draft-ietf-nntpext-base-15.txt   draft-ietf-nntpext-base-16.txt 
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Network News Transport Protocol Network News Transport Protocol
draft-ietf-nntpext-base-15.txt draft-ietf-nntpext-base-16.txt
1 Status of this memo 1 Status of this memo
This memo is an Internet-Draft and is in full conformance This memo is an Internet-Draft and is in full conformance
with Section 10 of RFC 2026. Internet-Drafts are working with Section 10 of RFC 2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its documents of the Internet Engineering Task Force (IETF), its
areas, and its working groups. Note that other groups may areas, and its working groups. Note that other groups may
also distribute working documents as Internet-Drafts. also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of Internet-Drafts are draft documents valid for a maximum of
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The list of Internet-Draft shadow directories can be accessed The list of Internet-Draft shadow directories can be accessed
at http://www.ietf.org/shadow.html. at http://www.ietf.org/shadow.html.
This section will be updated with the appropriate verbiage This section will be updated with the appropriate verbiage
from RFC 2223 should this memo have been found ready for from RFC 2223 should this memo have been found ready for
publication as an RFC. This update will include its standards publication as an RFC. This update will include its standards
track status. track status.
This memo is a product of the NNTP Working Group, chaired by This memo is a product of the NNTP Working Group, chaired by
Ned Freed and Stan Barber. Russ Allbery.
2 Abstract 2 Abstract
The Network News Transport Protocol has been in use in the The Network News Transport Protocol has been in use in the
Internet for a decade and remains one of the most popular Internet for a decade and remains one of the most popular
protocols (by volume) in use today. This memo is a protocols (by volume) in use today. This memo is a
replacement for RFC 977 and officially updates the protocol replacement for RFC 977 and officially updates the protocol
specification. It clarifies some vagueness in RFC 977, specification. It clarifies some vagueness in RFC 977,
includes some new base functionality and provides a specific includes some new base functionality and provides a specific
mechanism to add standardized extensions to NNTP. mechanism to add standardized extensions to NNTP.
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3 Introduction 3 Introduction
This memo specifies the Network News Transport Protocol This memo specifies the Network News Transport Protocol
(NNTP), which is used for the distribution, inquiry, (NNTP), which is used for the distribution, inquiry,
retrieval, and posting of net news articles using a reliable retrieval, and posting of net news articles using a reliable
stream-based mechanism. For news reading clients, NNTP stream-based mechanism. For news reading clients, NNTP
enables retrieval of news articles that are stored in a enables retrieval of news articles that are stored in a
central database, giving subscribers the ability to select central database, giving subscribers the ability to select
only those articles they wish to read. only those articles they wish to read.
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this memo are to be interpreted as described in "OPTIONAL" in this memo are to be interpreted as described in
RFC 2119[4]. RFC 2119[4].
An implementation is not compliant if it fails to satisfy one An implementation is not compliant if it fails to satisfy one
or more of the MUST requirements for this protocol. An or more of the MUST requirements for this protocol. An
implementation that satisfies all the MUST and all the SHOULD implementation that satisfies all the MUST and all the SHOULD
requirements for its protocols is said to be "unconditionally requirements for its protocols is said to be "unconditionally
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compliant"; one that satisfies all the MUST requirements but compliant"; one that satisfies all the MUST requirements but
not all the SHOULD requirements for NNTP is said to be not all the SHOULD requirements for NNTP is said to be
"conditionally compliant". "conditionally compliant".
For the remainder of this memo, the term "client host" refers For the remainder of this memo, the term "client host" refers
to a host making use of the NNTP service, while the term to a host making use of the NNTP service, while the term
"server host" refers to a host that offers the NNTP service. "server host" refers to a host that offers the NNTP service.
In addition, where examples of interactions between a client In addition, where examples of interactions between a client
host and a server host are provided a "[C]" will be used to 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 client host and a "[S]" will be used to
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NNTP service by listening on a TCP port. When a client host NNTP service by listening on a TCP port. When a client host
wishes to make use of the service, it MUST establish a TCP wishes to make use of the service, it MUST establish a TCP
connection with the server host by connecting to that host on connection with the server host by connecting to that host on
the same port on which the server is listening. This is the the same port on which the server is listening. This is the
CONNECTION step. When the connection is established, the CONNECTION step. When the connection is established, the
NNTP server host MUST send a greeting. This is the GREETING NNTP server host MUST send a greeting. This is the GREETING
step. The client host and server host SHOULD then exchange step. The client host and server host SHOULD then exchange
commands and responses (respectively) until the connection is commands and responses (respectively) until the connection is
closed or aborted. This final step is called the closed or aborted. This final step is called the
DISCONNECTION step. DISCONNECTION step.
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If there is a CONCLUSION step, it MUST immediately precede If there is a CONCLUSION step, it MUST immediately precede
the DISCONNECTION step. There MUST be only one CONNECTION, the DISCONNECTION step. There MUST be only one CONNECTION,
CONCLUSION and DISCONNECTION step for each NNTP session. All CONCLUSION and DISCONNECTION step for each NNTP session. All
other steps MAY be repeated as needed. For example, the other steps MAY be repeated as needed. For example, the
GREETING step may be repeated if the client makes use of 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 MODE READER command (See Section 7.2 for more on the MODE
READER command). READER command).
The character set for all NNTP commands is UTF-8. Commands in The character set for all NNTP commands is UTF-8. Commands in
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each being a stream of octets ending with 0x0D 0x0A (US-ASCII each being a stream of octets ending with 0x0D 0x0A (US-ASCII
CRLF). Apart from those line endings, the stream MUST NOT CRLF). Apart from those line endings, the stream MUST NOT
include the octets 0x00, 0x0A, or 0x0D (US-ASCII NUL, LF, and include the octets 0x00, 0x0A, or 0x0D (US-ASCII NUL, LF, and
CR). CR).
The first such line contains the response code as with a The first such line contains the response code as with a
single line response. single line response.
If any subsequent line begins with the "termination octet" If any subsequent line begins with the "termination octet"
(0x2E or US_ASCII "."), that line MUST be "byte-stuffed" by (0x2E or US_ASCII "."), that line MUST be "byte-stuffed" by
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pre-pending an additional termination octet (0x2E) to that pre-pending an additional termination octet (0x2E) to that
line of the response. line of the response.
The lines of the response MUST be followed by a terminating The lines of the response MUST be followed by a terminating
line consisting of a single termination octet (0x2E or line consisting of a single termination octet (0x2E or
US_ASCII ".")followed by CRLF in the normal way. Thus a US_ASCII ".")followed by CRLF in the normal way. Thus a
multi-line response is always terminated with the five octets multi-line response is always terminated with the five octets
"CRLF.CRLF" (in US-ASCII). "CRLF.CRLF" (in US-ASCII).
There is NO limit on the length of a line. There is NO limit on the length of a line.
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An NNTP server MAY have an inactivity autologout timer. Such An NNTP server MAY have an inactivity autologout timer. Such
a timer SHOULD be of at least three minutes duration, with a timer SHOULD be of at least three minutes duration, with
the exception that there MAY be a shorter limit on how long the exception that there MAY be a shorter limit on how long
the server is willing to wait for the first command from the the server is willing to wait for the first command from the
client. The receipt of any command from the client during client. The receipt of any command from the client during
the timer interval SHOULD suffice to reset the autologout the timer interval SHOULD suffice to reset the autologout
timer. Similarly, the receipt of any significant amount of timer. Similarly, the receipt of any significant amount of
data from the client while in the midst of sending a multi- data from the client while in the midst of sending a multi-
line message to the server (such as during a POST or IHAVE line message to the server (such as during a POST or IHAVE
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command) SHOULD suffice to reset the autologout timer. When command) SHOULD suffice to reset the autologout timer. When
the timer expires, the server SHOULD close the TCP connection the timer expires, the server SHOULD close the TCP connection
without sending any response to the client, including when without sending any response to the client, including when
the client is in the middle of sending a multi-line message the client is in the middle of sending a multi-line message
to the server. to the server.
4.1 Response Codes 4.1 Response Codes
Each response MUST begin with a three-digit status indicator. Each response MUST begin with a three-digit status indicator.
These are status reports from the server and indicate the These are status reports from the server and indicate the
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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 addition to the status indicator. In those cases, names in addition to the status indicator. In those cases,
the number and type of such parameters is fixed for each the number and type of such parameters is fixed for each
response code to simplify interpretation by the client (any response code to simplify interpretation by the client (any
extension MUST follow this principle as well). In all other extension MUST follow this principle as well). In all other
cases, the client MUST only use the status indicator itself cases, the client MUST only use the status indicator itself
to determine the nature of the response. The exact response to determine the nature of the response. The exact response
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codes that can be returned in response to a given command are codes that can be returned in response to a given command are
detailed in the description of the keyword that is the first detailed in the description of the keyword that is the first
part of the command. part of the command.
