Function of a Portmapper

The connection between the RPC client computers and RPC servers is serviced by a program known as the portmapper (or rpcbind). The portmapper provides a directory for the RPC services on the computer on which it runs.

A client application can request a connection to an RPC service by passing the RPC number to the portmapper. The portmapper responds by sending back the actual port number that the service is bound to. The client can then connect directly to the service using the service’s port.