draft-ietf-nntpext-base-16.txt   draft-ietf-nntpext-base-17.txt 
INTERNET DRAFT C. Feather NNTP C. Feather
Expires: July 31, 2003 Thus plc Internet-Draft Thus plc
January 2003 Expires: August 30, 2003 March 1, 2003
Network News Transport Protocol Network News Transport Protocol
draft-ietf-nntpext-base-16.txt draft-ietf-nntpext-base-17
1 Status of this memo Status of this Memo
This memo is an Internet-Draft and is in full conformance This document is an Internet-Draft and is in full conformance with
with Section 10 of RFC 2026. Internet-Drafts are working all provisions of Section 10 of RFC2026.
documents of the Internet Engineering Task Force (IETF), its
areas, and its working groups. Note that other groups may
also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of Internet-Drafts are working documents of the Internet Engineering
six months and may be updated, replaced, or made obsolete by Task Force (IETF), its areas, and its working groups. Note that
other documents at any time. It is inappropriate to use other groups may also distribute working documents as
Internet-Drafts as reference material or to cite them other Internet-Drafts.
than as "work in progress."
The list of current Internet-Drafts can be accesses at Internet-Drafts are draft documents valid for a maximum of six months
http://www.ietf.org/ietf/1id-abstracts.txt. and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of Internet-Draft shadow directories can be accessed The list of current Internet-Drafts can be accessed at http://
at http://www.ietf.org/shadow.html. www.ietf.org/ietf/1id-abstracts.txt.
This section will be updated with the appropriate verbiage The list of Internet-Draft Shadow Directories can be accessed at
from RFC 2223 should this memo have been found ready for http://www.ietf.org/shadow.html.
publication as an RFC. This update will include its standards
track status.
This memo is a product of the NNTP Working Group, chaired by This Internet-Draft will expire on August 30, 2003.
Russ Allbery.
2 Abstract Copyright Notice
The Network News Transport Protocol has been in use in the Copyright (C) The Internet Society (2003). All Rights Reserved.
Internet for a decade and remains one of the most popular
protocols (by volume) in use today. This memo is a
replacement for RFC 977 and officially updates the protocol
specification. It clarifies some vagueness in RFC 977,
includes some new base functionality and provides a specific
mechanism to add standardized extensions to NNTP.
Feather [Page 1] Abstract
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
3 Introduction The Network News Transport Protocol has been in use in the Internet
for a decade and remains one of the most popular protocols (by
volume) in use today. This document is a replacement for RFC 977 and
officially updates the protocol specification. It clarifies some
vagueness in RFC 977, includes some new base functionality and
provides a specific mechanism to add standardized extensions to NNTP.
This memo specifies the Network News Transport Protocol Administration
(NNTP), which is used for the distribution, inquiry,
retrieval, and posting of net news articles using a reliable
stream-based mechanism. For news reading clients, NNTP
enables retrieval of news articles that are stored in a
central database, giving subscribers the ability to select
only those articles they wish to read.
The netnews model provides for indexing, cross-referencing, This document is a product of the NNTP Working Group, chaired by Russ
and expiration of aged messages. For server-to-server Allbery.
interaction, NNTP is designed for efficient transmission of
net news articles over a reliable full duplex communication
channel.
Every attempt is made to ensure that the protocol This is draft 17 pre-publication version 2.
specification in this memo is compatible with the version
specified in RFC 977[1]. However, this version does not
support the ill-defined SLAVE command and permits four digit
years to be specified in the NEWNEWS and NEWGROUPS commands.
It changes the default character set to UTF-8[2] instead of
US-ASCII[3]. It also extends the newsgroup name matching
capabilities already documented in RFC 977.
Generally, new functionality is available using new keywords. Outstanding issues
Part of that new functionality involves a mechanism to
discover what new functionality is available to clients from
a server.
This mechanism can also be used to add more functionality as Outstanding substantive (as opposed to editorial) issues in the text
needs merit such additions. are shown as in the following case.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL OUTSTANDING ISSUE
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this memo are to be interpreted as described in
RFC 2119[4].
An implementation is not compliant if it fails to satisfy one Reference consistency: should every RFC that is mentioned be
or more of the MUST requirements for this protocol. An included in the references? Where the same document is referred to
implementation that satisfies all the MUST and all the SHOULD in more than one place, should every occasion have a reference
requirements for its protocols is said to be "unconditionally number (that is, "RFC 977 [3]" or similar), or only the first one,
or only the first one in each section?
Feather [Page 2] Author's Note
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
compliant"; one that satisfies all the MUST requirements but This draft is the first produced using a new formatting process. It
not all the SHOULD requirements for NNTP is said to be therefore may contain unintentional layout or formatting changes
"conditionally compliant". compared with previous drafts. The author would appreciate being
informed of any problems this has caused.
For the remainder of this memo, the term "client host" refers This draft is written in XML using an NNTP-specific DTD. Custom
to a host making use of the NNTP service, while the term software is used to convert this to RFC 2629 [12] format, and then
"server host" refers to a host that offers the NNTP service. the public "xml2rfc" package to further reduce this to text, nroff
In addition, where examples of interactions between a client source, and HTML.
host and a server host are provided a "[C]" will be used to
represent the client host and a "[S]" will be used to
represent the server host.
For the remainder of this memo, responses will be described No perl was used in producing this draft.
in tables listing the required format of a response followed
by the meaning that should be ascribed to that response.
4 Basic Operation. Rights
UNIX is a registered trademark of the X/Open Company Ltd.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . 7
2. Notation . . . . . . . . . . . . . . . . . . . . . . . . 8
3. Basic Operation . . . . . . . . . . . . . . . . . . . . 9
3.1 Response Codes . . . . . . . . . . . . . . . . . . . . . 11
3.1.1 Generic Response Codes . . . . . . . . . . . . . . . . . 13
3.1.1.1 Examples . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2 Pipelining . . . . . . . . . . . . . . . . . . . . . . . 16
3.2.1 Examples . . . . . . . . . . . . . . . . . . . . . . . . 17
4. The WILDMAT format . . . . . . . . . . . . . . . . . . . 18
4.1 Wildmat syntax . . . . . . . . . . . . . . . . . . . . . 18
4.2 Wildmat semantics . . . . . . . . . . . . . . . . . . . 18
4.3 Extensions . . . . . . . . . . . . . . . . . . . . . . . 19
4.4 Examples . . . . . . . . . . . . . . . . . . . . . . . . 20
5. The GREETING Step . . . . . . . . . . . . . . . . . . . 21
5.1 Initial Connection . . . . . . . . . . . . . . . . . . . 21
5.1.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1.2 Description . . . . . . . . . . . . . . . . . . . . . . 21
5.1.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 21
5.2 MODE READER . . . . . . . . . . . . . . . . . . . . . . 22
5.2.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.2.2 Description . . . . . . . . . . . . . . . . . . . . . . 22
5.2.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 23
6. The CAPABILITIES DISCOVERY step . . . . . . . . . . . . 25
6.1 LIST EXTENSIONS . . . . . . . . . . . . . . . . . . . . 25
6.1.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.1.2 Description . . . . . . . . . . . . . . . . . . . . . . 25
6.1.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 26
7. Article posting and retrieval . . . . . . . . . . . . . 27
7.1 Group and article selection . . . . . . . . . . . . . . 27
7.1.1 GROUP . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.1.1.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 28
7.1.1.2 Description . . . . . . . . . . . . . . . . . . . . . . 28
7.1.1.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 29
7.1.2 LAST . . . . . . . . . . . . . . . . . . . . . . . . . . 30
7.1.2.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 30
7.1.2.2 Description . . . . . . . . . . . . . . . . . . . . . . 30
7.1.2.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 31
7.1.3 NEXT . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.1.3.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.1.3.2 Description . . . . . . . . . . . . . . . . . . . . . . 32
7.1.3.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 32
7.2 Retrieval of articles and article sections . . . . . . . 33
7.2.1 ARTICLE . . . . . . . . . . . . . . . . . . . . . . . . 33
7.2.1.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.2.1.2 Description . . . . . . . . . . . . . . . . . . . . . . 34
7.2.1.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 35
7.2.2 HEAD . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.2.2.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.2.2.2 Description . . . . . . . . . . . . . . . . . . . . . . 37
7.2.2.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 37
7.2.3 BODY . . . . . . . . . . . . . . . . . . . . . . . . . . 39
7.2.3.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 39
7.2.3.2 Description . . . . . . . . . . . . . . . . . . . . . . 39
7.2.3.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 39
7.2.4 STAT . . . . . . . . . . . . . . . . . . . . . . . . . . 40
7.2.4.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 40
7.2.4.2 Description . . . . . . . . . . . . . . . . . . . . . . 41
7.2.4.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 41
7.3 Article posting . . . . . . . . . . . . . . . . . . . . 42
7.3.1 POST . . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.3.1.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.3.1.2 Description . . . . . . . . . . . . . . . . . . . . . . 43
7.3.1.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 44
7.3.2 IHAVE . . . . . . . . . . . . . . . . . . . . . . . . . 44
7.3.2.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 44
7.3.2.2 Description . . . . . . . . . . . . . . . . . . . . . . 45
7.3.2.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 46
8. Information commands . . . . . . . . . . . . . . . . . . 48
8.1 DATE . . . . . . . . . . . . . . . . . . . . . . . . . . 48
8.1.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 48
8.1.2 Description . . . . . . . . . . . . . . . . . . . . . . 48
8.1.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 48
8.2 HELP . . . . . . . . . . . . . . . . . . . . . . . . . . 48
8.2.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 48
8.2.2 Description . . . . . . . . . . . . . . . . . . . . . . 49
8.2.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 49
8.3 NEWGROUPS . . . . . . . . . . . . . . . . . . . . . . . 49
8.3.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 49
8.3.2 Description . . . . . . . . . . . . . . . . . . . . . . 49
8.3.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 50
8.4 NEWNEWS . . . . . . . . . . . . . . . . . . . . . . . . 50
8.4.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 51
8.4.2 Description . . . . . . . . . . . . . . . . . . . . . . 51
8.4.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 51
8.5 Time . . . . . . . . . . . . . . . . . . . . . . . . . . 52
8.5.1 Examples . . . . . . . . . . . . . . . . . . . . . . . . 52
8.6 The LIST commands . . . . . . . . . . . . . . . . . . . 53
8.6.1 LIST ACTIVE . . . . . . . . . . . . . . . . . . . . . . 53
8.6.1.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 53
8.6.1.2 Description . . . . . . . . . . . . . . . . . . . . . . 53
8.6.1.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 54
8.6.2 LIST ACTIVE.TIMES . . . . . . . . . . . . . . . . . . . 55
8.6.2.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 55
8.6.2.2 Description . . . . . . . . . . . . . . . . . . . . . . 55
8.6.2.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 55
8.6.3 LIST DISTRIBUTIONS . . . . . . . . . . . . . . . . . . . 56
8.6.3.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 56
8.6.3.2 Description . . . . . . . . . . . . . . . . . . . . . . 56
8.6.3.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 57
8.6.4 LIST DISTRIB.PATS . . . . . . . . . . . . . . . . . . . 57
8.6.4.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 57
8.6.4.2 Description . . . . . . . . . . . . . . . . . . . . . . 57
8.6.4.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 58
8.6.5 LIST NEWSGROUPS . . . . . . . . . . . . . . . . . . . . 58
8.6.5.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 58
8.6.5.2 Description . . . . . . . . . . . . . . . . . . . . . . 59
8.6.5.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 59
9. The CONCLUSION step . . . . . . . . . . . . . . . . . . 60
9.1 QUIT . . . . . . . . . . . . . . . . . . . . . . . . . . 60
9.1.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 60
9.1.2 Description . . . . . . . . . . . . . . . . . . . . . . 60
9.1.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 60
10. Framework for NNTP extensions . . . . . . . . . . . . . 61
10.1 Initial IANA registry . . . . . . . . . . . . . . . . . 63
10.2 Standard extensions . . . . . . . . . . . . . . . . . . 63
10.3 The LISTGROUP extension . . . . . . . . . . . . . . . . 63
10.3.1 LISTGROUP . . . . . . . . . . . . . . . . . . . . . . . 63
10.3.1.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 63
10.3.1.2 Description . . . . . . . . . . . . . . . . . . . . . . 64
10.3.1.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 64
10.4 Article metadata . . . . . . . . . . . . . . . . . . . . 65
10.4.1 The :bytes metadata item . . . . . . . . . . . . . . . . 65
10.4.2 The :lines metadata item . . . . . . . . . . . . . . . . 66
10.5 The OVER extension . . . . . . . . . . . . . . . . . . . 66
10.5.1 OVER . . . . . . . . . . . . . . . . . . . . . . . . . . 66
10.5.1.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 66
10.5.1.2 Description . . . . . . . . . . . . . . . . . . . . . . 67
10.5.1.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 68
10.5.2 LIST OVERVIEW.FMT . . . . . . . . . . . . . . . . . . . 69
10.5.2.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 69
10.5.2.2 Description . . . . . . . . . . . . . . . . . . . . . . 70
10.5.2.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 71
10.6 The HDR extension . . . . . . . . . . . . . . . . . . . 72
10.6.1 HDR . . . . . . . . . . . . . . . . . . . . . . . . . . 72
10.6.1.1 Usage . . . . . . . . . . . . . . . . . . . . . . . . . 72
10.6.1.2 Description . . . . . . . . . . . . . . . . . . . . . . 72
10.6.1.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 74
11. Augmented BNF Syntax for NNTP Commands . . . . . . . . . 76
12. Security Considerations . . . . . . . . . . . . . . . . 79
12.1 Personal and Proprietary Information . . . . . . . . . . 79
12.2 Abuse of Server Log Information . . . . . . . . . . . . 79
12.3 Weak Authentication and Access Control . . . . . . . . . 79
12.4 DNS Spoofing . . . . . . . . . . . . . . . . . . . . . . 80
12.5 UTF-8 issues . . . . . . . . . . . . . . . . . . . . . . 80
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . 82
Normative References . . . . . . . . . . . . . . . . . . 84
Informative References . . . . . . . . . . . . . . . . . 85
Author's Address . . . . . . . . . . . . . . . . . . . . 85
Intellectual Property and Copyright Statements . . . . . 86
1. Introduction
This document specifies the Network News Transport Protocol (NNTP),
which is used for the distribution, inquiry, retrieval, and posting
of net news articles using a reliable stream-based mechanism. For
news reading clients, NNTP enables retrieval of news articles that
are stored in a central database, giving subscribers the ability to
select only those articles they wish to read.
The net news model provides for indexing, cross-referencing, and
expiration of aged messages. For server-to-server interaction, NNTP
is designed for efficient transmission of net news articles over a
reliable full duplex communication channel.
Every attempt is made to ensure that the protocol specification in
this document is compatible with the version specified in RFC 977
[1]. However, this version does not support the ill-defined SLAVE
command and permits four digit years to be specified in the NEWNEWS
and NEWGROUPS commands. It changes the default character set to
UTF-8 [2] instead of US-ASCII [3]. It also extends the newsgroup
name matching capabilities already documented in RFC 977.
Generally, new functionality is made available using new commands.
Part of that new functionality involves a mechanism to discover what
new functionality is available to clients from a server.
This mechanism can also be used to add more functionality as needs
merit such additions.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [4].
An implementation is not compliant if it fails to satisfy one or more
of the MUST requirements for this protocol. An implementation that
satisfies all the MUST and all the SHOULD requirements for its
protocols is said to be "unconditionally compliant"; one that
satisfies all the MUST requirements but not all the SHOULD
requirements for NNTP is said to be "conditionally compliant".
For the remainder of this document, the term "client host" refers to
a host making use of the NNTP service, while the term "server host"
refers to a host that offers the NNTP service.
2. Notation
The following notational conventions are used in this document.
UPPERCASE indicates literal text to be included in the
command;
lowercase indicates a token described elsewhere;
[brackets] indicate that the parameter is optional;
ellipsis... indicates that the parameter may be repeated any
number of times (it must occur at least once);
vertical|bar indicates a choice of two mutually exclusive
parameters (exactly one must be provided).
The name "message-id" for a command or response parameter indicates
that it is the message-id of an article as described in Section 7.
The actual parameter MUST include the angle brackets.
The name "wildmat" for a parameter indicates that it is a wildmat as
defined in Section 4. If the parameter does not meet the
requirements of that section (for example, if it does not fit the
grammar of Section 4.1) the NNTP server MAY place some interpretation
on it (not specified by this document) or otherwise MUST treat it as
a syntax error.
Responses for each command will be described in tables listing the
required format of a response followed by the meaning that should be
ascribed to that response.
Examples in this document are not normative but serve to illustrate
usages, arguments, and responses. In the examples, a "[C]" will be
used to represent the client host and a "[S]" will be used to
represent the server host. Most of the examples do not rely on a
particular server state. In some cases, however, they do assume that
the current selected newsgroup (see the GROUP command (Section
7.1.1)) is invalid; when so, this is indicated at the start of the
example.
3. Basic Operation
Every NNTP session MUST involve the following in this order: Every NNTP session MUST involve the following in this order:
CONNECTION CONNECTION
GREETING GREETING
DISCONNECTION DISCONNECTION
Other steps may occur between the GREETING and DISCONNECTION Other steps may occur between the GREETING and DISCONNECTION step.
step. They are: They are:
CAPABILITIES DISCOVERY CAPABILITIES DISCOVERY
NEWS EXCHANGE NEWS EXCHANGE
CONCLUSION CONCLUSION
NNTP operates over any reliable data stream 8-bit-wide NNTP operates over any reliable data stream 8-bit-wide channel. When
channel. When running over TCP/IP, the official port for the running over TCP/IP, the official port for the NNTP service is 119.
NNTP service is 119. Initially, the server host starts the Initially, the server host starts the NNTP service by listening on a
NNTP service by listening on a TCP port. When a client host TCP port. When a client host wishes to make use of the service, it
wishes to make use of the service, it MUST establish a TCP MUST establish a TCP connection with the server host by connecting to
connection with the server host by connecting to that host on that host on the same port on which the server is listening. This is
the same port on which the server is listening. This is the the CONNECTION step. When the connection is established, the NNTP
CONNECTION step. When the connection is established, the server host MUST send a greeting. This is the GREETING step. The
NNTP server host MUST send a greeting. This is the GREETING client host and server host SHOULD then exchange commands and
step. The client host and server host SHOULD then exchange responses (respectively) until the connection is closed or aborted.
commands and responses (respectively) until the connection is This final step is called the DISCONNECTION step.
closed or aborted. This final step is called the
DISCONNECTION step.
Feather [Page 3] If there is a CONCLUSION step, it MUST immediately precede the
INTERNET DRAFT C. Feather DISCONNECTION step. There MUST be only one CONNECTION, CONCLUSION
Expires: July 31, 2003 Thus plc and DISCONNECTION step for each NNTP session. All other steps MAY be
January 2003 repeated as needed. For example, the GREETING step may be repeated
if the client makes use of the MODE READER command (see Section 5.2
for more on the MODE READER command).
If there is a CONCLUSION step, it MUST immediately precede OUTSTANDING ISSUE
the DISCONNECTION step. There MUST be only one CONNECTION,
CONCLUSION and DISCONNECTION step for each NNTP session. All
other steps MAY be repeated as needed. For example, the
GREETING step may be repeated if the client makes use of the
MODE READER command (See Section 7.2 for more on the MODE
READER command).
The character set for all NNTP commands is UTF-8. Commands in Do we actually need this GREETING / NEWS EXCHANGE / DISCONNECTION
the NNTP MUST consist of an US-ASCII case-insensitive type stuff? I don't see that it buys us anything compared with
keyword, which MAY be followed by one or more arguments. An simply saying that there's the initial greeting and a set of
US-ASCII CRLF pair MUST terminate all commands. Multiple commands.
commands MUST NOT be on the same line. Keywords MUST consist
of printable US-ASCII characters. Unless otherwise noted
elsewhere in this memo, arguments SHOULD consist of printable
US-ASCII characters. Keywords and arguments MUST be each
separated by one or more US-ASCII SPACE or US-ASCII TAB
characters. Keywords MUST be at least three US-ASCII
characters and MUST NOT exceed 12 US-ASCII characters.
Command lines MUST NOT exceed 512 octets, which includes the
terminating US-ASCII CRLF pair. Arguments MUST NOT exceed 497
octets.
Each response MUST start with a three-digit response code The character set for all NNTP commands is UTF-8. Commands in the
that is sufficient to distinguish all responses. Certain NNTP MUST consist of a keyword, which MAY be followed by one or more
valid responses are defined to be multi-line; for all others, arguments. An US-ASCII CRLF pair MUST terminate all commands.
the response is contained in a single line. All multi-line Multiple commands MUST NOT be on the same line. Keywords MUST
responses MUST adhere to the following format: consist of printable US-ASCII characters. Unless otherwise noted
elsewhere in this document, arguments SHOULD consist of printable
US-ASCII characters. Keywords and arguments MUST be each separated
by one or more US-ASCII SPACE or US-ASCII TAB characters. Keywords
MUST be at least three US-ASCII characters and MUST NOT exceed 12
US-ASCII characters. Command lines MUST NOT exceed 512 octets, which
includes the terminating US-ASCII CRLF pair. The arguments MUST NOT
exceed 497 octets.
The response consists of a sequence of one or more "lines", Commands may have variants, using a second keyword immediately after
each being a stream of octets ending with 0x0D 0x0A (US-ASCII the first to indicate which variant is required. The only such
CRLF). Apart from those line endings, the stream MUST NOT commands in this specification are LIST and MODE.
include the octets 0x00, 0x0A, or 0x0D (US-ASCII NUL, LF, and
CR).
The first such line contains the response code as with a Keywords are case-insensitive; the case of keywords for commands MUST
single line response. be ignored by the server. Command and response parameters are case
or language specific only when specified (either in this document or
in RFC 1036 [6]).
If any subsequent line begins with the "termination octet" An NNTP server MUST implement all the commands in this specification
(0x2E or US_ASCII "."), that line MUST be "byte-stuffed" by except for those marked as optional and those in extensions.
