Authentication using federated identity

Falcon Darkstar Momot falcon at
Fri Feb 9 21:35:32 AEDT 2024

Practically speaking, most popular IAM and SSO solutions offer OIDC SAML 
tokens but do not offer Kerberos tickets.  OpenID Connect is a standard 
which itself is based on RFC6749 (OAuth2). This provides a compelling 
reason to support it in addition to Kerberos.  I'll also note that OIDC 
tokens are easy to validate without a bidirectional trust relationship 
between the IdP and RP.

SSH authentication via OAuth2, in particular, would save complexity at 
most organizations I've worked with.  All of them so far have preferred 
things like automated SSH certificate signers or APIs that cause 
orchestration to add SSH keys to authorized_keys on hosts, before they 
implement Kerberos just for this.

On top of that, Active Directory is a legacy solution now.  Its 
successor uses OAuth2.

On 2024-02-08 23:49, Nico Kadel-Garcia wrote:
> On Thu, Feb 8, 2024 at 1:18 PM Chris Rapier <rapier at> wrote:
>> I know that there are some methods to use federated identities (e.g.
>> OAuth2) with SSH authentication but, from what I've seen, they largely
>> seem clunky and require users to interact with web browsers to get one
>> time tokens. Which is sort of acceptable for occasional logins but
>> doesn't work with automated/scripted actions.
> Is there some reason you wouldn't simply use Kerberos, baked into
> Samba and Active Directory, with the long established token handling
> provided by Kerberos? Convincing Kerbers and the AD admin who may not
> realize they have it to permit that underlying authentication
> technology, but it's been stable for decades  Part of the difficulty
> seems to be every bureaucracy's desire to have their own special rules
> and not talk to each other without a lot of Gant charts and big
> picture diagrams, but I've been taking advantage of the underlying
> Kerberos behind the backs of AD admin for decades.
> Unfortunately, everyone seems to want to have their own "invented
> here" form of authentication token handling, rather than sticking with
> basics. My old classmates at MIT worked *very hard* to make that work,
> and to resist abuse, and it still works quite well.
>> I'm just wondering if anyone has done any work on this or has thoughts
>> on it. I know it would be useful in some contexts (in my case, cross
>> realm access of independent yet federated services that are pretty
>> common in R&E HPC communities (e.g. ACCESS)).
>> Chris
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