Parameters MUST be separated from the numeric status Parameters MUST be separated from the numeric status
indicator and from each other by a single US-ASCII space. All indicator and from each other by a single US-ASCII space. All
numeric parameters MUST be in base 10 (decimal) format, and numeric parameters MUST be in base 10 (decimal) format, and
MAY have leading zeros. String parameters MUST contain at MAY have leading zeros. String parameters MUST contain at
least one character and MUST NOT contain US-ASCII spaces, CR, least one character and MUST NOT contain US-ASCII spaces, CR,
LF, or tab). The server MAY add any text after the response LF, or tab). The server MAY add any text after the response
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unexpected 4xx or 5xx as failure. unexpected 4xx or 5xx as failure.
Response codes not specified in this memo MAY be used for any Response codes not specified in this memo MAY be used for any
installation-specific additional commands also not specified. installation-specific additional commands also not specified.
These SHOULD be chosen to fit the pattern of x9x specified These SHOULD be chosen to fit the pattern of x9x specified
above. above.
Neither this memo nor any extension registered with IANA (see Neither this memo nor any extension registered with IANA (see
section 12) will specify any response codes of the x9x section 12) will specify any response codes of the x9x
pattern. (Implementers of extensions are accordingly pattern. (Implementers of extensions are accordingly
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cautioned not to use such responses for extensions that may cautioned not to use such responses for extensions that may
subsequently be submitted for registration.) subsequently be submitted for registration.)
4.1.1 Generic Response Codes 4.1.1 Generic Response Codes
The server MUST respond to any command with the appropriate The server MUST respond to any command with the appropriate
one of the following generic responses if it represents the one of the following generic responses if it represents the
situation. situation.
If the command is not recognized, or it is an optional If the command is not recognized, or it is an optional
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reason, it MUST give a 400 response code to the next command reason, it MUST give a 400 response code to the next command
and then immediately close the TCP connection. It MAY give a and then immediately close the TCP connection. It MAY give a
401 response code to any command to indicate that termination 401 response code to any command to indicate that termination
is imminent (following a 401 response, it MUST NOT close the is imminent (following a 401 response, it MUST NOT close the
TCP connection immediately). TCP connection immediately).
4.2 Streaming 4.2 Streaming
NNTP is designed to operate over a reliable bi-directional NNTP is designed to operate over a reliable bi-directional
connection such as TCP. Therefore, if a command does not connection such as TCP. Therefore, if a command does not
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depend on the response to the previous one, it should not depend on the response to the previous one, it should not
matter if it is sent before that response is received. Doing matter if it is sent before that response is received. Doing
this is called "streaming". However, certain server this is called "streaming". However, certain server
implementations throw away all text received from the client implementations throw away all text received from the client
following certain commands before sending their response. If following certain commands before sending their response. If
this happens, streaming will be affected because one or more this happens, streaming will be affected because one or more
commands will have been ignored or misinterpreted, and the commands will have been ignored or misinterpreted, and the
client will be matching the wrong responses to each command. client will be matching the wrong responses to each command.
Since there are significant benefits to streaming, but also Since there are significant benefits to streaming, but also
circumstances where it is reasonable or common for servers to circumstances where it is reasonable or common for servers to
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If the client uses blocking system calls to send commands, it If the client uses blocking system calls to send commands, it
MUST ensure that the amount of text sent in streaming does MUST ensure that the amount of text sent in streaming does
not cause a deadlock between transmission and reception. The not cause a deadlock between transmission and reception. The
amount of text involved will depend on window sizes in the amount of text involved will depend on window sizes in the
transmission layer, and is typically 4k bytes for TCP. transmission layer, and is typically 4k bytes for TCP.
5 The WILDMAT format 5 The WILDMAT format
The WILDMAT format described here is based on the version The WILDMAT format described here is based on the version
first developed by Rich Salz [5], which in turn was derived first developed by Rich Salz [5], which in turn was derived
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from the format used in the UNIX "find" command to articulate from the format used in the UNIX "find" command to articulate
file names. It was developed to provide a uniform mechanism file names. It was developed to provide a uniform mechanism
for matching newsgroup names in the same manner that the UNIX for matching newsgroup names in the same manner that the UNIX
shell matches filenames. shell matches filenames.
5.1 Wildmat syntax 5.1 Wildmat syntax
A wildmat is described by the following augmented BNF[6] A wildmat is described by the following augmented BNF[6]
syntax (note that this syntax contains ambiguities and syntax (note that this syntax contains ambiguities and
special cases described at the end): special cases described at the end):
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is commonly used to supress the special meaning of characters is commonly used to supress the special meaning of characters
and brackets to introduce sets, but there is no existing and brackets to introduce sets, but there is no existing
standard practice for these in wildmats and so they were standard practice for these in wildmats and so they were
omitted from this memo. A future extension to this memo may omitted from this memo. A future extension to this memo may
provide semantics for these characters. provide semantics for these characters.
5.2 Wildmat semantics 5.2 Wildmat semantics
A wildmat is tested against a string, and either matches or A wildmat is tested against a string, and either matches or
does not match. To do this, each constituent wildmat-pattern does not match. To do this, each constituent wildmat-pattern
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is matched against the string and the rightmost pattern that is matched against the string and the rightmost pattern that
matches is identified. If that wildmat-pattern is not matches is identified. If that wildmat-pattern is not
preceded with "!", the whole wildmat matches. If it is preceded with "!", the whole wildmat matches. If it is
preceded by "!", or if no wildmat-pattern matches, the whole preceded by "!", or if no wildmat-pattern matches, the whole
wildmat does not match. 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*"
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"*" matches zero or more characters. It can match an empty "*" matches zero or more characters. It can match an empty
string, but it cannot match a subsequence of a UTF-8 sequence string, but it cannot match a subsequence of a UTF-8 sequence
that is not aligned to the character boundaries. that is not aligned to the character boundaries.
5.3 Extensions 5.3 Extensions
An NNTP server or extension MAY extend the syntax or An NNTP server or extension MAY extend the syntax or
semantics of wildmats provided that all wildmats that meet semantics of wildmats provided that all wildmats that meet
the requirements of section 5.1 have the meaning ascribed to the requirements of section 5.1 have the meaning ascribed to
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them by section 5.2. Future editions of this memo may also them by section 5.2. Future editions of this memo may also
extend wildmats. extend wildmats.
5.4 Examples 5.4 Examples
In these examples, $ and @ are used to represent the two In these examples, $ and @ are used to represent the two
octets 0xC2 and 0xA3 respectively; $@ is thus the UTF-8 octets 0xC2 and 0xA3 respectively; $@ is thus the UTF-8
encoding for the pound sterling symbol, shown as # in the encoding for the pound sterling symbol, shown as # in the
descriptions. descriptions.
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6 Format for Keyword Descriptions 6 Format for Keyword Descriptions
On the following pages are descriptions of each keyword On the following pages are descriptions of each keyword
recognized by the NNTP server and the responses that will be recognized by the NNTP server and the responses that will be
returned by those commands. These keywords are grouped by the returned by those commands. These keywords are grouped by the
functional step in which they are used. functional step in which they are used.
Each keyword is shown in upper case for clarity, although the Each keyword is shown in upper case for clarity, although the
NNTP server ignores case in the interpretation of commands. NNTP server ignores case in the interpretation of commands.
Parameters are shown as follows: Parameters are shown as follows:
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UPPERCASE indicates literal text to be included in the UPPERCASE indicates literal text to be included in the
command; command;
lowercase indicates a token described elsewhere; lowercase indicates a token described elsewhere;
[brackets] indicate that the parameter is optional; [brackets] indicate that the parameter is optional;
ellipsis... indicates that the parameter may be repeated ellipsis... indicates that the parameter may be repeated
any number of times (it must occur at least any number of times (it must occur at least
once); once);
vertical|bar indicates a choice of two mutually exclusive vertical|bar indicates a choice of two mutually exclusive
parameters (exactly one must be provided). parameters (exactly one must be provided).
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including POST, the server MUST present a 200 greeting code. including POST, the server MUST present a 200 greeting code.
If the server will accept further commands from the client, If the server will accept further commands from the client,
but it is not authorized to post articles using the POST but it is not authorized to post articles using the POST
command, the server MUST present a 201 greeting code. command, the server MUST present a 201 greeting code.
Otherwise the server MUST present a 400 or 502 greeting code Otherwise the server MUST present a 400 or 502 greeting code
and then immediately close the connection. 502 MUST be used and then immediately close the connection. 502 MUST be used
if the client is not permitted under any circumstances to if the client is not permitted under any circumstances to
interact with the server and 400 otherwise. interact with the server and 400 otherwise.
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7.1.1 Responses 7.1.1 Responses
200 Service available, posting allowed 200 Service available, posting allowed
201 Service available, posting prohibited 201 Service available, posting prohibited
400 Service temporarily unavailable 400 Service temporarily unavailable
502 Service unavailable 502 Service unavailable
Following a 400 or 502 response the server MUST immediately Following a 400 or 502 response the server MUST immediately
close the connection. close the connection.
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10). 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 Example of a connection from any client where the server is
unable to provide service 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.]
