Hi pawwa,
the point is you need to make the applications you want to support Radius aware, best would be if they would talk radius directly and acct as a NAS.
It's sounds sure like work. I haven't seen that much radius integration but you have to really make sure the logon/logoff part works, especially the logoff part. I am not sure how the Windows logon procedure with radius is supposed to work, if there is a background service which activly updates your radius state and if this failes for a given amount of time the session times out ... If so, better.
I would resort only as a last possibility if I have no other means to talk directly to the radius database, for various reasons.
Why is kerberos out of the question? A lot of services are implemented for kerberos.
I do not know much about Dovecot but i now cyrus, and cyrus has pretty decent possibilities regarding authentication, it can do pam authentication. So if dovecot understands pam as well, and you use it for authentication your linux local users, you might be able to pull it off that way.
best
Ray