Feather [Page 4] Each response MUST start with a three-digit response code that is
INTERNET DRAFT C. Feather sufficient to distinguish all responses. Certain valid responses are
Expires: July 31, 2003 Thus plc defined to be multi-line; for all others, the response is contained
January 2003 in a single line.
pre-pending an additional termination octet (0x2E) to that OUTSTANDING ISSUE
line of the response.
The lines of the response MUST be followed by a terminating Should the initial response line be limited to 512 octets as well?
line consisting of a single termination octet (0x2E or Possible text:
US_ASCII ".")followed by CRLF in the normal way. Thus a
multi-line response is always terminated with the five octets
"CRLF.CRLF" (in US-ASCII).
There is NO limit on the length of a line. The first or only line of the response MUST NOT exceed 512 octets,
which includes the response code and the terminating US-ASCII CRLF
pair.
When interpreting a multi-line response, the "byte stuffing" The text further down about "does not place any limit on the
MUST be undone; i.e. the client MUST ensure that, in any line length" would need equivalent edits.
All multi-line responses MUST adhere to the following format:
1. The response consists of a sequence of one or more "lines", each
being a stream of octets ending with 0x0D 0x0A (US-ASCII CRLF).
Apart from those line endings, the stream MUST NOT include the
octets 0x00, 0x0A, or 0x0D (US-ASCII NUL, LF, and CR).
2. The first such line contains the response code as with a single
line response.
3. If any subsequent line begins with the "termination octet" (0x2E
or US_ASCII "."), that line MUST be "byte-stuffed" by pre-pending
an additional termination octet (0x2E) to that line of the
response.
4. The lines of the response MUST be followed by a terminating line
consisting of a single termination octet (0x2E or US_ASCII ".")
followed by CRLF in the normal way. Thus a multi-line response
is always terminated with the five octets CRLF "." CRLF (in
US-ASCII).
5. When interpreting a multi-line response, the "byte stuffing" MUST
be undone; i.e. the client MUST ensure that, in any line
beginning with the termination octet followed by octets other beginning with the termination octet followed by octets other
than US-ASCII CRLF, that initial termination octet is than US-ASCII CRLF, that initial termination octet is
disregarded. disregarded.
Likewise, the terminating line ".CRLF" (in US-ASCII) MUST NOT 6. Likewise, the terminating line "." CRLF (in US-ASCII) MUST NOT be
be considered part of the multi-line response; i.e. the considered part of the multi-line response; i.e. the client MUST
client MUST ensure that any line beginning with the ensure that any line beginning with the termination octet
termination octet followed immediately by US-ASCII CRLF is followed immediately by US-ASCII CRLF is disregarded; (the first
disregarded; (the first CRLF of the terminating "CRLF.CRLF" CRLF of the terminating CRLF "." CRLF is, of course, part of the
is, of course, part of the last line of the response). last line of the response).
NOTE: Texts using an encoding (such as UTF-16 or UTF-32) that
may contain the NUL octet or the CR or LF octets in contexts
other than the CRLF line ending cannot be reliably conveyed
in the above format.
Note also that, although this memo does not limit the length
of a line in any way, the standards that define the format of
articles may do so.
An NNTP server MAY have an inactivity autologout timer. Such Note that texts using an encoding (such as UTF-16 or UTF-32) that may
a timer SHOULD be of at least three minutes duration, with contain the NUL octet or the CR or LF octets in contexts other than
the exception that there MAY be a shorter limit on how long the CRLF line ending cannot be reliably conveyed in the above format.
the server is willing to wait for the first command from the
client. The receipt of any command from the client during
the timer interval SHOULD suffice to reset the autologout
timer. Similarly, the receipt of any significant amount of
data from the client while in the midst of sending a multi-
line message to the server (such as during a POST or IHAVE
Feather [Page 5] This document does not place any limit on the length of a line.
INTERNET DRAFT C. Feather However, the standards that define the format of articles may do so.
Expires: July 31, 2003 Thus plc
January 2003
command) SHOULD suffice to reset the autologout timer. When An NNTP server MAY have an inactivity autologout timer. Such a timer
the timer expires, the server SHOULD close the TCP connection SHOULD be of at least three minutes duration, with the exception that
without sending any response to the client, including when there MAY be a shorter limit on how long the server is willing to
the client is in the middle of sending a multi-line message wait for the first command from the client. The receipt of any
to the server. command from the client during the timer interval SHOULD suffice to
reset the autologout timer. Similarly, the receipt of any
significant amount of data from the client while in the midst of
sending a multi-line message to the server (such as during a POST or
IHAVE command) SHOULD suffice to reset the autologout timer. When
the timer expires, the server SHOULD close the TCP connection without
sending any response to the client, including when the client is in
the middle of sending a multi-line message to the server.
4.1 Response Codes 3.1 Response Codes
Each response MUST begin with a three-digit status indicator. Each response MUST begin with a three-digit status indicator. These
These are status reports from the server and indicate the are status reports from the server and indicate the response to the
response to the last command received from the client. last command received from the client.
The first digit of the response broadly indicates the The first digit of the response broadly indicates the success,
success, failure, or progress of the previous command. failure, or progress of the previous command.
1xx - Informative message 1xx - Informative message.
2xx - Command ok 2xx - Command completed OK.
3xx - Command ok so far, send the rest of it. 3xx - Command OK so far; send the rest of it.
4xx - Command was correct, but couldn't be performed for 4xx - Command was correct, but couldn't be performed for some
some reason. reason.
5xx - Command unimplemented, or incorrect, or a serious 5xx - Command unimplemented, or incorrect, or a serious program
program error occurred. error occurred.
The next digit in the code indicates the function response The next digit in the code indicates the function response category.
category.
x0x - Connection, setup, and miscellaneous messages x0x - Connection, setup, and miscellaneous messages
x1x - Newsgroup selection x1x - Newsgroup selection
x2x - Article selection x2x - Article selection
x3x - Distribution functions x3x - Distribution functions
x4x - Posting x4x - Posting
x8x - Reserved for authentication and authorization x8x - Reserved for authentication and authorization extensions
extensions
x9x - Reserved for private use (non-standard extensions) x9x - Reserved for private use (non-standard extensions)
Certain responses contain parameters such as numbers and Certain responses contain parameters such as numbers and names in
names in addition to the status indicator. In those cases, addition to the status indicator. In those cases, to simplify
the number and type of such parameters is fixed for each interpretation by the client the number and type of such parameters
response code to simplify interpretation by the client (any is fixed for each response code, as is whether or not the code
extension MUST follow this principle as well). In all other introduces a multi-line response. Any extension MUST follow this
cases, the client MUST only use the status indicator itself principle as well, but note that, for historical reasons, the 211
to determine the nature of the response. The exact response response code is an exception to this. In all other cases, the
client MUST only use the status indicator itself to determine the
nature of the response. The exact response codes that can be
returned by any given command are detailed in the description of that
command.
Feather [Page 6] Parameters MUST be separated from the numeric status indicator and
INTERNET DRAFT C. Feather from each other by a single US-ASCII space. All numeric parameters
Expires: July 31, 2003 Thus plc MUST be in base 10 (decimal) format, and MAY have leading zeros.
January 2003 String parameters MUST contain at least one character and MUST NOT
contain US-ASCII spaces, CR, LF, or tab. The server MAY add any text
after the response code or last parameter as appropriate, and the
client MUST NOT make decisions based on this text. Such text MUST be
separated from the numeric status indicator or the last parameter by
at least one US-ASCII space.
codes that can be returned in response to a given command are The server MUST respond to any command with the appropriate generic
detailed in the description of the keyword that is the first response (given in Section 3.1.1) if it represents the situation.
part of the command. Otherwise, each recognized command MUST return one of the response
codes specifically listed in its description or in an extension. A
server MAY provide extensions to this specification, including new
commands, new variants or features of existing commands, and other
ways of changing the internal state of the server. However, the
server MUST NOT produce any other responses to a client that does not
invoke any of the additional features. (Therefore a client that
restricts itself to this specification will only receive the
responses that are listed.)
Parameters MUST be separated from the numeric status If a client receives an unexpected response, it SHOULD use the first
indicator and from each other by a single US-ASCII space. All digit of the response to determine the result. For example, an
numeric parameters MUST be in base 10 (decimal) format, and unexpected 2xx should be taken as success and an unexpected 4xx or
MAY have leading zeros. String parameters MUST contain at 5xx as failure.
least one character and MUST NOT contain US-ASCII spaces, CR,
LF, or tab). The server MAY add any text after the response
code or last parameter as appropriate, and the client MUST
NOT make decisions based on this text. Such text MUST be
separated from the numeric status indicator or the last
parameter by at least one US-ASCII space.
The server MUST respond to any command with the appropriate Response codes not specified in this document MAY be used for any
generic response (given in section 4.1.1) if it represents installation-specific additional commands also not specified. These
the situation. Otherwise, each recognized command MUST return SHOULD be chosen to fit the pattern of x9x specified above.
one of the response codes specifically listed in its
description or in an extension. A server MAY provide
extensions to this memo, including new commands, new features
of existing commands, and other ways of changing the internal
state of the server. However, the server MUST NOT produce any
other responses to a client that does not invoke any of the
additional features. (Therefore a client that restricts
itself to this memo will only receive the responses that are
listed).
If a client receives an unexpected response, it SHOULD use Neither this document nor any extension registered with IANA (see
the first digit of the response to determine the result. For Section 10) will specify any response codes of the x9x pattern.
example, an unexpected 2xx should be taken as success and an (Implementers of extensions are accordingly cautioned not to use such
unexpected 4xx or 5xx as failure. responses for extensions that may subsequently be submitted for
registration.)
Response codes not specified in this memo MAY be used for any 3.1.1 Generic Response Codes
installation-specific additional commands also not specified.
These SHOULD be chosen to fit the pattern of x9x specified
above.
Neither this memo nor any extension registered with IANA (see The server MUST respond to any command with the appropriate one of
section 12) will specify any response codes of the x9x the following generic responses if it represents the situation.
pattern. (Implementers of extensions are accordingly
Feather [Page 7] If the command is not recognized, or it is an optional command or
INTERNET DRAFT C. Feather extension that is not implemented by the server, the response code
Expires: July 31, 2003 Thus plc 500 MUST be returned.
January 2003
cautioned not to use such responses for extensions that may If there is a syntax error in the arguments of a recognized command,
subsequently be submitted for registration.) including the case where more arguments are provided than the command
specifies, the response code 501 MUST be returned. Note that where a
command has variants depending on a second keyword (e.g. LIST ACTIVE
and LIST NEWSGROUPS), then 501 MUST be used when the requested
variant is not implemented but the base command is.
4.1.1 Generic Response Codes If the client is not authorized to use the specified facility when
the server is in its current state, the response code 502 MUST be
returned. A different command might change the server state and
permit the command if it is retried.
The server MUST respond to any command with the appropriate If the server does not provide an optional feature, then the response
one of the following generic responses if it represents the code 403 MUST be returned if the omission is temporary (e.g. because
situation. a necessary facility is unavailable) and the code 503 if it is
permanent (e.g. because the server does not store the required
information).
If the command is not recognized, or it is an optional OUTSTANDING ISSUE
command or extension that is not implemented by the server,
the response code 500 MUST be returned.
If there is a syntax error in the arguments of a recognized Is anyone aware of a server that implements 403, or is it an
command, the response code 501 MUST be returned. Note that invention of our own? If the latter, do we want to keep it? INN
where a command has variants depending on a keyword (e.g. apparently uses 503 for temporary errors; someone suggested adding
LIST ACTIVE and LIST NEWSGROUPS), then 501 MUST be used when the text:
the requested variant is not implemented but the base command
is.
If the client is not authorized to use the specified facility If the server encounters an unexpected internal error that
when the server is in its current state, the response code prevents it from completing a command, the response code 503
502 MUST be returned. A different command might change the MAY be returned.
server state and permit the command if it is retried.
If the server does not provide an optional feature, then the Some servers return 503 for things like "can't contact a posting
response code 403 MUST be returned if the omission is server" or "can't execute external authenticator".
temporary (e.g. because a necessary facility is unavailable)
and the code 503 if it is permanent (e.g. because the server
does not store the required information).
If the server has to terminate the connection for some OUTSTANDING ISSUE
reason, it MUST give a 400 response code to the next command
and then immediately close the TCP connection. It MAY give a
401 response code to any command to indicate that termination
is imminent (following a 401 response, it MUST NOT close the
TCP connection immediately).
4.2 Streaming The 503 response seems to have three separate meanings:
NNTP is designed to operate over a reliable bi-directional 1. LIST ACTIVE.TIMES etc. use it for "this data isn't stored".
connection such as TCP. Therefore, if a command does not HDR uses it for "this header can't be requested", which is
consistent. Are there other commands that can reasonably
return such a thing? If not, is this kind of 503 really a
generic response?
Feather [Page 8] 2. Temporary errors, the kind that 403 is supposed to represent.
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
depend on the response to the previous one, it should not 3. It's apparently returned by LIST EXTENSIONS, but what does it
matter if it is sent before that response is received. Doing mean in this case? Not "there are no extensions", because
this is called "streaming". However, certain server that's 402. Is this also an invention of our own? Again,
implementations throw away all text received from the client would a different code be better?
following certain commands before sending their response. If
this happens, streaming will be affected because one or more
commands will have been ignored or misinterpreted, and the
client will be matching the wrong responses to each command.
Since there are significant benefits to streaming, but also
circumstances where it is reasonable or common for servers to
behave in the above manner, this memo puts certain
requirements on both clients and servers.
Except where stated otherwise, a client MAY use streaming. If the server has to terminate the connection for some reason, it
That is, it may send a command before receiving the response MUST give a 400 response code to the next command and then
for the previous command. The server MUST allow streaming and immediately close the TCP connection. It MAY give a 401 response
MUST NOT throw away any text received after a command. code to any command to indicate that termination is imminent
Finally, the server MUST process commands in the order they (following a 401 response, it MUST NOT close the TCP connection
are sent. immediately).
If the specific description of a command describes it as "not OUTSTANDING ISSUE
streamable", that command MUST end any stream of commands.
That is, the client MUST NOT send any following command until
receiving the CRLF at the end of the response from the
command. The server MAY ignore any data received after the
command and before the CRLF at the end of the response is
sent to the client.
The initial connection must not be part of a stream; that is, Since the 401 doesn't terminate the session, what about commands
the client MUST NOT send any command until receiving the CRLF that change the status? For example, if GROUP returns 401 what
at the end of the greeting. happens to the current selected newsgroup.
If the client uses blocking system calls to send commands, it With the exception of mandatory commands and the 500 response, the
MUST ensure that the amount of text sent in streaming does client MUST be prepared to receive any of these responses for any
not cause a deadlock between transmission and reception. The command.
amount of text involved will depend on window sizes in the
transmission layer, and is typically 4k bytes for TCP.
5 The WILDMAT format 3.1.1.1 Examples
The WILDMAT format described here is based on the version Example of an unknown command:
first developed by Rich Salz [5], which in turn was derived
Feather [Page 9] [C] MAIL
INTERNET DRAFT C. Feather [S] 500 Unknown command
Expires: July 31, 2003 Thus plc
January 2003
from the format used in the UNIX "find" command to articulate Example of an unsupported extension:
file names. It was developed to provide a uniform mechanism
for matching newsgroup names in the same manner that the UNIX
shell matches filenames.
5.1 Wildmat syntax [C] LIST EXTENSIONS
[S] 202 Extensions supported:
[S] LISTGROUP
[S] .
[C] OVER
[S] 500 Unknown command
Example of an unsupported variant:
[C] MODE POSTER
[S] 501 Unknown MODE option
Example of a syntax error:
[C] ARTICLE a.message.id@no.angle.brackets
[S] 501 Syntax error
Example of an overlong command line:
[C] HEAD 53 54 55
[S] 501 Too many arguments
Example of a bad wildmat:
[C] LIST ACTIVE u[ks].*
[S] 501 Syntax error
Example of an attempt to access a restricted facility:
[C] GROUP secret.group
[S] 502 Permission denied
followed by a successful attempt following authentication:
[C] XSECRET fred flintstone
[S] 290 Password for fred accepted.
[C] GROUP secret.group
[S] 211 5 1 20 secret.group selected
Example of a temporary failure:
[C] GROUP archive.local
[S] 403 Archive server temporarily offline
Example of the server needing to close down immediately:
[C] ARTICLE 123
[S] 400 Power supply failed, running on UPS
[Server closes connection.]
Example of imminent termination of the server:
[C] STAT 123
[S] 401 Pre-payment expired, you have 10 seconds
[C] STAT 123
[S] 423 No such article number in this group
[C] NEXT
[S] 400 Time expired
[Server closes connection.]
3.2 Pipelining
NNTP is designed to operate over a reliable bi-directional connection
such as TCP. Therefore, if a command does not depend on the response
to the previous one, it should not matter if it is sent before that
response is received. Doing this is called "pipelining". However,
certain server implementations throw away all text received from the
client following certain commands before sending their response. If
this happens, pipelining will be affected because one or more
commands will have been ignored or misinterpreted, and the client
will be matching the wrong responses to each command. Since there
are significant benefits to pipelining, but also circumstances where
it is reasonable or common for servers to behave in the above manner,
this document puts certain requirements on both clients and servers.
Except where stated otherwise, a client MAY use pipelining. That is,
it may send a command before receiving the response for the previous
command. The server MUST allow pipelining and MUST NOT throw away
any text received after a command. Irrespective of whether or not
pipelining is used, the server MUST process commands in the order
they are sent.
If the specific description of a command say it "MUST NOT be
pipelined", that command MUST end any pipeline of commands. That is,
the client MUST NOT send any following command until receiving the
CRLF at the end of the response from the command. The server MAY
ignore any data received after the command and before the CRLF at the
end of the response is sent to the client.
The initial connection must not be part of a pipeline; that is, the
client MUST NOT send any command until receiving the CRLF at the end
of the greeting.
If the client uses blocking system calls to send commands, it MUST
ensure that the amount of text sent in pipelining does not cause a
deadlock between transmission and reception. The amount of text
involved will depend on window sizes in the transmission layer, and
is typically 4k octets for TCP.
3.2.1 Examples
Example of correct use of pipelining:
[C] GROUP misc.test
[C] STAT
[C] NEXT
[S] 211 1234 3000234 3002322 misc.test
[S] 223 3000234 <45223423@example.com> retrieved
[S] 223 3000237 <668929@example.org> retrieved
Example of incorrect use of pipelining (the LIST EXTENSIONS command
may not be pipelined):
[C] GROUP misc.test
[C] LIST EXTENSIONS
[C] DATE
[C] NEXT
[S] 211 1234 3000234 3002322 misc.test
[S] 402 server has no extensions
[S] 223 3000237 <668929@example.org> retrieved
The DATE command has been thrown away by the server and so there is
no 111 response to match it.
4. The WILDMAT format
The WILDMAT format described here is based on the version first
developed by Rich Salz [11], which in turn was derived from the
format used in the UNIX "find" command to articulate file names. It
was developed to provide a uniform mechanism for matching patterns in
the same manner that the UNIX shell matches filenames.
4.1 Wildmat syntax
A wildmat is described by the following augmented BNF [5] syntax
(note that this syntax contains ambiguities and special cases
described at the end):
A wildmat is described by the following augmented BNF[6]
syntax (note that this syntax contains ambiguities and
special cases described at the end):
wildmat = wildmat-pattern *("," ["!"] wildmat-pattern) wildmat = wildmat-pattern *("," ["!"] wildmat-pattern)
wildmat-pattern = 1*wildmat-item wildmat-pattern = 1*wildmat-item
wildmat-item = wildmat-exact / wildmat-wild wildmat-item = wildmat-exact / wildmat-wild
wildmat-exact = %x21-29 / %x2B / %x2D-3E / %x40-5A / %x5E- wildmat-exact = %x21-29 / %x2B / %x2D-3E / %x40-5A / %x5E-7E /
7F /UTF-8-non-ascii ; exclude * , ? [ \ ] UTF-8-non-ascii ; exclude * , ? [ \ ]
wildmat-wild = "*" / "?" wildmat-wild = "*" / "?"
UTF-8-non-ascii is defined in section 13. UTF-8-non-ascii is defined in Section 11
This syntax must be interpreted subject to the following
rule:
Where a wildmat-pattern is not immediately preceded by "!",
it shall not begin with a "!".
NOTE: the characters \ , [ and ] are not allowed in wildmats, This syntax must be interpreted subject to the following rule:
while * and ? are always wildcards. This should not be a
problem since these characters cannot occur in newsgroup
names, which is the only current use of wildmats. Backslash
is commonly used to supress the special meaning of characters
and brackets to introduce sets, but there is no existing
standard practice for these in wildmats and so they were
omitted from this memo. A future extension to this memo may
provide semantics for these characters.
5.2 Wildmat semantics Where a wildmat-pattern is not immediately preceded by "!", it shall
not begin with a "!".
A wildmat is tested against a string, and either matches or Note: the characters \ , [ and ] are not allowed in wildmats, while *
does not match. To do this, each constituent wildmat-pattern and ? are always wildcards. This should not be a problem since these
characters cannot occur in newsgroup names, which is the only current
use of wildmats. Backslash is commonly used to supress the special
meaning of characters and brackets to introduce sets, but there is no
existing standard practice for these in wildmats and so they were
omitted from this specification. A future extension to this
specification may provide semantics for these characters.
Feather [Page 10] 4.2 Wildmat semantics
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
is matched against the string and the rightmost pattern that A wildmat is tested against a string, and either matches or does not
matches is identified. If that wildmat-pattern is not match. To do this, each constituent wildmat-pattern is matched
preceded with "!", the whole wildmat matches. If it is against the string and the rightmost pattern that matches is
preceded by "!", or if no wildmat-pattern matches, the whole identified. If that wildmat-pattern is not preceded with "!", the
wildmat does not match. whole wildmat matches. If it is preceded by "!", or if no
wildmat-pattern matches, the whole wildmat does not match.
For example, consider the wildmat "a*,!*b,*c*": For example, consider the wildmat "a*,!*b,*c*":
the string "aaa" matches because the rightmost match is the string "aaa" matches because the rightmost match is with "a*"
with "a*"
the string "abb" does not match because the rightmost
match is with "*b"
the string "ccb" matches because the rightmost match is
with "*c*"
the string "xxx" does not match because no wildmat-pattern
matches
A wildmat-pattern matches a string if the string can be the string "abb" does not match because the rightmost match is
broken into components, each of which matches the with "*b"
corresponding wildmat-item in the pattern; the matches must
be in the same order, and the whole string must be used in
the match. The pattern is "anchored"; that is, the first and
last characters in the string must match the first and last
item respectively (unless that item is an asterisk matching
zero characters).