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7.2 MODE READER 7.2 MODE READER
MODE READER MODE READER
MODE READER SHOULD be sent by any client that intends to use MODE READER SHOULD be sent by any client that intends to use
any command other than IHAVE, HEAD, STAT, LIST, LIST any command other than IHAVE, HEAD, STAT, LIST, LIST
EXTENSIONS, or commands advertised by the server as available EXTENSIONS, or commands advertised by the server as available
via LIST EXTENSIONS. This command is not streamable. via LIST EXTENSIONS. This command is not streamable.
Servers MAY require that this command be issued before any Servers MAY require that this command be issued before any
other commands are sent and MAY reject any other commands other commands are sent and MAY reject any other commands
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to support some news architectures that switch between modes to support some news architectures that switch between modes
based on whether a given connection is a peer-to-peer based on whether a given connection is a peer-to-peer
connection with another server or a news reading client. connection with another server or a news reading client.
7.2.1 Responses 7.2.1 Responses
200 Posting permitted 200 Posting permitted
201 Posting prohibited 201 Posting prohibited
400 Service temporarily unavailable 400 Service temporarily unavailable
502 Service unavailable 502 Service unavailable
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Following a 400 or 502 response the server MUST immediately Following a 400 or 502 response the server MUST immediately
close the connection. close the connection.
Note that the response need not be the same as the one Note that the response need not be the same as the one
presented during the initial greeting. presented during the initial greeting.
7.2.2 MODE READER Examples 7.2.2 MODE READER Examples
Example of use of the MODE READER command by an authorized Example of use of the MODE READER command by an authorized
client client
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[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 Example of a connection from any client where the server is
unable to provide news reader service unable to provide news reader service
[C] MODE READER [C] MODE READER
[S] 400 NNTP Service temporarily unavailable [S] 400 NNTP Service temporarily unavailable
[Server closes connection.] [Server closes connection.]
8 The CAPABILITIES DISCOVERY Step 8 The CAPABILITIES DISCOVERY Step
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To discover what extensions are available, an NNTP client can To discover what extensions are available, an NNTP client can
query the server with the LIST EXTENSIONS command. query the server with the LIST EXTENSIONS command.
If a particular extension is unavailable, the client can If a particular extension is unavailable, the client can
attempt to work around it or it may wish to terminate the attempt to work around it or it may wish to terminate the
session. session.
See section 12 for further discussion of extensions. See section 12 for further discussion of extensions.
8.1 LIST EXTENSIONS 8.1 LIST EXTENSIONS
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A successful response starts with a 202 code and is followed A successful response starts with a 202 code and is followed
by a list of extensions, one per line. Each line MUST begin by a list of extensions, one per line. Each line MUST begin
with an extension-label and optionally one or more parameters with an extension-label and optionally one or more parameters
(separated by single spaces). The extension-label and the (separated by single spaces). The extension-label and the
meaning of the parameters are specified as part of the meaning of the parameters are specified as part of the
definition of the extension. The extension-label MUST be in definition of the extension. The extension-label MUST be in
uppercase. uppercase.
The server MUST NOT list the same extension twice in the The server MUST NOT list the same extension twice in the
response, and MUST list all supported extensions. The order response, and MUST list all supported extensions. The order
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in which the extensions are listed is not significant. The in which the extensions are listed is not significant. The
server need not even consistently return the same order. server need not even consistently return the same order.
If the server does not support any extensions, it SHOULD If the server does not support any extensions, it SHOULD
return a 402 failure response but MAY return an empty list return a 402 failure response but MAY return an empty list
instead. instead.
8.1.1 Responses 8.1.1 Responses
202 Extension list follows (multi-line response) 202 Extension list follows (multi-line response)
400 Service temporarily unavailable 400 Service temporarily unavailable
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meaning should be attributed to them. meaning should be attributed to them.
Example where no extensions are available, using preferred Example where no extensions are available, using preferred
format: 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 Example where no extensions are available, using an empty
list: list:
[C] LIST EXTENSIONS [C] LIST EXTENSIONS
[S] 202 Extensions supported: [S] 202 Extensions supported:
[S] . [S] .
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9 The NEWS EXCHANGE Step 9 The NEWS EXCHANGE Step
During this step, two basic types of transactions occur: During this step, two basic types of transactions occur:
* article retrieval from the server * article retrieval from the server
* article posting to the server * article posting to the server
9.1 Article Retrieval 9.1 Article Retrieval
News reading clients have available a variety of mechanisms News reading clients have available a variety of mechanisms
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inclusive. The client and server SHOULD NOT use leading inclusive. The client and server SHOULD NOT use leading
zeroes in specifying article numbers, and MUST NOT use more zeroes in specifying article numbers, and MUST NOT use more
than 16 digits. In some situations, the value zero replaces than 16 digits. In some situations, the value zero replaces
an article number to show some special situation. an article number to show some special situation.
Message ids are defined in RFC 2822 with the following Message ids are defined in RFC 2822 with the following
modifications: modifications:
* A message id MUST NOT contain a US-ASCII space within any * 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. * A message id MUST NOT be longer than 250 octets.
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* RFC 2822 obsolete syntax for message ids are not supported * RFC 2822 obsolete syntax for message ids are not supported
by the protocol specified in this memo. by the protocol specified in this memo.
9.1.1 Article Retrieval by Newsgroup Name and Article Number 9.1.1 Article Retrieval by Newsgroup Name and Article Number
The following commands are used to set the current newsgroup The following commands are used to set the current newsgroup
name and the "current article pointer" which is used by other name and the "current article pointer" which is used by other
commands for article retrieval. At the start of an NNTP commands for article retrieval. At the start of an NNTP
session, both of these values are undefined. session, both of these values are undefined.
9.1.1.1 GROUP 9.1.1.1 GROUP
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If the group is empty, one of the following three situations If the group is empty, one of the following three situations
will occur. Clients MUST accept all three cases; servers MUST will occur. Clients MUST accept all three cases; servers MUST
NOT represent an empty group in any other way. NOT represent an empty group in any other way.
The high water mark will be one less than the low water mark, The high water mark will be one less than the low water mark,
and the estimated article count will be zero. Servers SHOULD and the estimated article count will be zero. Servers SHOULD
use this method to show an empty group. This is the only time use this method to show an empty group. This is the only time
that the high water mark can be less than the low water mark. that the high water mark can be less than the low water mark.
All three numbers will be zero. All three numbers will be zero.
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The high water mark is greater than or equal to the low water 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 non-zero, the same requirements apply as for a non-empty if 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 carried out. That is: command is carried out. That is:
* articles may be removed from the group * articles may be removed from the group
* articles may be reinstated in the group with the same * articles may be reinstated in the group with the same
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as this can decrease if an article is removed, and then as this can decrease if an article is removed, and then
increase again if it is reinstated or if new articles arrive. increase again if it is reinstated or if new articles arrive.
When a valid group is selected by means of this command, the When a valid group is selected by means of this command, the
internally maintained "current article pointer" MUST be set internally maintained "current article pointer" MUST be set
to the first article in the group and the name of the current to the first article in the group and the name of the current
newsgroup MUST be set to the selected newsgroup name. If an newsgroup MUST be set to the selected newsgroup name. If an
invalid group is specified, the previously selected group, if invalid group is specified, the previously selected group, if
any, and article MUST remain selected. If an empty newsgroup any, and article MUST remain selected. If an empty newsgroup
is selected, the "current article pointer" is in an is selected, the "current article pointer" is in an
indeterminate state and MUST NOT be used. indeterminate state and MUST NOT be used.
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The GROUP keyword (or the LISTGROUP keyword, if implemented) The GROUP keyword (or the LISTGROUP keyword, if implemented)
MUST be used by a client and a successful response received MUST be used by a client and a successful response received
before the any other command is used that depends on having before the any other command is used that depends on having
the "current article pointer" be valid. the "current article pointer" be valid.
If the group specified is not available on the server, it If the group specified is not available on the server, it
MUST return a 411 error code. MUST return a 411 error code.
9.1.1.1.1 Responses 9.1.1.1.1 Responses
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If the current newsgroup is valid, the internally maintained If the current newsgroup is valid, the internally maintained
"current article pointer" MUST be set to the previous article "current article pointer" MUST be set to the previous article
in the current newsgroup. If already positioned at the first in the current newsgroup. If already positioned at the first
article of the newsgroup, an error message MUST be returned article of the newsgroup, an error message MUST be returned
and the current article MUST remain selected. and the current article MUST remain selected.
There MAY be no previous article in the group, although the There MAY be no previous article in the group, although the
current article number is not the reported low water mark. current article number is not the reported low water mark.
There MUST NOT be a previous article when the current article There MUST NOT be a previous article when the current article
number is the reported low water mark. number is the reported low water mark.
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Because articles can be removed and added, the results of Because articles can be removed and added, the results of
multiple LAST and NEXT commands MAY not be consistent over multiple LAST and NEXT commands MAY not be consistent over
the life of a particular NNTP session. the life of a particular NNTP session.
If successful, a response indicating the current article If successful, a response indicating the current article
number and a message-id string MUST be returned. No article number and a message-id string MUST be returned. No article
text is sent in response to this command. text is sent in response to this command.
