The Sun Remote Procedure Call (RPC) is a protocol used by the Network File System (NFS) and Network Information Service (NIS). NIS clients attempt to communicate with their administratively configured NIS server through RPC Portmapper requests immediately after bootup. The RPC portmapper service converts RPC program numbers into TCP/UDP ports. The RPC server tells portmapper what port number it is listening to and what RPC program numbers it will use. The client first contacts portmap on the server machine to determine the port number to which RPC packets should be sent. The default RPC portmapper port is 111.
Cisco ASA Sun RPC inspection provides the following:
To enable Sun RPC inspection, use the inspect rpc command.