A wildmat-exact matches the same character (which may be more the string "ccb" matches because the rightmost match is with "*c*"
than one octet in UTF-8).
"?" matches exactly one character (which may be more than one the string "xxx" does not match because no wildmat-pattern matches
octet).
"*" matches zero or more characters. It can match an empty A wildmat-pattern matches a string if the string can be broken into
string, but it cannot match a subsequence of a UTF-8 sequence components, each of which matches the corresponding wildmat-item in
that is not aligned to the character boundaries. the pattern; the matches must be in the same order, and the whole
string must be used in the match. The pattern is "anchored"; that
is, the first and last characters in the string must match the first
and last item respectively (unless that item is an asterisk matching
zero characters).
5.3 Extensions A wildmat-exact matches the same character (which may be more than
one octet in UTF-8).
An NNTP server or extension MAY extend the syntax or "?" matches exactly one character (which may be more than one octet).
semantics of wildmats provided that all wildmats that meet
the requirements of section 5.1 have the meaning ascribed to
Feather [Page 11] "*" matches zero or more characters. It can match an empty string,
INTERNET DRAFT C. Feather but it cannot match a subsequence of a UTF-8 sequence that is not
Expires: July 31, 2003 Thus plc aligned to the character boundaries.
January 2003
them by section 5.2. Future editions of this memo may also 4.3 Extensions
extend wildmats.
5.4 Examples An NNTP server or extension MAY extend the syntax or semantics of
wildmats provided that all wildmats that meet the requirements of
Section 4.1 have the meaning ascribed to them by Section 4.2. Future
editions of this document may also extend wildmats.
In these examples, $ and @ are used to represent the two 4.4 Examples
octets 0xC2 and 0xA3 respectively; $@ is thus the UTF-8
encoding for the pound sterling symbol, shown as # in the In these examples, $ and @ are used to represent the two octets 0xC2
descriptions. and 0xA3 respectively; $@ is thus the UTF-8 encoding for the pound
sterling symbol, shown as # in the descriptions.
Wildmat Description of strings that match Wildmat Description of strings that match
abc the one string "abc" abc the one string "abc"
abc,def the two strings "abc" and "def" abc,def the two strings "abc" and "def"
$@ the one character string "#" $@ the one character string "#"
a* any string that begins with "a" a* any string that begins with "a"
a*b any string that begins with "a" and ends with "b" a*b any string that begins with "a" and ends with "b"
a*,*b any string that begins with "a" or ends with "b" a*,*b any string that begins with "a" or ends with "b"
a*,!*b any string that begins with "a" and does not end with a*,!*b any string that begins with "a" and does not end with
"b" "b"
any string that begins with "a" and does not end with a*,!*b,c* any string that begins with "a" and does not end with
a*,!*b,c* "b", and any string that begins with "c" no matter "b", and any string that begins with "c" no matter
what it ends with what it ends with
any string that begins with "a" or "c" and does not a*,c*,!*b any string that begins with "a" or "c" and does not
a*,c*,!*b end with "b" end with "b"
?a* any string with "a" as its second character ?a* any string with "a" as its second character
??a* any string with "a" as its third character ??a* any string with "a" as its third character
*a? any string with "a" as its penultimate character *a? any string with "a" as its penultimate character
*a?? any string with "a" as its antepenultimate character *a?? any string with "a" as its antepenultimate character
6 Format for Keyword Descriptions 5. The GREETING Step
On the following pages are descriptions of each keyword
recognized by the NNTP server and the responses that will be
returned by those commands. These keywords are grouped by the
functional step in which they are used.
Each keyword is shown in upper case for clarity, although the
NNTP server ignores case in the interpretation of commands.
Parameters are shown as follows:
Feather [Page 12]
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
UPPERCASE indicates literal text to be included in the
command;
lowercase indicates a token described elsewhere;
[brackets] indicate that the parameter is optional;
ellipsis... indicates that the parameter may be repeated
any number of times (it must occur at least
once);
vertical|bar indicates a choice of two mutually exclusive
parameters (exactly one must be provided).
Parameters are case or language specific only when specified
(either in this memo or in RFC 1036[7]).
The name "wildmat" for a parameter indicates that it is a 5.1 Initial Connection
wildmat format pattern as defined in section 5. If the
parameter does not meet the requirements of that section (for
example, if it does not fit the grammar of 5.1) the NNTP
server MAY place some interpretation on it (not specified by
this memo) or otherwise MUST generate a 501 response.
7 The GREETING Step 5.1.1 Usage
7.1 Initial Connection Responses
200 Service available, posting allowed
201 Service available, posting prohibited
400 Service temporarily unavailable [1]
502 Service permanently unavailable [1]
There is no keyword presented by the client upon initial These are the only valid response codes for the initial greeting;
connection to the server. The server MUST present an the server MUST not return any other generic response code.
appropriate response code as a greeting to the client. This
response informs the client about what steps the client
should take to reach the news exchange step.
If the server will accept further commands from the client [1] Following a 400 or 502 response the server MUST immediately close
including POST, the server MUST present a 200 greeting code. the connection.
If the server will accept further commands from the client,
but it is not authorized to post articles using the POST
command, the server MUST present a 201 greeting code.
Otherwise the server MUST present a 400 or 502 greeting code 5.1.2 Description
and then immediately close the connection. 502 MUST be used
if the client is not permitted under any circumstances to
interact with the server and 400 otherwise.
Feather [Page 13] There is no command presented by the client upon initial connection
INTERNET DRAFT C. Feather to the server. The server MUST present an appropriate response code
Expires: July 31, 2003 Thus plc as a greeting to the client. This response informs the client about
January 2003 what steps the client should take to reach the news exchange step.
7.1.1 Responses If the server will accept further commands from the client including
POST, the server MUST present a 200 greeting code. If the server
will accept further commands from the client, but it is not
authorized to post articles using the POST command, the server MUST
present a 201 greeting code.
200 Service available, posting allowed Otherwise the server MUST present a 400 or 502 greeting code and then
201 Service available, posting prohibited immediately close the connection. 502 MUST be used if the client is
400 Service temporarily unavailable not permitted under any circumstances to interact with the server and
502 Service unavailable 400 otherwise.
Following a 400 or 502 response the server MUST immediately 5.1.3 Examples
close the connection.
7.1.2 Initial Connection Example Example of a normal connection from an authorized client which then
jumps directly to the conclusion step (see Section 9):
Example of a normal connection from an authorized client
[Initial TCP connection setup completed.] [Initial TCP connection setup completed.]
[C] Initial TCP connection completed
[S] 200 NNTP Service Ready, posting permitted [S] 200 NNTP Service Ready, posting permitted
Client can send commands at this point. In this example, the
client jumps directly to the conclusion step (See section
10).
[C] QUIT [C] QUIT
[S] 205 NNTP Service exits normally [S] 205 NNTP Service exits normally
[Server closes connection.] [Server closes connection.]
Example of a normal connection from an unauthorized client Example of a normal connection from an authorized client that is not
[C] Initial TCP connection completed permitted to post; it also jumps directly to the conclusion step:
[S] 502 NNTP Service Unavailable
[Server closes connection.]
Example of a normal connection from an authorized client that
is not permitted to post
[Initial TCP connection setup completed.] [Initial TCP connection setup completed.]
[S] 201 NNTP Service Ready, posting prohibited [S] 201 NNTP Service Ready, posting prohibited
Client can send commands at this point. In this example, the
client jumps directly to the conclusion step (See section
10).
[C] QUIT [C] QUIT
[S] 205 NNTP Service exits normally [S] 205 NNTP Service exits normally
[Server closes connection.] [Server closes connection.]
Example of a connection from any client where the server is
unable to provide service Example of a normal connection from an unauthorized client:
[Initial TCP connection setup completed.]
[S] 502 NNTP Service permanently unavailable
[Server closes connection.]
Example of a connection from a client where the server is unable to
provide service:
[Initial TCP connection setup completed.] [Initial TCP connection setup completed.]
[S] 400 NNTP Service temporarily unavailable [S] 400 NNTP Service temporarily unavailable
[Server closes connection.] [Server closes connection.]
Feather [Page 14] 5.2 MODE READER
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
7.2 MODE READER 5.2.1 Usage
This command MUST NOT be pipelined.
Syntax
MODE READER MODE READER
MODE READER SHOULD be sent by any client that intends to use
any command other than IHAVE, HEAD, STAT, LIST, LIST
EXTENSIONS, or commands advertised by the server as available
via LIST EXTENSIONS. This command is not streamable.
Servers MAY require that this command be issued before any Responses
other commands are sent and MAY reject any other commands 200 Posting allowed
until after a MODE READER command has been sent. 201 Posting prohibited
400 Service temporarily unavailable [1]
502 Service permanently unavailable [1]
The server MUST present a response using the same codes as [1] Following a 400 or 502 response the server MUST immediately close
the initial greeting (as described in section 7.1) to the connection.
indicate its ability to provide reading service to the
client.
Clients SHOULD wait for a response to MODE READER after 5.2.2 Description
sending this command and SHOULD NOT send any additional
commands until that response has been received from the
server.
Once MODE READER is sent, IHAVE (and any extensions intended MODE READER SHOULD be sent by any client that intends to use any
for peer-to-peer article transfer) MAY no longer be command other than IHAVE, HEAD, STAT, LIST ACTIVE, LIST EXTENSIONS,
permitted, even if it were permitted before the MODE READER or commands advertised by the server as available via LIST
command. The results of LIST EXTENSIONS MAY be different EXTENSIONS.
following a MODE READER command than prior to the issuing of
that command.
Servers are encouraged to not require this command even Servers MAY require that this command be issued before any other
though clients SHOULD send it when appropriate. It is present commands are sent and MAY reject any other commands until after a
to support some news architectures that switch between modes MODE READER command has been sent.
based on whether a given connection is a peer-to-peer
connection with another server or a news reading client.
7.2.1 Responses The server MUST return a response using the same codes as the initial
200 Posting permitted greeting (as described in Section 5.1.1) to indicate its ability to
201 Posting prohibited provide reading service to the client. Note that the response need
400 Service temporarily unavailable not be the same as the one presented during the initial greeting.
502 Service unavailable
Feather [Page 15] Once MODE READER is sent, IHAVE (and any extensions intended for
INTERNET DRAFT C. Feather peer-to-peer article transfer) MAY no longer be permitted, even if it
Expires: July 31, 2003 Thus plc were permitted before the MODE READER command. The results of LIST
January 2003 EXTENSIONS MAY be different following a MODE READER command than
prior to the issuing of that command.
Following a 400 or 502 response the server MUST immediately Servers are encouraged to not require this command even though
close the connection. clients SHOULD send it when appropriate. It is present to support
some news architectures that switch between modes based on whether a
given connection is a peer-to-peer connection with another server or
a news reading client.
Note that the response need not be the same as the one 5.2.3 Examples
presented during the initial greeting.
7.2.2 MODE READER Examples Example of use of the MODE READER command by an authorized client
which then jumps directly to the conclusion step (see Section 9):
Example of use of the MODE READER command by an authorized
client
[C] MODE READER [C] MODE READER
[S] 200 NNTP Service Ready, posting permitted [S] 200 NNTP Service Ready, posting permitted
Client can send commands at this point. In this example, the
client jumps directly to the conclusion step (See section
10).
[C] QUIT [C] QUIT
[S] 205 NNTP Service exits normally [S] 205 NNTP Service exits normally
[Server closes connection.] [Server closes connection.]
Example of use of MODE READER by a client not authorized to
receive service from the server as a news reader Example of use of the MODE READER command by an authorized client
[C] MODE READER that is not permitted to post; it also jumps directly to the
[S] 502 Service Unavailable conclusion step:
[Server closes connection.]
Example of a normal connection from an authorized client that
is not permitted to post
[C] MODE READER [C] MODE READER
[S] 201 NNTP Service Ready, posting prohibited [S] 201 NNTP Service Ready, posting prohibited
Client can send commands at this point. In this example, the
client jumps directly to the conclusion step (See section
10).
[C] QUIT [C] QUIT
[S] 205 NNTP Service exits normally [S] 205 NNTP Service exits normally
[Server closes connection.] [Server closes connection.]
Example of a connection from any client where the server is
unable to provide news reader service Example of use of MODE READER by a client not authorized to receive
service from the server as a news reader:
[C] MODE READER [C] MODE READER
[S] 502 NNTP Service permanently unavailable
[Server closes connection.]
Example of a connection from any client where the server is unable to
provide news reader service:
[C] QUIT
[S] 400 NNTP Service temporarily unavailable [S] 400 NNTP Service temporarily unavailable
[Server closes connection.] [Server closes connection.]
8 The CAPABILITIES DISCOVERY Step 6. The CAPABILITIES DISCOVERY step
Feather [Page 16] To discover what extensions are available, an NNTP client can query
INTERNET DRAFT C. Feather the server with the LIST EXTENSIONS command. If a particular
Expires: July 31, 2003 Thus plc extension is unavailable, the client can attempt to work around it or
January 2003 it may wish to terminate the session.
To discover what extensions are available, an NNTP client can See Section 10 for further discussion of extensions.
query the server with the LIST EXTENSIONS command.
If a particular extension is unavailable, the client can
attempt to work around it or it may wish to terminate the
session.
See section 12 for further discussion of extensions. 6.1 LIST EXTENSIONS
8.1 LIST EXTENSIONS 6.1.1 Usage
The LIST EXTENSIONS command allows a client to determine This command is optional.
which extensions are supported by the server. This command
MUST be implemented by any server that implements any
extensions defined in this memo. This command is not
streamable.
To discover what extensions are available, an NNTP client This command MUST NOT be pipelined.
SHOULD query the server early in the session for extensions
information by issuing the LIST EXTENSIONS command. This
command MAY be issued at anytime during a session. It is not
required that the client issues this command before
attempting to make use of any extension. The response
generated by this command MAY change during a session because
of other state information. However, an NNTP client MUST NOT
cache (for use in another session) any information returned
if the LIST EXTENSIONS command succeeds. That is, an NNTP
client is only able to get the current and correct
information concerning available extensions during a session
by issuing a LIST EXTENSIONS command during that session and
processing that response.
A successful response starts with a 202 code and is followed Syntax
by a list of extensions, one per line. Each line MUST begin LIST EXTENSIONS
with an extension-label and optionally one or more parameters
(separated by single spaces). The extension-label and the
meaning of the parameters are specified as part of the
definition of the extension. The extension-label MUST be in
uppercase.
The server MUST NOT list the same extension twice in the Responses
response, and MUST list all supported extensions. The order 202 Extension list follows (multiline)
402 Server has no extensions
503 Extension information not available
Feather [Page 17] 6.1.2 Description
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
in which the extensions are listed is not significant. The The LIST EXTENSIONS command allows a client to determine which
server need not even consistently return the same order. extensions are supported by the server. This command MUST be
If the server does not support any extensions, it SHOULD implemented by any server that implements any extensions defined in
return a 402 failure response but MAY return an empty list this document.
instead.
8.1.1 Responses To discover what extensions are available, an NNTP client SHOULD
query the server early in the session for extensions information by
issuing the LIST EXTENSIONS command. This command MAY be issued at
anytime during a session. It is not required that the client issues
this command before attempting to make use of any extension. The
response generated by this command MAY change during a session
because of other state information. However, an NNTP client MUST NOT
cache (for use in another session) any information returned if the
LIST EXTENSIONS command succeeds. That is, an NNTP client is only
able to get the current and correct information concerning available
extensions during a session by issuing a LIST EXTENSIONS command
during that session and processing that response.
202 Extension list follows (multi-line response) The list of extensions is returned as a multi-line response following
400 Service temporarily unavailable the 202 response code. Each extension is listed on a separate line;
402 Server has no extensions the line MUST begin with an extension-label and optionally one or
500 Unknown Command more parameters (separated by single spaces). The extension-label
501 Syntax Error and the meaning of the parameters are specified as part of the
502 Program error, function not performed definition of the extension. The extension-label MUST be in
uppercase.
Following a 502 response an extension might still be The server MUST NOT list the same extension twice in the response,
available, and the client MAY attempt to use it and MUST list all supported extensions. The order in which the
The LIST EXTENSIONS command is optional, and a server MAY extensions are listed is not significant. The server need not even
issue a 500 (unknown command) or 501 (syntax error) response consistently return the same order. If the server does not support
to it. any extensions, a 402 response SHOULD be returned, but it MAY instead
8.1.1.1 LIST EXTENSIONS Examples return an empty list.
Following a 503 response an extension might still be available, and
the client MAY attempt to use it.
6.1.3 Examples
Example of a successful response: Example of a successful response:
[C] LIST EXTENSIONS [C] LIST EXTENSIONS
[S] 202 Extensions supported: [S] 202 Extensions supported:
[S] OVER [S] OVER
[S] HDR [S] HDR
[S] LISTGROUP [S] LISTGROUP
[S] . [S] .
The particular extensions shown here are simply examples of
what might be defined in other places, and no particular The particular extensions shown here are simply examples of what
meaning should be attributed to them. might be defined in other places, and no particular meaning should be
Example where no extensions are available, using preferred attributed to them.
format:
Example where no extensions are available, using preferred format:
[C] LIST EXTENSIONS [C] LIST EXTENSIONS
[S] 402 Server has no extensions [S] 402 Server has no extensions
Example where no extensions are available, using an empty
list: Example where no extensions are available, using an empty list:
[C] LIST EXTENSIONS [C] LIST EXTENSIONS
[S] 202 Extensions supported: [S] 202 Extensions supported:
[S] . [S] .
Feather [Page 18] 7. Article posting and retrieval
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
9 The NEWS EXCHANGE Step
During this step, two basic types of transactions occur:
* article retrieval from the server
* article posting to the server
9.1 Article Retrieval
News reading clients have available a variety of mechanisms News reading clients have available a variety of mechanisms to
to retrieve articles via NNTP. The news articles are stored retrieve articles via NNTP. The news articles are stored and indexed
and indexed using three types of keys. One key is the message using three types of keys. One key is the message-id of an article.
id of an article. According to RFC 1036, this identifier According to RFC 1036, this identifier should be globally unique.
should be globally unique. Another key is composed of the Another key is composed of the newsgroup name and the article number
newsgroup name and the article number within that newsgroup. within that newsgroup. That key MUST be unique to a particular
That key MUST be unique to a particular server (there will be server (there will be only one article with that number within a
only one article with that number within a particular particular newsgroup), but is not required to be globally unique.
newsgroup), but is not required to be globally unique.
Additionally, because the same article can be cross-posted to Additionally, because the same article can be cross-posted to
multiple newsgroups, there may be multiple keys that point to multiple newsgroups, there may be multiple keys that point to the
the same article on the same server. The final key is the same article on the same server. The final key is the arrival
arrival timestamp, giving the time that the article arrived timestamp, giving the time that the article arrived at the server.
at the server.
The server MUST ensure that article numbers are issued in The server MUST ensure that article numbers are issued in order of
order of arrival timestamp; that is, articles arriving later arrival timestamp; that is, articles arriving later MUST have higher
MUST have higher numbers than those that arrive earlier. The numbers than those that arrive earlier. The server SHOULD allocate
server SHOULD allocate the next sequential unused number to the next sequential unused number to each new article.
each new article.
Article numbers MUST lie between 1 and 4,294,967,295 Article numbers MUST lie between 1 and 4,294,967,295 inclusive. The
inclusive. The client and server SHOULD NOT use leading client and server SHOULD NOT use leading zeroes in specifying article
zeroes in specifying article numbers, and MUST NOT use more numbers, and MUST NOT use more than 16 digits. In some situations,
than 16 digits. In some situations, the value zero replaces the value zero replaces an article number to show some special
an article number to show some special situation. situation.
Message ids are defined in RFC 2822 with the following Message-ids are as defined in RFC 2822 [7] with the following
modifications: modifications:
* A message id MUST NOT contain a US-ASCII space within any
o A message-id MUST NOT contain a US-ASCII space within any
quoted-pair. quoted-pair.
* A message id MUST NOT be longer than 250 octets.
Feather [Page 19] o A message-id MUST NOT be longer than 250 octets.
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
* RFC 2822 obsolete syntax for message ids are not supported o RFC 2822 obsolete syntax for message-ids is not supported by the
by the protocol specified in this memo. protocol specified in this document.
9.1.1 Article Retrieval by Newsgroup Name and Article Number 7.1 Group and article selection
The following commands are used to set the current newsgroup The following commands are used to set the "current selected
name and the "current article pointer" which is used by other newsgroup" and the "current article number", which are used by
commands for article retrieval. At the start of an NNTP various commands. At the start of an NNTP session, both of these
session, both of these values are undefined. values are set to the special value "invalid".
9.1.1.1 GROUP
7.1.1 GROUP
7.1.1.1 Usage
Syntax
GROUP ggg GROUP ggg
Responses
211 n l h ggg Group successfully selected
411 No such newsgroup
Parameters
ggg = name of newsgroup
n = estimated number of articles in the group
l = reported low water mark
h = reported high water mark
7.1.1.2 Description
The required parameter ggg is the name of the newsgroup to be The required parameter ggg is the name of the newsgroup to be
selected (e.g. "news.software.b"). A list of valid newsgroups selected (e.g. "news.software.b"). A list of valid newsgroups may
may be obtained by using the LIST keyword. See section 9.4 be obtained by using the LIST ACTIVE command (see Section 8.6.1).
for more information on the LIST keyword.
The successful selection response will return the article The successful selection response will return the article numbers of
numbers of the first and last articles in the group at the the first and last articles in the group at the moment of selection
moment of selection (these numbers are referred to as the (these numbers are referred to as the "reported low water mark" and
"reported low water mark" and the "reported high water the "reported high water mark"), and an estimate of the number of
mark"), and an estimate of the number of articles on file in articles on file in the group.
the group.
