Is this even possible? Looking for a way (plugin / software or combination) that will let me authenticate users against the existing Wordpress user database using RADIUS.

Does anybody know of any way I might be able to authenticate users via RADIUS against the Wordpress database? It doesn't have to be a "pretty" solution, I just need it to work without requiring significant changes to the existing user database and preferably without forcing any action on the user's part (password change / etc).

I realize it's a rather strange request, and I understand that there are methods to do the opposite (sign in to a Wordpress site using an external RADIUS user), but I need it to go this way for various reasons.