Network Working Group R. Srinivasan
Request for Comments: 1833 Sun Microsystems
Category: Standards Track August 1995
Binding Protocols for ONC RPC Version 2
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
ABSTRACT
This document describes the binding protocols used in conjunction
with the ONC Remote Procedure Call (ONC RPC Version 2) protocols.
TABLE OF CONTENTS
1. Introduction 1
2. RPCBIND Program Protocol 2
2.1 RPCBIND Protocol Specification (in RPC Language) 3
2.2 RPCBIND Operation 9
2.2.1 RPCBIND Version 3 9
2.2.2 RPCBIND, Version 4 10
3. Port Mapper Program Protocol 11
3.1 Port Mapper Protocol Specification (in RPC Language) 11
3.2 Port Mapper Operation 13
References 14
Security Considerations 14
Author's Address 14
1. Introduction
This document specifies the binding protocols used in conjunction
with ONC RPC Version 2. As a prerequisite, the reader is expected to
be familiar with [1] and [2] which describe the ONC RPC Version 2 and
XDR (eXternal Data Representation) protocols.
An RPC service is identified by its RPC program number, version
number, and the transport address where it may be reached. The
transport address, in turn, consists of a network address and a
transport selector. In the case of a service available over TCP/IP
or UDP/IP, the network address will be an IP address, and the
transport selector will be a TCP or UDP port number.
Srinivasan Standards Track [Page 1]
RFC 1833 Binding Protocols for ONC RPC Version 2 August 1995
A client program needs to know the RPC program number, version
number, and the transport address corresponding to a service in order
to utilize the service. Of these, the RPC program number and version
number are usually built into the client program, as part of the
service definition. The network address component of the transport
address is usually available in a name service, or is given as a
parameter to the client program. The transport selector (ie., the
TCP or UDP port) is usually determined dynamically, and varies with
each invocation of the service. Server programs allocate a transport
address, and register it with a well-known lookup service (well-known
because it uses a fixed transport selector, and resides at the same
network address as the server). Client programs consult the lookup
service in order to obtain the server's transport address.
Such a lookup service is very desirable because the range of well-
known transport selectors is very small for some transports and the
number of services is potentially very large. By running only the
lookup service on a well-known transport selector, the transport
addresses of other remote programs can be ascertained by querying the
lookup service.
This document describes three versions of a lookup service, all of
which use the same RPC program number (100000). They all use port
111 over TCP and UDP transports. Versions 3 and 4 are described in
Section 2 ("RPCBIND Program Protocol"). Version 2 is described in
Section 3 ("Port Mapper Program Protocol").
The distinguishing characteristic of RPCBIND (versions 3 and 4) is
that this protocol uses a transport-independent format for the
transport address, known as the universal address format. An address
in universal address format is an ASCII string representation of the
transport dependent address. String representation of addresses
corresponding to a transport are defined by the addressing authority
for the transport. The RPCBIND protocol can be used for binding ONC
RPC clients and servers over any transport.
The Port Mapper (version 2), on the other hand, is an older protocol
that is specific to TCP and UDP. It handles TCP and UDP ports
directly.
2. RPCBIND Program Protocol
The RPCBIND program maps RPC program and version numbers to universal
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