AllowUsers
This keyword can be followed by a list of user name patterns, separated by spaces.  If specified, login is allowed only for user names that match one of the patterns.  Only user names are valid; a numerical user ID is not recognized.  By default, login is allowed for all users.  If the pattern takes the form USER@HOST thenUSER and HOST are separately checked, restricting logins to particular users from particular hosts.  HOST criteria may additionally contain addresses to match in CIDR address/masklen format.  The allow/deny users directives are processed in the following order: DenyUsers, AllowUsers.