draft-ietf-nfsv4-rfc1831bis-07.txt   draft-ietf-nfsv4-rfc1831bis-08.txt 
INTERNET-DRAFT Robert Thurlow Network File System Version 4 Working Group R. Thurlow
Expires: August 1, 2008 January 30, 2008 Internet-Draft Sun Microsystems
Intended status: Informational Intended status: Draft Standard
Obsoletes: 1831
Expires: August 25, 2008 February 22, 2008
RPC: Remote Procedure Call Protocol Specification Version 2 RPC: Remote Procedure Call Protocol Specification Version 2
draft-ietf-nfsv4-rfc1831bis-07.txt draft-ietf-nfsv4-rfc1831bis-08.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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Discussion and suggestions for improvement are requested. This Discussion and suggestions for improvement are requested. This
document will expire in July, 2008. Distribution of this draft is document will expire in July, 2008. Distribution of this draft is
unlimited. unlimited.
Abstract Abstract
This document describes the ONC (Open Network Computing) Remote This document describes the ONC (Open Network Computing) Remote
Procedure Call (ONC RPC Version 2) protocol as it is currently Procedure Call (ONC RPC Version 2) protocol as it is currently
deployed and accepted. It is meant to supersede [RFC1831]. deployed and accepted. It is meant to supersede [RFC1831].
Title Remote Procedure Call Protocol Version 2 January 2008
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 1
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Changes since RFC 1831 . . . . . . . . . . . . . . . . . . . 1
3. The RPC Model . . . . . . . . . . . . . . . . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 1
4. Transports and Semantics . . . . . . . . . . . . . . . . . . 5 4. The RPC Model . . . . . . . . . . . . . . . . . . . . . . . 1
5. Binding and Rendezvous Independence . . . . . . . . . . . . 6 5. Transports and Semantics . . . . . . . . . . . . . . . . . . 1
6. Authentication . . . . . . . . . . . . . . . . . . . . . . . 6 6. Binding and Rendezvous Independence . . . . . . . . . . . . 1
7. RPC Protocol Requirements . . . . . . . . . . . . . . . . . 6 7. Authentication . . . . . . . . . . . . . . . . . . . . . . . 1
7.1. RPC Programs and Procedures . . . . . . . . . . . . . . . 7 8. RPC Protocol Requirements . . . . . . . . . . . . . . . . . 1
7.2. Authentication . . . . . . . . . . . . . . . . . . . . . . 8 8.1. RPC Programs and Procedures . . . . . . . . . . . . . . . 1
7.3. Program Number Assignment . . . . . . . . . . . . . . . . 9 8.2. Authentication . . . . . . . . . . . . . . . . . . . . . . 1
7.4. Other Uses of the RPC Protocol . . . . . . . . . . . . . . 9 8.3. Program Number Assignment . . . . . . . . . . . . . . . . 1
7.4.1. Batching . . . . . . . . . . . . . . . . . . . . . . . . 9 8.4. Other Uses of the RPC Protocol . . . . . . . . . . . . . . 1
7.4.2. Broadcast Remote Procedure Calls . . . . . . . . . . . . 9 8.4.1. Batching . . . . . . . . . . . . . . . . . . . . . . . . 1
8. The RPC Message Protocol . . . . . . . . . . . . . . . . . 10 8.4.2. Broadcast Remote Procedure Calls . . . . . . . . . . . . 1
9. Authentication Protocols . . . . . . . . . . . . . . . . . 13 9. The RPC Message Protocol . . . . . . . . . . . . . . . . . . 1
9.1. Null Authentication . . . . . . . . . . . . . . . . . . 14 10. Authentication Protocols . . . . . . . . . . . . . . . . . 1
10. Record Marking Standard . . . . . . . . . . . . . . . . . 14 10.1. Null Authentication . . . . . . . . . . . . . . . . . . . 1
11. The RPC Language . . . . . . . . . . . . . . . . . . . . 14 11. Record Marking Standard . . . . . . . . . . . . . . . . . . 1
11.1. An Example Service Described in the RPC Language . . . 15 12. The RPC Language . . . . . . . . . . . . . . . . . . . . . 1
11.2. The RPC Language Specification . . . . . . . . . . . . 16 12.1. An Example Service Described in the RPC Language . . . . 1
11.3. Syntax Notes . . . . . . . . . . . . . . . . . . . . . 16 12.2. The RPC Language Specification . . . . . . . . . . . . . 1
12. IANA Considerations . . . . . . . . . . . . . . . . . . . 17 12.3. Syntax Notes . . . . . . . . . . . . . . . . . . . . . . 1
12.1. Numbering Requests to IANA . . . . . . . . . . . . . . 17 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . 1
12.2. Protecting Past Assignments . . . . . . . . . . . . . . 17 13.1. Numbering Requests to IANA . . . . . . . . . . . . . . . 1
12.3. RPC Number Assignment . . . . . . . . . . . . . . . . . 17 13.2. Protecting Past Assignments . . . . . . . . . . . . . . . 1
12.3.1. To be assigned by IANA . . . . . . . . . . . . . . . 18 13.3. RPC Number Assignment . . . . . . . . . . . . . . . . . . 1
12.3.2. Defined by local administrator . . . . . . . . . . . 18 13.3.1. To be assigned by IANA . . . . . . . . . . . . . . . . 1
12.3.3. Transient block . . . . . . . . . . . . . . . . . . . 18 13.3.2. Defined by local administrator . . . . . . . . . . . . 1
12.3.4. Reserved block . . . . . . . . . . . . . . . . . . . 19 13.3.3. Transient block . . . . . . . . . . . . . . . . . . . . 1
12.3.5. RPC Number Sub-Blocks . . . . . . . . . . . . . . . . 19 13.3.4. Reserved block . . . . . . . . . . . . . . . . . . . . 1
12.4. RPC Authentication Flavor Number Assignment . . . . . . 20 13.3.5. RPC Number Sub-Blocks . . . . . . . . . . . . . . . . . 1
13. Security Considerations . . . . . . . . . . . . . . . . . 21 13.4. RPC Authentication Flavor Number Assignment . . . . . . . 1
14. Appendix A: System Authentication . . . . . . . . . . . . 21 14. Security Considerations . . . . . . . . . . . . . . . . . . 1
15. Appendix B: Requesting RPC program or authentication 15. Appendix A: System Authentication . . . . . . . . . . . . . 1
numbers . . . . . . . . . . . . . . . . . . . . . . . . . 22 16. Appendix B: Requesting RPC program or authentication
16. Full Copyright Statement . . . . . . . . . . . . . . . . 24 numbers . . . . . . . . . . . . . . . . . . . . . . . . . . 1
17. Intellectual property . . . . . . . . . . . . . . . . . . 24 17. Full Copyright Statement . . . . . . . . . . . . . . . . . 1
18. Acknowledgment . . . . . . . . . . . . . . . . . . . . . 24 18. Intellectual property . . . . . . . . . . . . . . . . . . . 1
19. Normative References . . . . . . . . . . . . . . . . . . 26 19. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . 1
20. Informative References . . . . . . . . . . . . . . . . . 26 20. Normative References . . . . . . . . . . . . . . . . . . . 1
21. Author's Address . . . . . . . . . . . . . . . . . . . . 28 21. Informative References . . . . . . . . . . . . . . . . . . 1
22. Author's Address . . . . . . . . . . . . . . . . . . . . . 1
Title Remote Procedure Call Protocol Version 2 January 2008
1. Introduction 1. Introduction
This document specifies version two of the message protocol used in This document specifies version two of the message protocol used in
ONC Remote Procedure Call (RPC). The message protocol is specified ONC Remote Procedure Call (RPC). The message protocol is specified
with the eXternal Data Representation (XDR) language [RFC4506]. This with the eXternal Data Representation (XDR) language [RFC4506]. This
document assumes that the reader is familiar with XDR. It does not document assumes that the reader is familiar with XDR. It does not
attempt to justify remote procedure calls systems or describe their attempt to justify remote procedure calls systems or describe their
use. The paper by Birrell and Nelson [XRPC] is recommended as an use. The paper by Birrell and Nelson [XRPC] is recommended as an
excellent background for the remote procedure call concept. excellent background for the remote procedure call concept.