If the group is not empty, the estimate MUST be at least the If the group is not empty, the estimate MUST be at least the actual
actual number of articles available, and MUST be no greater number of articles available, and MUST be no greater than one more
than one more than the difference between the reported low than the difference between the reported low and high water marks.
and high water marks. (Some implementations will actually (Some implementations will actually count the number of articles on
count the number of articles on file. Others will just file. Others will just subtract the low water mark from the high
subtract the low water mark from the high water mark and add water mark and add one to get an estimate.)
one to get an estimate.)
If the group is empty, one of the following three situations If the group is empty, one of the following three situations will
will occur. Clients MUST accept all three cases; servers MUST occur. Clients MUST accept all three cases; servers MUST NOT
NOT represent an empty group in any other way. represent an empty group in any other way.
The high water mark will be one less than the low water mark, o The high water mark will be one less than the low water mark, and
and the estimated article count will be zero. Servers SHOULD the estimated article count will be zero. Servers SHOULD use this
use this method to show an empty group. This is the only time method to show an empty group. This is the only time that the
that the high water mark can be less than the low water mark. high water mark can be less than the low water mark.
All three numbers will be zero.
Feather [Page 20] o All three numbers will be zero.
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
The high water mark is greater than or equal to the low water o The high water mark is greater than or equal to the low water
mark; the estimated article count might be zero or non-zero; mark. The estimated article count might be zero or non-zero; if
if non-zero, the same requirements apply as for a non-empty non-zero, the same requirements apply as for a non-empty group.
group.
The set of articles in a group may change after the GROUP The set of articles in a group may change after the GROUP command is
command is carried out. That is: carried out. That is:
* articles may be removed from the group
* articles may be reinstated in the group with the same
article number, but those articles MUST have numbers no
less than the reported low water mark (note that this is a
reinstatement of the previous article, not a new article
reusing the number)
* new articles may be added with article numbers greater
than the reported high water mark (if an article that was
the one with the highest number has been removed, the next
new article will not have the number one greater than the
reported high water mark)
Except when the group is empty and all three numbers are o articles may be removed from the group
zero, whenever a subsequent GROUP command for the same
newsgroup is issued, either by the same client or a different
client, the reported low water mark in the response MUST be
no less than that in any previous response for that newsgroup
sent to any client. The client may make use of the low water
mark to remove all remembered information about articles with
lower numbers, as these will never recur. This includes the
situation when the high water mark is one less than the low
water mark.
No similar assumption can be made about the high water mark, o articles may be reinstated in the group with the same article
as this can decrease if an article is removed, and then number, but those articles MUST have numbers no less than the
increase again if it is reinstated or if new articles arrive. reported low water mark (note that this is a reinstatement of the
When a valid group is selected by means of this command, the previous article, not a new article reusing the number)
internally maintained "current article pointer" MUST be set
to the first article in the group and the name of the current
newsgroup MUST be set to the selected newsgroup name. If an
invalid group is specified, the previously selected group, if
any, and article MUST remain selected. If an empty newsgroup
is selected, the "current article pointer" is in an
indeterminate state and MUST NOT be used.
Feather [Page 21] o new articles may be added with article numbers greater than the
INTERNET DRAFT C. Feather reported high water mark (if an article that was the one with the
Expires: July 31, 2003 Thus plc highest number has been removed, the next new article will not
January 2003 have the number one greater than the reported high water mark)
The GROUP keyword (or the LISTGROUP keyword, if implemented) Except when the group is empty and all three numbers are zero,
MUST be used by a client and a successful response received whenever a subsequent GROUP command for the same newsgroup is issued,
before the any other command is used that depends on having either by the same client or a different client, the reported low
the "current article pointer" be valid. water mark in the response MUST be no less than that in any previous
response for that newsgroup sent to any client. The client may make
use of the low water mark to remove all remembered information about
articles with lower numbers, as these will never recur. This
includes the situation when the high water mark is one less than the
low water mark.
If the group specified is not available on the server, it No similar assumption can be made about the high water mark, as this
MUST return a 411 error code. can decrease if an article is removed, and then increase again if it
is reinstated or if new articles arrive. When a valid group is
selected by means of this command, the current selected newsgroup
MUST be set to that group and the current article number MUST be set
to the first article in the group. If an empty newsgroup is
selected, the current article pointer is made invalid. If an invalid
group is specified, the current selected newsgroup and current
article number MUST NOT be changed.
9.1.1.1.1 Responses The GROUP command (or the LISTGROUP command, if implemented) MUST be
used by a client and a successful response received before the any
other command is used that depends on the value of the current
selected newsgroup or current article number.
211 n l h ggg Group successfully selected (n = If the group specified is not available on the server, a 411 response
estimated number of articles in the MUST be returned.
group, l = low water mark, h = high
water mark, ggg = name of the group
411 No such newsgroup
9.1.1.1.2 GROUP Examples 7.1.1.3 Examples
Example for a group known to the server:
Example for a group known to the server
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
Example for a group unknown to the server Example for a group unknown to the server:
[C] GROUP example.is.sob.bradner.or.barber [C] GROUP example.is.sob.bradner.or.barber
[S] 411 example.is.sob.bradner.or.barber is unknown [S] 411 example.is.sob.bradner.or.barber is unknown
9.1.1.2 LAST
LAST Example of an empty group using the preferred response:
If the current newsgroup is valid, the internally maintained
"current article pointer" MUST be set to the previous article
in the current newsgroup. If already positioned at the first
article of the newsgroup, an error message MUST be returned
and the current article MUST remain selected.
There MAY be no previous article in the group, although the [C] GROUP example.currently.empty.newsgroup
current article number is not the reported low water mark. [S] 211 0 4000 3999 example.currently.empty.newsgroup
There MUST NOT be a previous article when the current article
number is the reported low water mark.
Feather [Page 22] Example of an empty group using an alternative response:
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
Because articles can be removed and added, the results of [C] GROUP example.currently.empty.newsgroup
multiple LAST and NEXT commands MAY not be consistent over [S] 211 0 0 0 example.currently.empty.newsgroup
the life of a particular NNTP session.
If successful, a response indicating the current article Example of an empty group using a different alternative response:
number and a message-id string MUST be returned. No article
text is sent in response to this command.
9.1.1.2.1 Responses
223 n a Article found (n = number, a = message-id) [C] GROUP example.currently.empty.newsgroup
[S] 211 0 4000 4321 example.currently.empty.newsgroup
7.1.2 LAST
7.1.2.1 Usage
Syntax
LAST
Responses
223 n message-id Article found
412 No newsgroup selected 412 No newsgroup selected
420 Current article pointer is invalid 420 Current article number is invalid
422 No previous article in this group 422 No previous article in this group
9.1.1.2.2 LAST Examples Parameters
n = article number
message-id = article message-id
7.1.2.2 Description
If the current selected newsgroup is valid, the current article
number MUST be set to the previous article in that newsgroup (that
is, the highest existing article number less than the current article
number). If successful, a response indicating the new current
article number and the message-id of that article MUST be returned.
No article text is sent in response to this command.
There MAY be no previous article in the group, although the current
article number is not the reported low water mark. There MUST NOT be
a previous article when the current article number is the reported
low water mark.
Because articles can be removed and added, the results of multiple
LAST and NEXT commands MAY not be consistent over the life of a
particular NNTP session.
If the current article number is already the first article of the
newsgroup, a 422 response MUST be returned. If the current article
number is invalid, a 420 response MUST be returned. If the current
selected newsgroup is invalid, a 412 response MUST be returned. In
all three cases the current selected newsgroup and current article
number MUST NOT be altered.
7.1.2.3 Examples
Example of a successful article retrieval using LAST:
Example of a successful article retrieval using LAST
[S] 200 NNTP Service Ready
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
[C] NEXT [C] NEXT
[S] 223 3000237 <668929@example.org> retrieved [S] 223 3000237 <668929@example.org> retrieved
[C] LAST [C] LAST
[S] 223 3000234 <45223423@example.com> retrieved [S] 223 3000234 <45223423@example.com> retrieved
Example of an attempt to retrieve an article without having
selected a group (via the GROUP command) first Example of an attempt to retrieve an article without having selected
[S] 200 NNTP Service ready a group (via the GROUP command) first:
[Assumes current selected newsgroup is invalid.]
[C] LAST [C] LAST
[S] 412 no newsgroup selected [S] 412 no newsgroup selected
Example of an attempt to retrieve an article using the LAST
command when the current article pointer is pointing at the Example of an attempt to retrieve an article using the LAST command
first article in the group when the current article number is that of the first article in the
[S] 200 NNTP Service Ready group:
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
[C] LAST [C] LAST
[S] 422 No previous article to retrieve [S] 422 No previous article to retrieve
Example of an attempt to retrieve an article using the LAST
command when the current group selected is empty
Feather [Page 23] Example of an attempt to retrieve an article using the LAST command
INTERNET DRAFT C. Feather when the current selected newsgroup is empty:
Expires: July 31, 2003 Thus plc
January 2003
[S] 200 NNTP Service Ready
[C] GROUP example.empty.newsgroup [C] GROUP example.empty.newsgroup
[S] 211 0 0 0 example.empty.newsgroup [S] 211 0 0 0 example.empty.newsgroup
[C] LAST [C] LAST
[S] 420 No current article selected [S] 420 No current article selected
9.1.1.3 NEXT
NEXT 7.1.3 NEXT
If the current newsgroup is valid, the internally maintained
"current article pointer" MUST be advanced to the next
article in the current newsgroup. If no more articles remain
in the current group, an error message MUST be returned and
the current article MUST remain selected.
If successful, a response indicating the current article 7.1.3.1 Usage
number and the message-id string MUST be returned. No
article text is sent in response to this command.
9.1.1.3.1 Responses Syntax
NEXT
223 n a Article found (n = number, a = message-id) Responses
223 n message-id Article found
412 No newsgroup selected 412 No newsgroup selected
420 Current article pointer is invalid 420 Current article number is invalid
421 No next article in this group 421 No next article in this group
9.1.1.3.2 NEXT Examples Parameters
n = article number
message-id = article message-id
7.1.3.2 Description
If the current selected newsgroup is valid, the current article
number MUST be set to the next article in that newsgroup (that is,
the lowest existing article number greater than the current article
number). If successful, a response indicating the new current
article number and the message-id of that article MUST be returned.
No article text is sent in response to this command.
If the current article number is already the last article of the
newsgroup, a 421 response MUST be returned. In all other aspects
(apart, of course, from the lack of 422 response) this command is
identical to the LAST command (Section 7.1.2).
7.1.3.3 Examples
Example of a successful article retrieval using NEXT:
Example of a successful article retrieval using NEXT
[S] 200 NNTP Service Ready
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
[C] NEXT [C] NEXT
[S] 223 3000237 <668929@example.org> retrieved [S] 223 3000237 <668929@example.org> retrieved
Example of an attempt to retrieve an article without having
selected a group (via the GROUP command) first Example of an attempt to retrieve an article without having selected
[S] 200 NNTP Service ready a group (via the GROUP command) first:
[Assumes current selected newsgroup is invalid.]
[C] NEXT [C] NEXT
[S] 412 no newsgroup selected [S] 412 no newsgroup selected
Feather [Page 24] Example of an attempt to retrieve an article using the NEXT command
INTERNET DRAFT C. Feather when the current article number is that of the last article in the
Expires: July 31, 2003 Thus plc group:
January 2003
Example of an attempt to retrieve an article using the NEXT
command when the current article pointer is pointing at the
last article in the group
[S] 200 NNTP Service Ready
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
[C] ARTICLE 3002322 [C] STAT 3002322
[S] 220 3002322 <411@example.net> retrieved [S] 223 3002322 <411@example.net> retrieved
[S] Path: pathost!demo!whitehouse!not-for-mail
[S] From: ˘Demo User÷ <nobody@example.net>
[S] Newsgroups: misc.test
[S] Subject: I am just a test article
[S] Date: 6 Oct 1998 04:38:40 -0500
[S] Organization: An Example Net, Uncertain, Texas
[S] Message-ID: <411@example.net>
[S]
[S] This is just a test article.
[S] .
[C] NEXT [C] NEXT
[S] 421 No next article to retrieve [S] 421 No next article to retrieve
Example of an attempt to retrieve an article using the NEXT
command when the current group selected is empty Example of an attempt to retrieve an article using the NEXT command
[S] 200 NNTP Service Ready when the current selected newsgroup is empty:
[C] GROUP example.empty.newsgroup [C] GROUP example.empty.newsgroup
[S] 211 0 0 0 example.empty.newsgroup [S] 211 0 0 0 example.empty.newsgroup
[C] NEXT [C] NEXT
[S] 420 No current article selected [S] 420 No current article selected
9.2 Retrieval of Articles and Article Sections 7.2 Retrieval of articles and article sections
The ARTICLE, BODY, HEAD, and STAT commands are very similar. The ARTICLE, BODY, HEAD, and STAT commands are very similar. They
They differ only in the parts of the article that are differ only in the parts of the article that are presented to the
presented to the client and in the successful response code. client and in the successful response code. The ARTICLE command is
The ARTICLE command is described here in full, while the described here in full, while the other commands are described in
other commands are described in terms of the differences. terms of the differences. An article, as defined by RFC 1036,
An article, as defined by RFC 1036, consists of two parts: consists of two parts: the article headers and the article body.
the article headers and the article body. When responding to When responding to one of these commands, the server presents the
one of these commands, the server presents the entire article entire article or appropriate part and does not attempt to alter or
or appropriate part and does not attempt to alter or
translate it in any way. translate it in any way.
Feather [Page 25] 7.2.1 ARTICLE
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
9.2.1 ARTICLE 7.2.1.1 Usage
ARTICLE <message-id> Syntax
ARTICLE message-id
ARTICLE [number] ARTICLE [number]
The ARTICLE command selects an article based on the arguments Responses
and presents the header, a blank line, and the body of that
article. The command has two forms.
In the first form, a message-id is specified (including the First form (message-id specified)
angle brackets), and the server presents the article with 220 0 message-id Article follows (multiline)
that message-id in its headers. In this case, the server MUST 430 No article found with that message-id
NOT alter the "current article pointer". This is both to
facilitate the presentation of articles that may be
referenced within another article being read, and because of
the semantic difficulties of determining the proper sequence
and membership of an article that may have been crossposted
to more than one newsgroup.
In the second form, an article number may be specified. If Second form (optional article number specified)
so, and if there is an article with that number in the 220 n message-id Article follows (multiline)
currently selected group, the server MUST set the current 412 No newsgroup selected
article pointer to that number. 420 Current article number is invalid [1]
423 No such article in this newsgroup
Then, whether or not a number was specified, the article Parameters
indicated by the current article pointer is presented to the number = Requested article number
client. n = Returned article number
message-id = Article message-id
Note that a previously valid article number MAY become [1] The 420 response can only occur if no article number has been
invalid if the article has been removed. A previously invalid specified.
article number MAY become valid if the article has been
reinstated, but such an article number MUST be no less than
the reported low water mark for that group.
The server MUST NOT change the currently selected group as a 7.2.1.2 Description
result of this command. The server MUST NOT change the
current selected article except when an article number
argument was provided and the article exists; in particular,
it MUST NOT change it following an unsuccessful response.
9.2.1.1 Responses
First form (message-id specified):
Feather [Page 26] The ARTICLE command selects an article based on the arguments and
INTERNET DRAFT C. Feather presents the header, a blank line, and the body of that article. The
Expires: July 31, 2003 Thus plc command has two forms.
January 2003
220 0 a Article follows (multi-line response, a = In the first form, a message-id is specified (including the angle
message-id) brackets), and the server presents the article with that message-id
430 No article found with that message-id in its headers. In this case, the server MUST NOT alter the current
502 Program error, function not performed selected newsgroup or current article number. This is both to
facilitate the presentation of articles that may be referenced within
another article being read, and because of the semantic difficulties
of determining the proper sequence and membership of an article that
may have been crossposted to more than one newsgroup.
Second form (optional article number specified): In the response, the article number is replaced with zero (that is,
the server is not required to determine whether the article is in the
current group or what article number(s) it has).
220 n a Article follows (multi-line response, n = In the second form, an article number may be specified. If so, and
article number, a = message-id) if there is an article with that number in the currently selected
412 No newsgroup selected newsgroup, the server MUST set the current article number to that
420 No current article selected number.
423 No such article in this newsgroup
502 Program error, function not performed
The 420 response only occurs if no article number has been Then, whether or not a number was specified, the article indicated by
specified. the current article number is presented to the client.
In the 220 response, the first parameter is 0 for the first Note that a previously valid article number MAY become invalid if the
form and the article number (within the current group) for article has been removed. A previously invalid article number MAY
the second form. The second parameter is the message-id of become valid if the article has been reinstated, but such an article
the article (within angle brackets). This is taken from the number MUST be no less than the reported low water mark for that
message-id header line of the article (required by RFC 1036). group.
If there is no such line, the message-id "<0>" MUST be used
instead (without the double quotes).
Since the message-id field is unique for each article, it may The server MUST NOT change the current selected newsgroup as a result
be used by a client to skip duplicate displays of articles of this command. The server MUST NOT change the current article
that have been posted more than once, or to more than one number except when an article number argument was provided and the
newsgroup. article exists; in particular, it MUST NOT change it following an
unsuccessful response.
The message-id of the article is taken from the message-id header
line of the article (required by RFC 1036). If there is no such
line, the message-id "<0>" MUST be used instead (without the double
quotes).
Since the message-id field is unique for each article, it may be used
by a client to skip duplicate displays of articles that have been
posted more than once, or to more than one newsgroup.
The article headers and body are returned as a multi-line response
following the 220 response code.
If the current article number is invalid, a 420 response MUST be
returned. If there is no article with the specified number, a 423
response MUST be returned. If the current selected newsgroup is
invalid, a 412 response MUST be returned.
7.2.1.3 Examples
Example of a successful retrieval of an article (using no article
number):
The article headers and body are returned as a multi-line
response following the initial response line.
9.2.1.2 Examples
Example of a successful retrieval of an article (using no
article number)
[S] 200 NNTP Service Ready
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
[C] ARTICLE [C] ARTICLE
[S] 220 3000234 <45223423@example.com> [S] 220 3000234 <45223423@example.com>
[S] Path: pathost!demo!whitehouse!not-for-mail
Feather [Page 27] [S] From: "Demo User" <nobody@example.net>
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
[S] Path: pathost!demo!somewhere!not-for-mail
[S] From: ˘Demo User÷ <nobody@example.com>
[S] Newsgroups: misc.test [S] Newsgroups: misc.test
[S] Subject: I am just a test article [S] Subject: I am just a test article
[S] Date: 6 Oct 1998 04:38:40 -0500 [S] Date: 6 Oct 1998 04:38:40 -0500
[S] Organization: An Example Com, San Jose, CA [S] Organization: An Example Net, Uncertain, Texas
[S] Message-ID: <45223423@example.com> [S] Message-ID: <411@example.net>
[S] [S]
[S] This is just a test article. [S] This is just a test article.
[S] . [S] .
Example of a successful retrieval of an article by message-id
[S] 200 NNTP Service Ready Example of a successful retrieval of an article by message-id:
[C] ARTICLE <45223423@example.com> [C] ARTICLE <45223423@example.com>
[S] 220 0 <45223423@example.com> [S] 220 0 <45223423@example.com>
[S] Path: pathost!demo!somewhere!not-for-mail [S] Path: pathost!demo!whitehouse!not-for-mail
[S] From: ˘Demo User÷ <nobody@example.com> [S] From: "Demo User" <nobody@example.net>
[S] Newsgroups: misc.test [S] Newsgroups: misc.test
[S] Subject: I am just a test article [S] Subject: I am just a test article
[S] Date: 6 Oct 1998 04:38:40 -0500 [S] Date: 6 Oct 1998 04:38:40 -0500
[S] Organization: An Example Com, San Jose, CA [S] Organization: An Example Net, Uncertain, Texas
[S] Message-ID: <45223423@example.com> [S] Message-ID: <411@example.net>
[S] [S]
[S] This is just a test article. [S] This is just a test article.
[S] . [S] .
Example of an unsuccessful retrieval of an article by
message-id Example of an unsuccessful retrieval of an article by message-id:
[S] 200 NNTP Service Ready
[C] ARTICLE <i.am.not.there@example.com> [C] ARTICLE <i.am.not.there@example.com>
[S] 430 No Such Article Found [S] 430 No Such Article Found
Example of an unsuccessful retrieval of an article by number
[S] 200 NNTP Service Ready Example of an unsuccessful retrieval of an article by number:
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 news.groups [S] 211 1234 3000234 3002322 news.groups
[C] ARTICLE 300256 [C] ARTICLE 300256
[S] 423 No such article number in this group [S] 423 No such article number in this group
Example of an unsuccessful retrieval of an article by number
because no newsgroup was selected first Example of an unsuccessful retrieval of an article by number because
[S] 200 NNTP Service Ready no newsgroup was selected first:
[Assumes current selected newsgroup is invalid.]
[C] ARTICLE 300256 [C] ARTICLE 300256
[S] 412 No newsgroup selected [S] 412 No newsgroup selected
Example of an attempt to retrieve an article when the current
group selected is empty
Feather [Page 28] Example of an attempt to retrieve an article when the current
INTERNET DRAFT C. Feather selected newsgroup is empty:
Expires: July 31, 2003 Thus plc
January 2003
[S] 200 NNTP Service Ready
[C] GROUP example.empty.newsgroup [C] GROUP example.empty.newsgroup
[S] 211 0 0 0 example.empty.newsgroup [S] 211 0 0 0 example.empty.newsgroup
[C] ARTICLE [C] ARTICLE
[S] 420 No current article selected [S] 420 No current article selected
Example of a failure due to the service being unavailable
[S] 200 NNTP Service Ready
[C] ARTICLE <i.am.a.test.article@example.com>
[S] 502 Service unavailable
9.2.2 HEAD 7.2.2 HEAD
HEAD <message-id> 7.2.2.1 Usage
Syntax
HEAD message-id
HEAD [number] HEAD [number]
The HEAD command behaves identically to the ARTICLE command
except that, if the article exists, only the headers are
presented (the blank line separating the headers and body
MUST NOT be included).
