Meta server: allow to configure rpc names and the corresponding host ips that require no authentication, with default to allow no authentication from loop back interface for stat rpcs used by meta server web ui. Enforce authentication, if configured, in the client and chunk server state machines, by returning "permission denied" status in the case if client [connection] isn't authenticated, immediately without attempting to run rcps through the normal dispatch. Set "check all ops" permissions mode with authentication / security enabled.