Samba - Authenticating with Local User Accounts

I'm looking to have my users use their local accounts on my Linux servers without the need to create a separate user/password for Samba. Is there any way to use the /etc/passwd file as the the authentication mechanism when they go to map a drive? Can this be done using PAM?

I don't want to use AD as the domain ID's are different than those on the Linux servers.

Any advice/direction would be greatly appreciated.

samba cannot just use passwd/shadow, because several additional attributes are to be stored.

But you can setup samba with tdbsam-backend and let samba synchronise the passwords.

Or you setup an open ldap-backend for system and samba auth. But this is not that trivial ....