Improve the Kerberos testing infrastructure

[filipnavara]

Related to #71427.

I've tried locally that on macOS and Linux it's possible to redirect the Kerberos configuration through the KRB5_CONFIG variable that points to a file like this:

[realms]
    corp2.identityintervention.com = {
        kdc = tcp/127.0.0.1:8888
    }

It is possible to mock the KDC through Kerberos.NET (sample) and then use the system GSSAPI to authenticate against the made-up corp2.identityintervention.com domain name.

I verified locally that this setup can work although there's certainly some work necessary to get all the pieces in place.

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Issue Details

---

Related to #71427.

I've tried locally that on macOS and Linux it's possible to redirect the Kerberos configuration through the KRB5_CONFIG variable that points to a file like this:

[realms]
    corp2.identityintervention.com = {
        kdc = tcp/127.0.0.1:8888
    }

It is possible to mock the KDC through Kerberos.NET (sample) and then use the system GSSAPI to authenticate against the made-up corp2.identityintervention.com domain name.

I verified locally that this setup can work although there's certainly some work necessary to get all the pieces in place.

Author:	filipnavara
Assignees:	-
Labels:	area-System.Net.Security, test-enhancement
Milestone:	Future

[filipnavara]

Here's an example of a loopback test - https://github.com/filipnavara/KerberosLoopback. Currently it crashes with SIGSEGV, filed as #71463.