2.1.1 RPC Transport
The Messenger Service Remote Protocol MUST use either the RPC over UDP protocol sequence (NCADG_IP_UDP) or the RPC over Named Pipes (NCACN_NP) protocol sequence, as specified in [MS-RPCE], depending on the interface used. When RPC over Named Pipes is used as the RPC protocol sequence, the pipe name that MUST be used is \PIPE\MSGSVC. For the NCADG_IP_UDP, see section 3.2.4. For the NCACN_NP protocol, see section 3.1.4.
This protocol MUST use the following UUIDs:
17FDD703-1827-4E34-79D4-24A55C53BB37 (for recipient name management methods)
5A7B91F8-FF00-11D0-A9B2-00C04FB6E6FC (for the NetrSendMessage method)
For each recipient name registered with the message server, on each bound local area network adapter (LANA), the message server MUST register the corresponding NetBIOS name using the convention defined in [MS-NBTE] section 1.8, with a NetBIOS suffix value of 0x03.
This protocol allows any user to establish a connection to the RPC server. When using named pipes as the RPC transport, the protocol uses the underlying RPC protocol to retrieve the identity of the caller that made the method call, as specified in [MS-RPCE]. The message server SHOULD use this identity to perform method-specific access checks, as specified in section 188.8.131.52. When using UDP as the RPC transport, the protocol does not perform authentication.