9.2.2.1 Responses
First form (message-id specified): Responses
221 0 a Article follows (multi-line response, a = First form (message-id specified)
message-id) 221 0 message-id Headers follow (multiline)
430 No article found with that message-id 430 No article found with that message-id
502 Program error, function not performed
Second form (optional article number specified):
221 n a Article follows (multi-line response, n = Second form (optional article number specified)
article number, a = message-id) 221 n message-id Headers follow (multiline)
412 No newsgroup selected 412 No newsgroup selected
420 No current article selected 420 Current article number is invalid [1]
423 No such article in this newsgroup 423 No such article in this newsgroup
502 Program error, function not performed
Except that only the headers are included in the response, Parameters
the 221 response behaves identically to the 220 response of number = Requested article number
the ARTICLE command. n = Returned article number
message-id = Article message-id
Feather [Page 29] [1] The 420 response can only occur if no article number has been
INTERNET DRAFT C. Feather specified.
Expires: July 31, 2003 Thus plc
January 2003
9.2.2.2 Examples 7.2.2.2 Description
The HEAD command behaves identically to the ARTICLE command except
that, if the article exists, the response code is 221 instead of 220
and only the headers are presented (the blank line separating the
headers and body MUST NOT be included).
7.2.2.3 Examples
Example of a successful retrieval of the headers in an article (using
no article number):
Example of a successful retrieval of the headers in an
article (using no article number)
[S] 200 NNTP Service Ready
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
[C] HEAD [C] HEAD
[S] 221 3000234 <45223423@example.com> [S] 221 3000234 <45223423@example.com>
[S] Path: pathost!demo!somewhere!not-for-mail [S] Path: pathost!demo!whitehouse!not-for-mail
[S] From: ˘Demo User÷ <nobody@example.com> [S] From: "Demo User" <nobody@example.net>
[S] Newsgroups: misc.test [S] Newsgroups: misc.test
[S] Subject: I am just a test article [S] Subject: I am just a test article
[S] Date: 6 Oct 1998 04:38:40 -0500 [S] Date: 6 Oct 1998 04:38:40 -0500
[S] Organization: An Example Com, San Jose, CA [S] Organization: An Example Net, Uncertain, Texas
[S] Message-ID: <45223423@example.com> [S] Message-ID: <411@example.net>
[S] . [S] .
Example of a successful retrieval of the headers in an
article by message-id Example of a successful retrieval of the headers in an article by
[S] 200 NNTP Service Ready message-id:
[C] HEAD <45223423@example.com> [C] HEAD <45223423@example.com>
[S] 221 0 <45223423@example.com> [S] 221 0 <45223423@example.com>
[S] Path: pathost!demo!somewhere!not-for-mail [S] Path: pathost!demo!whitehouse!not-for-mail
[S] From: ˘Demo User÷ <nobody@example.com> [S] From: "Demo User" <nobody@example.net>
[S] Newsgroups: misc.test [S] Newsgroups: misc.test
[S] Subject: I am just a test article [S] Subject: I am just a test article
[S] Date: 6 Oct 1998 04:38:40 -0500 [S] Date: 6 Oct 1998 04:38:40 -0500
[S] Organization: An Example Com, San Jose, CA [S] Organization: An Example Net, Uncertain, Texas
[S] Message-ID: <45223423@example.com> [S] Message-ID: <411@example.net>
[S] . [S] .
Example of an unsuccessful retrieval of the header of an
article by message-id Example of an unsuccessful retrieval of the header of an article by
[S] 200 NNTP Service Ready message-id:
[C] HEAD <i.am.not.there@example.com> [C] HEAD <i.am.not.there@example.com>
[S] 430 No Such Article Found [S] 430 No Such Article Found
Example of an unsuccessful retrieval of the header of an
article by number Example of an unsuccessful retrieval of the header of an article by
[S] 200 NNTP Service Ready number:
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
[C] HEAD 300256 [C] HEAD 300256
[S] 423 No such article number in this group [S] 423 No such article number in this group
Feather [Page 30] Example of an unsuccessful retrieval the header of an article by
INTERNET DRAFT C. Feather number because no newsgroup was selected first:
Expires: July 31, 2003 Thus plc
January 2003
Example of an unsuccessful retrieval the header of an article [Assumes current selected newsgroup is invalid.]
by number because no newsgroup was selected first
[S] 200 NNTP Service Ready
[C] HEAD 300256 [C] HEAD 300256
[S] 412 No newsgroup selected [S] 412 No newsgroup selected
Example of an attempt to retrieve the header of an article
when the current group selected is empty Example of an attempt to retrieve the header of an article when the
[S] 200 NNTP Service Ready current selected newsgroup is empty:
[C] GROUP example.empty.newsgroup [C] GROUP example.empty.newsgroup
[S] 211 0 0 0 example.empty.newsgroup [S] 211 0 0 0 example.empty.newsgroup
[C] HEAD [C] HEAD
[S] 420 No current article selected [S] 420 No current article selected
Example of a failure due to the service being unavailable
[S] 200 NNTP Service Ready
[C] HEAD <i.am.a.test.article@example.com>
[S] 502 Service unavailable
9.2.3 BODY 7.2.3 BODY
BODY <message-id> 7.2.3.1 Usage
Syntax
BODY message-id
BODY [number] BODY [number]
The BODY command behaves identically to the ARTICLE command
except that, if the article exists, only the body is
presented (the blank line separating the headers and body
MUST NOT be included).
9.2.3.1 Responses
First form (message-id specified): Responses
222 0 a Article follows (multi-line response, a = First form (message-id specified)
message-id) 222 0 message-id Body follows (multiline)
430 No article found with that message-id 430 No article found with that message-id
502 Program error, function not performed
Second form (optional article number specified): Second form (optional article number specified)
222 n message-id Body follows (multiline)
222 n a Article follows (multi-line response, n =
article number, a = message-id)
412 No newsgroup selected 412 No newsgroup selected
420 No current article selected 420 Current article number is invalid [1]
423 No such article in this newsgroup 423 No such article in this newsgroup
Feather [Page 31] Parameters
INTERNET DRAFT C. Feather number = Requested article number
Expires: July 31, 2003 Thus plc n = Returned article number
January 2003 message-id = Article message-id
502 Program error, function not performed [1] The 420 response can only occur if no article number has been
specified.
Except that only the body is included in the response, the 7.2.3.2 Description
222 response behaves identically to the 220 response of the
ARTICLE command. The BODY command behaves identically to the ARTICLE command except
9.2.3.2 Examples that, if the article exists, the response code is 222 instead of 220
and only the body is presented (the blank line separating the headers
and body MUST NOT be included).
7.2.3.3 Examples
Example of a successful retrieval of the body of an article (using no
article number):
Example of a successful retrieval of the body of an article
(using no article number)
[S] 200 NNTP Service Ready
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
[C] BODY [C] BODY
[S] 222 3000234 <45223423@example.com> [S] 222 3000234 <45223423@example.com>
[S] This is just a test article. [S] This is just a test article.
[S] . [S] .
Example of a successful retrieval of the body of an article
by message-id Example of a successful retrieval of the body of an article by
[S] 200 NNTP Service Ready message-id:
[C] BODY <45223423@example.com> [C] BODY <45223423@example.com>
[S] 222 0 <45223423@example.com> [S] 222 0 <45223423@example.com>
[S] This is just a test article. [S] This is just a test article.
[S] . [S] .
Example of an unsuccessful retrieval of the body of an
article by message-id Example of an unsuccessful retrieval of the body of an article by
[S] 200 NNTP Service Ready message-id:
[C] BODY <i.am.not.there@example.com> [C] BODY <i.am.not.there@example.com>
[S] 430 No Such Article Found [S] 430 No Such Article Found
Example of an unsuccessful retrieval of the body of an
article by number Example of an unsuccessful retrieval of the body of an article by
[S] 200 NNTP Service Ready number:
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
[C] BODY 300256 [C] BODY 300256
[S] 423 No such article number in this group [S] 423 No such article number in this group
Example of an unsuccessful retrieval of the body of an
article by number because no newsgroup was selected first Example of an unsuccessful retrieval of the body of an article by
[S] 200 NNTP Service Ready number because no newsgroup was selected first:
[Assumes current selected newsgroup is invalid.]
[C] BODY 300256 [C] BODY 300256
[S] 412 No newsgroup selected [S] 412 No newsgroup selected
Feather [Page 32] Example of an attempt to retrieve the body of an article when the
INTERNET DRAFT C. Feather current selected newsgroup is empty:
Expires: July 31, 2003 Thus plc
January 2003
Example of an attempt to retrieve the body of an article when
the current group selected is empty
[S] 200 NNTP Service Ready
[C] GROUP example.empty.newsgroup [C] GROUP example.empty.newsgroup
[S] 211 0 0 0 example.empty.newsgroup [S] 211 0 0 0 example.empty.newsgroup
[C] BODY [C] BODY
[S] 420 No current article selected [S] 420 No current article selected
Example of a failure due to the service being unavailable
[S] 200 NNTP Service Ready
[C] BODY <i.am.a.test.article@example.com>
[S] 502 Service unavailable
9.2.4 STAT
STAT <message-id> 7.2.4 STAT
STAT [number]
The STAT command behaves identically to the ARTICLE command
except that, if the article exists, it is NOT presented to
the client.
This command allows the client to determine whether an 7.2.4.1 Usage
article exists, and in the second form what its message-id
is, without having to process an arbitrary amount of text.
9.2.4.1 Responses
First form (message-id specified): Syntax
STAT message-id
STAT [number]
Responses
223 0 a Article exists (a = message-id) First form (message-id specified)
223 0 message-id Article exists
430 No article found with that message-id 430 No article found with that message-id
502 Program error, function not performed
Second form (optional article number specified):
223 n a Article exists (n = article number, a = Second form (optional article number specified)
message-id) 223 n message-id Article exists
412 No newsgroup selected 412 No newsgroup selected
420 No current article selected 420 Current article number is invalid [1]
423 No such article in this newsgroup 423 No such article in this newsgroup
502 Program error, function not performed
Feather [Page 33] Parameters
INTERNET DRAFT C. Feather number = Requested article number
Expires: July 31, 2003 Thus plc n = Returned article number
January 2003 message-id = Article message-id
The parameters of the 223 response are identical to those [1] The 420 response can only occur if no article number has been
that would have been given in a 220 response to the specified.
equivalent ARTICLE command. However, the response is NOT
multi-line. 7.2.4.2 Description
9.2.4.2 Examples
The STAT command behaves identically to the ARTICLE command except
that, if the article exists, it is NOT presented to the client and
the response code is 223 instead of 220. Note that the response is
NOT multi-line.
This command allows the client to determine whether an article
exists, and in the second form what its message-id is, without having
to process an arbitrary amount of text.
7.2.4.3 Examples
Example of STAT on an existing article (using no article number):
Example of STAT on an existing article (using no article
number)
[S] 200 NNTP Service Ready
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
[C] STAT [C] STAT
[S] 223 3000234 <45223423@example.com> [S] 223 3000234 <45223423@example.com>
Example of a STAT of an existing article by message-id
[S] 200 NNTP Service Ready Example of a STAT of an existing article by message-id:
[C] STAT <45223423@example.com> [C] STAT <45223423@example.com>
[S] 223 0 <45223423@example.com> [S] 223 0 <45223423@example.com>
Example of an STAT of an article not on the server by
message-id Example of an STAT of an article not on the server by message-id:
[S] 200 NNTP Service Ready
[C] STAT <i.am.not.there@example.com> [C] STAT <i.am.not.there@example.com>
[S] 430 No Such Article Found [S] 430 No Such Article Found
Example of STAT of an article not in the server by number
[S] 200 NNTP Service Ready Example of STAT of an article not in the server by number:
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
[C] STAT 300256 [C] STAT 300256
[S] 423 No such article number in this group [S] 423 No such article number in this group
Example of STAT of an article by number when no newsgroup was Example of STAT of an article by number when no newsgroup was
selected first selected first:
[S] 200 NNTP Service Ready
[Assumes current selected newsgroup is invalid.]
[C] STAT 300256 [C] STAT 300256
[S] 412 No newsgroup selected [S] 412 No newsgroup selected
Example of STAT of an article when the current group selected
is empty Example of STAT of an article when the current selected newsgroup is
[S] 200 NNTP Service Ready empty:
[C] GROUP example.empty.newsgroup [C] GROUP example.empty.newsgroup
[S] 211 0 0 0 example.empty.newsgroup [S] 211 0 0 0 example.empty.newsgroup
[C] STAT [C] STAT
[S] 420 No current article selected [S] 420 No current article selected
Example of a failure due to the service being unavailable
Feather [Page 34] 7.3 Article posting
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
[S] 200 NNTP Service Ready Article posting is done in one of two modes: individual article
[C] STAT <i.am.a.test.article@example.com> posting from news reading clients using POST, and article transfer
[S] 502 Service unavailable from other news servers using IHAVE.
9.3 Article Posting 7.3.1 POST
Article posting is done in one of two modes: individual 7.3.1.1 Usage
article posting from news reading clients and article
transfer from other news servers.
9.3.1 POST This command MUST NOT be pipelined.
Syntax
POST POST
If posting is allowed, response code 340 MUST be returned to
indicate that the article to be posted should be sent.
Response code 440 MUST be sent if that posting is prohibited
for some installation-dependent reason.
If posting is permitted, the article MUST be presented to the Responses
server by the client in the format specified by RFC 1036 (or
by any of its successors or extensions). The text forming the
header and body of the message to be posted MUST be sent by
the client in the format defined above (section 0) for multi-
line responses (except that there is no initial line
containing a response code). Thus a single period (".") on a
line indicates the end of the text, and lines starting with a
period in the original text have that period doubled during
transmission.
Following the presentation of the termination sequence by the Initial responses
client, the server MUST return a response code indicating 340 Send article to be posted
success or failure of the article transfer. Note that 440 Posting not permitted
response codes 340 and 440 are used in direct response to the Subsequent responses
POST command. Others are returned following the sending of 240 Article received OK
the article. 441 Posting failed
No attempt shall be made by the server to filter characters, 7.3.1.2 Description
fold or limit lines, or otherwise process incoming text. The
intent is that the server just passes the incoming message to
be posted to the server installation's news posting software,
which is not defined by this memo.
Feather [Page 35] If posting is allowed, a 340 response MUST be returned to indicate
INTERNET DRAFT C. Feather that the article to be posted should be sent. If posting is
Expires: July 31, 2003 Thus plc prohibited for some installation-dependent reason, a 440 response
January 2003 MUST be returned.
The client SHOULD NOT assume that the article has been If posting is permitted, the article MUST be presented to the server
successfully transferred unless it receives an affirmative by the client in the format specified by RFC 1036 (or by any of its
response from the server. Since, however, the affirmative successors or extensions). The text forming the header and body of
response may have been sent and lost, the client SHOULD use the message to be posted MUST be sent by the client in the format
the same message-id in the article when resending it or check defined above (Section 3) for multi-line responses (except that there
whether the article was successfully posted before resending is no initial line containing a response code). Thus a single dot
it to ensure that the resend will not result in a duplicate (".") on a line indicates the end of the text, and lines starting
article. with a dot in the original text have that dot doubled during
transmission.
This command is not streamable. Following the presentation of the termination sequence by the client,
9.3.1.1 Responses the server MUST return a response indicating success or failure of
the article transfer. Note that response codes 340 and 440 are used
in direct response to the POST command. Others are returned
following the sending of the article.
240 Article received ok A response of 240 SHOULD indicate that, barring unforseen server
340 Send article to be posted errors, the posted article will be made available on the server and/
440 Posting not permitted or transferred to other servers as appropriate. In other words,
441 Posting failed articles not wanted by the server SHOULD be rejected with a 411
response and not accepted and silently discarded.
9.3.1.2 Examples No attempt shall be made by the server to filter characters, fold or
limit lines, or otherwise process incoming text. The intent is that
the server just passes the incoming message to be posted to the
server installation's news posting software, which is not defined by
this document.
The client SHOULD NOT assume that the article has been successfully
transferred unless it receives an affirmative response from the
server. If the session is interrupted before the response is
received, it is possible that an affirmative response was sent but
has been lost. Therefore, in any subsequent session the client
SHOULD use the same message-id in the article when resending it or
check whether the article was successfully posted before resending it
to ensure that the resend will not result in a duplicate article.
7.3.1.3 Examples
Example of a successful posting:
Example of a successful posting
[S] 200 NNTP Service Ready
[C] POST [C] POST
[S] 340 Input article. End with <CR-LF>.<CR-LF> [S] 340 Input article; end with <CR-LF>.<CR-LF>
[C] From: ˘Demo User÷ <nobody@example.net> [C] From: "Demo User" <nobody@example.net>
[C] Newsgroups: misc.test [C] Newsgroups: misc.test
[C] Subject: I am just a test article [C] Subject: I am just a test article
[C] Organization: An Example Net [C] Organization: An Example Net
[C] [C]
[C] This is just a test article. [C] This is just a test article.
[C] . [C] .
[S] 240 Article received ok [S] 240 Article received OK
Example of an unsuccessful posting
[S] 200 NNTP Service Ready Example of an unsuccessful posting:
[C] POST [C] POST
[S] 340 Input article. End with <CR-LF>.<CR-LF> [S] 340 Input article; end with <CR-LF>.<CR-LF>
[C] From: ˘Demo User÷ <nobody@example.net> [C] From: "Demo User" <nobody@example.net>
[C] Newsgroups: misc.test [C] Newsgroups: misc.test
[C] Subject: I am just a test article [C] Subject: I am just a test article
[C] Organization: An Example Net [C] Organization: An Example Net
[C] [C]
Feather [Page 36]
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
[C] This is just a test article. [C] This is just a test article.
[C] . [C] .
[S] 441 Posting failed [S] 441 Posting failed
Example of an attempt to post when posting is not allowed
[S] 201 NNTP Service Ready, read-only Example of an attempt to post when posting is not allowed:
[C] MODE READER
[S] 201 NNTP Service Ready, posting prohibited
[C] POST [C] POST
[S] 440 Posting not permitted [S] 440 Posting not permitted
9.3.2 IHAVE 7.3.2 IHAVE
IHAVE <message-id> 7.3.2.1 Usage
The IHAVE command informs the server that the client has an
article whose id is <message-id>. If the server desires a
copy of that article, it MUST return response code 335
instructing the client to send the entire article. If the
server does not want the article (if, for example, the server
already has a copy of it), response code 435 indicating that
the article is not wanted MUST be returned. Finally, if the
article isn't wanted immediately but the client should retry
later if possible (if, for example, another client is in the
process of sending the same article to the server), response
code 436 MUST be returned.
If transmission of the article is requested, the client MUST This command MUST NOT be pipelined.
send the entire article, including header and body, in the
format defined above (section 4) for multi-line responses
(except that there is no initial line containing a response
code). Thus a single period (".") on a line indicates the end
of the text, and lines starting with a period in the original
text have that period doubled during transmission. The server
MUST return either response code 235, indicating that the
article was successfully transferred, response code 436,
indicating that the transfer failed but should be tried again
later, or response code 437, indicating that the article was
rejected.
This function differs from the POST command in that it is Syntax
intended for use in transferring already-posted articles IHAVE message-id
between hosts. It SHOULD NOT be used when the client is a
personal news reading program, since this command indicates
that the forthcoming article has already been posted at
another site and is being forwarded from another host.
Feather [Page 37] Responses
INTERNET DRAFT C. Feather Initial responses
Expires: July 31, 2003 Thus plc 335 Send article to be transferred
January 2003 435 Article not wanted
436 Transfer not possible; try again later
However, the server MAY elect not to post or forward the Subsequent responses
article if after further examination of the article it deems 235 Article transferred OK
it inappropriate to do so. Reasons for such subsequent 436 Transfer failed; try again later
rejection of an article may include such problems as 437 Transfer rejected; do not retry
inappropriate newsgroups or distributions, disk space
limitations, article lengths, garbled headers, and the like. Parameters
These are typically restrictions enforced by the server message-id = Article message-id
host's news software and not necessarily the NNTP server
7.3.2.2 Description
The IHAVE command informs the server that the client has an article
with the specified message-id. If the server desires a copy of that
article a 335 response MUST be returned, instructing the client to
send the entire article. If the server does not want the article
(if, for example, the server already has a copy of it), a 435
response MUST be returned, indicating that the article is not wanted.
Finally, if the article isn't wanted immediately but the client
should retry later if possible (if, for example, another client is in
the process of sending the same article to the server), a 436
response MUST be returned.
If transmission of the article is requested, the client MUST send the
entire article, including header and body, in the format defined
above (Section 3) for multi-line responses (except that there is no
initial line containing a response code). Thus a single dot (".") on
a line indicates the end of the text, and lines starting with a dot
in the original text have that dot doubled during transmission. The
server MUST return either a 235 response, indicating that the article
was successfully transferred, a 436 response, indicating that the
transfer failed but should be tried again later, or a 437 response,
indicating that the article was rejected.
This function differs from the POST command in that it is intended
for use in transferring already-posted articles between hosts. It
SHOULD NOT be used when the client is a personal news reading
program, since this command indicates that the forthcoming article
has already been posted at another site and is being forwarded from
another host. However, the server MAY elect not to post or forward
the article if after further examination of the article it deems it
inappropriate to do so. Reasons for such subsequent rejection of an
article may include such problems as inappropriate newsgroups or
distributions, disc space limitations, article lengths, garbled
headers, and the like. These are typically restrictions enforced by
the server host's news software and not necessarily the NNTP server
itself. itself.
The client SHOULD NOT assume that the article has been The client SHOULD NOT assume that the article has been successfully
successfully transferred unless it receives an affirmative transferred unless it receives an affirmative response from the
response from the server. A lack of response (such as a server. A lack of response (such as a dropped network connection or
dropped network connection or a network timeout) SHOULD be a network timeout) SHOULD be treated the same as a 436 response.
treated the same as a 436 error response.
Because some news server software may not be able immediately Because some news server software may not be able immediately to
to determine whether or not an article is suitable for determine whether or not an article is suitable for posting or
posting or forwarding, an NNTP server MAY acknowledge the forwarding, an NNTP server MAY acknowledge the successful transfer of
successful transfer of the article (with a 235 response) but the article (with a 235 response) but later silently discard it.
later silently discard it.
