[wplug] Two-factor authentication systems on Linux

[Pat Barron]

Can anyone speak to the topic of what two-factor authentication systems 
might be available on any current Linux distributions?  In particular, 
I've been looking lately for ways to get S/Key working on Debian and 
Fedora, and I can't seem to find any packages that would enable them.  
Also interested in other two-factor authentication schemes as well (my 
personal favorite is the good old Securenet Key, but as far as I know, 
those aren't manufactured anymore...).

I know about YubiKey, but I'm less interested in that since it requires 
that you plug a physical piece of hardware into the machine you're 
working with.

My interest has been sparked by messing around with various "software 
token" authentication tools on Android, trying to see if I can leverage 
something like that on some of my Linux systems.

Thanks,
--Pat.