9.1.1.2.1 Responses 9.1.1.2.1 Responses
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Example of an attempt to retrieve an article using the LAST Example of an attempt to retrieve an article using the LAST
command when the current article pointer is pointing at the command when the current article pointer is pointing at the
first article in the group first article in the group
[S] 200 NNTP Service Ready [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] 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 Example of an attempt to retrieve an article using the LAST
command when the current group selected is empty command when the current group selected is empty
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[S] 200 NNTP Service Ready [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 9.1.1.3 NEXT
NEXT NEXT
If the current newsgroup is valid, the internally maintained If the current newsgroup is valid, the internally maintained
"current article pointer" MUST be advanced to the next "current article pointer" MUST be advanced to the next
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[S] 200 NNTP Service Ready [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 Example of an attempt to retrieve an article without having
selected a group (via the GROUP command) first selected a group (via the GROUP command) first
[S] 200 NNTP Service ready [S] 200 NNTP Service ready
[C] NEXT [C] NEXT
[S] 412 no newsgroup selected [S] 412 no newsgroup selected
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Example of an attempt to retrieve an article using the NEXT Example of an attempt to retrieve an article using the NEXT
command when the current article pointer is pointing at the command when the current article pointer is pointing at the
last article in the group last article in the group
[S] 200 NNTP Service Ready [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] ARTICLE 3002322
[S] 220 3002322 <411@example.net> retrieved [S] 220 3002322 <411@example.net> retrieved
[S] Path: pathost!demo!whitehouse!not-for-mail [S] Path: pathost!demo!whitehouse!not-for-mail
[S] From: ˘Demo User÷ <nobody@example.net> [S] From: ˘Demo User÷ <nobody@example.net>
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They differ only in the parts of the article that are They differ only in the parts of the article that are
presented to the client and in the successful response code. presented to the client and in the successful response code.
The ARTICLE command is described here in full, while the The ARTICLE command is described here in full, while the
other commands are described in terms of the differences. other commands are described in terms of the differences.
An article, as defined by RFC 1036, consists of two parts: An article, as defined by RFC 1036, consists of two parts:
the article headers and the article body. When responding to the article headers and the article body. When responding to
one of these commands, the server presents the entire article one of these commands, the server presents the 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.
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9.2.1 ARTICLE 9.2.1 ARTICLE
ARTICLE <message-id> ARTICLE <message-id>
ARTICLE [number] ARTICLE [number]
The ARTICLE command selects an article based on the arguments The ARTICLE command selects an article based on the arguments
and presents the header, a blank line, and the body of that and presents the header, a blank line, and the body of that
article. The command has two forms. article. The command has two forms.
In the first form, a message-id is specified (including the In the first form, a message-id is specified (including the
angle brackets), and the server presents the article with angle brackets), and the server presents the article with
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the reported low water mark for that group. the reported low water mark for that group.
The server MUST NOT change the currently selected group as a The server MUST NOT change the currently selected group as a
result of this command. The server MUST NOT change the result of this command. The server MUST NOT change the
current selected article except when an article number current selected article except when an article number
argument was provided and the article exists; in particular, argument was provided and the article exists; in particular,
it MUST NOT change it following an unsuccessful response. it MUST NOT change it following an unsuccessful response.
9.2.1.1 Responses 9.2.1.1 Responses
First form (message-id specified): First form (message-id specified):
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220 0 a Article follows (multi-line response, a = 220 0 a Article follows (multi-line response, a =
message-id) message-id)
430 No article found with that message-id 430 No article found with that message-id
502 Program error, function not performed 502 Program error, function not performed
Second form (optional article number specified): Second form (optional article number specified):
220 n a Article follows (multi-line response, n = 220 n a Article follows (multi-line response, n =
article number, a = message-id) article number, a = message-id)
412 No newsgroup selected 412 No newsgroup selected
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The article headers and body are returned as a multi-line The article headers and body are returned as a multi-line
response following the initial response line. response following the initial response line.
9.2.1.2 Examples 9.2.1.2 Examples
Example of a successful retrieval of an article (using no Example of a successful retrieval of an article (using no
article number) article number)
[S] 200 NNTP Service Ready [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>
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[S] Path: pathost!demo!somewhere!not-for-mail [S] Path: pathost!demo!somewhere!not-for-mail
[S] From: ˘Demo User÷ <nobody@example.com> [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 Com, San Jose, CA
[S] Message-ID: <45223423@example.com> [S] Message-ID: <45223423@example.com>
[S] [S]
[S] This is just a test article. [S] This is just a test article.
[S] . [S] .
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[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 Example of an unsuccessful retrieval of an article by number
because no newsgroup was selected first because no newsgroup was selected first
[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
[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 Example of an attempt to retrieve an article when the current
group selected is empty group selected is empty
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[S] 200 NNTP Service Ready [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 Example of a failure due to the service being unavailable
[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
[C] ARTICLE <i.am.a.test.article@example.com> [C] ARTICLE <i.am.a.test.article@example.com>
[S] 502 Service unavailable [S] 502 Service unavailable
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article number, a = message-id) article number, a = message-id)
412 No newsgroup selected 412 No newsgroup selected
420 No current article selected 420 No current article selected
423 No such article in this newsgroup 423 No such article in this newsgroup
502 Program error, function not performed 502 Program error, function not performed
Except that only the headers are included in the response, Except that only the headers are included in the response,
the 221 response behaves identically to the 220 response of the 221 response behaves identically to the 220 response of
the ARTICLE command. the ARTICLE command.
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9.2.2.2 Examples 9.2.2.2 Examples
Example of a successful retrieval of the headers in an Example of a successful retrieval of the headers in an
article (using no article number) article (using no article number)
[S] 200 NNTP Service Ready [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!somewhere!not-for-mail
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[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
[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 Example of an unsuccessful retrieval of the header of an
article by number article by number
[S] 200 NNTP Service Ready [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 300256 [C] HEAD 300256
[S] 423 No such article number in this group [S] 423 No such article number in this group
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Example of an unsuccessful retrieval the header of an article Example of an unsuccessful retrieval the header of an article
by number because no newsgroup was selected first by number because no newsgroup was selected first
[S] 200 NNTP Service Ready [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 Example of an attempt to retrieve the header of an article
when the current group selected is empty when the current group selected is empty
[S] 200 NNTP Service Ready [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
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430 No article found with that message-id 430 No article found with that message-id
502 Program error, function not performed 502 Program error, function not performed
Second form (optional article number specified): Second form (optional article number specified):
222 n a Article follows (multi-line response, n = 222 n a Article follows (multi-line response, n =
article number, a = message-id) article number, a = message-id)
412 No newsgroup selected 412 No newsgroup selected
420 No current article selected 420 No current article selected
423 No such article in this newsgroup 423 No such article in this newsgroup
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502 Program error, function not performed 502 Program error, function not performed
Except that only the body is included in the response, the Except that only the body is included in the response, the
222 response behaves identically to the 220 response of the 222 response behaves identically to the 220 response of the
ARTICLE command. ARTICLE command.
9.2.3.2 Examples 9.2.3.2 Examples
Example of a successful retrieval of the body of an article Example of a successful retrieval of the body of an article
(using no article number) (using no article number)
[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
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[S] 200 NNTP Service Ready [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 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 Example of an unsuccessful retrieval of the body of an
article by number because no newsgroup was selected first article by number because no newsgroup was selected first
[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
[C] BODY 300256 [C] BODY 300256
[S] 412 No newsgroup selected [S] 412 No newsgroup selected
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Example of an attempt to retrieve the body of an article when Example of an attempt to retrieve the body of an article when
the current group selected is empty the current group selected is empty
[S] 200 NNTP Service Ready [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 Example of a failure due to the service being unavailable
[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
[C] BODY <i.am.a.test.article@example.com> [C] BODY <i.am.a.test.article@example.com>
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Second form (optional article number specified): Second form (optional article number specified):
223 n a Article exists (n = article number, a = 223 n a Article exists (n = article number, a =
message-id) message-id)
412 No newsgroup selected 412 No newsgroup selected
420 No current article selected 420 No current article selected
423 No such article in this newsgroup 423 No such article in this newsgroup
502 Program error, function not performed 502 Program error, function not performed
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The parameters of the 223 response are identical to those The parameters of the 223 response are identical to those
that would have been given in a 220 response to the that would have been given in a 220 response to the
equivalent ARTICLE command. However, the response is NOT equivalent ARTICLE command. However, the response is NOT
multi-line. multi-line.
9.2.4.2 Examples 9.2.4.2 Examples
Example of STAT on an existing article (using no article Example of STAT on an existing article (using no article
number) number)
[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
[C] GROUP misc.test [C] GROUP misc.test
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[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 Example of STAT of an article when the current group selected
is empty is empty
[S] 200 NNTP Service Ready [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] 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 Example of a failure due to the service being unavailable
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[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
[C] STAT <i.am.a.test.article@example.com> [C] STAT <i.am.a.test.article@example.com>
[S] 502 Service unavailable [S] 502 Service unavailable
9.3 Article Posting 9.3 Article Posting
Article posting is done in one of two modes: individual Article posting is done in one of two modes: individual
article posting from news reading clients and article article posting from news reading clients and article
transfer from other news servers. transfer from other news servers.
