If you use a third-party authentication server, you do not have to keep a separate user database on the XTM device. You can configure a third-party server, install the authentication server with access to your XTM device, and put the server behind the device for security. You then configure the device to forward user authentication requests to that server. If you create a user group on the XTM device that authenticates to a third-party server, make sure you create a group on the server that has the same name as the user group on the device.
For detailed information about how to configure an XTM device for use with third-party authentication servers, see:
About User Authentication