The SUS* and WUS* team have updated their FAQ based on customer feedback about licensing issues. Here's the scoop:

SUS and WUS are components of Windows Server (2000 and 2003) and Windows Small Business Server (2000 and 2003). SUS is – and WUS will be - available at no additional charge to licensees of these products.

SUS and WUS do not have their own client access license (CAL). However, because the client machines updated using SUS or WUS access the server on which the SUS or WUS server component is running, each client machine requires a Windows or Core CAL to access the server. Note that this is a licensing requirement for the Windows Server on which the SUS or WUS server is running, and not a licensing requirement specific to SUS or WUS.

The general exceptions to this CAL licensing requirement for Windows Server are:

  1. When the access is through the Internet and unauthenticated
  2. When the service being accessed can be run on Windows Server 2003 Web Edition (i.e., the service and the way in which it is used meets the requirements specified in the product use rights for Windows Server 2003 Web Edition)

Since machines updated using SUS or WUS access the SUS or WUS server via the organization’s internal network, the first exception does not apply to use of SUS or WUS. When SUS is used, the second exception is applicable when the SUS server is running on Windows Server 2003 Web Edition. When WUS is used, the second exception is applicable when the WUS server is running on Windows Server 2003 Web Edition and is using the default built-in WUS database or a MSDE database installed on the same machine (i.e., using a remote database invalidates this exception for WUS).

In summary, if machines are being updated using a SUS or WUS server running on Windows Server 2003 Web Edition and a remote database is not being used by the WUS server, no CALs are required for updating these machines. For all other situations, each machine updated using SUS or WUS requires a Windows or Core CAL.

*Software Update Services and Windows Update Services