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response codes 340 and 440 are used in direct response to the response codes 340 and 440 are used in direct response to the
POST command. Others are returned following the sending of POST command. Others are returned following the sending of
the article. the article.
No attempt shall be made by the server to filter characters, No attempt shall be made by the server to filter characters,
fold or limit lines, or otherwise process incoming text. The fold or limit lines, or otherwise process incoming text. The
intent is that the server just passes the incoming message to intent is that the server just passes the incoming message to
be posted to the server installation's news posting software, be posted to the server installation's news posting software,
which is not defined by this memo. which is not defined by this memo.
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The client SHOULD NOT assume that the article has been The client SHOULD NOT assume that the article has been
successfully transferred unless it receives an affirmative successfully transferred unless it receives an affirmative
response from the server. Since, however, the affirmative response from the server. Since, however, the affirmative
response may have been sent and lost, the client SHOULD use response may have been sent and lost, the client SHOULD use
the same message-id in the article when resending it or check the same message-id in the article when resending it or check
whether the article was successfully posted before resending whether the article was successfully posted before resending
it to ensure that the resend will not result in a duplicate it to ensure that the resend will not result in a duplicate
article. article.
This command is not streamable. This command is not streamable.
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[S] 240 Article received ok [S] 240 Article received ok
Example of an unsuccessful posting Example of an unsuccessful posting
[S] 200 NNTP Service Ready [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]
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[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 Example of an attempt to post when posting is not allowed
[S] 201 NNTP Service Ready, read-only [S] 201 NNTP Service Ready, read-only
[C] POST [C] POST
[S] 440 Posting not permitted [S] 440 Posting not permitted
9.3.2 IHAVE 9.3.2 IHAVE
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indicating that the transfer failed but should be tried again indicating that the transfer failed but should be tried again
later, or response code 437, indicating that the article was later, or response code 437, indicating that the article was
rejected. rejected.
This function differs from the POST command in that it is This function differs from the POST command in that it is
intended for use in transferring already-posted articles intended for use in transferring already-posted articles
between hosts. It SHOULD NOT be used when the client is a between hosts. It SHOULD NOT be used when the client is a
personal news reading program, since this command indicates personal news reading program, since this command indicates
that the forthcoming article has already been posted at that the forthcoming article has already been posted at
another site and is being forwarded from another host. another site and is being forwarded from another host.
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However, the server MAY elect not to post or forward the However, the server MAY elect not to post or forward the
article if after further examination of the article it deems article if after further examination of the article it deems
it inappropriate to do so. Reasons for such subsequent it inappropriate to do so. Reasons for such subsequent
rejection of an article may include such problems as rejection of an article may include such problems as
inappropriate newsgroups or distributions, disk space inappropriate newsgroups or distributions, disk space
limitations, article lengths, garbled headers, and the like. limitations, article lengths, garbled headers, and the like.
These are typically restrictions enforced by the server These are typically restrictions enforced by the server
host's news software and not necessarily the NNTP server host's news software and not necessarily the NNTP server
itself. itself.
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Example of successfully sending an article to another site Example of successfully sending an article to another site
[S] 200 NNTP Service Ready [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
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[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 Example of sending an article to another site that rejects it
[S] 200 NNTP Service Ready [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>
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[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 Example of sending an article to a site that already has it
[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
[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
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Example of sending an article to a site that requests the Example of sending an article to a site that requests the
article be tried again later article be tried again later
[S] 200 NNTP Service Ready [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 9.4 The LIST Keyword
9.4.1 LIST 9.4.1 LIST
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"reported low water mark" and the <last> field corresponds to "reported low water mark" and the <last> field corresponds to
the "reported high water mark" described in the GROUP command the "reported high water mark" described in the GROUP command
(see Section 9.1.1.1). (see Section 9.1.1.1).
The status of a newsgroup only indicates how posts to that The status of a newsgroup only indicates how posts to that
newsgroup are processed. It does not indicate if the current newsgroup are processed. It does not indicate if the current
client is permitted to post. That is indicated by the status client is permitted to post. That is indicated by the status
code returned as part of the greeting. code returned as part of the greeting.
Please note that an empty list (i.e., the text body returned Please note that an empty list (i.e., the text body returned
by this command consists only of the terminating period) is a by this command consists only of the terminating period) is a
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possible valid response, and indicates that there are possible valid response, and indicates that there are
currently no valid newsgroups. currently no valid newsgroups.
If the optional wildmat parameter is specified, the list is If the optional wildmat parameter is specified, the list is
limited to only the groups that match the pattern. limited to only the groups that match the pattern.
9.4.1.1 Responses 9.4.1.1 Responses
215 Information Follows (multi-line response) 215 Information Follows (multi-line response)
9.4.1.2 Examples 9.4.1.2 Examples
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fields separated from each other by one or more US-ASCII fields separated from each other by one or more US-ASCII
space characters. The first field is the name of the space characters. The first field is the name of the
newsgroup. The second is the time when this group was created newsgroup. The second is the time when this group was created
on this news server measured in seconds since the start of on this news server measured in seconds since the start of
January 1, 1970. The third is the email address of the January 1, 1970. The third is the email address of the
entity that created the newsgroup and must be a mailbox as entity that created the newsgroup and must be a mailbox as
defined in RFC 28228. When executed, the information is defined in RFC 28228. When executed, the information is
displayed following the 215 response. When display is displayed following the 215 response. When display is
completed, the server will send a period on a line by itself. completed, the server will send a period on a line by itself.
If the information is not available, the server will return If the information is not available, the server will return
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the 503 error response. If the server does not recognize the the 503 error response. If the server does not recognize the
command, it SHOULD return the 501 error response. command, it SHOULD return the 501 error response.
If the optional wildmat parameter is specified, the list is If the optional wildmat parameter is specified, the list is
limited to only the groups that match the pattern. limited to only the groups that match the pattern.
9.4.2.1 Responses 9.4.2.1 Responses
215 Information Follows (multi-line response) 215 Information Follows (multi-line response)
501 Syntax error 501 Syntax error
503 Program error, function not performed 503 Program error, function not performed
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[C] LIST ACTIVE.TIMES [C] LIST ACTIVE.TIMES
[S] 501 Syntax Error [S] 501 Syntax Error
9.4.3 LIST DISTRIBUTIONS 9.4.3 LIST DISTRIBUTIONS
LIST DISTRIBUTIONS LIST DISTRIBUTIONS
The distributions file is maintained by some news transport The distributions file is maintained by some news transport
systems to contain information about valid values for the systems to contain information about valid values for the
Distribution: line in a news article header and about what Distribution: line in a news article header and about what
the values mean. Each line contains two fields, the value and the values mean. Each line contains two fields, the value and
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a short explanation on the meaning of the value. The first a short explanation on the meaning of the value. The first
field is separated from the second field by one or more US- field is separated from the second field by one or more US-
ASCII spaces. When executed, the information is displayed ASCII spaces. When executed, the information is displayed
following the 215 response. When display is completed, the following the 215 response. When display is completed, the
server will send a period on a line by itself. If the server will send a period on a line by itself. If the
information is not available, the server will return the 503 information is not available, the server will return the 503
error response. If the server does not recognize this error response. If the server does not recognize this
command, it SHOULD return the 501 error response. command, it SHOULD return the 501 error response.
9.4.3.1 Responses 9.4.3.1 Responses
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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 the command (e.g. The server does not maintain this
information regardless of configuration.) information regardless of configuration.)
[S] 200 NNTP Service Ready [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 9.4.4 LIST DISTRIB.PATS
LIST DISTRIB.PATS LIST DISTRIB.PATS
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The distrib.pats file is maintained by some news transport The distrib.pats file is maintained by some news transport
systems to allow clients to choose a value for the systems to allow clients to choose a value for the
Distribution: line in the header of a news article being Distribution: line in the header of a news article being
posted. The information returned consists of lines, in no posted. The information returned consists of lines, in no
particular order, each of which contains three fields particular order, each of which contains three fields
separated by colons. These fields are a weight, a wildmat separated by colons. These fields are a weight, a wildmat
(which may be a simple group name), and a Distribution: (which may be a simple group name), and a Distribution:
value, in that order. value, in that order.
The client MAY use this information to select a Distribution: The client MAY use this information to select a Distribution:
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[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] . [S] .
Example of LIST DISTRIB.PATS returning an error (e.g. The Example of LIST DISTRIB.PATS returning an error (e.g. The
server software is not configured to maintain this server software is not configured to maintain this
information, but does recognize the command as valid.) information, but does recognize the command as valid.)
[S] 200 NNTP Service Ready [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
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Example of LIST DISTRIB.PATS sent to a server that does not Example of LIST DISTRIB.PATS sent to a server that does not
recognize the command (e.g. The software does not maintain recognize the command (e.g. The software does not maintain
this information regardless of configuration.) this information regardless of configuration.)
