Multiple users may be specified in a comma-delimited list, in which case the supplied password will be tested against each username in turn (left to right). The username line is needed only when the PC is unable to supply its own username. This is the case for the COREPLUS protocol or where your users have different WfWg usernames to UNIX usernames. In both these cases you may also be better using the \\server\share%user syntax instead. The username line is not a great solution in many cases as it means Samba will try to validate the supplied password against each of the usernames in the username line in turn. This is slow and a bad idea for lots of users in case of duplicate passwords. You may get timeouts or security breaches using this parameter unwisely. Samba relies on the underlying UNIX security. This parameter does not restrict who can login, it just offers hints to the Samba server as to what usernames might correspond to the supplied password. Users can login as whoever they please and they will be able to do no more damage than if they started a telnet session. The daemon runs as the user that they log in as, so they cannot do anything that user cannot do. To restrict a service to a particular set of users you can use the valid users parameter. If any of the usernames begin with a '@' then the name will be looked up first in the NIS netgroups list (if Samba is compiled with netgroup support), followed by a lookup in the UNIX groups database and will expand to a list of all users in the group of that name. If any of the usernames begin with a '+' then the name will be looked up only in the UNIX groups database and will expand to a list of all users in the group of that name. If any of the usernames begin with a '&' then the name will be looked up only in the NIS netgroups database (if Samba is compiled with netgroup support) and will expand to a list of all users in the netgroup group of that name. Note that searching though a groups database can take quite some time, and some clients may time out during the search. See the section NOTE ABOUT USERNAME/PASSWORD VALIDATION for more information on how this parameter determines access to the services. Default: The guest account if a guest service, else <empty string>. Examples:username = fred, mary, jack, jane, @users, @pcgroup