[Samba] Access to shares for authenticated domain users only

[Kevin]

I am running several samba servers (2.2.3a and 2.2.7) in various places as
pdcs. Everything seems to be running smoothly, but I can't find any way of
restricting access to only those uses who have logged on to the domain. Is
this possible? ie at the moment, any user can map a drive to \\server\share,
put in a valid user/password pair and have access to that share without
going through any logon script or pol files. This is what I would like to
avoid. I believe that if I can do this, it would also stop any unauthorised
machines from accessing the shares, as these machines would not be joined to
the domain.

Is this sort of authorisation possible?