3.1 Netlogon Common Authentication Details
The Netlogon RPC interface is used to establish and maintain the secure channel. The client MUST attempt to establish this secure channel with a domain controller within the client's domain. (Common Error Processing Rule C MUST be applied whenever a secure connection to a DC is required by a method.) Establishing the secure channel is accomplished by first negotiating a session key (as specified in section 188.8.131.52) over nonprotected RPC (nonprotected RPC is an RPC connection without any underlying security support), resulting in both the client and server mutually verifying each other's credentials. Verifying Netlogon credentials on both the client and server establishes that both ends shared the same password information for the requesting client. Therefore, both Netlogon credentials are valid. The client and server both store a copy of the Netlogon credential computed by using the client challenge. This stored client Netlogon credential serves as a seed for authenticating further client-to-server operations.
Upon successful mutual verification, both client and server have the information necessary to compute a session key. The session key is used to secure further RPC communication between the two machines.
The following sections specify the common steps in the authentication portion of the Netlogon RPC interface, including Netlogon credential computation and the derivation and use of the session key.