8 Wintry Words to Defrost Your Vocabulary
A server that converts TCP/IP protocol port numbers into RPC program numbers. It must be running in order to make RPC calls.
When an RPC server starts, it tells portmap the port number it is listening on and what RPC program numbers it serves. Before a client can call a given RPC program number, it must contacts portmap on the server machine to determine the port number to which RPC packets should be sent.