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          INTERNET DRAFT                                          S. Barber
          Expires: May 14, 2000                  Academ Consulting Services
                                                              November 1999

                           Network News Transport Protocol

                           draft-ietf-nntpext-base-09.txt

          1. Status of this Document

            This document is an Internet-Draft and is in full conformance
            with Section 10 of RFC 2026. Internet-Drafts are working
            documents of the Internet Engineering Task Force (IETF), its
            areas, and its working groups.  Note that other groups may
            also distribute working documents as Internet-Drafts.

            Internet-Drafts are draft documents valid for a maximum of six
            months and may be updated, replaced, or made obsolete by other
            documents at any time.  It is inappropriate to use Internet-
            Drafts as reference material or to cite them other than as
            "work in progress."

            The list of current Internet-Drafts can be accesses at
            http://www.ietf.org/ietf/1id-abstracts.txt.

            The list of Internet-Draft shadow directories can be accessed
            at http://www.ietf.org/shadow.html.

            This section will be updated with the appropriate verbiage
            from RFC 2223 should this document has been found ready for
            publication as an RFC.

            This document is a product of the NNTP Working Group, chaired
            by Ned Freed and Stan Barber.

          2.  Abstract
            The Network News Transport Protocol has been in use in the
            Internet for a decade and remains one of the most popular
            protocols (by volume) in use today. This document is a
            replacement for RFC 977 and officially updates the protocol
            specification. It clarifies some vagueness in RFC 977,
            includes some new base functionality and provides a specific
            mechanism to add standardized extensions to NNTP.

          3. Introduction
            This document specifies the Network News Transport Protocol
            (NNTP), which is used for the distribution, inquiry,
            retrieval, and posting of net news articles using a reliable
            stream-based mechanism. For news reading clients, NNTP enables
            retrieval of news articles that are stored in a central
            database, giving subscribers the ability to select only those
            articles they wish to read.

          Barber                                              [Page 1]

          INTERNET DRAFT                                 November 1999

            The netnews model provides for indexing, cross-referencing,
            and expiration of aged messages. For server-to-server
            interaction, NNTP is designed for efficient transmission of
            net news articles over a reliable full duplex communication
            method.

            Every attempt is made to insure that the protocol
            specification in this document is compatible with the version
            specified in RFC 977[1]. However, this version does not
            support the ill-defined SLAVE command and permits four digit
            years to be specified in the NEWNEWS and NEWGROUPS commands.
            It changes the default character set to UTF-8[2] instead of
            US-ASCII[3]. It also extends the newsgroup name matching
            capabilities already documented in RFC 977.

            Generally, new functionality is available using new keywords.
            Part of that new functionality involves a mechanism to
            discover what new functionality is available to clients from a
            server.

            This mechanism can also be used to add more functionality as
            needs merit such additions.

            The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
            NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
            "OPTIONAL" in this document are to be interpreted as described
            in RFC 2119[4].

            An implementation is not compliant if it fails to satisfy one
            or more of the MUST requirements for this protocol.  An
            implementation that satisfies all the MUST and all the SHOULD
            requirements for its protocols is said to be "unconditionally
            compliant"; one that satisfies all the MUST requirements but
            not all the SHOULD requirements for NNTP is said to be
            "conditionally compliant".

            For the remainder of this memo, the term "client host" refers
            to a host making use of the NNTP service, while the term
            "server host" refers to a host that offers the NNTP service.
            In addition, where examples of interactions between a client
            host and a server host are provided a "[C]" will be used to
            represent the client host and a "[S]" will be used to
            represent the server host.

          4. Basic Operation.

            Every NNTP session MUST involve the following in this order:

            CONNECTION
            GREETING
            DISCONNECTION

          Barber                                                 [Page 2]

          INTERNET DRAFT                                 November 1999

            Other steps may occur between the GREETING and DISCONNECTION
            step. They are:

            CAPABILITIES DISCOVERY
            NEWS EXCHANGE
            CONCLUSION

            NNTP operates over any reliable data stream 8-bit-wide
            channel. When running over TCP/IP, the official port for the
            NNTP service is 119. Initially, the server host starts the
            NNTP service by listening on a TCP port.  When a client host
            wishes to make use of the service, it MUST establish a TCP
            connection with the server host by connecting to that host on
            the same port on which the server is listening. This is the
            CONNECTION step.  When the connection is established, the NNTP
            server host MUST send a greeting. This is the GREETING step.
            The client host and server host SHOULD then exchange commands
            and responses (respectively) until the connection is closed or
            aborted. This final step is called the DISCONNECTION step.

