Comment # 3 on bug 1005669 from Josef M�llers

Maybe yu fell into the same trap as I did:
You need to run TWO commands:
pam-config --add --krb3
pam-config --add --krb3-ignore_unknown_principals
The first will add pam_krb5.so, the second will then add the
"ignore_unknown_principals" option!
This sequence did work for me.

Can you please try and report your findings back here?

Thanks and ... have a nice weekend.