OSF DCE Application Development Guide--Core Components

RPC and Other DCE Components
14.2.1.1 Cross-Cell Authentication
A client can engage in authenticated RPC with a target server that is in the client’s cell
or in a foreign cell. In the case of cross-cell authentication, DCE security performs the
necessary additional steps on behalf of the client.
To establish authenticated RPC with a foreign server, a client must supply the fully
qualified principal name of the server. A fully qualified name includes the name of the
cell as well as the name of the principal and takes the following form:
/.../cell_name/principal_name
14.2.1.2 Protection Levels
When a client establishes authenticated RPC, it can specify the level of protection to be
applied to its communications with the server. The protection level determines how
much of client/server messages are encrypted. As a rule, the more restrictive the
protection level, the greater the impact on performance. Different levels are provided so
that applications can control the protection versus performance tradeoffs.
Note that the protection level is entirely a client responsibility. When a server registers
its supported authentication service with the RPC runtime, it does not specify any
protection information for that service. However, the server can include the protection
level used for a particular operation when deciding if the caller is authorized to perform
the operation.
Authenticated RPC supports the following protection levels:
rpc_c_protect_level_default
Uses the default protection level for the specified authentication service.
rpc_c_protect_level_none
There is no protection level.
rpc_c_protect_level_connect
Performs protection only when the client establishes a relationship with
the server. This level performs an encrypted handshake when the client
first communicates with the server. Encryption or decryption is not
performed on the data sent between the client and server. The fact that
the handshake succeeds indicates that the client is active on the
network.
rpc_c_protect_level_call
Performs protection only at the beginning of each remote procedure call
when the server receives the request. This level attaches a verifier to
each client call and server response.
This level does not apply to remote procedure calls made over a
connection-based protocol sequence; that is, ncacn_ip_tcp. If this level
is specified and the binding handle uses a connection-based protocol
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