RPC Security Callback Has No Implicit Security Context

Calls to RpcImpersonateClient, RpcBindingInqAuthClient, or any function that expects an implicit security context may not succeed and may generate one of the following error messages: This behavior can occur if the following conditions exist:

• RpcServerRegisterIfEx is used to register an interface with the Remote Procedure Call (RPC) run time and a security callback is specified.
• A connection-oriented protocol sequence is used (ncacn_*).

Because of a problem in RPC in Windows 2000, no implicit security context is set in the callback functionality.

There are two known workarounds to this problem:

• Use the context that is passed to the security callback function explicitly in calls to functions that require an implicit security context.
• Use ncalrpc or a non-connection-oriented protocol sequence (ncadg_*). Note that ncalrpc works only locally.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.