9.3.2.1 Responses
235 Article transferred ok 7.3.2.3 Examples
335 Send article to be transferred
435 Article not wanted, please donĂt send it.
436 Transfer failed, try again later.
437 Article rejected, please donĂt sent it again.
9.3.2.2 Examples Example of successfully sending an article to another site:
Example of successfully sending an article to another site
[S] 200 NNTP Service Ready
[C] IHAVE <i.am.an.article.you.will.want@example.com> [C] IHAVE <i.am.an.article.you.will.want@example.com>
[S] 335 Send it. End with <CR-LF>.<CR-LF> [S] 335 Send it; end with <CR-LF>.<CR-LF>
[C] Path: pathost!demo!somewhere!not-for-mail [C] Path: pathost!demo!somewhere!not-for-mail
[C] From: ˘Demo User÷ <nobody@example.com> [C] From: "Demo User" <nobody@example.com>
[C] Newsgroups: misc.test [C] Newsgroups: misc.test
[C] Subject: I am just a test article [C] Subject: I am just a test article
[C] Date: 6 Oct 1998 04:38:40 -0500 [C] Date: 6 Oct 1998 04:38:40 -0500
Feather [Page 38]
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
[C] Organization: An Example Com, San Jose, CA [C] Organization: An Example Com, San Jose, CA
[C] Message-ID: <i.am.a.test.article@example.com> [C] Message-ID: <i.am.a.test.article@example.com>
[C] [C]
[C] This is just a test article. [C] This is just a test article.
[C] . [C] .
[S] 235 Article transferred ok [S] 235 Article transferred OK
Example of sending an article to another site that rejects it
[S] 200 NNTP Service Ready Example of sending an article to another site that rejects it:
[C] IHAVE <i.am.an.article.you.will.want@example.com> [C] IHAVE <i.am.an.article.you.will.want@example.com>
[S] 335 Send it. End with <CR-LF>.<CR-LF> [S] 335 Send it; end with <CR-LF>.<CR-LF>
[C] Path: pathost!demo!somewhere!not-for-mail [C] Path: pathost!demo!somewhere!not-for-mail
[C] From: ˘Demo User÷ <nobody@example.com> [C] From: "Demo User" <nobody@example.com>
[C] Newsgroups: misc.test [C] Newsgroups: misc.test
[C] Subject: I am just a test article [C] Subject: I am just a test article
[C] Date: 6 Oct 1998 04:38:40 -0500 [C] Date: 6 Oct 1998 04:38:40 -0500
[C] Organization: An Example Com, San Jose, CA [C] Organization: An Example Com, San Jose, CA
[C] Message-ID: <i.am.a.test.article@example.com> [C] Message-ID: <i.am.a.test.article@example.com>
[C] [C]
[C] This is just a test article. [C] This is just a test article.
[C] . [C] .
[S] 437 Article rejected. Don't send again [S] 437 Article rejected; don't send again
Example of sending an article to another site where the Example of sending an article to another site where the transfer
transfer fails fails:
[S] 200 NNTP Service Ready
[C] IHAVE <i.am.an.article.you.will.want@example.com> [C] IHAVE <i.am.an.article.you.will.want@example.com>
[S] 335 Send it. End with <CR-LF>.<CR-LF> [S] 335 Send it; end with <CR-LF>.<CR-LF>
[C] Path: pathost!demo!somewhere!not-for-mail [C] Path: pathost!demo!somewhere!not-for-mail
[C] From: ˘Demo User÷ <nobody@example.com> [C] From: "Demo User" <nobody@example.com>
[C] Newsgroups: misc.test [C] Newsgroups: misc.test
[C] Subject: I am just a test article [C] Subject: I am just a test article
[C] Date: 6 Oct 1998 04:38:40 -0500 [C] Date: 6 Oct 1998 04:38:40 -0500
[C] Organization: An Example Com, San Jose, CA [C] Organization: An Example Com, San Jose, CA
[C] Message-ID: <i.am.a.test.article@example.com> [C] Message-ID: <i.am.a.test.article@example.com>
[C] [C]
[C] This is just a test article. [C] This is just a test article.
[C] . [C] .
[S] 436 Transfer failed [S] 436 Transfer failed
Example of sending an article to a site that already has it
[S] 200 NNTP Service Ready Example of sending an article to a site that already has it:
[C] IHAVE <i.am.an.article.you.have@example.com> [C] IHAVE <i.am.an.article.you.have@example.com>
[S] 435 Duplicate [S] 435 Duplicate
Feather [Page 39] Example of sending an article to a site that requests the article be
INTERNET DRAFT C. Feather tried again later:
Expires: July 31, 2003 Thus plc
January 2003
Example of sending an article to a site that requests the
article be tried again later
[S] 200 NNTP Service Ready
[C] IHAVE <i.am.an.article.you.defer@example.com> [C] IHAVE <i.am.an.article.you.defer@example.com>
[S] 436 Retry later [S] 436 Retry later
9.4 The LIST Keyword 8. Information commands
9.4.1 LIST This section lists other commands that may be used at any time
between the beginning of a session and its termination. Using these
commands does not alter any state information, but the response
generated from their use may provide useful information to clients.
All servers MUST implement these commands.
8.1 DATE
8.1.1 Usage
Syntax
DATE
Responses
111 yyyymmddhhmmss server date and time
Parameters
yyyymmddHHmmss = Current UTC date and time on server
8.1.2 Description
This command exists to help clients find out the current Coordinated
Universal Time [9] from the server's perspective. This command MUST
NOT be used as a substitute for NTP [10], but to provide information
that might be useful when using the NEWNEWS command (see Section
8.4). A system providing NNTP service SHOULD implement NTP for the
purposes of keeping the system clock as accurate as possible.
The server MUST return a 111 response specifying the date and time on
the server in the form yyyymmddhhmmss. This date and time is in
Coordinated Universal Time.
8.1.3 Examples
[C] DATE
[S] 111 19990623135624
8.2 HELP
8.2.1 Usage
Syntax
HELP
Responses
100 Help text follows (multiline)
8.2.2 Description
This command provides a short summary of commands that are understood
by this implementation of the server. The help text will be
presented as a multiline response following the 100 response code.
This text is not guaranteed to be in any particular format and MUST
NOT be used by clients as a replacement for the LIST EXTENSIONS
command described in Section 6.1
8.2.3 Examples
[C] HELP
[S] 100 Help text follows
[S] This is some help text. There is no specific
[S] formatting requirement for this test, though
[S] it is customary for it to list the valid commands
[S] and give a brief definition of what they do
[S] .
8.3 NEWGROUPS
8.3.1 Usage
Syntax
NEWGROUPS date time [GMT]
Responses
231 List of new newsgroups follows (multiline)
Parameters
date = Date in yymmdd or yyyymmdd format
time = Time in hhmmss format
8.3.2 Description
This command returns a list of newsgroups created on the server since
the specified date and time. The results are in the same format as
the LIST ACTIVE command (see Section 8.6.1).
OUTSTANDING ISSUE
Does the output include high/low/status or not? If so, the
examples are wrong. If not, the above text is wrong.
The date is specified as 6 or 8 digits in the format [xx]yymmdd,
where xx is the first two digits of the year (19-99), yy is the last
two digits of the year (00-99), mm is the month (01-12), and dd is
the day of the month (01-31). If the first two digits of the year
are not specified, the year is to be taken from the current century
if yy is smaller than or equal to the current year, otherwise the
year is from the previous century.
The time is specified as 6 digits in the format hhmmss, where hh is
the hours in the 24-hour clock (00-23), mm is the minutes (00-59),
and ss is the seconds (00-60, to allow for leap seconds). The token
"GMT" specifies that the date and time are given in Coordinated
Universal Time; if it is omitted then the date and time are specified
in the server's local timezone. Note that there is no way using the
protocol specified in this document to establish the server's local
timezone.
Note that an empty list is a possible valid response and indicates
that there are no new newsgroups since that date-time.
Clients SHOULD make all queries using Coordinated Universal Time
(i.e. by including the "GMT" parameter) when possible.
8.3.3 Examples
Example where there are new groups:
[C] NEWGROUPS 19990624 000000 GMT
[S] 231 list of new newsgroups follows
[S] alt.rfc-writers.recovery
[S] tx.natives.recovery
[S] .
Example where there are no new groups:
[C] NEWGROUPS 19990624 000000 GMT
[S] 231 list of new newsgroups follows
[S] .
8.4 NEWNEWS
8.4.1 Usage
Syntax
NEWNEWS wildmat date time [GMT]
Responses
230 List of new articles follows (multiline)
Parameters
wildmat = Newsgroups of interest
date = Date in yymmdd or yyyymmdd format
time = Time in hhmmss format
8.4.2 Description
This command returns a list of message-ids of articles posted or
received on the server, in the newsgroups whose names match the
wildmat, since the specified date and time. One message-id is sent
on each line; the order of the response has no specific significance
and may vary from response to response in the same session. A
message-id MAY appear more than once; if it does so, it has the same
meaning as if it appeared only once.
Date and time are in the same format as the NEWGROUPS command (see
Section 8.3).
Note that an empty list is a possible valid response and indicates
that there is currently no new news in the relevant groups.
Clients SHOULD make all queries in Coordinated Universal Time (i.e.
by using the "GMT" parameter) when possible.
8.4.3 Examples
Example where there are new articles:
[C] NEWNEWS news.*,sci.* 19990624 000000 GMT
[S] 230 list of new articles by message-id follows
[S] <i.am.a.new.article@example.com>
[S] <i.am.another.new.article@example.com>
[S] .
Example where there are no new articles:
[C] NEWNEWS alt.* 19990624 000000 GMT
[S] 230 list of new articles by message-id follows
[S] .
8.5 Time
As described in Section 7, each article has an arrival timestamp.
Each newsgroup also has a creation timestamp. These timestamps are
used by the NEWNEWS and NEWGROUP commands to construct their
reponses.
The DATE command MUST return a timestamp from the same clock as is
used for determining article arrival and group creation times. This
clock SHOULD be monotonic, and adjustments SHOULD be made by running
it fast or slow compared to "real" time rather than by making sudden
jumps.
Clients can ensure that they do not have gaps in lists of articles or
groups by using the DATE command in the following manner:
First session:
Issue DATE command and record result
Issue NEWNEWS command using a previously chosen timestamp
Subsequent sessions:
Issue DATE command and hold result in temporary storage
Issue NEWNEWS command using timestamp saved from previous session
Overwrite saved timestamp with that currently in temporary storage
In order to allow for minor errors, clients MAY want to adjust the
timestamp back by two or three minutes before using it in NEWNEWS.
8.5.1 Examples
First session:
[C] DATE
[S] 111 20010203112233
[C] NEWNEWS local.chat 20001231 235959 GMT
[S] 230 list follows
[S] <article.1@local.service>
[S] <article.2@local.service>
[S] <article.3@local.service>
[S] .
Second session (the client has subtracted 3 minutes from the
timestamp returned previously):
[C] DATE
[S] 111 20010204003344
[C] NEWNEWS local.chat 20010203 111933 GMT
[S] 230 list follows
[S] <article.3@local.service>
[S] <article.4@local.service>
[S] <article.5@local.service>
[S] .
Note how <article.3@local.service> arrived in the 3 minute gap and so
is listed in both responses.
8.6 The LIST commands
8.6.1 LIST ACTIVE
8.6.1.1 Usage
Syntax
LIST ACTIVE [wildmat]
Responses
215 Information follows (multiline)
Parameters
wildmat = groups of interest
8.6.1.2 Description
The LIST ACTIVE command with no parameters returns a list of valid
newsgroups and associated information. Each newsgroup is sent as a
line of text in the following format:
LIST [ACTIVE [wildmat]]
The response to the LIST keyword with no parameters returns a
list of valid newsgroups and associated information. Each
newsgroup is sent as a line of text in the following format:
group first last status group first last status
where <group> is the name of the newsgroup, <last> is the
number of the last known article currently in that newsgroup, where:
<first> is the number of the first article currently in the
newsgroup, and <status> indicates the current status of the "group" is the name of the newsgroup;
group on this server. Typically, the <status> will consist of
the US-ASCII character 'y' where posting is permitted, 'n' "first" is the current low water mark for the group;
where posting is not permitted and 'm' where postings will be
forwarded to the newsgroup moderator by the news server. "last" is the current high water mark for the group;
"status" is the current status of the group on this server; typically
this is one of:
"y" posting is permitted
"n" posting is not permitted
"m" postings will be forwarded to the newsgroup moderator
Other status strings may exist. The definition of these other Other status strings may exist. The definition of these other
values and the circumstances under which they are returned is values and the circumstances under which they are returned is
covered in other specifications. Each field in the line is covered in other specifications.
separated from its neighboring fields by one or more US-ASCII
spaces.
The <first> and <last> fields will always be numeric. They OUTSTANDING ISSUE
may have leading zeros. The <first> field corresponds to the
"reported low water mark" and the <last> field corresponds to
the "reported high water mark" described in the GROUP command
(see Section 9.1.1.1).
The status of a newsgroup only indicates how posts to that Is the order "group first last status" or "group last first
newsgroup are processed. It does not indicate if the current status"? The examples match the description above, but they
client is permitted to post. That is indicated by the status don't match the news server I have tested.
code returned as part of the greeting.
Please note that an empty list (i.e., the text body returned
by this command consists only of the terminating period) is a
Feather [Page 40] Each field in the line is separated from its neighboring fields by
INTERNET DRAFT C. Feather one or more US-ASCII spaces.
Expires: July 31, 2003 Thus plc
January 2003
possible valid response, and indicates that there are The "first" and "last" fields correspond to the high and low water
currently no valid newsgroups. marks described in the GROUP command (see Section 7.1.1).
If the optional wildmat parameter is specified, the list is The status of a newsgroup only indicates how posts to that newsgroup
limited to only the groups that match the pattern. are processed. It does not indicate if the current client is
9.4.1.1 Responses permitted to post. That is indicated by the status code returned as
215 Information Follows (multi-line response) part of the greeting. Note that an empty list is a possible valid
response, and indicates that there are currently no valid newsgroups.
9.4.1.2 Examples If the optional wildmat parameter is specified, the list is limited
to only the groups whose names match the wildmat. If no wildmat is
specified, the keyword ACTIVE MAY be omitted without altering the
effect of the command.
Example of LIST returning a list of newsgroups 8.6.1.3 Examples
[S] 200 NNTP Service Ready
[C] LIST Example of LIST ACTIVE returning a list of newsgroups:
[C] LIST ACTIVE
[S] 215 list of newsgroups follows [S] 215 list of newsgroups follows
[S] misc.test 3000234 3002322 y [S] misc.test 3000234 3002322 y
[S] alt.fc-writers.recovery 1 4 y [S] alt.fc-writers.recovery 1 4 y
[S] tx.natives.recovery 56 89 y [S] tx.natives.recovery 56 89 y
[S] . [S] .
Example of LIST returning no newsgroups
[S] 200 NNTP Service Ready Example of LIST ACTIVE omitting the second keyword and returning no
newsgroups:
[C] LIST [C] LIST
[S] 215 list of newsgroups follows [S] 215 list of newsgroups follows
[S] . [S] .
9.4.2 LIST ACTIVE.TIMES Example of LIST ACTIVE with a wildmat:
[C] LIST ACTIVE *.recovery
[S] 215 list of newsgroups follows
[S] alt.fc-writers.recovery 1 4 y
[S] tx.natives.recovery 56 89 y
[S] .
8.6.2 LIST ACTIVE.TIMES
8.6.2.1 Usage
This command is optional.
Syntax
LIST ACTIVE.TIMES [wildmat] LIST ACTIVE.TIMES [wildmat]
The active.times file is maintained by some news transport
systems to contain information about who created a particular
newsgroup and when. The format of this file includes three
fields separated from each other by one or more US-ASCII
space characters. The first field is the name of the
newsgroup. The second is the time when this group was created
on this news server measured in seconds since the start of
January 1, 1970. The third is the email address of the
entity that created the newsgroup and must be a mailbox as
defined in RFC 28228. When executed, the information is
displayed following the 215 response. When display is
completed, the server will send a period on a line by itself.
If the information is not available, the server will return
Feather [Page 41] Responses
INTERNET DRAFT C. Feather 215 Information follows (multiline)
Expires: July 31, 2003 Thus plc 503 Facility not available
January 2003
the 503 error response. If the server does not recognize the Parameters
command, it SHOULD return the 501 error response. wildmat = groups of interest
If the optional wildmat parameter is specified, the list is 8.6.2.2 Description
limited to only the groups that match the pattern.
9.4.2.1 Responses
215 Information Follows (multi-line response) The active.times file is maintained by some news transport systems to
501 Syntax error contain information about who created a particular newsgroup and
503 Program error, function not performed when. Each line of this file consists of three fields separated from
9.4.2.2 Examples each other by one or more US-ASCII space characters. The first field
is the name of the newsgroup. The second is the time when this group
was created on this news server, measured in seconds since the start
of January 1, 1970. The third is the email address of the entity
that created the newsgroup, and must be a mailbox as defined in RFC
2822 [7].
If the information is available, it is returned as a multi-line
response following the 215 response code. If the information is not
available, a 503 response MUST be returned. If the server does not
recognize the command, a 501 response MUST be returned.
If the optional wildmat parameter is specified, the list is limited
to only the groups whose names match the wildmat (and therefore may
be empty).
8.6.2.3 Examples
Example of LIST ACTIVE.TIMES returning a list of newsgroups:
Example of LIST ACTIVE.TIMES returning a list of newsgroups
[S] 200 NNTP Service Ready
[C] LIST ACTIVE.TIMES [C] LIST ACTIVE.TIMES
[S] 215 information follows [S] 215 information follows
[S] misc.test 930445408 <creatme@isc.org> [S] misc.test 930445408 <creatme@isc.org>
[S] alt.rfc-writers.recovery 930562309 <m@example.com> [S] alt.rfc-writers.recovery 930562309 <m@example.com>
[S] tx.natives.recovery 930678923 <sob@academ.com> [S] tx.natives.recovery 930678923 <sob@academ.com>
[S] . [S] .
Example of LIST ACTIVE.TIMES returning an error (The server
software is not configured to maintain this information, but Example of LIST ACTIVE.TIMES returning an error where the command is
does recognize the command as valid.) recognised but the software does not maintain this information:
[S] 200 NNTP Service Ready
[C] LIST ACTIVE.TIMES [C] LIST ACTIVE.TIMES
[S] 503 program error, function not performed [S] 503 program error, function not performed
Example of LIST ACTIVE.TIMES sent to a server that does not
recognize this argument (e.g. The software does not maintain Example of LIST ACTIVE.TIMES sent to a server that does not recognize
this information.) this command:
[S] 200 NNTP Service Ready
[C] LIST ACTIVE.TIMES [C] LIST ACTIVE.TIMES
[S] 501 Syntax Error [S] 501 Syntax Error
9.4.3 LIST DISTRIBUTIONS 8.6.3 LIST DISTRIBUTIONS
8.6.3.1 Usage
This command is optional.
Syntax
LIST DISTRIBUTIONS LIST DISTRIBUTIONS
The distributions file is maintained by some news transport
systems to contain information about valid values for the
Distribution: line in a news article header and about what
the values mean. Each line contains two fields, the value and
Feather [Page 42] Responses
INTERNET DRAFT C. Feather 215 Information follows (multiline)
Expires: July 31, 2003 Thus plc 503 Facility not available
January 2003
a short explanation on the meaning of the value. The first 8.6.3.2 Description
field is separated from the second field by one or more US-
ASCII spaces. When executed, the information is displayed
following the 215 response. When display is completed, the
server will send a period on a line by itself. If the
information is not available, the server will return the 503
error response. If the server does not recognize this
command, it SHOULD return the 501 error response.
9.4.3.1 Responses
215 Information Follows (multi-line response) The distributions file is maintained by some news transport systems
501 Syntax error to contain information about valid values for the Distribution: line
503 Program error, function not performed in a news article header and about what the values mean. Each line
of this file consists of two fields separated from each other by one
or more US-ASCII space characters. The first field is a value and
the second is a short explanation of the meaning of that value.
9.4.3.2 Examples If the information is available, it is returned as a multi-line
response following the 215 response code. If the information is not
available, a 503 response MUST be returned. If the server does not
recognize the command, a 501 response MUST be returned.
8.6.3.3 Examples
Example of LIST DISTRIBUTIONS returning a list of distributions:
Example of LIST DISTRIBUTIONS returning a list of newsgroups
[S] 200 NNTP Service Ready
[C] LIST DISTRIBUTIONS [C] LIST DISTRIBUTIONS
[S] 215 information follows [S] 215 information follows
[S] usa United States of America [S] usa United States of America
[S] na North America [S] na North America
[S] world All over the World [S] world All over the World
[S] . [S] .
Example of LIST DISTRIBUTIONS returning an error (e.g. The
server software is not configured to maintain this Example of LIST DISTRIBUTIONS returning an error where the command is
information, but does recognize the command as valid.) recognised but the software does not maintain this information:
[S] 200 NNTP Service Ready
[C] LIST DISTRIBUTIONS [C] LIST DISTRIBUTIONS
[S] 503 program error, function not performed [S] 503 program error, function not performed
Example of LIST DISTRIBUTIONS sent to a server that does not Example of LIST DISTRIBUTIONS sent to a server that does not
recognize the command (e.g. The server does not maintain this recognize this command:
information regardless of configuration.)
[S] 200 NNTP Service Ready
[C] LIST DISTRIBUTIONS [C] LIST DISTRIBUTIONS
[S] 501 Syntax Error [S] 501 Syntax Error
9.4.4 LIST DISTRIB.PATS 8.6.4 LIST DISTRIB.PATS
8.6.4.1 Usage
This command is optional.
Syntax
LIST DISTRIB.PATS LIST DISTRIB.PATS
Feather [Page 43] Responses
INTERNET DRAFT C. Feather 215 Information follows (multiline)
Expires: July 31, 2003 Thus plc 503 Facility not available
January 2003
The distrib.pats file is maintained by some news transport 8.6.4.2 Description
systems to allow clients to choose a value for the
Distribution: line in the header of a news article being
posted. The information returned consists of lines, in no
particular order, each of which contains three fields
separated by colons. These fields are a weight, a wildmat
(which may be a simple group name), and a Distribution:
value, in that order.