            If there is a CONCLUSION step, it MUST immediately precede the
            DISCONNECTION step. There MUST be only one CONNECTION,
            CONCLUSION and DISCONNECTION step for each NNTP session. All
            other steps MAY be repeated as needed.

            The character set for all NNTP commands is UTF-8. Commands in
            the NNTP MUST consist of an US-ASCII case-insensitive keyword,
            which MAY be followed by one or more arguments.  An US-ASCII
            CRLF pair MUST terminate all commands. Multiple commands MUST
            NOT be on the same line. Keywords MUST consist of printable
            US-ASCII characters.  Unless otherwise noted elsewhere in this
            document, arguments SHOULD consist of printable US-ASCII
            characters. Keywords and arguments MUST be each separated by
            one or more US-ASCII SPACE or US-ASCII TAB characters.
            Keywords MUST be at least three US-ASCII characters and MUST
            NOT exceed 12 US-ASCII characters.  Command lines MUST NOT
            exceed 512 octets, which includes the terminating US-ASCII
            CRLF pair. Arguments MUST NOT exceed 497 octets.

            Each response MUST start with a three-digit response code that
            is sufficient to distinguish all responses. Unless
            specifically specified as one of the valid responses for a
            command (such as those described later in this document), each
            response is contained in a single line. However, certain
            commands MAY permit multi-line responses. All multi-line
            responses MUST adhere to the following format: After sending
            the first line of the response and an US-ASCII CRLF, any
            additional lines are sent, each terminated by an US-ASCII CRLF
            pair. When all lines of the response have been sent, a final
            line MUST be sent, consisting of a termination octet (US-ASCII
            decimal code 046, ".") and an US-ASCII CRLF pair.  If any line
            of the multi-line response begins with the termination octet,
            the line MUST be "byte-stuffed" by pre-pending the termination

          Barber                                                 [Page 3]

          INTERNET DRAFT                                 November 1999

            octet to that line of the response. Hence, a multi-line
            response is terminated with the five octets "CRLF.CRLF" (in
            US-ASCII).  When examining a multi-line response, the client
            MUST check to see if the line begins with the termination
            octet. If so and if octets other than US-ASCII CRLF follow,
            the first octet of the line (the termination octet) MUST be
            stripped away.  If so and if US-ASCII CRLF immediately follows
            the termination character, then the response from the NNTP
            server is ended and the line containing ".CRLF" (in US-ASCII)
            MUST NOT considered part of the multi-line response. The
            keywords that support multi-line responses have the format of
            those responses described in the responses section.

            A NNTP server MAY have an inactivity autologout timer. Such a
            timer MUST be of at least three minutes duration.  The receipt
            of any command from the client during that interval should
            suffice to reset the autologout timer.  When the timer
            expires, the server should close the TCP connection without
            sending any response to the client.

          4.1  Response Codes

            Each response MUST begin with a three-digit status indicator.
            These are status reports from the server and indicate the
            response to the last command received from the client.

            The first digit of the response broadly indicates the success,
            failure, or progress of the previous command.

            1xx - Informative message
            2xx - Command ok
            3xx - Command ok so far, send the rest of it.
            4xx - Command was correct, but couldn't be performed for some
               reason.
            5xx - Command unimplemented, or incorrect, or a serious
               program error occurred.
            The next digit in the code indicates the function response
            category.

            x0x - Connection, setup, and miscellaneous messages
            x1x - Newsgroup selection
            x2x - Article selection
            x3x - Distribution functions
            x4x - Posting
            x8x - Nonstandard (private implementation) extensions
            x9x - Debugging output

            The exact response codes that can be returned in response to a
            given command are detailed in the description of the keyword
            that is the first part of the command. In addition, below is
            listed a general set of response codes that MAY be received at
            any time.

          Barber                                                 [Page 4]

          INTERNET DRAFT                                 November 1999

            Certain response codes contain parameters such as numbers and
            names in addition to the status indicator. In those cases, the
            number and type of such parameters MUST be fixed for each
            response code to simplify interpretation of the response. In
            all other cases, the client MUST only use the status indicator
            itself to determine the nature of the response.

