As discussed at a high level in Chapter 3, security within SharePoint Portal Server is achieved by leveraging the existing Windows NT security model. The security component provides granular security control and simplified security management. While integrating with existing Windows NT Security is important, additional role-based security allows documents to be accessed only by individuals who are granted access through SharePoint Portal Server security specific roles.
SharePoint Portal Server uses existing NT user-IDs and native Windows NT–based Access Control Lists (ACLs). SharePoint Portal Server must be run on a Windows 2000 Server platform. However, both NT and Windows 2000 directory security can be used.