2. Terminology 2. Changes since RFC 1831
This document is intended to replace RFC 1831 as the authoritative
document describing RPC, without introducing any over-the-wire
protocol changes. The main changes from RFC 1831 are:
o Addition of an Appendix which describes how an implementor can
request new RPC program numbers and authentication flavor
numbers from IANA, rather than from Sun Microsystems
o Addition of an "IANA Considerations" section which describes
past program and authentication flavor number assignment policy
and how IANA is intended to assign them in future
o Clarification of the RPC Language Specification to match current
usage
o Enhancement of the "Security Considerations" section to reflect
experience with strong security flavors
o Specification of new authentication errors that are in common
use in modern RPC implementations
o Updates for the latest IETF intellectual property statements
3. Terminology
This document discusses clients, calls, servers, replies, services, This document discusses clients, calls, servers, replies, services,
programs, procedures, and versions. Each remote procedure call has programs, procedures, and versions. Each remote procedure call has
two sides: an active client side that makes the call to a server, two sides: an active client side that makes the call to a server,
which sends back a reply. A network service is a collection of one which sends back a reply. A network service is a collection of one
or more remote programs. A remote program implements one or more or more remote programs. A remote program implements one or more
remote procedures; the procedures, their parameters, and results are remote procedures; the procedures, their parameters, and results are
documented in the specific program's protocol specification. A documented in the specific program's protocol specification. A
server may support more than one version of a remote program in order server may support more than one version of a remote program in order
to be compatible with changing protocols. to be compatible with changing protocols.
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client of the network file service would call the procedures client of the network file service would call the procedures
associated with the two programs of the service on behalf of the associated with the two programs of the service on behalf of the
client. client.
The terms client and server only apply to a particular transaction; a The terms client and server only apply to a particular transaction; a
particular hardware entity (host) or software entity (process or particular hardware entity (host) or software entity (process or
program) could operate in both roles at different times. For program) could operate in both roles at different times. For
example, a program that supplies remote execution service could also example, a program that supplies remote execution service could also
be a client of a network file service. be a client of a network file service.
3. The RPC Model 4. The RPC Model
The ONC RPC protocol is based on the remote procedure call model, The ONC RPC protocol is based on the remote procedure call model,
which is similar to the local procedure call model. In the local which is similar to the local procedure call model. In the local
case, the caller places arguments to a procedure in some well- case, the caller places arguments to a procedure in some well-
specified location (such as a register window). It then transfers specified location (such as a register window). It then transfers
control to the procedure, and eventually regains control. At that control to the procedure, and eventually regains control. At that
point, the results of the procedure are extracted from the well- point, the results of the procedure are extracted from the well-
specified location, and the caller continues execution. specified location, and the caller continues execution.
Title Remote Procedure Call Protocol Version 2 January 2008
The remote procedure call model is similar. One thread of control The remote procedure call model is similar. One thread of control
logically winds through two processes: the caller's process, and a logically winds through two processes: the caller's process, and a
server's process. The caller process first sends a call message to server's process. The caller process first sends a call message to
the server process and waits (blocks) for a reply message. The call the server process and waits (blocks) for a reply message. The call
message includes the procedure's parameters, and the reply message message includes the procedure's parameters, and the reply message
includes the procedure's results. Once the reply message is includes the procedure's results. Once the reply message is
received, the results of the procedure are extracted, and caller's received, the results of the procedure are extracted, and caller's
execution is resumed. execution is resumed.
On the server side, a process is dormant awaiting the arrival of a On the server side, a process is dormant awaiting the arrival of a
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o Authentication: since remote procedure calls can be transported o Authentication: since remote procedure calls can be transported
over unsecured networks, authentication may be necessary. over unsecured networks, authentication may be necessary.
Authentication prevents one entity from masquerading as some Authentication prevents one entity from masquerading as some
other entity. other entity.
The conclusion is that even though there are tools to automatically The conclusion is that even though there are tools to automatically
generate client and server libraries for a given service, protocols generate client and server libraries for a given service, protocols
must still be designed carefully. must still be designed carefully.
Title Remote Procedure Call Protocol Version 2 January 2008 5. Transports and Semantics
4. Transports and Semantics
The RPC protocol can be implemented on several different transport The RPC protocol can be implemented on several different transport
protocols. The RPC protocol does not care how a message is passed protocols. The RPC protocol does not care how a message is passed
from one process to another, but only with specification and from one process to another, but only with specification and
interpretation of messages. However, the application may wish to interpretation of messages. However, the application may wish to
obtain information about (and perhaps control over) the transport obtain information about (and perhaps control over) the transport
layer through an interface not specified in this document. For layer through an interface not specified in this document. For
example, the transport protocol may impose a restriction on the example, the transport protocol may impose a restriction on the
maximum size of RPC messages, or it may be stream-oriented like TCP maximum size of RPC messages, or it may be stream-oriented like TCP
[RFC793] with no size limit. The client and server must agree on [RFC793] with no size limit. The client and server must agree on
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entity in matching replies to calls. However, a client application entity in matching replies to calls. However, a client application
may choose to reuse its previous transaction ID when retransmitting a may choose to reuse its previous transaction ID when retransmitting a
call. The server may choose to remember this ID after executing a call. The server may choose to remember this ID after executing a
call and not execute calls with the same ID in order to achieve some call and not execute calls with the same ID in order to achieve some
degree of execute-at-most-once semantics. The server is not allowed degree of execute-at-most-once semantics. The server is not allowed
to examine this ID in any other way except as a test for equality. to examine this ID in any other way except as a test for equality.
On the other hand, if using a "reliable" transport such as TCP, the On the other hand, if using a "reliable" transport such as TCP, the
application can infer from a reply message that the procedure was application can infer from a reply message that the procedure was
executed exactly once, but if it receives no reply message, it cannot executed exactly once, but if it receives no reply message, it cannot
Title Remote Procedure Call Protocol Version 2 January 2008
assume that the remote procedure was not executed. Note that even if assume that the remote procedure was not executed. Note that even if
a connection-oriented protocol like TCP is used, an application still a connection-oriented protocol like TCP is used, an application still
needs time-outs and reconnection to handle server crashes. needs time-outs and reconnection to handle server crashes.
There are other possibilities for transports besides datagram- or There are other possibilities for transports besides datagram- or
connection-oriented protocols. For example, a request-reply protocol connection-oriented protocols. For example, a request-reply protocol
such as [VMTP] is perhaps a natural transport for RPC. ONC RPC such as [VMTP] is perhaps a natural transport for RPC. ONC RPC
currently uses both TCP and UDP transport protocols. Section 10 currently uses both TCP and UDP transport protocols. Section 10
(Record Marking Standard) describes the mechanism employed by ONC RPC (Record Marking Standard) describes the mechanism employed by ONC RPC
to utilize a connection-oriented, stream-oriented transport such as to utilize a connection-oriented, stream-oriented transport such as
TCP. The mechanism by which future transports having different TCP. The mechanism by which future transports having different
structural characteristics should be used to transfer ONC RPC structural characteristics should be used to transfer ONC RPC
messages should be specified by means of a standards-track RFC, once messages should be specified by means of a standards-track RFC, once
such additional transports are defined. such additional transports are defined.
