That exact scenario is covered by the concept of "cached credentials" in the case of SSSD. If your authentication services or down (or the box you're attempting

That exact scenario is covered by the concept of "cached credentials" in the case of SSSD. If your authentication services or down (or the box you're attempting to log into is offline) there's a period in which you can log in using the last used password for your account. Granted you only have the configurable cache time out in which to solve your problem, but that's usually on the matter of days. If your authentication infrastructure is down for longer than that you have bigger fish to fry.