular 
> username/password field, but also with an option to login with Kerberos
> * A variant on the above where if a user has logged-out from Kerberos 
> the user would be displayed with a "Is this you?" when login, if the 
> user selects yes the Kerberos authenticator would continue, if not the 
> regular username/password form would be displayed
+1 to support "Is this you" screen. However maybe this should be 
configurable as some deployments may not want to display the screen, but 
want to relogin automatically.

Classic example is redhat.com. When I have kerberos ticket, I can never 
see the login screen on saml.redhat.com . If we enforce adding "Is this 
you", some employees may complain "Hey, why there is another splash 
screen I need to click. Why I am not logged automatically" etc. But 
maybe I am wrong here. Maybe good opportunity to ask IT guys on the call 
today as they have experience with the real world scenarios ;-)

Conclusion of my point of view: Add variable support for "Is this you" 
screen and in addition have the support for skip_auth_mechanism Michael 
implemented.

Marek

> * Implement account switcher - where a user can login to multiple 
> accounts at a time and select which account to use
>
> Other ideas? Points for ideas that requires no hacks in applications ;)
>
> On 30 September 2015 at 15:39, Michael Gerber <gerbermichi at me.com 
> <mailto:gerbermichi at me.com>> wrote:
>
>     Hi all,
>
>     I would like to use kerberos as my standard authentication
>     mechanism, but I also want to have the possibility to log in as an
>     admin over the login form.
>     Therefore, I want to skip the kerberos authenticator after a
>     successful logout.
>     https://issues.jboss.org/browse/KEYCLOAK-1727
>
>     How would you solve this problem?
>
>     I've got two solutions, one sets a logout session cookie after a
>     logout and then skips the kerberos authentication and another
>     which allows users to skip any kind of alternative authenticators
>     with a query parameter.
>
>     Logout Session Cookie
>     https://github.com/gerbermichi/keycloak/commit/f804d9e13573cb666cf6d2eff1407978c9e5e854
>
>     Query Param
>     https://github.com/gerbermichi/keycloak/commit/abd3bd87f5aa4c28914da677653268c0f44fe6cc
>
>     Michael
>
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