5. Binding and Rendezvous Independence 6. Binding and Rendezvous Independence
The act of binding a particular client to a particular service and The act of binding a particular client to a particular service and
transport parameters is NOT part of this RPC protocol specification. transport parameters is NOT part of this RPC protocol specification.
This important and necessary function is left up to some higher-level This important and necessary function is left up to some higher-level
software. software.
Implementors could think of the RPC protocol as the jump-subroutine Implementors could think of the RPC protocol as the jump-subroutine
instruction ("JSR") of a network; the loader (binder) makes JSR instruction ("JSR") of a network; the loader (binder) makes JSR
useful, and the loader itself uses JSR to accomplish its task. useful, and the loader itself uses JSR to accomplish its task.
Likewise, the binding software makes RPC useful, possibly using RPC Likewise, the binding software makes RPC useful, possibly using RPC
to accomplish this task. to accomplish this task.
6. Authentication 7. Authentication
The RPC protocol provides the fields necessary for a client to The RPC protocol provides the fields necessary for a client to
identify itself to a service, and vice-versa, in each call and reply identify itself to a service, and vice-versa, in each call and reply
message. Security and access control mechanisms can be built on top message. Security and access control mechanisms can be built on top
of this message authentication. Several different authentication of this message authentication. Several different authentication
protocols can be supported. A field in the RPC header indicates protocols can be supported. A field in the RPC header indicates
which protocol is being used. More information on specific which protocol is being used. More information on specific
authentication protocols is in section 9: "Authentication Protocols". authentication protocols is in section 9: "Authentication Protocols".
7. RPC Protocol Requirements 8. RPC Protocol Requirements
The RPC protocol must provide for the following: The RPC protocol must provide for the following:
o Unique specification of a procedure to be called. o Unique specification of a procedure to be called.
o Provisions for matching response messages to request messages. o Provisions for matching response messages to request messages.
o Provisions for authenticating the caller to service and vice- o Provisions for authenticating the caller to service and vice-
versa. versa.
Title Remote Procedure Call Protocol Version 2 January 2008
Besides these requirements, features that detect the following are Besides these requirements, features that detect the following are
worth supporting because of protocol roll-over errors, implementation worth supporting because of protocol roll-over errors, implementation
bugs, user error, and network administration: bugs, user error, and network administration:
o RPC protocol mismatches. o RPC protocol mismatches.
o Remote program protocol version mismatches. o Remote program protocol version mismatches.
o Protocol errors (such as misspecification of a procedure's o Protocol errors (such as misspecification of a procedure's
parameters). parameters).
o Reasons why remote authentication failed. o Reasons why remote authentication failed.
o Any other reasons why the desired procedure was not called. o Any other reasons why the desired procedure was not called.
7.1. RPC Programs and Procedures 8.1. RPC Programs and Procedures
The RPC call message has three unsigned integer fields -- remote The RPC call message has three unsigned integer fields -- remote
program number, remote program version number, and remote procedure program number, remote program version number, and remote procedure
number -- which uniquely identify the procedure to be called. number -- which uniquely identify the procedure to be called.
Program numbers are administered by a central authority (IANA). Once Program numbers are administered by a central authority (IANA). Once
implementors have a program number, they can implement their remote implementors have a program number, they can implement their remote
program; the first implementation would most likely have the version program; the first implementation would most likely have the version
number 1. Because most new protocols evolve, a version field of the number 1. Because most new protocols evolve, a version field of the
call message identifies which version of the protocol the caller is call message identifies which version of the protocol the caller is
using. Version numbers enable support of both old and new protocols using. Version numbers enable support of both old and new protocols
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The reply message to a request message has enough information to The reply message to a request message has enough information to
distinguish the following error conditions: distinguish the following error conditions:
o The remote implementation of RPC does not support protocol o The remote implementation of RPC does not support protocol
version 2. The lowest and highest supported RPC version numbers version 2. The lowest and highest supported RPC version numbers
are returned. are returned.
o The remote program is not available on the remote system. o The remote program is not available on the remote system.
Title Remote Procedure Call Protocol Version 2 January 2008
o The remote program does not support the requested version o The remote program does not support the requested version
number. The lowest and highest supported remote program version number. The lowest and highest supported remote program version
numbers are returned. numbers are returned.
o The requested procedure number does not exist. (This is usually o The requested procedure number does not exist. (This is usually
a client side protocol or programming error.) a client side protocol or programming error.)
o The parameters to the remote procedure appear to be garbage from o The parameters to the remote procedure appear to be garbage from
the server's point of view. (Again, this is usually caused by a the server's point of view. (Again, this is usually caused by a
disagreement about the protocol between client and service.) disagreement about the protocol between client and service.)
7.2. Authentication 8.2. Authentication
Provisions for authentication of caller to service and vice-versa are Provisions for authentication of caller to service and vice-versa are
provided as a part of the RPC protocol. The call message has two provided as a part of the RPC protocol. The call message has two
authentication fields, the credential and verifier. The reply authentication fields, the credential and verifier. The reply
message has one authentication field, the response verifier. The RPC message has one authentication field, the response verifier. The RPC
protocol specification defines all three fields to be the following protocol specification defines all three fields to be the following
opaque type (in the eXternal Data Representation (XDR) language opaque type (in the eXternal Data Representation (XDR) language
[RFC4506]): [RFC4506]):
enum auth_flavor { enum auth_flavor {
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(uninterpreted by) the RPC protocol implementation. (uninterpreted by) the RPC protocol implementation.
The interpretation and semantics of the data contained within the The interpretation and semantics of the data contained within the
authentication fields is specified by individual, independent authentication fields is specified by individual, independent
authentication protocol specifications. (Section 9 defines the authentication protocol specifications. (Section 9 defines the
various authentication protocols.) various authentication protocols.)
If authentication parameters were rejected, the reply message If authentication parameters were rejected, the reply message
contains information stating why they were rejected. contains information stating why they were rejected.
Title Remote Procedure Call Protocol Version 2 January 2008 8.3. Program Number Assignment
7.3. Program Number Assignment
Program numbers are given out in groups of hexadecimal 20000000 Program numbers are given out in groups of hexadecimal 20000000
(decimal 536870912) according to the following chart: (decimal 536870912) according to the following chart:
0 Reserved 0 Reserved
1 - 0x1fffffff To be assigned by IANA 1 - 0x1fffffff To be assigned by IANA
0x20000000 - 0x3fffffff Defined by local administrator 0x20000000 - 0x3fffffff Defined by local administrator
(some blocks assigned here) (some blocks assigned here)
0x40000000 - 0x5fffffff Transient 0x40000000 - 0x5fffffff Transient
0x60000000 - 0x7effffff Reserved 0x60000000 - 0x7effffff Reserved
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be identical for all sites. The second range is for applications be identical for all sites. The second range is for applications
peculiar to a particular site. This range is intended primarily for peculiar to a particular site. This range is intended primarily for
debugging new programs. When a site develops an application that debugging new programs. When a site develops an application that
might be of general interest, that application should be given an might be of general interest, that application should be given an
assigned number in the first range. Application developers may apply assigned number in the first range. Application developers may apply
for blocks of RPC program numbers in the first range by methods for blocks of RPC program numbers in the first range by methods
described in Appendix B. The third group is for applications that described in Appendix B. The third group is for applications that
generate program numbers dynamically. The final groups are reserved generate program numbers dynamically. The final groups are reserved
for future use, and should not be used. for future use, and should not be used.
7.4. Other Uses of the RPC Protocol 8.4. Other Uses of the RPC Protocol
The intended use of this protocol is for calling remote procedures. The intended use of this protocol is for calling remote procedures.
Normally, each call message is matched with a reply message. Normally, each call message is matched with a reply message.
