Network access: Sharing and security model for local accounts
Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options
Determines how network logons that use local accounts are authenticated. If this setting is set to Classic, network logons that use local account credentials authenticate by using those credentials. If this setting is set to Guest only, network logons that use local accounts are automatically mapped to the Guest account. The Classic model allows fine control over access to resources. By using the Classic model, you can grant different types of access to different users for the same resource. Using the Guest only model, all users are treated equally. All users authenticate as Guest, and they all receive the same level of access to a given resource, which can be either Read Only or Modify.
There are two models available:
Default: Guest only on Windows XP Professional.
This policy does not apply on Windows 2000 computers.
For more information, see: