Building a custom auth back-end.

[Ben Johnson]

I may be wrong, but...  If you really can't install PAM on some systems,
I think making a library that masquerades as PAM might be the easiest
way.  The interface PAM exports to PAM clients is not very complicated,
so making a pretend PAM would be a lot easier than making PAM from
scratch.  make your pretend PAM connect directly to your authentication
server and you're done.

- Ben