However, the protocol itself is a message-passing protocol with which However, the protocol itself is a message-passing protocol with which
other (non-procedure call) protocols can be implemented. other (non-procedure call) protocols can be implemented.
7.4.1. Batching 8.4.1. Batching
Batching is useful when a client wishes to send an arbitrarily large Batching is useful when a client wishes to send an arbitrarily large
sequence of call messages to a server. Batching typically uses sequence of call messages to a server. Batching typically uses
reliable byte stream protocols (like TCP) for its transport. In the reliable byte stream protocols (like TCP) for its transport. In the
case of batching, the client never waits for a reply from the server, case of batching, the client never waits for a reply from the server,
and the server does not send replies to batch calls. A sequence of and the server does not send replies to batch calls. A sequence of
batch calls is usually terminated by a legitimate remote procedure batch calls is usually terminated by a legitimate remote procedure
call operation in order to flush the pipeline and get positive call operation in order to flush the pipeline and get positive
acknowledgement. acknowledgement.
7.4.2. Broadcast Remote Procedure Calls 8.4.2. Broadcast Remote Procedure Calls
In broadcast protocols, the client sends a broadcast call to the In broadcast protocols, the client sends a broadcast call to the
network and waits for numerous replies. This requires the use of network and waits for numerous replies. This requires the use of
packet-based protocols (like UDP) as its transport protocol. Servers packet-based protocols (like UDP) as its transport protocol. Servers
Title Remote Procedure Call Protocol Version 2 January 2008
that support broadcast protocols usually respond only when the call that support broadcast protocols usually respond only when the call
is successfully processed and are silent in the face of errors, but is successfully processed and are silent in the face of errors, but
this varies with the application. this varies with the application.
The principles of broadcast RPC also apply to multicasting - an RPC The principles of broadcast RPC also apply to multicasting - an RPC
request can be sent to a multicast address. request can be sent to a multicast address.
8. The RPC Message Protocol 9. The RPC Message Protocol
This section defines the RPC message protocol in the XDR data This section defines the RPC message protocol in the XDR data
description language [RFC4506]. description language [RFC4506].
enum msg_type { enum msg_type {
CALL = 0, CALL = 0,
REPLY = 1 REPLY = 1
}; };
A reply to a call message can take on two forms: The message was A reply to a call message can take on two forms: The message was
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enum reject_stat { enum reject_stat {
RPC_MISMATCH = 0, /* RPC version number != 2 */ RPC_MISMATCH = 0, /* RPC version number != 2 */
AUTH_ERROR = 1 /* remote can't authenticate caller */ AUTH_ERROR = 1 /* remote can't authenticate caller */
}; };
Why authentication failed: Why authentication failed:
enum auth_stat { enum auth_stat {
AUTH_OK = 0, /* success */ AUTH_OK = 0, /* success */
Title Remote Procedure Call Protocol Version 2 January 2008
/* /*
* failed at remote end * failed at remote end
*/ */
AUTH_BADCRED = 1, /* bad credential (seal broken) */ AUTH_BADCRED = 1, /* bad credential (seal broken) */
AUTH_REJECTEDCRED = 2, /* client must begin new session */ AUTH_REJECTEDCRED = 2, /* client must begin new session */
AUTH_BADVERF = 3, /* bad verifier (seal broken) */ AUTH_BADVERF = 3, /* bad verifier (seal broken) */
AUTH_REJECTEDVERF = 4, /* verifier expired or replayed */ AUTH_REJECTEDVERF = 4, /* verifier expired or replayed */
AUTH_TOOWEAK = 5, /* rejected for security reasons */ AUTH_TOOWEAK = 5, /* rejected for security reasons */
/* /*
* failed locally * failed locally
skipping to change at page 12, line 5 skipping to change at page 12, line 26
struct rpc_msg { struct rpc_msg {
unsigned int xid; unsigned int xid;
union switch (msg_type mtype) { union switch (msg_type mtype) {
case CALL: case CALL:
call_body cbody; call_body cbody;
case REPLY: case REPLY:
reply_body rbody; reply_body rbody;
} body; } body;
}; };
Title Remote Procedure Call Protocol Version 2 January 2008
Body of an RPC call: Body of an RPC call:
In version 2 of the RPC protocol specification, rpcvers must be equal In version 2 of the RPC protocol specification, rpcvers must be equal
to 2. The fields prog, vers, and proc specify the remote program, to 2. The fields prog, vers, and proc specify the remote program,
its version number, and the procedure within the remote program to be its version number, and the procedure within the remote program to be
called. After these fields are two authentication parameters: cred called. After these fields are two authentication parameters: cred
(authentication credential) and verf (authentication verifier). The (authentication credential) and verf (authentication verifier). The
two authentication parameters are followed by the parameters to the two authentication parameters are followed by the parameters to the
remote procedure, which are specified by the specific program remote procedure, which are specified by the specific program
protocol. protocol.
skipping to change at page 13, line 4 skipping to change at page 13, line 26
field is an authentication verifier that the server generates in field is an authentication verifier that the server generates in
order to validate itself to the client. It is followed by a union order to validate itself to the client. It is followed by a union
whose discriminant is an enum accept_stat. The SUCCESS arm of the whose discriminant is an enum accept_stat. The SUCCESS arm of the
union is protocol specific. The PROG_UNAVAIL, PROC_UNAVAIL, union is protocol specific. The PROG_UNAVAIL, PROC_UNAVAIL,
GARBAGE_ARGS, and SYSTEM_ERR arms of the union are void. The GARBAGE_ARGS, and SYSTEM_ERR arms of the union are void. The
PROG_MISMATCH arm specifies the lowest and highest version numbers of PROG_MISMATCH arm specifies the lowest and highest version numbers of
the remote program supported by the server. the remote program supported by the server.
struct accepted_reply { struct accepted_reply {
opaque_auth verf; opaque_auth verf;
Title Remote Procedure Call Protocol Version 2 January 2008
union switch (accept_stat stat) { union switch (accept_stat stat) {
case SUCCESS: case SUCCESS:
opaque results[0]; opaque results[0];
/* /*
* procedure-specific results start here * procedure-specific results start here
*/ */
case PROG_MISMATCH: case PROG_MISMATCH:
struct { struct {
unsigned int low; unsigned int low;
unsigned int high; unsigned int high;
skipping to change at page 13, line 46 skipping to change at page 14, line 17
union rejected_reply switch (reject_stat stat) { union rejected_reply switch (reject_stat stat) {
case RPC_MISMATCH: case RPC_MISMATCH:
struct { struct {
unsigned int low; unsigned int low;
unsigned int high; unsigned int high;
} mismatch_info; } mismatch_info;
case AUTH_ERROR: case AUTH_ERROR:
auth_stat stat; auth_stat stat;
}; };
9. Authentication Protocols 10. Authentication Protocols
As previously stated, authentication parameters are opaque, but As previously stated, authentication parameters are opaque, but
open-ended to the rest of the RPC protocol. This section defines two open-ended to the rest of the RPC protocol. This section defines two
standard "flavors" of authentication. Implementors are free to standard "flavors" of authentication. Implementors are free to
invent new authentication types, with the same rules of flavor number invent new authentication types, with the same rules of flavor number
assignment as there is for program number assignment. The "flavor" assignment as there is for program number assignment. The "flavor"
of a credential or verifier refers to the value of the "flavor" field of a credential or verifier refers to the value of the "flavor" field
in the opaque_auth structure. Flavor numbers, like RPC program in the opaque_auth structure. Flavor numbers, like RPC program
Title Remote Procedure Call Protocol Version 2 January 2008
numbers, are also administered centrally, and developers may assign numbers, are also administered centrally, and developers may assign
new flavor numbers by methods described in Appendix B. Credentials new flavor numbers by methods described in Appendix B. Credentials
and verifiers are represented as variable length opaque data (the and verifiers are represented as variable length opaque data (the
"body" field in the opaque_auth structure). "body" field in the opaque_auth structure).