The client MAY use this information to select a Distribution: The distrib.pats file is maintained by some news transport systems to
value based on the name of a newsgroup. To do so, it should choose a value for the Distribution: line in the header of a news
determine the lines whose second field matches the newsgroup article being posted. Each line of this file consists of three
name, select that line with the highest weight (with 0 being fields separated from each other by a US-ASCII colon. The first
the lowest), and use the Distribution: field from that line. field is a weight, the second field is a wildmat (which may be a
When executed, the information is displayed following the 215 simple group name), and the third field is a value for the
response. When display is completed, the server will send a Distribution: header.
period on a line by itself. If the information is not
available, the server will return the 503 error response. If
this command is not recognized, the server SHOULD return the
501 error response.
9.4.4.1 Responses
215 Information Follows (multi-line response) The client MAY use this information to select a Distribution: value
501 Syntax error based on the name of a newsgroup. To do so, it should determine the
503 Program error, function not performed lines whose second field matches the newsgroup name, select from
among them the line with the highest weight (with 0 being the
lowest), and use the value of the third field to construct the
Distribution: header.
9.4.4.2 Examples If the information is available, it is returned as a multi-line
response following the 215 response code. If the information is not
available, a 503 response MUST be returned. If the server does not
recognize the command, a 501 response MUST be returned.
8.6.4.3 Examples
Example of LIST DISTRIB.PATS returning a list of newsgroups:
Example of LIST DISTRIB.PATS returning a list of newsgroups
[S] 200 NNTP Service Ready
[C] LIST DISTRIB.PATS [C] LIST DISTRIB.PATS
[S] 215 information follows [S] 215 information follows
[S] 10:local.*:local [S] 10:local.*:local
[S] 5:*:world
[S] 20:local.here.*:thissite
[S] . [S] .
Example of LIST DISTRIB.PATS returning an error (e.g. The
server software is not configured to maintain this Example of LIST DISTRIB.PATS returning an error where the command is
information, but does recognize the command as valid.) recognised but the software does not maintain this information:
[S] 200 NNTP Service Ready
[C] LIST DISTRIB.PATS [C] LIST DISTRIB.PATS
[S] 503 program error, function not performed [S] 503 program error, function not performed
Feather [Page 44] Example of LIST DISTRIB.PATS sent to a server that does not recognize
INTERNET DRAFT C. Feather this command:
Expires: July 31, 2003 Thus plc
January 2003
Example of LIST DISTRIB.PATS sent to a server that does not
recognize the command (e.g. The software does not maintain
this information regardless of configuration.)
[S] 200 NNTP Service Ready
[C] LIST DISTRIB.PATS [C] LIST DISTRIB.PATS
[S] 501 Syntax Error [S] 501 Syntax Error
9.4.5 LIST NEWSGROUPS 8.6.5 LIST NEWSGROUPS
8.6.5.1 Usage
This command is optional.
Syntax
LIST NEWSGROUPS [wildmat] LIST NEWSGROUPS [wildmat]
The newsgroups file is maintained by some news transport
systems to contain the name of each newsgroup that is active
on the server and a short description about the purpose of
each newsgroup. Each line in the file contains two fields,
the newsgroup name and a short explanation of the purpose of
that newsgroup. The first field is separated from the second
field by one or more US-ASCII spaces. When executed, the
information is displayed following the 215 response. When
display is completed, the server will send a period on a line
by itself. If the information is not available, the server
will return the 503 response. If the server does not
recognize the command it should return a 501 response. If the
optional wildmat parameter is specified, the list is limited
to only those groups that match the wildmat (no matching is
done on the group descriptions). If nothing is matched an
empty list is returned, not an error.
9.4.5.1 Responses
215 Information Follows (multi-line response) Responses
501 Syntax error 215 Information follows (multiline)
503 Program error, function not performed 503 Facility not available
Parameters
wildmat = groups of interest
9.4.5.2 Examples 8.6.5.2 Description
The newsgroups file is maintained by some news transport systems to
contain the name of each newsgroup that is available on the server
and a short description about the purpose of the group. Each line of
this file consists of two fields separated from each other by one or
more US-ASCII space characters. The first field is the name of the
newsgroup and the second is a short description of the group. Note
that an empty list is a possible valid response, and indicates that
there are currently no valid newsgroups.
If the information is available, it is returned as a multi-line
response following the 215 response code. If the information is not
available, a 503 response MUST be returned. If the server does not
recognize the command, a 501 response MUST be returned.
If the optional wildmat parameter is specified, the list is limited
to only the groups whose names match the wildmat.
8.6.5.3 Examples
Example of LIST NEWSGROUPS returning a list of newsgroups:
Example of LIST NEWSGROUPS returning a list of newsgroups
[S] 200 NNTP Service Ready
[C] LIST NEWSGROUPS [C] LIST NEWSGROUPS
[S] 215 information follows [S] 215 information follows
[S] misc.test General Usenet testing [S] misc.test General Usenet testing
[S] alt.rfc-writers.recovery RFC Writers Recovery [S] alt.rfc-writers.recovery RFC Writers Recovery
Feather [Page 45]
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
[S] tx.natives.recovery Texas Natives Recovery [S] tx.natives.recovery Texas Natives Recovery
[S] . [S] .
Example of LIST NEWSGROUPS returning an error (e.g. The
server software recognizes the command as valid, but the Example of LIST NEWSGROUPS returning an error where the command is
information is not available.) recognised but the software does not maintain this information:
[S] 200 NNTP Service Ready
[C] LIST NEWSGROUPS [C] LIST NEWSGROUPS
[S] 503 program error, function not performed [S] 503 program error, function not performed
9.5 Standard extensions Example of LIST NEWSGROUPS sent to a server that does not recognize
this command:
Each of the following sections describes an extension that a [C] LIST NEWSGROUPS
server MAY provide. If the server provides the extension, it [S] 501 Syntax error
MUST include the appropriate extension label in the response
to LIST EXTENSIONS. If it does not provide it, it MUST NOT
include the appropriate extension label. The descriptions of
facilities in each section are written as if the extension is
provided. If it is not provided, the entire section should be
ignored.
9.5.1 LISTGROUP extension 9. The CONCLUSION step
This extension provides one command and has the extension 9.1 QUIT
label LISTGROUP.
9.5.1.1 The LISTGROUP Command 9.1.1 Usage
Syntax
QUIT
Responses
205 Connection closing
9.1.2 Description
The server process MUST acknowledge the QUIT command and then close
the connection to the client. This is the preferred method for a
client to indicate that it has finished all its transactions with the
NNTP server.
If a client simply disconnects (or the connection times out or some
other fault occurs), the server MUST gracefully cease its attempts to
service the client, disconnecting from its end if necessary.
9.1.3 Examples
[C] QUIT
[S] 205 closing connection
[Server closes connection.]
10. Framework for NNTP extensions
Although NNTP is widely and robustly deployed, some parts of the
Internet community might wish to extend the NNTP service. This
document defines a means whereby an extended NNTP client can query
the server to determine the service extensions that it supports.
It must be emphasized that any extension to the NNTP service should
not be considered lightly. NNTP's strength comes primarily from its
simplicity. Experience with many protocols has shown that:
Protocols with few options tend towards ubiquity, whilst protocols
with many options tend towards obscurity.
This means that each and every extension, regardless of its benefits,
must be carefully scrutinized with respect to its implementation,
deployment, and interoperability costs. In many cases, the cost of
extending the NNTP service will likely outweigh the benefit.
Given this environment, the framework for extensions described in
this document consists of:
o a mechanism for clients to determine a server's available
extensions
o a registry of NNTP service extensions
The LIST EXTENSIONS command is described in this document (see
Section 6.1) and is the mechanism for clients to use to determine
what extensions are available.
The IANA shall maintain a registry of NNTP service extensions.
An extension is identified by a unique extension-label, which is a
string of 1 to 12 uppercase letters. The extension-label will often
be the name of a new command that the extension adds. However this
is not a requirement: an extension might not add any new commands or
keywords.
An extension is either a private extension or else it is included in
the IANA registry and is defined in an RFC. Such RFCs either must be
on the standards-track or must define an IESG-approved experimental
protocol.
The definition of an extension must include:
o a descriptive name for the extension
o the extension-label (which is returned by LIST EXTENSIONS to
indicate to the client that the server supports this particular
extension)
o the syntax, values, and meanings of any parameters following the
extension-label in the output of LIST EXTENSIONS
o any new NNTP commands associated with the extension
o the syntax and possible values of parameters associated with the
new NNTP commands
o any new parameters the extension associates with any other
pre-existing NNTP commands
o how support for the extension affects the behavior of a server and
NNTP client
o any increase in the maximum length of commands over the value
specified in this document
o a specific statement about the effect on pipelining this extension
may have (if any)
The extension-label of private extensions MUST begin with "X". The
extension-label of registered extensions MUST NOT begin with "X".
A server MUST NOT provide any extension, whether or not listed in the
output from LIST EXTENSIONS, unless it is either a registered
extension or a private extension.
Except where stated otherwise, the commands in this document are
understood (even if not supported) by all servers and are not
described in the list of features returned by the LIST EXTENSIONS
command.
A server MAY provide additional keywords - either for new commands or
new variants of existing commands - as part of a private extension.
These new keywords MUST begin with "X".
A server MUST NOT send different response codes to basic NNTP
commands documented here or commands documented in registered
extensions in response to the availability or use of a private
extension.
10.1 Initial IANA registry
The IANA's initial registry of NNTP service extensions consists of
these entries:
Extension Label Added behavior
Specific article numbers LISTGROUP Defined in this document
Overview support OVER Defined in this document
Header pattern matching HDR Defined in this document
10.2 Standard extensions
Each of the following sections describes an extension that a server
MAY provide. If the server provides the extension, it MUST include
the appropriate extension label in the response to LIST EXTENSIONS.
If it does not provide it, it MUST NOT include the appropriate
extension label. The descriptions of facilities in each section are
written as if the extension is provided. If it is not provided, the
entire section should be ignored.
If the server provides an extension, it MUST implement all of the
commands in the specification of the extension except for those
marked as optional. If it does not provide an extension, it MUST NOT
implement any of the commands in the specification of that extension.
10.3 The LISTGROUP extension
This extension provides one command and has the extension label
LISTGROUP.
10.3.1 LISTGROUP
10.3.1.1 Usage
Syntax
LISTGROUP [ggg] LISTGROUP [ggg]
The LISTGROUP command is used to get a listing of all the
article numbers in a particular newsgroup.
The optional parameter ggg is the name of the newsgroup to be Responses
selected (e.g. "news.software.misc"). A list of valid 211 Article numbers follow (multiline)
newsgroups may be obtained from the LIST command. If no group 411 No such newsgroup
is specified, the current group is used as the default 412 No newsgroup selected [1]
argument.
The successful selection response will be a list of the Parameters
article numbers in the group followed by a period on a line ggg = name of newsgroup
by itself. The list starts on the next line following the 211 [1] The 412 response can only occur if no group has been specified.
response code.
Feather [Page 46] 10.3.1.2 Description
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
When a valid group is selected by means of this command, the The LISTGROUP command is used to get a listing of all the article
internally maintained "current article pointer" MUST be set numbers in a particular newsgroup.
to the first article in the group and the name of the current
newsgroup MUST be set to the selected newsgroup name. If an
invalid group is specified, the previously selected group and
article remain selected. If an empty newsgroup is selected,
the "current article pointer" may be in an indeterminate
state and should not be used.
The LISTGROUP keyword MAY be used by a client as a The optional parameter ggg is the name of the newsgroup to be
replacement for the GROUP command in establishing a valid selected (e.g. "news.software.misc"). A list of valid newsgroups
"current article pointer." After a successful response is may be obtained from the LIST ACTIVE command. If no group is
received, any other command may be used that depends on specified, the current selected newsgroup is used.
having the "current article pointer" be valid.
If a group name is specified and that group is not available OUTSTANDING ISSUE
on that server, the server MUST respond with the 411 error
code.
A server that does not implement this command SHOULD return a On at least some servers the 211 response line is the same as with
500 error response. GROUP. Should this be a requirement?
9.5.1.1.1 Responses
211 List of article numbers follow (multi-line The list of article numbers is returned as a multi-line response
response) following the 211 response code. It contains one number per line, is
411 No such group in numerical order, and lists precisely those articles that exist in
412 No newsgroup currently selected the group.
500 Command not recognized
9.5.1.1.2 Examples When a valid group is selected by means of this command, the current
selected newsgroup MUST be set to that group and the current article
number MUST be set to the first article in the group. If an empty
newsgroup is selected, the current article pointer is made invalid.
If an invalid group is specified, the current selected newsgroup and
current article number MUST NOT be changed.
The LISTGROUP command MAY be used by a client as a replacement for
the GROUP command in establishing a valid current selected newsgroup
and current article number.
If the group specified is not available on the server, a 411 response
MUST be returned. If no group is specified and the current selected
newsgroup is invalid, a 412 response MUST be returned.
10.3.1.3 Examples
Example of LISTGROUP on an empty group: Example of LISTGROUP on an empty group:
[S] 200 NNTP Service Ready
[C] LISTGROUP example.empty.newsgroup [C] LISTGROUP example.empty.newsgroup
[S] 211 list of article numbers follows [S] 211 list of article numbers follows
[S] . [S] .
Example of LISTGROUP on a valid current group:
[S] 200 NNTP Service Ready
[C] GROUP misc.test
[S] 211 2000 3000234 3002322 misc.test selected
Feather [Page 47] Example of LISTGROUP on a valid current selected newsgroup:
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
[C] GROUP misc.test
[S] 211 2000 3000234 3002322 misc.test selected
[C] LISTGROUP [C] LISTGROUP
[S] 211 list follows [S] 211 list follows
[S] 3000234 [S] 3000234
[S] 3000237 [S] 3000237
[S] 3000238 [S] 3000238
[S] 3000239 [S] 3000239
[S] 3002322 [S] 3002322
[S] . [S] .
Example of LISTGROUP failing because no group has been
selected: Example of LISTGROUP failing because no group has been selected:
[S] 200 NNTP Service Ready
[Assumes current selected newsgroup is invalid.]
[C] LISTGROUP [C] LISTGROUP
[S] 412 no current group [S] 412 no current group
[C] GROUP example.is.sob.bradner.or.barber [C] GROUP example.is.sob.bradner.or.barber
[S] 411 no such group [S] 411 no such group
[C] LISTGROUP [C] LISTGROUP
[S] 412 no current group [S] 412 no current group
9.5.2 The OVER Extension 10.4 Article metadata
This extension provides two commands, OVER and LIST The OVER and HDR extensions refer to the concept of "article
OVERVIEW.FMT. The label for this extension is OVER. metadata". This is data about articles that does not occur within
9.5.2.1 LIST OVERVIEW.FMT the article itself. Each metadata item has a name which MUST begin
with a colon. Note that a historical feature of the LIST
OVERVIEW.FMT command means that metadata names SHOULD NOT end with
":full".
LIST OVERVIEW.FMT When generating a metadata item, the server MUST compute it for
The overview.fmt file is maintained by some news transport itself and MUST NOT trust any related value provided in the article.
systems to contain the order in which header information is (In particular, a Lines: or Bytes: header in the article MUST NOT be
stored in the overview databases for each newsgroup. When assumed to specify the correct number of lines or bytes in the
executed, news article header fields are displayed one line article.)
at a time in the order in which they are stored in the
overview database[9] following the 215 response. When
display is completed, the server will send a period on a line
by itself. If the information is not available, the server
will return the 503 response.
If the header has the word "full" (without quotes) after the This specification defines two metadata items: ":bytes" and ":lines".
colon, the header's name is prepended to its field in the Implementations and other extensions may define other metadata items.
output returned by the server.
This is command is part of the optional OVER extension which 10.4.1 The :bytes metadata item
includes the OVER command defined in section . If the OVER
Feather [Page 48] The :bytes metadata item for an article is a decimal integer. It
INTERNET DRAFT C. Feather MUST equal the number of octets in the entire article - headers,
Expires: July 31, 2003 Thus plc body, and separating blank line - except that the US-ASCII CRLF at
January 2003 the end of each line MAY (but SHOULD NOT) be counted as a single
octet.
extension is not implemented, then this command MUST NOT be OUTSTANDING ISSUE
implemented. If that case, the server MUST return a 501 error
response when this command is presented by the client.
9.5.2.1.1 Responses Should this be called ":octets" instead? Or should it be a count
of UTF characters rather than octets?
215 Information follows (multi-line response) 10.4.2 The :lines metadata item
501 Syntax Error
503 Program error, function not performed
9.5.2.1.2 Examples The :lines metadata item for an article is a decimal integer. It
MUST equal the number of lines in the article body (excluding the
blank line separating headers and body); equivalently, it is two less
than the number of US-ASCII CRLF pairs that the BODY command would
return for that article (the extra two are those following the
response code and the termination octet).
Example of LIST OVERVIEW.FMT returning a list of newsgroups 10.5 The OVER extension
[S] 200 NNTP Service Ready
[C] LIST OVERVIEW.FMT This extension provides two commands, OVER and LIST OVERVIEW.FMT.
[S] 215 Order of fields in overview database. The label for this extension is OVER.
[S] Subject:
[S] From: The OVER extension provides access to the overview database [8],
[S] Date: which is a database of header lines extracted from incoming articles.
[S] Message-ID: Only certain headers are included in the database. The database also
[S] . includes some article metadata.
Example of LIST OVERVIEW.FMT returning an error
[S] 200 NNTP Service Ready The information stored in the database may change over time. The
[C] LIST OVERVIEW.FMT LIST OVERVIEW.FMT command describes the information that would be
[S] 503 program error, function not performed stored for an article arriving at the same time as the command was
9.5.2.2 OVER executed.
10.5.1 OVER
10.5.1.1 Usage
Syntax
OVER [range] OVER [range]
The OVER command returns specific header information for the
article(s) specified from the current selected group. The
information returned in the response to this command can be
used by clients to follow discussion threads.
The optional range argument may be any of the following:
* an article number
* an article number followed by a dash to indicate all
following
* an article number followed by a dash followed by another
article number
Feather [Page 49] Responses
INTERNET DRAFT C. Feather 224 Overview information follows (multiline)
Expires: July 31, 2003 Thus plc 412 No newsgroup selected
January 2003 420 Current article number is invalid
423 No articles in that range
If no argument is specified, then information from the Parameters
current article is displayed. Successful responses start with range = Article(s) to return information for
a 224 response followed by the overview information for all
matched messages. Once the output is complete, a period is
sent on a line by itself. A newsgroup must have been selected
earlier, else a 412 error response is returned. If no
articles are in the range specified, the server returns a 420
error response. A 502 response will be returned if the client
only has permission to transfer articles. A 500 response
SHOULD be returned by servers that do not implement this
command.
The output consists of one line per article, sorted in 10.5.1.2 Description
numerical order of article number. Each line consists of a
number of fields separated by an US-ASCII TAB character. The
first 8 fields MUST be the following, in order: article
number, subject, author, date, message-ID, references, byte
count, line count.
The article number field should contain the article number The OVER command returns the contents of the headers and metadata in
(within the group). The line count and byte count are the database for the article(s) specified from the current selected
calculated by the server based on the actual size and number newsgroup.
of lines in the article. The content of the rest of the
fields is formed by taking the original header content (such
as the raw subject line from the article), removing all US-
ASCII CRLF pairs, and then replacing each remaining US-ASCII
NUL, TAB, CR, or LF character with a single US-ASCII space.
The content of any subsequent field is given by the response
to the LIST OVERVIEW.FMT command. A field may be empty (in
which case there will be two adjacent US-ASCII tabs, and a
sequence of trailing US-ASCII tabs may be omitted).
The server SHOULD not produce output for articles that no
longer exist.
9.5.2.2.1 Responses
224 Overview information follows (multi-line The optional range argument may be any of the following:
response)
412 No newsgroup currently selected
420 No article(s) selected
500 Command not recognized
502 Program error, functions no performed
Feather [Page 50] o an article number
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
9.5.2.2.2 Examples o an article number followed by a dash to indicate all following
Example of a successful retrieval of overview information for o an article number followed by a dash followed by another article
an article (using no article number) number
[S] 200 NNTP Service Ready
[C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test
[C] OVER
[S] 224 Overview information follows
300234|I am just a test article|÷Demo User÷
<nobody@example.com>|6 Oct 1998 04:38:40 -0500|
<45223423@example.com>|<45454@example.net>|1234|
17|Xref: news.example.com misc.test:3000363
[S] .
[Please note that the line that begins with 300234 is all one
line that has been wrapped for readability. A vertical bar
has been inserted to show where the US-ASCII TAB should
actually be.]
Example of an unsuccessful retrieval of overview information
on an article by number
[S] 200 NNTP Service Ready
[C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test
[C] OVER 300256
[S] 420 No such article in this group
Example of an unsuccessful retrieval of overview information
by number because no newsgroup was selected first
[S] 200 NNTP Service Ready
[C] OVER
[S] 412 No newsgroup selected
Example of an attempt to retrieve an article when the current
group selected is empty
[S] 200 NNTP Service Ready
[C] GROUP example.empty.newsgroup
[S] 211 0 0 0 example.empty.newsgroup
[C] OVER
[S] 420 No current article selected
9.5.3 The HDR Extension If no argument is specified, then the current article number is used.
Feather [Page 51] If the information is available, it is returned as a multi-line
INTERNET DRAFT C. Feather response following the 224 response code. If the current selected
Expires: July 31, 2003 Thus plc newsgroup is invalid, a 412 response MUST be returned. If there are
January 2003 no articles in the range specified, a 423 response MUST be returned.
If OVER is sent without any arguments and the current article number
is invalid, a 420 response MUST be returned. If the client does not
have permission to access the overview database, a 502 response MUST
be returned.
This extension provides one new command, HDR. The label for OUTSTANDING ISSUE
this extension is HDR
9.5.3.1 HDR
HDR header range|<message-id> Should this be 502 ("not permitted") or 503 ("there is no overview
The HDR command is used to retrieve specific headers from database")? In which case, why provide the command?
specific articles in the currently selected group.
The required header parameter is the name of a header line For a successful response, the output consists of one line per
(e.g. "subject") in a newsgroup article. See RFC-1036 for a article, sorted in numerical order of article number. Each line
list of valid header lines. The required range argument may consists of a number of fields separated by an US-ASCII TAB
be any of the following: character. A field may be empty (in which case there will be two
* an article number adjacent US-ASCII TABs), and a sequence of trailing US-ASCII TABs may
* an article number followed by a dash to indicate all be omitted.
following
* an article number followed by a dash followed by another
article number.
