Chapter 11. Group Mapping ” MS Windows and Unix
Starting with Samba-3, new group mapping functionality is available to create associations between Windows group SIDs and UNIX groups. The groupmap subcommand included with the net tool can be used to manage these associations.
The new facility for mapping NT Groups to UNIX system groups allows the administrator to decide which NT Domain Groups are to be exposed to MS Windows clients . Only those NT Groups that map to a UNIX group that has a value other than the default ( “1 ) will be exposed in group selection lists in tools that access domain users and groups.