[S] 200 NNTP Service Ready [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 9.4.5 LIST NEWSGROUPS
LIST NEWSGROUPS [wildmat] LIST NEWSGROUPS [wildmat]
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503 Program error, function not performed 503 Program error, function not performed
9.4.5.2 Examples 9.4.5.2 Examples
Example of LIST NEWSGROUPS returning a list of newsgroups Example of LIST NEWSGROUPS returning a list of newsgroups
[S] 200 NNTP Service Ready [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
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[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 Example of LIST NEWSGROUPS returning an error (e.g. The
server software recognizes the command as valid, but the server software recognizes the command as valid, but the
information is not available.) information is not available.)
[S] 200 NNTP Service Ready [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 9.5 Standard extensions
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selected (e.g. "news.software.misc"). A list of valid selected (e.g. "news.software.misc"). A list of valid
newsgroups may be obtained from the LIST command. If no group newsgroups may be obtained from the LIST command. If no group
is specified, the current group is used as the default is specified, the current group is used as the default
argument. argument.
The successful selection response will be a list of the The successful selection response will be a list of the
article numbers in the group followed by a period on a line article numbers in the group followed by a period on a line
by itself. The list starts on the next line following the 211 by itself. The list starts on the next line following the 211
response code. response code.
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When a valid group is selected by means of this command, the When a valid group is selected by means of this command, the
internally maintained "current article pointer" MUST be set internally maintained "current article pointer" MUST be set
to the first article in the group and the name of the current to the first article in the group and the name of the current
newsgroup MUST be set to the selected newsgroup name. If an newsgroup MUST be set to the selected newsgroup name. If an
invalid group is specified, the previously selected group and invalid group is specified, the previously selected group and
article remain selected. If an empty newsgroup is selected, article remain selected. If an empty newsgroup is selected,
the "current article pointer" may be in an indeterminate the "current article pointer" may be in an indeterminate
state and should not be used. state and should not be used.
The LISTGROUP keyword MAY be used by a client as a The LISTGROUP keyword MAY be used by a client as a
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Example of LISTGROUP on an empty group: Example of LISTGROUP on an empty group:
[S] 200 NNTP Service Ready [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: Example of LISTGROUP on a valid current group:
[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
[C] GROUP misc.test [C] GROUP misc.test
[S] 211 2000 3000234 3002322 misc.test selected [S] 211 2000 3000234 3002322 misc.test selected
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[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 Example of LISTGROUP failing because no group has been
selected: selected:
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display is completed, the server will send a period on a line display is completed, the server will send a period on a line
by itself. If the information is not available, the server by itself. If the information is not available, the server
will return the 503 response. will return the 503 response.
If the header has the word "full" (without quotes) after the If the header has the word "full" (without quotes) after the
colon, the header's name is prepended to its field in the colon, the header's name is prepended to its field in the
output returned by the server. output returned by the server.
This is command is part of the optional OVER extension which This is command is part of the optional OVER extension which
includes the OVER command defined in section . If the OVER includes the OVER command defined in section . If the OVER
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extension is not implemented, then this command MUST NOT be extension is not implemented, then this command MUST NOT be
implemented. If that case, the server MUST return a 501 error implemented. If that case, the server MUST return a 501 error
response when this command is presented by the client. response when this command is presented by the client.
9.5.2.1.1 Responses 9.5.2.1.1 Responses
215 Information follows (multi-line response) 215 Information follows (multi-line response)
501 Syntax Error 501 Syntax Error
503 Program error, function not performed 503 Program error, function not performed
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article(s) specified from the current selected group. The article(s) specified from the current selected group. The
information returned in the response to this command can be information returned in the response to this command can be
used by clients to follow discussion threads. used by clients to follow discussion threads.
The optional range argument may be any of the following: The optional range argument may be any of the following:
* an article number * an article number
* an article number followed by a dash to indicate all * an article number followed by a dash to indicate all
following following
* an article number followed by a dash followed by another * an article number followed by a dash followed by another
article number article number
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If no argument is specified, then information from the If no argument is specified, then information from the
current article is displayed. Successful responses start with current article is displayed. Successful responses start with
a 224 response followed by the overview information for all a 224 response followed by the overview information for all
matched messages. Once the output is complete, a period is matched messages. Once the output is complete, a period is
sent on a line by itself. A newsgroup must have been selected sent on a line by itself. A newsgroup must have been selected
earlier, else a 412 error response is returned. If no earlier, else a 412 error response is returned. If no
articles are in the range specified, the server returns a 420 articles are in the range specified, the server returns a 420
error response. A 502 response will be returned if the client error response. A 502 response will be returned if the client
only has permission to transfer articles. A 500 response only has permission to transfer articles. A 500 response
SHOULD be returned by servers that do not implement this SHOULD be returned by servers that do not implement this
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The server SHOULD not produce output for articles that no The server SHOULD not produce output for articles that no
longer exist. longer exist.
9.5.2.2.1 Responses 9.5.2.2.1 Responses
224 Overview information follows (multi-line 224 Overview information follows (multi-line
response) response)
412 No newsgroup currently selected 412 No newsgroup currently selected
420 No article(s) selected 420 No article(s) selected
500 Command not recognized 500 Command not recognized
502 Program error, functions no performed 502 Program error, functions no performed
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9.5.2.2.2 Examples 9.5.2.2.2 Examples
Example of a successful retrieval of overview information for Example of a successful retrieval of overview information for
an article (using no article number) an article (using no article number)
[S] 200 NNTP Service Ready [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] OVER [C] OVER
[S] 224 Overview information follows [S] 224 Overview information follows
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Example of an attempt to retrieve an article when the current Example of an attempt to retrieve an article when the current
group selected is empty group selected is empty
[S] 200 NNTP Service Ready [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] OVER [C] OVER
[S] 420 No current article selected [S] 420 No current article selected
9.5.3 The HDR Extension 9.5.3 The HDR Extension
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This extension provides one new command, HDR. The label for This extension provides one new command, HDR. The label for
this extension is HDR this extension is HDR
9.5.3.1 HDR 9.5.3.1 HDR
HDR header range|<message-id> HDR header range|<message-id>
The HDR command is used to retrieve specific headers from The HDR command is used to retrieve specific headers from
specific articles in the currently selected group. specific articles in the currently selected group.
The required header parameter is the name of a header line The required header parameter is the name of a header line
(e.g. "subject") in a newsgroup article. See RFC-1036 for a (e.g. "subject") in a newsgroup article. See RFC-1036 for a
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and no such article exists, a 430 error response shall be and no such article exists, a 430 error response shall be
returned. A 502 response shall be returned if the client only returned. A 502 response shall be returned if the client only
has permission to transfer articles. A 500 response SHOULD be has permission to transfer articles. A 500 response SHOULD be
issued by all servers that do not recognize this command. issued by all servers that do not recognize this command.
9.5.3.1.1 Responses 9.5.3.1.1 Responses
221 Header follows (multi-line response) 221 Header follows (multi-line response)
412 No newsgroup selected 412 No newsgroup selected
430 No such article 430 No such article
500 Command not recognized 500 Command not recognized
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502 Program error, function not performed 502 Program error, function not performed
9.5.3.1.2 Examples 9.5.3.1.2 Examples
Example of a successful retrieval of subject lines from a Example of a successful retrieval of subject lines from a
range of articles range of articles
[S] 200 NNTP Service Ready [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 3000234-300238 [C] HDR Subject 3000234-300238
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[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
[C] HDR subject 300256- [C] HDR subject 300256-
[S] 412 No newsgroup selected [S] 412 No newsgroup selected
Example of an unsuccessful retrieval of headers from articles Example of an unsuccessful retrieval of headers from articles
by message-id because no newsgroup was selected first by message-id because no newsgroup was selected first
[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
[C] HDR subject <i.am.a.test.article@example.com> [C] HDR subject <i.am.a.test.article@example.com>
[S] 412 No newsgroup selected [S] 412 No newsgroup selected
Example of retrieving header information when the current Example of retrieving header information when the current
group selected is empty group selected is empty
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[S] 200 NNTP Service Ready [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] HDR subject 0- [C] HDR subject 0-
[S] 221 Headers follow [S] 221 Headers follow
. .
Example of a failure due to restrictions configured into the Example of a failure due to restrictions configured into the
server server
[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
[C] GROUP news.group [C] GROUP news.group
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10.1.2 Example 10.1.2 Example
[S] 200 NNTP Service Ready [S] 200 NNTP Service Ready
[C] QUIT [C] QUIT
[S] 205 closing connection [S] 205 closing connection
[Server closes connection.] [Server closes connection.]
11 Other Keywords 11 Other Keywords
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There are other keywords that may be used at any time between There are other keywords that may be used at any time between
the beginning of a session and its termination. Using these the beginning of a session and its termination. Using these
keywords does not alter any state information, but the keywords does not alter any state information, but the
response generated from the use of these keywords may provide response generated from the use of these keywords may provide
useful information to clients that use them. useful information to clients that use them.
11.1 DATE 11.1 DATE
DATE DATE
This command exists to help clients find out the current This command exists to help clients find out the current
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[S] 111 19990623135624 [S] 111 19990623135624
11.2 The HELP Command 11.2 The HELP Command
HELP HELP
This command provides a short summary of commands that are This command provides a short summary of commands that are
understood by this implementation of the server. The help understood by this implementation of the server. The help
text will be presented as a textual response terminated by a text will be presented as a textual response terminated by a
single period on a line by itself. single period on a line by itself.