In this document, two flavors of authentication are described. Of In this document, two flavors of authentication are described. Of
these, Null authentication (described in the next subsection) is these, Null authentication (described in the next subsection) is
mandatory - it must be available in all implementations. System mandatory - it must be available in all implementations. System
authentication (AUTH_SYS) is described in Appendix A. It is strongly authentication (AUTH_SYS) is described in Appendix A. It is strongly
recommended that implementors include AUTH_SYS in their recommended that implementors include AUTH_SYS in their
implementations to promote interoperability, since many applications implementations to promote interoperability, since many applications
make use of this flavor. See "Security Considerations" for make use of this flavor. See "Security Considerations" for
information about other, more secure, authentication flavors. information about other, more secure, authentication flavors.
9.1. Null Authentication 10.1. Null Authentication
Often calls must be made where the client does not care about its Often calls must be made where the client does not care about its
identity or the server does not care who the client is. In this identity or the server does not care who the client is. In this
case, the flavor of the RPC message's credential, verifier, and reply case, the flavor of the RPC message's credential, verifier, and reply
verifier is "AUTH_NONE". Opaque data associated with "AUTH_NONE" is verifier is "AUTH_NONE". Opaque data associated with "AUTH_NONE" is
undefined. It is recommended that the length of the opaque data be undefined. It is recommended that the length of the opaque data be
zero. zero.
10. Record Marking Standard 11. Record Marking Standard
When RPC messages are passed on top of a byte stream transport When RPC messages are passed on top of a byte stream transport
protocol (like TCP), it is necessary to delimit one message from protocol (like TCP), it is necessary to delimit one message from
another in order to detect and possibly recover from protocol errors. another in order to detect and possibly recover from protocol errors.
This is called record marking (RM). One RPC message fits into one RM This is called record marking (RM). One RPC message fits into one RM
record. record.
A record is composed of one or more record fragments. A record A record is composed of one or more record fragments. A record
fragment is a four-byte header followed by 0 to (2**31) - 1 bytes of fragment is a four-byte header followed by 0 to (2**31) - 1 bytes of
fragment data. The bytes encode an unsigned binary number; as with fragment data. The bytes encode an unsigned binary number; as with
XDR integers, the byte order is from highest to lowest. The number XDR integers, the byte order is from highest to lowest. The number
encodes two values -- a boolean which indicates whether the fragment encodes two values -- a boolean which indicates whether the fragment
is the last fragment of the record (bit value 1 implies the fragment is the last fragment of the record (bit value 1 implies the fragment
is the last fragment) and a 31-bit unsigned binary value which is the is the last fragment) and a 31-bit unsigned binary value which is the
length in bytes of the fragment's data. The boolean value is the length in bytes of the fragment's data. The boolean value is the
highest-order bit of the header; the length is the 31 low-order bits. highest-order bit of the header; the length is the 31 low-order bits.
(Note that this record specification is NOT in XDR standard form!) (Note that this record specification is NOT in XDR standard form!)
11. The RPC Language 12. The RPC Language
Just as there was a need to describe the XDR data-types in a formal Just as there was a need to describe the XDR data-types in a formal
language, there is also need to describe the procedures that operate language, there is also need to describe the procedures that operate
on these XDR data-types in a formal language as well. The RPC on these XDR data-types in a formal language as well. The RPC
Language is an extension to the XDR language, with the addition of Language is an extension to the XDR language, with the addition of
Title Remote Procedure Call Protocol Version 2 January 2008
"program", "procedure", and "version" declarations. The following "program", "procedure", and "version" declarations. The following
example is used to describe the essence of the language. example is used to describe the essence of the language.
11.1. An Example Service Described in the RPC Language 12.1. An Example Service Described in the RPC Language
Here is an example of the specification of a simple ping program. Here is an example of the specification of a simple ping program.
program PING_PROG { program PING_PROG {
/* /*
* Latest and greatest version * Latest and greatest version
*/ */
version PING_VERS_PINGBACK { version PING_VERS_PINGBACK {
void void
PINGPROC_NULL(void) = 0; PINGPROC_NULL(void) = 0;
skipping to change at page 16, line 5 skipping to change at page 16, line 26
convention, procedure 0 of any RPC protocol should have the same convention, procedure 0 of any RPC protocol should have the same
semantics, and never require any kind of authentication. The second semantics, and never require any kind of authentication. The second
procedure is used for the client to have the server do a reverse ping procedure is used for the client to have the server do a reverse ping
operation back to the client, and it returns the amount of time (in operation back to the client, and it returns the amount of time (in
microseconds) that the operation used. The next version, microseconds) that the operation used. The next version,
PING_VERS_ORIG, is the original version of the protocol and it does PING_VERS_ORIG, is the original version of the protocol and it does
not contain PINGPROC_PINGBACK procedure. It is useful for not contain PINGPROC_PINGBACK procedure. It is useful for
compatibility with old client programs, and as this program matures compatibility with old client programs, and as this program matures
it may be dropped from the protocol entirely. it may be dropped from the protocol entirely.
Title Remote Procedure Call Protocol Version 2 January 2008 12.2. The RPC Language Specification
11.2. The RPC Language Specification
The RPC language is identical to the XDR language defined in RFC The RPC language is identical to the XDR language defined in RFC
1014, except for the added definition of a "program-def" described 1014, except for the added definition of a "program-def" described
below. below.
program-def: program-def:
"program" identifier "{" "program" identifier "{"
version-def version-def
version-def * version-def *
"}" "=" constant ";" "}" "=" constant ";"
skipping to change at page 16, line 33 skipping to change at page 17, line 5
"}" "=" constant ";" "}" "=" constant ";"
procedure-def: procedure-def:
proc-return identifier "(" proc-firstarg proc-return identifier "(" proc-firstarg
("," type-specifier )* ")" "=" constant ";" ("," type-specifier )* ")" "=" constant ";"
proc-return: "void" | type-specifier proc-return: "void" | type-specifier
proc-firstarg: "void" | type-specifier proc-firstarg: "void" | type-specifier
11.3. Syntax Notes 12.3. Syntax Notes
o The following keywords are added and cannot be used as o The following keywords are added and cannot be used as
identifiers: "program" and "version"; identifiers: "program" and "version";
o A version name cannot occur more than once within the scope of a o A version name cannot occur more than once within the scope of a
program definition. Nor can a version number occur more than program definition. Nor can a version number occur more than
once within the scope of a program definition. once within the scope of a program definition.
o A procedure name cannot occur more than once within the scope of o A procedure name cannot occur more than once within the scope of
a version definition. Nor can a procedure number occur more than a version definition. Nor can a procedure number occur more than
once within the scope of version definition. once within the scope of version definition.
o Program identifiers are in the same name space as constant and o Program identifiers are in the same name space as constant and
type identifiers. type identifiers.
o Only unsigned constants can be assigned to programs, versions o Only unsigned constants can be assigned to programs, versions
and procedures. and procedures.
o Current RPC language compilers do not generally support more o Current RPC language compilers do not generally support more
Title Remote Procedure Call Protocol Version 2 January 2008
than one type-specifier in procedure argument lists; the usual than one type-specifier in procedure argument lists; the usual
practice is to wrap arguments into a structure. practice is to wrap arguments into a structure.
12. IANA Considerations 13. IANA Considerations
The assignment of RPC program numbers and authentication flavor The assignment of RPC program numbers and authentication flavor
numbers has in the past been performed by Sun Microsystems, Inc. numbers has in the past been performed by Sun Microsystems, Inc.
