Every operation in UNIX/Linux requires a user identifier (UID), just as in MS Windows NT4/200x this requires a security identifier (SID). Samba provides two means for mapping an MS Windows user to a UNIX/Linux UID.

First, all Samba SAM database accounts require a UNIX/Linux UID that the account will map to. As users are added to the account information database, Samba will call the add user script interface to add the account to the Samba host OS. In essence all accounts in the local SAM require a local user account.

The second way to map Windows SID to UNIX UID is via the idmap uid and idmap gid parameters in smb.conf. Please refer to the man page for information about these parameters. These parameters are essential when mapping users from a remote (non-member Windows client or a member of a foreign domain) SAM server.