Add a container (i.e., Group) only for SecurityCenter users and allow existing Active Directory users to become members of the newly created group. Use the Distinguished Name (DN) of this group as the “Search Base”. For example:
Save the changes and new users who are members of this group will be able to log in. No restart is required.
Option 1 Example
Choose System -> Configuration -> LDAP
Create the new user and when entering the LDAP “Search String” enter “=*”: