The Print System Remote Protocol uses RPC over named pipes ([MS-RPCE] section 184.108.40.206) for RPC sequences. The well-known endpoint \pipe\spoolss is used for RPC calls made from the print client to the print server. The client MUST use no authentication, and the server MUST accept connections without authentication.
An endpoint with the same name MUST also be used for RPC calls made from the server to send printer change notifications back to the client; those calls are RpcReplyOpenPrinter (section 220.127.116.11.1), RpcRouterReplyPrinter (section 18.104.22.168.2), RpcReplyClosePrinter (section 22.214.171.124.3), and RpcRouterReplyPrinterEx (section 126.96.36.199.4).
The client MUST accept connections without authentication from the server for these methods. If the client provides authentication information ([MS-RPCE] section 188.8.131.52.8), the server SHOULD<3> impersonate the client ([MS-RPCE] section 184.108.40.206.9), while processing a method.