[Freeipa-users] External collaboration edits

Wed Jun 11 08:51:31 UTC 2014

On Sat, Jun 07, 2014 at 09:21:29PM +0000, Nordgren, Bryce L -FS wrote:
> Dimitri, thanks for the reply! Pls forgive my lateness.
> 
> I fear I am not currently up to fighting with MS Outlook to convince it to let me respond inline. It wants to block quote your entire message and if I type in the middle it keeps the "quoted" style.
> 
> In any case:
> 
> #1] Making small things work first and accumulating functionality is definitely the way to go. If it were simple and straightforward, everyone would be doing it already.
> 
> #2] I looked at "views" (Ticket 3979 as well as http://www.freeipa.org/page/V4/Migrating_existing_environments_to_Trust). I think I follow most of it (a default view which applies to the whole domain, custom views which may be applied to particular targets). +1 +1 +1. One concern I have is that the design page seems to be written around a single upstream source (trust with AD). What happens if there are many "upstreams"?  All in all, though, it sounds like my current RFE is a duplicate of views. If we could add in my use case to the Views ticket/design, we can close mine out.

It's not only about AD, but use-case and examples in the design page
currently all refer to AD. The key is to find a unique reference to the
upstream object which in the AD case is obviously the SID. In a
previous version of the page there were a bit more details who the
original/upstream objects can be referenced, e.g. it can a fully
qualified name or Kerberos principal.

bye,
Sumit

> 
> #3] Kerberos based auto provisioning will fall apart if the authentication path cannot be walked by the client (not the FreeIPA server). When I'm sitting in my office, I can see my KDC as well as the collaboration environment, and I can walk the path. However, if I cannot convince my CIO to poke a hole in the firewall so that FreeIPA in the collaboration domain can get to the internal AD (to query attributes, etc), then an AD trust is not possible and a vanilla Kerberos trust is all that is available. Kerberos-trust based auto-provisioning may be able to handle situations that AD trusts can't. By and large, I need my boxes to know my username, and could care less if they know my givenName, sn, mail, telephoneNumber, etc. As long as FreeIPA can synthesize a uidNumber for me in the absence of an SID, the rest is gravy.
> 
> #4] One user/Many Accounts. This is an unavoidable reality. Also, there's a namespace collision issue here. My Kerberos cname at crealm is bnordgren at DS.FS.FED.US<mailto:bnordgren at DS.FS.FED.US> as issued from my AD. My SAML uid is "bnordgren at fs" from https://www.eauth.usda.gov/Login/login.aspx. My Google OpenID is bnordgren from "wherever". There is also a "bnordgren" from a university out of SLC, Utah. I occasionally get mis-addressed email for him. Typically spam, but once from his mom. Fundamentally, whenever multiple domains are consolidated into a single namespace (as is already a use case for views), one typically tries to avoid username collisions just as vigilantly as they try to avoid uidNumber collisions. What is needed here is a method for the users to override the default collision avoidance such that they allow all of their accounts to be mapped onto their One True Username for the domain. In the spirit of point #1, implementing collision avoidance will be required for views, so it needs to happen now even without external collaboration. Figuring out how to let users override it can happen in the future.
> 
> 
> Bryce
> 
> 
> From: freeipa-users-bounces at redhat.com [mailto:freeipa-users-bounces at redhat.com] On Behalf Of Dmitri Pal
> Sent: Wednesday, May 14, 2014 4:13 PM
> To: freeipa-users at redhat.com
> Subject: Re: [Freeipa-users] External collaboration edits
> 
> On 04/19/2014 07:46 PM, Nordgren, Bryce L -FS wrote:
> I've run out of time for today, but the external collaboration pages are slowly evolving.
> 
> 
> http://www.freeipa.org/page/External_Users_in_IPA
> 
> Dimitri observed that my RFE page was too long. I observe it also has too much stuff unrelated to the actual meat of the RFE. So I factored out most of the Kerberos stuff into a different page. I also tried to focus the RFE to just creating entries in LDAP for external users so they can: a] participate in POSIX groups; and b] have locally-defined POSIX attributes.
> 
> http://www.freeipa.org/page/Collaboration_with_Kerberos
> 
> This is where all the Kerberos stuff went. I also added  in "Option A" from Petr's email. Option B will come along later, when I pick this up again. Mechanism three has more to do with Ipsilon than IPA, and basic functions required of the Ipsilon gateway server are articulated there (regardless of the particular authentication method.)
> 
> Send comments to the list. I really appreciate Option A! Send more stuff I didn't think of.
> 
> Hello,
> 
> 
> I finally read the pages, sorry for the delay. great writeup!
> 
> Here are some comments.
> 
> 1) You are right that we need to have a record in IPA to be able to have a DN and take over some of the posix attributes. We already have this use case and this is a high priority. We call it views: https://fedorahosted.org/freeipa/ticket/3979
> Once this is implemented we will have mechanism to have a local entry without credential for the external user.
> 2) The second issue is provisioning as automatic as possible. And this is where there will be some issues.
> If we want to leverage Kerberos trusts then two things should happen:
> a) the trust should first be established
> b) the home realm should be accessible for the KDC in the collaboration domain.
> This rises practical operational questions about what is the home domain. If the home domain is another collaboration domain then user is natively have been created in that domain and has his credential in that domain. Hm but that violates the idea that the collaboration domains have external "auto-provisioned users". If the home domain is the internal domain than most likely the cross forest trust can't be established because admin of the internal domain would not want to expose his domain to somebody's external domain on the internet.
> So IMO the kerberos based auto-provisioning falls apart.
> 
> However if we use a gateway that would allow a person to self register and use technologies similar to OpenID then we would be able to create his own account. The gateway would check that the user is from some trusted source that is configured for that domain. We would have to figure that part out. But IMO this component is external to IPA. It is a similar gateway to Ipsilon. I suspect that as we move forward Ipsilon will transform from an IdP server to being a collection of "gateway services". One would be able to deploy IdP instances, Kerberos -> cert service, account registration service etc.
> 
> This would rely on some of the functionality in IPA but can evolve independently.
> IMO if we go this path and you are interested in contributing to this effort we can start prototyping such service.
> We can start simple: create a service that allows one to authenticate using google or facebook and once user authenticated agains one of them call an ipa user-add against IPA.
> That would be a good first step towards what you want to accomplish.
> Then it can be enhanced to redirect to an external IdP (Ipsilon). Then the setup will be:
> 
> * User connects to the self registration portal.
> * Portal reditrects him to the IdP that is configured for the portal
> * IdP performas an authentication against user home domain and creates assertion
> * Assertion is presented to the registration portal
> * The portal gets user infor from the assertion and adds a user
> 
> It also seems that OpenID connect might be quite relevant here.
> So exploring how it can be used in in conjunction with registration portal would be another path.
> 
> 3) The problem of the credential yet stays open. If the user can be created in different ways it might not be quite easy for the user to know or remember that he must use his kerberos/Google/facebook or other credential wit ha specific domain. May be we should consider creating a full user also with a password or OTP token to access the collaboration domain. Then user would always know that he needs to use his token. I wonder if actually just OTP would be a good option in this case. It can be provisioned to the freeOTP app at the moment of the user registration.
> 
> 
> 
> Thanks
> Dmitri
> 
> 
> 
> Bryce
> 
> 
> 
> 
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> --
> 
> Thank you,
> 
> Dmitri Pal
> 
> 
> 
> Sr. Engineering Manager IdM portfolio
> 
> Red Hat, Inc.

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