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This text is not guaranteed to be in any particular format This text is not guaranteed to be in any particular format
and SHALL NOT be used by clients as a replacement for the and SHALL NOT be used by clients as a replacement for the
LIST EXTENSIONS command described in section 8.1. LIST EXTENSIONS command described in section 8.1.
11.2.1 Responses 11.2.1 Responses
100 Help text follows (multi-line response) 100 Help text follows (multi-line response)
11.2.2 Example 11.2.2 Example
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the current year, otherwise the year is from the previous the current year, otherwise the year is from the previous
century. century.
Time must also be specified. It must be as 6 digits HHMMSS Time must also be specified. It must be as 6 digits HHMMSS
with HH being hours in the 24-hour clock 00-23, MM minutes with HH being hours in the 24-hour clock 00-23, MM minutes
00-59, and SS seconds 00-60, which allows for leap seconds. 00-59, and SS seconds 00-60, which allows for leap seconds.
The token "GMT" specifies that the date and time are given in The token "GMT" specifies that the date and time are given in
Coordinated Universal Time. If the token "GMT" is omitted Coordinated Universal Time. If the token "GMT" is omitted
then the date and time are specified in the server's local then the date and time are specified in the server's local
timezone. Note that there is no way using the protocol timezone. Note that there is no way using the protocol
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specified in this memo to establish the server's local specified in this memo to establish the server's local
timezone. timezone.
Note that an empty list (i.e., the text body returned by this Note that an empty list (i.e., the text body returned by this
command consists only of the terminating period) is a command consists only of the terminating period) is a
possible valid response, and indicates that there are possible valid response, and indicates that there are
currently no new newsgroups. currently no new newsgroups.
Clients SHOULD make all queries using Coordinated Universal Clients SHOULD make all queries using Coordinated Universal
Time (i.e. by including the ˘GMT÷ parameter) when possible. Time (i.e. by including the ˘GMT÷ parameter) when possible.
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11.4 NEWNEWS 11.4 NEWNEWS
NEWNEWS wildmat date time [GMT] NEWNEWS wildmat date time [GMT]
A list of message-ids of articles posted or received on the A list of message-ids of articles posted or received on the
server to the list of newsgroups that match the wildmat since server to the list of newsgroups that match the wildmat since
"date" will be listed. The format of the listing will be one "date" will be listed. The format of the listing will be one
message-id per line, as though text were being sent. The message-id per line, as though text were being sent. The
order of the response has no specific significance and may order of the response has no specific significance and may
vary from response to response in the same session. If a vary from response to response in the same session. If a
message-id appears more than once it has the same meaning as message-id appears more than once it has the same meaning as
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if it appears only once. A single line consisting solely of if it appears only once. A single line consisting solely of
one period followed by CR-LF will terminate the list. one period followed by CR-LF will terminate the list.
Date and time are in the same format as the NEWGROUPS Date and time are in the same format as the NEWGROUPS
command. command.
Note that an empty list (i.e., the text body returned by this Note that an empty list (i.e., the text body returned by this
command consists only of the terminating period) is a command consists only of the terminating period) is a
possible valid response, and indicates that there is possible valid response, and indicates that there is
currently no new news. currently no new news.
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[S] . [S] .
12 Framework for NNTP Extensions 12 Framework for NNTP Extensions
Although NNTP is widely and robustly deployed, some parts of Although NNTP is widely and robustly deployed, some parts of
the Internet community might wish to extend the NNTP service. the Internet community might wish to extend the NNTP service.
This memo defines a means whereby an extended NNTP client may This memo defines a means whereby an extended NNTP client may
query the server to determine the service extensions that it query the server to determine the service extensions that it
supports. supports.
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It must be emphasized that any extension to the NNTP service It must be emphasized that any extension to the NNTP service
should not be considered lightly. NNTP's strength comes should not be considered lightly. NNTP's strength comes
primarily from its simplicity. Experience with many primarily from its simplicity. Experience with many
protocols has shown that: protocols has shown that:
Protocols with few options tend towards ubiquity, whilst Protocols with few options tend towards ubiquity, whilst
protocols with many options tend towards obscurity. protocols with many options tend towards obscurity.
This means that each and every extension, regardless of its This means that each and every extension, regardless of its
benefits, must be carefully scrutinized with respect to its benefits, must be carefully scrutinized with respect to its
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adds. However this is not a requirement: an extension might adds. However this is not a requirement: an extension might
not add any new commands or keywords. not add any new commands or keywords.
An extension is either a private extension or else it is An extension is either a private extension or else it is
included in the IANA registry and is defined in an RFC. Such included in the IANA registry and is defined in an RFC. Such
RFCs either must be on the standards-track or must define an RFCs either must be on the standards-track or must define an
IESG-approved experimental protocol. IESG-approved experimental protocol.
The definition of an extension must include: The definition of an extension must include:
* a descriptive name for the extension * a descriptive name for the extension
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* the extension-label (which is returned by LIST EXTENSIONS * the extension-label (which is returned by LIST EXTENSIONS
to indicate to the client that the server supports this to indicate to the client that the server supports this
particular extension) particular extension)
* the syntax, values, and meanings of any parameters * the syntax, values, and meanings of any parameters
following the extension-label in the output of LIST following the extension-label in the output of LIST
EXTENSIONS EXTENSIONS
* any new NNTP keywords associated with the extension * any new NNTP keywords associated with the extension
* the syntax and possible values of parameters associated * the syntax and possible values of parameters associated
with the new NNTP keywords with the new NNTP keywords
* any new parameters the extension associates with any other * any new parameters the extension associates with any other
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EXTENSIONS command. EXTENSIONS command.
A server MAY provide additional keywords - either new A server MAY provide additional keywords - either new
commands or new parameters to existing commands - as part of commands or new parameters to existing commands - as part of
a private extension. These new keywords MUST begin with "X". a private extension. These new keywords MUST begin with "X".
A server MUST NOT send different response codes to basic NNTP A server MUST NOT send different response codes to basic NNTP
commands documented here or commands documented in registered commands documented here or commands documented in registered
extensions in response to the availability or use of a extensions in response to the availability or use of a
private extension. private extension.
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12.1 Initial IANA Registry 12.1 Initial IANA Registry
The IANA's initial registry of NNTP service extensions The IANA's initial registry of NNTP service extensions
consists of these entries: consists of these entries:
Service Extension NNTP Extension Label Added Behavior Service Extension NNTP Extension Label Added Behavior
Overview Support OVER Defined in this memo Overview Support OVER Defined in this memo
Specific Article Specific Article
LISTGROUP Defined in this memo LISTGROUP Defined in this memo
Numbers Numbers
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last-command / last-command /
list-active-times-command / list-active-times-command /
list-distrib-pats-command / list-distrib-pats-command /
list-distributions-command / list-distributions-command /
list-extensions-command / list-extensions-command /
list-newsgroups-command / list-newsgroups-command /
list-overview-fmt-command / list-overview-fmt-command /
list-command / list-command /
listgroup-command / listgroup-command /
mode-reader-command / mode-reader-command /
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newgroups-command / newgroups-command /
newnews-command / newnews-command /
next-command / next-command /
over-command / over-command /
hdr-command / hdr-command /
post-command / post-command /
quit-command / quit-command /
stat-command stat-command
CR = %x0D CR = %x0D
CRLF = CR LF CRLF = CR LF
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*WSP CRLF *WSP CRLF
list-extensions-command = "LIST" 1*WSP "EXTENSIONS" *WSP list-extensions-command = "LIST" 1*WSP "EXTENSIONS" *WSP
CRLF CRLF
list-newsgroups-command = "LIST" 1*WSP "NEWSGROUPS" [1*WSP list-newsgroups-command = "LIST" 1*WSP "NEWSGROUPS" [1*WSP
wildmat] *WSP CRLF wildmat] *WSP CRLF
list-overview-fmt-command = "LIST" 1*WSP "OVERVIEW.FMT" list-overview-fmt-command = "LIST" 1*WSP "OVERVIEW.FMT"
*WSP CRLF *WSP CRLF
listgroup-command = "LISTGROUP" [1*WSP wildmat] *WSP CRLF listgroup-command = "LISTGROUP" [1*WSP wildmat] *WSP CRLF
mode-reader-command = "MODE" 1*WSP "READER" *WSP CRLF mode-reader-command = "MODE" 1*WSP "READER" *WSP CRLF
msg-id = <defined in section 9.1 of this memo> msg-id = <defined in section 9.1 of this memo>
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newgroups-command = "NEWGROUPS" 1*WSP date 1*WSP time newgroups-command = "NEWGROUPS" 1*WSP date 1*WSP time
1*WSP "GMT"] *WSP CRLF 1*WSP "GMT"] *WSP CRLF
newnews-command = "NEWNEWS" 1*WSP wildmat 1*WSP date newnews-command = "NEWNEWS" 1*WSP wildmat 1*WSP date
1*WSP time [1*WSP "GMT÷]*WSP CRLF 1*WSP time [1*WSP "GMT÷]*WSP CRLF
next-command = "NEXT" *WSP CRLF next-command = "NEXT" *WSP CRLF
over-command = "OVER" [1*WSP range] *WSP CRLF over-command = "OVER" [1*WSP range] *WSP CRLF
parameter = 1*(%x21-FF) ; generic command parameter parameter = 1*(%x21-FF) ; generic command parameter
post-command = "POST" *WSP CRLF post-command = "POST" *WSP CRLF
quit-command = "QUIT" *WSP CRLF quit-command = "QUIT" *WSP CRLF
range = article-number ["-" [article-number]] range = article-number ["-" [article-number]]
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This section is meant to inform application developers, This section is meant to inform application developers,
information providers, and users of the security limitations information providers, and users of the security limitations
in NNTP as described by this memo. The discussion does not in NNTP as described by this memo. The discussion does not
include definitive solutions to the problems revealed, though include definitive solutions to the problems revealed, though
it does make some suggestions for reducing security risks. it does make some suggestions for reducing security risks.