This is inappropriate for an IETF standard protocol, as such work is This is inappropriate for an IETF standard protocol, as such work is
done well by the Internet Assigned Numbers Authority (IANA). This done well by the Internet Assigned Numbers Authority (IANA). This
document proposes the transfer of authority over RPC program numbers document proposes the transfer of authority over RPC program numbers
and authentication flavor numbers described here from Sun and authentication flavor numbers described here from Sun
Microsystems, Inc. to IANA and proposes how IANA will maintain and Microsystems, Inc. to IANA and proposes how IANA will maintain and
assign RPC program numbers and authentication flavor numbers. Users assign RPC program numbers and authentication flavor numbers. Users
of RPC protocols will benefit by having an independent body of RPC protocols will benefit by having an independent body
responsible for RPC number assignments. responsible for RPC number assignments.
12.1. Numbering Requests to IANA 13.1. Numbering Requests to IANA
Appendix B of this document describes the information to be sent to Appendix B of this document describes the information to be sent to
IANA to request one or more RPC numbers and the rules that apply. IANA to request one or more RPC numbers and the rules that apply.
IANA should review this part of the document as well. IANA should review this part of the document as well.
12.2. Protecting Past Assignments 13.2. Protecting Past Assignments
Sun has made assignments in both number spaces since the original Sun has made assignments in both number spaces since the original
deployment of RPC. The assignments made by Sun Microsystems are deployment of RPC. The assignments made by Sun Microsystems are
still valid, and will be preserved. Sun will communicate all current still valid, and will be preserved. Sun will communicate all current
assignments in both number spaces to IANA before final handoff of assignments in both number spaces to IANA before final handoff of
number assignment is done. number assignment is done.
12.3. RPC Number Assignment 13.3. RPC Number Assignment
Future IANA practice should deal with the following partitioning of Future IANA practice should deal with the following partitioning of
the 32-bit number space: the 32-bit number space:
0 Reserved 0 Reserved
1 - 0x1fffffff To be assigned by IANA 1 - 0x1fffffff To be assigned by IANA
0x20000000 - 0x3fffffff Defined by local administrator 0x20000000 - 0x3fffffff Defined by local administrator
(see note1) (see note1)
0x40000000 - 0x5fffffff Transient 0x40000000 - 0x5fffffff Transient
0x60000000 - 0x7effffff Reserved 0x60000000 - 0x7effffff Reserved
0x7f000000 - 0x7fffffff Assignment outstanding 0x7f000000 - 0x7fffffff Assignment outstanding
0x80000000 - 0xffffffff Reserved 0x80000000 - 0xffffffff Reserved
Title Remote Procedure Call Protocol Version 2 January 2008
Detailed information for the administration of these blocks is given Detailed information for the administration of these blocks is given
below. below.
12.3.1. To be assigned by IANA 13.3.1. To be assigned by IANA
The first block will be administered by IANA, with previous The first block will be administered by IANA, with previous
assignments by Sun protected. Previous assignments were restricted assignments by Sun protected. Previous assignments were restricted
to the range decimal 100000-399999 (0x000186a0 to 0x00061a7f), to the range decimal 100000-399999 (0x000186a0 to 0x00061a7f),
therefore IANA should begin assignments at decimal 400000. therefore IANA should begin assignments at decimal 400000.
Individual numbers should be grated on a first-come, first-served Individual numbers should be grated on a first-come, first-served
basis, and blocks should be granted under rules related to the size basis, and blocks should be granted under rules related to the size
of the block. of the block.
12.3.2. Defined by local administrator 13.3.2. Defined by local administrator
The "Defined by local administrator" block is available for any local The "Defined by local administrator" block is available for any local
administrative domain to use, in a similar manner to IP address administrative domain to use, in a similar manner to IP address
ranges reserved for private use. The expected use would be through ranges reserved for private use. The expected use would be through
the establishment of a local domain "authority" for assigning numbers the establishment of a local domain "authority" for assigning numbers
from this range. This authority would establish any policies or from this range. This authority would establish any policies or
procedures to be used within that local domain for use or assignment procedures to be used within that local domain for use or assignment
of RPC numbers from the range. The local domain should be of RPC numbers from the range. The local domain should be
sufficiently isolated that it would be unlikely that RPC applications sufficiently isolated that it would be unlikely that RPC applications
developed by other local domains could communicate with the domain. developed by other local domains could communicate with the domain.
This could result in RPC number contention, which would cause one of This could result in RPC number contention, which would cause one of
the applications to fail. In the absence of a local administrator, the applications to fail. In the absence of a local administrator,
this block can be utilized in a "Private Use" manner per [RFC2434]. this block can be utilized in a "Private Use" manner per [RFC2434].
12.3.3. Transient block 13.3.3. Transient block
The "Transient" block can be used by any RPC application on a "as The "Transient" block can be used by any RPC application on a "as
available" basis. This range is intended for services that can available" basis. This range is intended for services that can
communicate a dynamically selected RPC program number to clients of communicate a dynamically selected RPC program number to clients of
the service. Any mechanism can be used to communicate the number. the service. Any mechanism can be used to communicate the number.
Examples include shared memory when the client and server are located Examples include shared memory when the client and server are located
on the same system, or a network message (either RPC or otherwise) on the same system, or a network message (either RPC or otherwise)
that disseminates the selected number. that disseminates the selected number.
The transient block is not administered. An RPC service uses this The transient block is not administered. An RPC service uses this
range by selecting a number in the transient range and attempting to range by selecting a number in the transient range and attempting to
register that number with the local system's RPC bindery (see the register that number with the local system's RPC bindery (see the
RPCBPROC_SET or PMAPPROC_SET procedures in "Binding Protocols for ONC RPCBPROC_SET or PMAPPROC_SET procedures in "Binding Protocols for ONC
RPC", [RFC1833]). If successful, no other RPC service was using that RPC", [RFC1833]). If successful, no other RPC service was using that
number and the RPC Bindery has assigned that number to the requesting number and the RPC Bindery has assigned that number to the requesting
RPC application. The registration is valid until the RPC Bindery RPC application. The registration is valid until the RPC Bindery
terminates, which normally would only happen if the system reboots terminates, which normally would only happen if the system reboots
Title Remote Procedure Call Protocol Version 2 January 2008
causing all applications, including the RPC service using the causing all applications, including the RPC service using the
transient number, to terminate. If the transient number registration transient number, to terminate. If the transient number registration
fails, another RPC application is using the number and the requestor fails, another RPC application is using the number and the requestor
must select another number and try again. To avoid conflicts, the must select another number and try again. To avoid conflicts, the
recommended method is to select a number randomly from the transient recommended method is to select a number randomly from the transient
range. range.
12.3.4. Reserved block 13.3.4. Reserved block
The "Reserved" blocks are available for future use. RPC applications The "Reserved" blocks are available for future use. RPC applications
must not use numbers in these ranges unless their use is allowed by must not use numbers in these ranges unless their use is allowed by
future action by the IESG. future action by the IESG.
12.3.5. RPC Number Sub-Blocks 13.3.5. RPC Number Sub-Blocks
RPC numbers are usually assigned for specific RPC services. Some RPC numbers are usually assigned for specific RPC services. Some
applications, however, require multiple RPC numbers for a service. applications, however, require multiple RPC numbers for a service.
The most common example is an RPC service that needs to have multiple The most common example is an RPC service that needs to have multiple
instances of the service active simultaneously at a specific site. instances of the service active simultaneously at a specific site.