The required message-id argument indicates a specific The first 8 fields MUST be the following, in order:
article. The range and message-id arguments are mutually
exclusive.
A successful response consists of a 221 code followed by the article number
output from the command. The output consists of one line for "Subject" header
each article where the relevant header line exists. The line "From" header
consists of the article number, a US-ASCII space, and then "Date" header
the contents of the header (without the header name). A valid "Message-ID" header
response includes an empty list (indicating that there were "References" header
no matches). Once the output is complete, a period is sent on :bytes metadata item
a line by itself. If the optional argument is a message-id :lines metadata item
and no such article exists, a 430 error response shall be Any subsequent fields are the contents of the other headers and
returned. A 502 response shall be returned if the client only metadata held in the database.
has permission to transfer articles. A 500 response SHOULD be
issued by all servers that do not recognize this command.
9.5.3.1.1 Responses
221 Header follows (multi-line response) For the five mandatory headers, the content of each field MUST be
412 No newsgroup selected based on the original header with the header name and following colon
430 No such article and space removed. If the article does not contain that header, or
500 Command not recognized if there is nothing following the colon and space, the field MUST be
empty. For the two mandatory metadata items, the content of the
field MUST be just the value, with no other text.
Feather [Page 52] For all subsequent fields that contain headers, the content MUST be
INTERNET DRAFT C. Feather based on the entire header including the name. For all subsequent
Expires: July 31, 2003 Thus plc fields that contain metadata, the field consists of the metadata
January 2003 name, a single US-ASCII space, and then the value.
502 Program error, function not performed For all fields, the value is processed by first removing all US-ASCII
CRLF pairs and then replacing each remaining US-ASCII NUL, TAB, CR,
or LF character with a single US-ASCII space (for example, CR LF LF
TAB will become two spaces). If there is no such header in the
article, or no such metadata item, or no header or item stored in the
database for that article, the corresponding field MUST be empty.
9.5.3.1.2 Examples The server SHOULD NOT produce output for articles that no longer
exist.
10.5.1.3 Examples
In the first two examples, US-ASCII tab has been replaced by vertical
bar and some lines have been folded for readability.
Example of a successful retrieval of overview information for an
article (using no article number):
Example of a successful retrieval of subject lines from a
range of articles
[S] 200 NNTP Service Ready
[C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test
[C] HDR Subject 3000234-300238
[S] 221 Header Follows
[S] 3000234 I am just a test article
[S] 3000237 Re: I am just a test article
[S] 3000238 Ditto
[S] .
Example of a successful retrieval of header from an article
by message-id
[S] 200 NNTP Service Ready
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
[C] HDR subject <i.am.a.test.article@example.com> [C] OVER
[S] 221 Header information follows [S] 224 Overview information follows
[S] 3000345 I am just a test article [S] 300234|I am just a test article|"Demo User"
<nobody@example.com>|6 Oct 1998 04:38:40 -0500|
<45223423@example.com>|<45454@example.net>|1234|
17|Xref: news.example.com misc.test:3000363
[S] . [S] .
Example of an unsuccessful retrieval of a header from an
article by message-id
[S] 200 NNTP Service Ready
[C] HDR subject <i.am.not.there@example.com>
[S] 430 No Such Article Found
Example of an unsuccessful retrieval of headers from articles
by number because no newsgroup was selected first
[S] 200 NNTP Service Ready
[C] HDR subject 300256-
[S] 412 No newsgroup selected
Example of an unsuccessful retrieval of headers from articles
by message-id because no newsgroup was selected first
[S] 200 NNTP Service Ready
[C] HDR subject <i.am.a.test.article@example.com>
[S] 412 No newsgroup selected
Example of retrieving header information when the current
group selected is empty
Feather [Page 53] Example of a successful retrieval of overview information for a range
INTERNET DRAFT C. Feather of articles:
Expires: July 31, 2003 Thus plc
January 2003
[S] 200 NNTP Service Ready [C] GROUP misc.test
[C] GROUP example.empty.newsgroup
[S] 211 0 0 0 example.empty.newsgroup
[C] HDR subject 0-
[S] 221 Headers follow
.
Example of a failure due to restrictions configured into the
server
[S] 200 NNTP Service Ready
[C] GROUP news.group
[S] 211 1234 3000234 3002322 misc.test [S] 211 1234 3000234 3002322 misc.test
[C] HDR Subject 3000234-300238 [C] OVER 3000234-3000240
[S] 502 Service Unavailable [S] 224 Overview information follows
[S] 300234|I am just a test article|"Demo User"
<nobody@example.com>|6 Oct 1998 04:38:40 -0500|
<45223423@example.com>|<45454@example.net>|1234|
17|Xref: news.example.com misc.test:3000363
[S] 3000235|Another test article|nobody@nowhere.to
(Demo User)|6 Oct 1998 04:38:45 -0500|<45223425@to.to>||
4818|37||Distribution: fi
[S] 3000238|Re: I am just a test article|somebody@elsewhere.to|
7 Oct 1998 11:38:40 +1200|<kfwer3v@elsewhere.to>|
<45223423@to.to>|9234|51
[S] .
10 The CONCLUSION Step Note the missing "References" and Xref headers in the second line,
the missing trailing field(s) in the first and last lines, and that
there are only results for those articles that still exist.
10.1 QUIT Example of an unsuccessful retrieval of overview information on an
article by number:
QUIT [C] GROUP misc.test
The server process MUST acknowledge the QUIT command and then [S] 211 1234 3000234 3002322 misc.test
close the connection to the client. This is the preferred [C] OVER 300256
method for a client to indicate that it has finished all its [S] 420 No such article in this group
transactions with the NNTP server.
If a client simply disconnects (or the connection times out Example of an unsuccessful retrieval of overview information by
or some other fault occurs), the server MUST gracefully cease number because no newsgroup was selected first:
its attempts to service the client, disconnecting from its
end if necessary.
10.1.1 Responses [Assumes current selected newsgroup is invalid.]
[C] OVER
[S] 412 No newsgroup selected
250 Connection closing Example of an attempt to retrieve information when the current
selected newsgroup is empty:
10.1.2 Example [C] GROUP example.empty.newsgroup
[S] 211 0 0 0 example.empty.newsgroup
[C] OVER
[S] 420 No current article selected
[S] 200 NNTP Service Ready 10.5.2 LIST OVERVIEW.FMT
[C] QUIT
[S] 205 closing connection
[Server closes connection.]
11 Other Keywords 10.5.2.1 Usage
Syntax
LIST OVERVIEW.FMT
Feather [Page 54] Responses
INTERNET DRAFT C. Feather 215 Information follows (multiline)
Expires: July 31, 2003 Thus plc 503 Facility not available
January 2003
There are other keywords that may be used at any time between 10.5.2.2 Description
the beginning of a session and its termination. Using these
keywords does not alter any state information, but the
response generated from the use of these keywords may provide
useful information to clients that use them.
11.1 DATE OUTSTANDING ISSUE
DATE Should this be optional even when the OVER extension is provided?
This command exists to help clients find out the current If so, is there a point in the 503 response?
Coordinated Universal Time[10] from the server's perspective.
This command MUST NOT be used as a substitute for NTP[11],
but to provide information that might be useful when using
the NEWNEWS command (see section 11.4). A system providing
NNTP service SHOULD implement NTP for the purposes of keeping
the system clock as accurate as possible.
This command returns a one-line response code of 111 followed The LIST OVERVIEW.FMT command returns a description of the fields in
by the date and time on the server in the form the database. The fields MUST be listed in the order that they will
YYYYMMDDhhmmss. This date and time is presented in be returned by the OVER command for a newly-received article (the
Coordinated Universal Time. information stored for articles may change over time).
11.1.1 Response If the information is available, it is returned as a multi-line
response following the 215 response code. If the information is not
available, a 503 response MUST be returned. The information contains
one line per field in the order they are returned by the OVER
command; he first 7 lines MUST be exactly:
111 YYYYMMDDhhmmss Current date and time on server Subject:
presented in Coordinated From:
Universal Time Date:
Message-ID:
References:
:bytes
:lines
11.1.2 Example except that, for compatibility with existing implementations, the
last two lines MAY instead be:
[S] 200 NNTP Service Ready Bytes:
[C] DATE Lines:
[S] 111 19990623135624
11.2 The HELP Command even though they refer to metadata, not headers.
HELP All subsequent lines MUST consist of either a header name followed by
This command provides a short summary of commands that are ":full", or the name of a piece of metadata.
understood by this implementation of the server. The help
text will be presented as a textual response terminated by a
single period on a line by itself.
Feather [Page 55] There are no leading or trailing spaces in the output.
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
This text is not guaranteed to be in any particular format Note that the 7 fixed lines describe the 2nd to 8th fields of the
and SHALL NOT be used by clients as a replacement for the OVER output. The "full" suffix is a reminder that the corresponding
LIST EXTENSIONS command described in section 8.1. fields include the header name.
11.2.1 Responses This command MAY generate different results if used more than once in
a session.
100 Help text follows (multi-line response) 10.5.2.3 Examples
11.2.2 Example Example of LIST OVERVIEW.FMT output corresponding to the example OVER
output above, using the preferred format:
[S] 200 NNTP Service Ready [C] LIST OVERVIEW.FMT
[C] HELP [S] 215 Order of fields in overview database.
[S] 100 Help text follows [S] Subject:
[S] This is some help text. There is no specific [S] From:
[S] formatting requirement for this test, though [S] Date:
[S] it is customary for it to list the valid commands [S] Message-ID:
[S] and give a brief definition of what they do [S] References:
[S] :bytes
[S] :lines
[S] Xref:full
[S] Distribution:full
[S] . [S] .
11.3 NEWGROUPS Example of LIST OVERVIEW.FMT output corresponding to the example OVER
output above, using the alternative format:
NEWGROUPS date time [GMT] [C] LIST OVERVIEW.FMT
A list of newsgroups created since <date and time> MUST be [S] 215 Order of fields in overview database.
listed in the same format as the LIST command. [S] Subject:
[S] From:
[S] Date:
[S] Message-ID:
[S] References:
[S] Bytes:
[S] Lines:
[S] Xref:full
[S] Distribution:full
[S] .
The date is sent as 6 or 8 digits in the format [XX]YYMMDD, Example of LIST OVERVIEW.FMT returning an error:
where XX is the first two digits of the year, YY is the last
two digits of the year, MM is the two digits of the month
(with leading zero, if appropriate), and DD is the day of the
month (with leading zero, if appropriate). If the first two
digits of the year are not specified, the year is to be taken
from the current century if YY is smaller than or equal to
the current year, otherwise the year is from the previous
century.
Time must also be specified. It must be as 6 digits HHMMSS [C] LIST OVERVIEW.FMT
with HH being hours in the 24-hour clock 00-23, MM minutes [S] 503 overview.fmt not available
00-59, and SS seconds 00-60, which allows for leap seconds.
The token "GMT" specifies that the date and time are given in
Coordinated Universal Time. If the token "GMT" is omitted
then the date and time are specified in the server's local
timezone. Note that there is no way using the protocol
Feather [Page 56] 10.6 The HDR extension
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
specified in this memo to establish the server's local This extension provides one new command: HDR. The label for this
timezone. extension is HDR.
Note that an empty list (i.e., the text body returned by this 10.6.1 HDR
command consists only of the terminating period) is a
possible valid response, and indicates that there are
currently no new newsgroups.
Clients SHOULD make all queries using Coordinated Universal 10.6.1.1 Usage
Time (i.e. by including the ˘GMT÷ parameter) when possible.
11.3.1 Responses Syntax
HDR header range
HDR header message-id
HDR header
231 List of new newsgroups follows (multi-line Responses
response)
11.3.2 Examples First form (range specified)
225 Headers follow (multiline)
412 No newsgroup selected
423 No articles in that range
Example where there are new groups Second form (message-id specified)
[S] 200 NNTP Service Ready 225 Headers follow (multiline)
[C] NEWGROUPS 19990624 000000 GMT 430 No article with that message-id
[S] 231 list of new newsgroups follows
[S] alt.rfc-writers.recovery
[S] tx.natives.recovery
[S] .
Example where there are no new groups
[S] 200 NNTP Service Ready
[C] NEWGROUPS 19990624 000000 GMT
[S] 231 list of new newsgroups follows
[S] .
11.4 NEWNEWS Third form (current article number used)
225 Headers follow (multiline)
412 No newsgroup selected
420 Current article number is invalid
NEWNEWS wildmat date time [GMT] Parameters
A list of message-ids of articles posted or received on the header = name of header, without the colon
server to the list of newsgroups that match the wildmat since range = number(s) of articles
"date" will be listed. The format of the listing will be one message-id = message-id of article
message-id per line, as though text were being sent. The
order of the response has no specific significance and may
vary from response to response in the same session. If a
message-id appears more than once it has the same meaning as
Feather [Page 57] 10.6.1.2 Description
INTERNET DRAFT C. Feather
Expires: July 31, 2003 Thus plc
January 2003
if it appears only once. A single line consisting solely of The HDR command retrieves specific headers from an article or
one period followed by CR-LF will terminate the list. specified range of articles in the current selected newsgroup, or
from an article specified by message-id. It can also return certain
metadata about the article or articles.
Date and time are in the same format as the NEWGROUPS The required header parameter is the name of a header (e.g.
command. "subject") in an article, or the name of a metadata item, and is
case-insensitive. See RFC 1036 [6] for a list of valid header lines.
Names of metadata items always include a colon. Except where stated
otherwise, metadata items are treated as if they were header values,
and references to headers in this description apply equally to
metadata items.
Note that an empty list (i.e., the text body returned by this OUTSTANDING ISSUE
command consists only of the terminating period) is a
possible valid response, and indicates that there is
currently no new news.
Clients SHOULD make all queries in Coordinated Universal Time Should this be changed to require the name to *begin* with a
(i.e. by using the ˘GMT÷ parameter) when possible. colon?
11.4.1 Responses The range parameter may be any of the following:
230 List of new articles by message-id follows (may be a o an article number
multi-line response)
11.4.2 Examples o an article number followed by a dash to indicate all following
Example where there are new articles o an article number followed by a dash followed by another article
[S] 200 NNTP Service Ready number
[C] NEWNEWS news.*,sci.* 19990624 000000 GMT
[S] 230 list of new articles by message-id follows
[S] <i.am.a.new.article@example.com>
[S] <i.am.another.new.article@example.com>
Example where there are no new articles The message-id argument indicates a specific article. As shown by
[S] 200 NNTP Service Ready the syntax, the range and message-id arguments are mutually
[C] NEWNEWS alt.* 19990624 000000 GMT exclusive; if neither are specified, the current article number is
[S] 230 list of new articles by message-id follows used.
[S] .
12 Framework for NNTP Extensions If the information is available, it is returned as a multi-line
response following the 225 response code and contains one line for
each article where the relevant header line exists. The line
consists of the article number, a US-ASCII space, and then the
contents of the header (without the header name or the colon and
space that follow it) or metadata item. If the article is specified
by message-id rather than by article range, the article number is
given as "0".
Although NNTP is widely and robustly deployed, some parts of Header contents are modified as follows: all US-ASCII CRLF pairs are
the Internet community might wish to extend the NNTP service. removed, and then each remaining US-ASCII NUL, TAB, CR, or LF
This memo defines a means whereby an extended NNTP client may character is replaced with a single US-ASCII space. (Note that this
query the server to determine the service extensions that it is the same transformation as is performed by the OVER extension.)
supports.
Feather [Page 58] The header content is in all cases taken from the article. This
INTERNET DRAFT C. Feather means that, for example, a request for the header "Lines" returns the
Expires: July 31, 2003 Thus plc contents of the "Lines" header of the specified articles, if any, not
January 2003 the line count metadata or any other server-generated value. If the
header occurs in a given article multiple times, only the value of
the first occurrence is returned by HDR.
It must be emphasized that any extension to the NNTP service If the requested header is not present in the article or if it is
should not be considered lightly. NNTP's strength comes present but empty, a line for that article is included in the output
primarily from its simplicity. Experience with many but the header content portion of the line is empty (the space after
protocols has shown that: the article number MAY be retained or omitted). If any article
number in the provided range does not exist in the group, no line for
that article number is included in the output.
Protocols with few options tend towards ubiquity, whilst If the optional argument is a message-id and no such article exists,
protocols with many options tend towards obscurity. a 430 response MUST be returned. If the optional argument is not a
message-id and the current selected newsgroup is invalid, a 412
response MUST be returned. If the optional argument is an article
number or number range and no article with that number or in that
number range exists in the current selected newsgroup, a 423 response
MUST be returned. If HDR is sent without any arguments and the
current article number is invalid, a 420 response MUST be returned.
A server MAY only allow HDR commands for a limited set of headers and
metadata items (such as those present in the overview database). If
so, it MUST respond with a 503 response to attempts to request other
headers, rather than returning erroneous results such as a successful
empty response.
This means that each and every extension, regardless of its 10.6.1.3 Examples
benefits, must be carefully scrutinized with respect to its
implementation, deployment, and interoperability costs. In
many cases, the cost of extending the NNTP service will
likely outweigh the benefit.
Given this environment, the framework for the extensions Example of a successful retrieval of subject lines from a range of
described in this memo consists of: articles (3000235 has no Subject header, and 3000236 is missing):
* a mechanism for clients to determine a server's available
extensions
* a registry of NNTP service extensions
The LIST EXTENSIONS command is described in section 8.1 of [C] GROUP misc.test
this memo and is the mechanism for clients to use to [S] 211 1234 3000234 3002322 misc.test
determine what extensions are available for client use. [C] HDR Subject 3000234-300238
[S] 225 Headers follow
[S] 3000234 I am just a test article
[S] 3000235
[S] 3000237 Re: I am just a test article
[S] 3000238 Ditto
[S] .
The IANA shall maintain a registry of NNTP service Example of a successful retrieval of line counts from a range of
extensions. articles:
An extension is identified by a unique extension-label, which [C] GROUP misc.test
is a string of 1 to 12 uppercase letters. The extension-label [S] 211 1234 3000234 3002322 misc.test
will often be the name of a new command that the extension [C] HDR :lines 3000234-300238
adds. However this is not a requirement: an extension might [S] 225 Headers follow
not add any new commands or keywords. [S] 3000234 42
[S] 3000235 5
[S] 3000237 11
[S] 3000238 2378
[S] .
An extension is either a private extension or else it is Example of a successful retrieval of the subject line from an article
included in the IANA registry and is defined in an RFC. Such by message-id:
RFCs either must be on the standards-track or must define an
IESG-approved experimental protocol.
The definition of an extension must include: [C] GROUP misc.test
* a descriptive name for the extension [S] 211 1234 3000234 3002322 misc.test
[C] HDR subject <i.am.a.test.article@example.com>
[S] 225 Header information follows
[S] 0 I am just a test article
[S] .
Feather [Page 59] Example of a successful retrieval of the subject line from the
INTERNET DRAFT C. Feather current article:
Expires: July 31, 2003 Thus plc
January 2003
* the extension-label (which is returned by LIST EXTENSIONS [C] GROUP misc.test
to indicate to the client that the server supports this [S] 211 1234 3000234 3002322 misc.test
particular extension) [C] HDR subject
* the syntax, values, and meanings of any parameters [S] 225 Header information follows
following the extension-label in the output of LIST [S] 3000234 I am just a test article
EXTENSIONS [S] .
* any new NNTP keywords associated with the extension
* the syntax and possible values of parameters associated
with the new NNTP keywords
* any new parameters the extension associates with any other
pre-existing NNTP keywords
* how support for the extension affects the behavior of a
server and NNTP client
* any increase in the maximum length of commands over the
value specified in this memo
* a specific statement about the effect on streaming this
extension may have (if any)
The extension-label of private extensions MUST begin with Example of an unsuccessful retrieval of a header from an article by
"X". The extension-label of registered extensions MUST NOT message-id:
begin with "X".
Any keyword values presented in the NNTP response that do not [C] HDR subject <i.am.not.there@example.com>
begin with "X" MUST correspond to a standard, standards- [S] 430 No Such Article Found
track, or IESG-approved experimental NNTP service extension
registered with IANA. A conforming server MUST NOT offer non
"X" prefixed keyword values that are not described in a
registered extension.
Except where stated otherwise, the commands in this memo are Example of an unsuccessful retrieval of headers from articles by
understood (even if not supported) by all servers and are not number because no newsgroup was selected first:
described in the list of features returned by the LIST
EXTENSIONS command.
A server MAY provide additional keywords - either new [Assumes current selected newsgroup is invalid.]
commands or new parameters to existing commands - as part of [C] HDR subject 300256-
a private extension. These new keywords MUST begin with "X". [S] 412 No newsgroup selected
A server MUST NOT send different response codes to basic NNTP Example of an unsuccessful retrieval of headers because the current
commands documented here or commands documented in registered selected newsgroup is empty:
extensions in response to the availability or use of a
private extension.
Feather [Page 60] [C] GROUP example.empty.newsgroup
INTERNET DRAFT C. Feather [S] 211 0 0 0 example.empty.newsgroup
Expires: July 31, 2003 Thus plc [C] HDR subject 1-
January 2003 [S] 423 No articles in that range
12.1 Initial IANA Registry Example of an unsuccessful retrieval of headers because the server
does not allow HDR commands for that header:
The IANA's initial registry of NNTP service extensions [C] GROUP misc.test
consists of these entries: [S] 211 1234 3000234 3002322 misc.test
Service Extension NNTP Extension Label Added Behavior [C] HDR Content-Type 3000234-300238
Overview Support OVER Defined in this memo [S] 503 HDR not permitted on Content-Type
Specific Article
LISTGROUP Defined in this memo
Numbers
Header Pattern
HDR Defined in this memo
Matching
13 Augmented BNF Syntax for NNTP Commands 11. Augmented BNF Syntax for NNTP Commands
This syntax defines the non-terminal "command". The non- This syntax defines the non-terminal "command-line". Note that ABNF
terminal "parameter" is used for command parameters whose strings are case insensitive.
syntax is specified elsewhere. The syntax is in alphabetical