14.1 Personal and Proprietary Information 14.1 Personal and Proprietary Information
NNTP, because it was created to distribute network news NNTP, because it was created to distribute network news
articles, will forward whatever information is stored in articles, will forward whatever information is stored in
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those articles. Specification of that information is outside those articles. Specification of that information is outside
this scope of this memo, but it is likely that some personal this scope of this memo, but it is likely that some personal
and/or proprietary information is available in some of those and/or proprietary information is available in some of those
articles. It is very important that designers and articles. It is very important that designers and
implementers provide informative warnings to users so implementers provide informative warnings to users so
personal and/or proprietary information is not disclosed personal and/or proprietary information is not disclosed
inadvertently. Additionally, effective and easily understood inadvertently. Additionally, effective and easily understood
mechanisms to manage the distribution of news articles must mechanisms to manage the distribution of news articles must
be provided to NNTP Server administrators, so that they are be provided to NNTP Server administrators, so that they are
able to report with confidence what information is and is not able to report with confidence what information is and is not
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optional, doing so is strongly encouraged. optional, doing so is strongly encouraged.
Other mechanisms are also available. For example, a proxy Other mechanisms are also available. For example, a proxy
server could be put in place that requires authentication server could be put in place that requires authentication
before connecting via the proxy to the NNTP server. before connecting via the proxy to the NNTP server.
14.4 DNS Spoofing 14.4 DNS Spoofing
Many existing NNTP implementations authorize incoming Many existing NNTP implementations authorize incoming
connections by checking the IP address of that connection connections by checking the IP address of that connection
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against the IP addresses obtained via DNS lookups of lists of against the IP addresses obtained via DNS lookups of lists of
domain names given in local configuration files. Servers domain names given in local configuration files. Servers
that use this type of authentication, and clients that find a that use this type of authentication, and clients that find a
server by doing a DNS lookup of the server name, rely very server by doing a DNS lookup of the server name, rely very
heavily on the Domain Name Service, and are thus generally heavily on the Domain Name Service, and are thus generally
prone to security attacks based on the deliberate prone to security attacks based on the deliberate
misassociation of IP addresses and DNS names. Clients and misassociation of IP addresses and DNS names. Clients and
servers need to be cautious in assuming the continuing servers need to be cautious in assuming the continuing
validity of an IP number/DNS name association. validity of an IP number/DNS name association.
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address changes. As network renumbering is expected to become address changes. As network renumbering is expected to become
increasingly common, the possibility of this form of attack increasingly common, the possibility of this form of attack
will grow. Observing this requirement thus reduces this will grow. Observing this requirement thus reduces this
potential security vulnerability. potential security vulnerability.
This requirement also improves the load-balancing behavior of This requirement also improves the load-balancing behavior of
clients for replicated servers using the same DNS name and clients for replicated servers using the same DNS name and
reduces the likelihood of a user's experiencing failure in reduces the likelihood of a user's experiencing failure in
accessing sites that use that strategy. accessing sites that use that strategy.
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15 References 15 References
1 Kantor, B and P. Lapsley, "Network News Transfer Protocol", 1 Kantor, B and P. Lapsley, "Network News Transfer Protocol",
RFC-977, U.C. San Diego and U.C. Berkeley, February, 1986. RFC-977, U.C. San Diego and U.C. Berkeley, February, 1986.
2 Yergeau, F., "UTF-8, a transformation format of ISO 10646", 2 Yergeau, F., "UTF-8, a transformation format of ISO 10646",
RFC 2279, Alis Technologies, January, 1998. RFC 2279, Alis Technologies, January, 1998.
3 Coded Character Set-7-bit American Standard Code for 3 Coded Character Set-7-bit American Standard Code for
Information Interchange, ANSI x3.4-1986. Information Interchange, ANSI x3.4-1986.
4 Bradner, Scott, "Keywords for use in RFCs to Indicate 4 Bradner, Scott, "Keywords for use in RFCs to Indicate
Requirement Levels", RFC-2119, Harvard University, March, Requirement Levels", RFC-2119, Harvard University, March,
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16 Notes 16 Notes
UNIX is a registered trademark of the X/Open Company Ltd. UNIX is a registered trademark of the X/Open Company Ltd.
17 Acknowledgments 17 Acknowledgments
The author acknowledges the original authors of NNTP as The author acknowledges the original authors of NNTP as
documented in RFC 977: Brian Kantor and Phil Lapsey. documented in RFC 977: Brian Kantor and Phil Lapsey.
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The author gratefully acknowledges the work of the NNTP The author gratefully acknowledges the work of the NNTP
committee chaired by Eliot Lear. The organization of this committee chaired by Eliot Lear. The organization of this
memo was influenced by the last available draft from this memo was influenced by the last available draft from this
working group. A special thanks to Eliot for generously working group. A special thanks to Eliot for generously
providing the original machine-readable sources for that providing the original machine-readable sources for that
document. document.
The author gratefully acknowledges the work of the Marshall The author gratefully acknowledges the work of the Marshall
Rose & John G. Meyers in RFC 1939 and the work of the DRUMS Rose & John G. Meyers in RFC 1939 and the work of the DRUMS
working group, specifically RFC 1869, which is the basis of working group, specifically RFC 1869, which is the basis of
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for providing specific and relevant examples of security for providing specific and relevant examples of security
issues that should be considered for HTTP. Since many of the issues that should be considered for HTTP. Since many of the
same considerations exist for NNTP, those examples that are same considerations exist for NNTP, those examples that are
relevant have been included here with some minor rewrites. relevant have been included here with some minor rewrites.
The author gratefully acknowledges the comments and The author gratefully acknowledges the comments and
additional information provided by the following individuals additional information provided by the following individuals
in preparing one or more of the progenitors of this memo: in preparing one or more of the progenitors of this memo:
Russ Allbery <rra@stanford.edu> Russ Allbery <rra@stanford.edu>
Wayne Davison <davison@armory.com> Wayne Davison <davison@armory.com>
Clive D.W. Feather <clive@demon.net>
Chris Lewis <clewis@bnr.ca> Chris Lewis <clewis@bnr.ca>
Tom Limoncelli <tal@mars.superlink.net> Tom Limoncelli <tal@mars.superlink.net>
Eric Schnoebelen <eric@egsner.cirr.com> Eric Schnoebelen <eric@egsner.cirr.com>
Rich Salz <rsalz@osf.org> Rich Salz <rsalz@osf.org>
This work was motivated by the work of various news reader This work was motivated by the work of various news reader
authors and news server authors, which includes those listed authors and news server authors, which includes those listed
below: below:
Rick Adams-Original author of the NNTP extensions to the Rick Adams-Original author of the NNTP extensions to the
RN news reader and last maintainer of Bnews RN news reader and last maintainer of Bnews
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Geoff Huston-Original author of ANU NEWS Geoff Huston-Original author of ANU NEWS
Phil Lapsey-Original author of the UNIX reference Phil Lapsey-Original author of the UNIX reference
implementation for NNTP implementation for NNTP
Iain Lea-Original maintainer of the TIN news reader Iain Lea-Original maintainer of the TIN news reader
Chris Lewis-First known implementer of the AUTHINFO Chris Lewis-First known implementer of the AUTHINFO
GENERIC extension GENERIC extension
Rich Salz-Original author of INN Rich Salz-Original author of INN
Henry Spencer-One of the original authors of CNEWS Henry Spencer-One of the original authors of CNEWS
Kim Storm-Original author of the NN news reader Kim Storm-Original author of the NN news reader
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The present author gratefully acknowledges the vast amount of
work put into previous drafts by the original author:
Stan Barber <sob@academ.com>
18 Author's Address 18 Author's Address
Stan Barber Clive Feather
P.O. Box 300481 Thus plc
Houston, Texas 77230 322 Regents Park Road
Email: sob@academ.com London
N3 2QQ
United Kingdom
This memo expires July 15, 2002. Email: clive@demon.net
or: clive@davros.org
Tel: +44 20 8371 1138
This memo expires July 31, 2003.
 End of changes. 

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