RPC does not have an "instance identifier" in the protocol, so either RPC does not have an "instance identifier" in the protocol, so either
a mechanism must be implemented to multiplex RPC requests amongst a mechanism must be implemented to multiplex RPC requests amongst
various instances of the service, or unique RPC numbers must be used various instances of the service, or unique RPC numbers must be used
by each instance. by each instance.
skipping to change at page 19, line 47 skipping to change at page 20, line 15
Assignment of RPC Number Sub-Blocks is controlled by the size of the Assignment of RPC Number Sub-Blocks is controlled by the size of the
sub-block being requested. "Specification Required" and "IESG sub-block being requested. "Specification Required" and "IESG
Approval" are used as defined by [RFC2434] Section 2. Approval" are used as defined by [RFC2434] Section 2.
Size of sub-block Assignment Method Authority Size of sub-block Assignment Method Authority
----------------- ----------------- --------- ----------------- ----------------- ---------
Up to 100 numbers First Come First Served IANA Up to 100 numbers First Come First Served IANA
Up to 1000 numbers Specification Required IANA Up to 1000 numbers Specification Required IANA
More than 1000 numbers IESG Approval required IESG More than 1000 numbers IESG Approval required IESG
Note: sub-blocks can be any size. The limits given above are Note: sub-blocks can be any size. The limits given above are
maximums and smaller size sub-blocks are allowed. maximums and smaller size sub-blocks are allowed.
Sub-blocks sized up to 100 numbers may be assigned by IANA on a First Sub-blocks sized up to 100 numbers may be assigned by IANA on a First
Come First Served basis. The RPC Service Description included in the Come First Served basis. The RPC Service Description included in the
Title Remote Procedure Call Protocol Version 2 January 2008
range must include an indication of how the sub-block is managed. At range must include an indication of how the sub-block is managed. At
minimum, the statement should indicate whether the sub-block is used minimum, the statement should indicate whether the sub-block is used
with a single RPC protocol or multiple RPC protocols, and whether the with a single RPC protocol or multiple RPC protocols, and whether the
numbers are dynamically assigned or statically (through numbers are dynamically assigned or statically (through
administrative action) assigned. administrative action) assigned.
Sub-blocks of up to 1000 numbers must be documented in detail. The Sub-blocks of up to 1000 numbers must be documented in detail. The
documentation must describe the RPC protocol or protocols that are to documentation must describe the RPC protocol or protocols that are to
be used in the range. It must also describe how the numbers within be used in the range. It must also describe how the numbers within
the sub-block are to be assigned or used. the sub-block are to be assigned or used.
skipping to change at page 20, line 44 skipping to change at page 21, line 9
Required assignment for incremental requests of less than 100 Required assignment for incremental requests of less than 100
numbers. numbers.
If an individual or entity has under 1000 numbers and later requests If an individual or entity has under 1000 numbers and later requests
an additional set of numbers such that the individual or entity would an additional set of numbers such that the individual or entity would
over 1000 numbers, then the individual or entity will have the over 1000 numbers, then the individual or entity will have the
additional request submitted to the IESG. IESG is free to waive the additional request submitted to the IESG. IESG is free to waive the
IESG Action Required assignment method for incremental requests of IESG Action Required assignment method for incremental requests of
less than 1000 numbers. less than 1000 numbers.
12.4. RPC Authentication Flavor Number Assignment 13.4. RPC Authentication Flavor Number Assignment
The second number space is the authentication mechanism identifier, The second number space is the authentication mechanism identifier,
or "flavor", number. This number is used to distinguish between or "flavor", number. This number is used to distinguish between
various authentication mechanisms which can be optionally used with various authentication mechanisms which can be optionally used with
an RPC message. An authentication identifier is used in the "flavor" an RPC message. An authentication identifier is used in the "flavor"
field of the "opaque_auth" structure. field of the "opaque_auth" structure.
Recent progress in RPC security has moved away from new auth flavors Recent progress in RPC security has moved away from new auth flavors
as used by AUTH_DH [DH], and focused on using the existing RPCSEC_GSS as used by AUTH_DH [DH], and focused on using the existing RPCSEC_GSS
Title Remote Procedure Call Protocol Version 2 January 2008
[RFC2203] flavor and inventing novel GSS-API mechanisms which can be [RFC2203] flavor and inventing novel GSS-API mechanisms which can be
used with it, such as Even though RPCSEC_GSS is an assigned used with it. Even though RPCSEC_GSS is an assigned authentication
authentication flavor, use of a new RPCSEC_GSS mechanism with NFS flavor, use of a new RPCSEC_GSS mechanism with NFS ([RFC1094]
([RFC1094] [RFC1813] and [RFC3530]) will require the registration of [RFC1813] and [RFC3530]) will require the registration of 'pseudo-
'pseudo-flavors' which are used to negotiate security mechanisms in flavors' which are used to negotiate security mechanisms in an
an unambiguous way, as defined by [RFC2623]. Existing pseudo-flavors unambiguous way, as defined by [RFC2623]. Existing pseudo-flavors
have been granted in the decimal range 390000-390255 as described in have been granted in the decimal range 390000-390255 as described in
2.2. 2.2.
For non-pseudo-flavor requests, IANA should begin granting RPC For non-pseudo-flavor requests, IANA should begin granting RPC
authentication flavor numbers at 400000 to avoid conflicts with authentication flavor numbers at 400000 to avoid conflicts with
currently granted numbers. currently granted numbers.
For authentication flavors to be used on the Internet, it is strongly For authentication flavors to be used on the Internet, it is strongly
advised that an informational or standards-track RFC be published advised that an informational or standards-track RFC be published
describing the authentication mechanism behaviour and parameters. describing the authentication mechanism behaviour and parameters.
13. Security Considerations 14. Security Considerations
AUTH_SYS as described in Appendix A is known to be insecure due to AUTH_SYS as described in Appendix A is known to be insecure due to
the lack of a verifier to permit the credential to be validated. Use the lack of a verifier to permit the credential to be validated. Use
of AUTH_SYS is not recommended for services which permit clients to of AUTH_SYS is not recommended for services which permit clients to
modify data. modify data.
[RFC2203] defines a new security flavor, RPCSEC_GSS, which permits [RFC2203] defines a new security flavor, RPCSEC_GSS, which permits
GSS-API [RFC2743] mechanisms to be used for securing RPC. All non- GSS-API [RFC2743] mechanisms to be used for securing RPC. All non-
trivial RPC programs developed in future should implement trivial RPC programs developed in future should implement
RPCSEC_GSS-based security appropriately. [RFC2623] describes how RPCSEC_GSS-based security appropriately. [RFC2623] describes how
this was done for a widely deployed RPC program. this was done for a widely deployed RPC program.
14. Appendix A: System Authentication 15. Appendix A: System Authentication
The client may wish to identify itself, for example, as it is The client may wish to identify itself, for example, as it is
identified on a UNIX(tm) system. The flavor of the client credential identified on a UNIX(tm) system. The flavor of the client credential
is "AUTH_SYS". The opaque data constituting the credential encodes is "AUTH_SYS". The opaque data constituting the credential encodes
the following structure: the following structure:
struct authsys_parms { struct authsys_parms {
unsigned int stamp; unsigned int stamp;
string machinename<255>; string machinename<255>;
unsigned int uid; unsigned int uid;
unsigned int gid; unsigned int gid;
unsigned int gids<16>; unsigned int gids<16>;
}; };
The "stamp" is an arbitrary ID which the caller machine may generate. The "stamp" is an arbitrary ID which the caller machine may generate.
