Anyone have luck setting up two-factor auth for Fedora in "the Cloud" - preferably, at AWS?  Yes, I got one of the token generators discussed at

However, those only appear to help with authentication to (per the faq):
What if I need to multi-factor auth to the instances themselves?  Anyone know if there's a service out there that does this for Fedora (or RedHat, which can easily be made to work for...) instances in the "cloud?"

I'm used to doing this locally and then making the remote systems only allow access via a limited number of machines (which themselves do 2-factor).  I'm now in a situation though with every workstation being outside the trust zone completely, VPN not being something that could change that (too many details...), and thus needing to accomplish the 2-factor in the cloud itself.  Most of the results from "two factor authentication cloud" I get are about cloud-based providers authenticating the local machines...versus what I need, which is a service that I can auth cloud-based machines against for the second factor.  I know of many industries that would *have* to have a 2-factor solution to use cloud instances, so surely my google-fu is just not working...anyone gone down this road themselves yet?