Title Remote Procedure Call Protocol Version 2 January 2008
The "machinename" is the name of the caller's machine (like The "machinename" is the name of the caller's machine (like
"krypton"). The "uid" is the caller's effective user ID. The "gid" "krypton"). The "uid" is the caller's effective user ID. The "gid"
is the caller's effective group ID. The "gids" is a counted array of is the caller's effective group ID. The "gids" is a counted array of
groups which contain the caller as a member. The verifier groups which contain the caller as a member. The verifier
accompanying the credential should have "AUTH_NONE" flavor value accompanying the credential should have "AUTH_NONE" flavor value
(defined above). Note this credential is only unique within a (defined above). Note this credential is only unique within a
particular domain of machine names, uids, and gids. particular domain of machine names, uids, and gids.
The flavor value of the verifier received in the reply message from The flavor value of the verifier received in the reply message from
the server may be "AUTH_NONE" or "AUTH_SHORT". In the case of the server may be "AUTH_NONE" or "AUTH_SHORT". In the case of
skipping to change at page 22, line 40 skipping to change at page 23, line 5
It should be noted that use of this flavor of authentication does not It should be noted that use of this flavor of authentication does not
guarantee any security for the users or providers of a service, in guarantee any security for the users or providers of a service, in
itself. The authentication provided by this scheme can be considered itself. The authentication provided by this scheme can be considered
legitimate only when applications using this scheme and the network legitimate only when applications using this scheme and the network
can be secured externally, and privileged transport addresses are can be secured externally, and privileged transport addresses are
used for the communicating end-points (an example of this is the use used for the communicating end-points (an example of this is the use
of privileged TCP/UDP ports in Unix systems - note that not all of privileged TCP/UDP ports in Unix systems - note that not all
systems enforce privileged transport address mechanisms). systems enforce privileged transport address mechanisms).
15. Appendix B: Requesting RPC program or authentication numbers 16. Appendix B: Requesting RPC program or authentication numbers
RPC numbers which must be unique across all networks are assigned by RPC numbers which must be unique across all networks are assigned by
the Internet Assigned Number Authority. To apply for a single number the Internet Assigned Number Authority. To apply for a single number
or a block of numbers, electronic mail must be sent to IANA or a block of numbers, electronic mail must be sent to IANA
<iana@isi.edu> with the following information: <iana@isi.edu> with the following information:
o The type of number(s) (program number or authentication flavor o The type of number(s) (program number or authentication flavor
number) sought number) sought
o How many numbers are sought o How many numbers are sought
o The name of person or company which will use the number o The name of person or company which will use the number
Title Remote Procedure Call Protocol Version 2 January 2008
o An "identifier string" which associates the number with a o An "identifier string" which associates the number with a
service service
o Email address of the contact person for the service which will o Email address of the contact person for the service which will
be using the number. be using the number.
o A short description of the purpose and use of the number o A short description of the purpose and use of the number
o If an authentication flavor number is sought, and the number o If an authentication flavor number is sought, and the number
will be a 'pseudo-flavor' intended for use with RPCSEC_GSS and will be a 'pseudo-flavor' intended for use with RPCSEC_GSS and
skipping to change at page 24, line 5 skipping to change at page 24, line 5
required. required.
Specific numbers cannot be requested. Numbers are assigned on a Specific numbers cannot be requested. Numbers are assigned on a
First Come First Served basis. First Come First Served basis.
For all RPC authentication flavor numbers to used on the Internet, it For all RPC authentication flavor numbers to used on the Internet, it
is strongly advised that an informational or standards-track RFC be is strongly advised that an informational or standards-track RFC be
published describing the authentication mechanism behaviour and published describing the authentication mechanism behaviour and
parameters. parameters.
Title Remote Procedure Call Protocol Version 2 January 2008 17. Full Copyright Statement
16. Full Copyright Statement
Copyright (C) The IETF Trust (2008). Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
17. Intellectual property 18. Intellectual property
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
skipping to change at page 24, line 47 skipping to change at page 24, line 45
such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf- this standard. Please address the information to the IETF at ietf-
ipr@ietf.org. ipr@ietf.org.
18. Acknowledgment 19. Acknowledgment
Funding for the RFC Editor function is provided by the IETF Funding for the RFC Editor function is provided by the IETF
Title Remote Procedure Call Protocol Version 2 January 2008
Administrative Support Activity (IASA). Administrative Support Activity (IASA).
Title Remote Procedure Call Protocol Version 2 January 2008 20. Normative References
19. Normative References
[RFC4506] [RFC4506]
Eisler, M., "XDR: External Data Representation Standard", RFC 4506, Eisler, M., "XDR: External Data Representation Standard", RFC 4506,
20. Informative References 21. Informative References
[XRPC] [XRPC]
Birrell, A. D. & Nelson, B. J., "Implementing Remote Procedure Birrell, A. D. & Nelson, B. J., "Implementing Remote Procedure
Calls", XEROX CSL-83-7, October 1983. Calls", XEROX CSL-83-7, October 1983.
[VMTP] [VMTP]
Cheriton, D., "VMTP: Versatile Message Transaction Protocol", Cheriton, D., "VMTP: Versatile Message Transaction Protocol",
Preliminary Version 0.3, Stanford University, January 1987. Preliminary Version 0.3, Stanford University, January 1987.
[DH] [DH]
skipping to change at page 27, line 4 skipping to change at page 26, line 4
[RFC1094] [RFC1094]
Sun Microsystems, Inc., "NFS: Network File System Protocol Sun Microsystems, Inc., "NFS: Network File System Protocol
Specification", RFC 1094, March 1989. Specification", RFC 1094, March 1989.
[RFC1813] [RFC1813]
Callaghan, B., Pawlowski, B., Staubach, P., "NFS Version 3 Protocol Callaghan, B., Pawlowski, B., Staubach, P., "NFS Version 3 Protocol
Specification", RFC 1813, June 1995. Specification", RFC 1813, June 1995.
[RFC1831] [RFC1831]
Title Remote Procedure Call Protocol Version 2 January 2008
R. Srinivasan, "RPC: Remote Procedure Call Protocol Specification R. Srinivasan, "RPC: Remote Procedure Call Protocol Specification
Version 2", RFC 1831, August 1995. Version 2", RFC 1831, August 1995.
[RFC1833] [RFC1833]
R. Srinivasan, "Binding Protocols for ONC RPC Version 2", RFC 1833, R. Srinivasan, "Binding Protocols for ONC RPC Version 2", RFC 1833,
August 1995. August 1995.
[RFC2203] [RFC2203]
Eisler, M., Chiu, A., Ling, L., "RPCSEC_GSS Protocol Specification", Eisler, M., Chiu, A., Ling, L., "RPCSEC_GSS Protocol Specification",
RFC 2203, September 1997 RFC 2203, September 1997
skipping to change at page 28, line 5 skipping to change at page 27, line 5
[RFC2743] [RFC2743]
Linn. J., "Generic Security Service Application Program Interface Linn. J., "Generic Security Service Application Program Interface
Version 2, Update 1", RFC 2743, January 2000. Version 2, Update 1", RFC 2743, January 2000.
[RFC3530] [RFC3530]
Shepler, S., Callaghan, B., Robinson, D., Thurlow, R., Beame, C., Shepler, S., Callaghan, B., Robinson, D., Thurlow, R., Beame, C.,
Eisler, M., Noveck, D., "Network File System (NFS) version 4 Eisler, M., Noveck, D., "Network File System (NFS) version 4
Protocol", RFC 3530, April 2003. Protocol", RFC 3530, April 2003.
Title Remote Procedure Call Protocol Version 2 January 2008 22. Author's Address
21. Author's Address
Address comments related to this memorandum to: Address comments related to this memorandum to:
nfsv4@ietf.org nfsv4@ietf.org
Robert Thurlow Robert Thurlow
Sun Microsystems, Inc. Sun Microsystems, Inc.
500 Eldorado Boulevard, UBRM05-171 500 Eldorado Boulevard, UBRM05-171
Broomfield, CO 80021 Broomfield, CO 80021
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