            Parameters MUST be separated from the numeric status indicator
            and from each other by a single US-ASCII space. All numeric
            parameters MUST be in base 10 (decimal) format, and may have
            leading zeros. All string parameters MUST begin after the
            separating space, and MUST end before the following separating
            space or the US-ASCII CRLF pair at the end of the line.
            (Therefore, string parameters MUST NOT contain US-ASCII
            spaces.) All text, if any, in the response which is not a
            parameter of the response must follow and be separated from
            the last parameter by an US-ASCII space.  Also, note that the
            text following a response number may vary in different
            implementations of the server. The 3-digit numeric status
            indicator should be used to determine what response was sent.

            Response codes not specified in this standard MAY be used for
            any installation-specific additional commands also not
            specified. These SHOULD be chosen to fit the pattern of x8x
            specified above. (Note that debugging is provided for
            explicitly in the x9x response codes.)

            The use of unspecified response codes for a standard command
            is prohibited.

            The status indicator pattern x9x is provided for debugging.
            Since much debugging output may be classed as "informative
            messages", it MUST be the case that responses 190 through 199
            WILL be used for various debugging outputs.  There is no
            requirement in this specification for debugging output.
            However, if such is provided over the connected stream, it
            MUST use these response codes.  If appropriate to a specific
            implementation, other x9x codes MAY be used for debugging.
            (For example, response code 290 could be used to acknowledge a
            remote debugging request.)

            A server MUST respond to an unrecognized, unimplemented, or
            syntactically invalid command with a negative response
            code(status indicators of the form 5XX).  A server MUST
            respond to a command issued when the session is in an
            incorrect state by responding with a negative status
            indicator. This may be from either the 4XX or 5XX group as
            appropriate.

          5. The WILDMAT format

          Barber                                                 [Page 5]

          INTERNET DRAFT                                 November 1999

            The WILDMAT format[5] described here is based on the version
            first developed by Rich Salz which was derived from the format
            used in the UNIX "find" command to articulate file names. It
            was developed to provide a uniform mechanism for matching
            patterns in the same manner that the UNIX shell matches
            filenames. Patterns are implicitly anchored at the beginning
            and end of each string when testing for a match.  There are
            five pattern-matching operations other than a strict one-to-
            one match between the pattern and the source to be checked for
            a match. The first is an asterisk (*) to match any sequence of
            zero or more UTF-8 characters. The second is a question mark
            (?) to match any single UTF-8 character. The third specifies a
            specific set of characters. The set is specified as a list of
            characters, or as a range of characters where the beginning
            and end of the range are separated by a minus (or dash)
            character, or as any combination of lists and ranges. The dash
            can also be included in the set as a character it if is the
            beginning or end of the set. This set is enclosed in square
            brackets. The close square bracket (]) may be used in a set if
            it is the first character in the set. The fourth operation is
            the same as the logical not of the third operation and is
            specified the same way as the third with the addition of a
            caret character (^) at the beginning of the test string just
            inside the open square bracket. The final operation uses the
            backslash character to invalidate the special meaning of the
            open square bracket ([), the asterisk, backslash, or the
            question mark. The meaning of the backslash operator cannot be
            negated by the exclamation point. Two backslashes in sequence
            will result in the evaluation of the backslash as a character
            with no special meaning.

          5.1 Negating the expression
            The exclamation point can be used at the beginning of a
            wildmat to negate it. If it appears as any other character
            other than the first one, it has no special meaning.

          5.2 Examples

                 a) [^]-] -- matches any single character other than a
                    close square bracket or a minus sign/dash.
                 b) *bdc  -- matches any string that ends with the string
                    "bdc" including the string "bdc" (without quotes).
                 c) [0-9a-zA-Z] -- matches any single printable
                    alphanumeric ASCII character.
                 d) a??d  --  matches any four character string which
                    begins with a and ends with d.
                 e)!bc*d -- matches any string that does not start with
                    "bc" and end with "d" (without quotes)

          6. Format for Keyword Descriptions
            On the following pages are descriptions of each keyword
            recognized by the NNTP server and the responses that will be

          Barber                                                 [Page 6]

          INTERNET DRAFT                                 November 1999

            returned by those commands. These keywords are grouped by the
            functional step in which they are used.

            Each keyword is shown in upper case for clarity, although the
            NNTP server ignores case in the interpretation of commands.
            Any parameters are shown in lower case.  A parameter shown in
            [square brackets] is optional. For example, [GMT] indicates
            that the triglyph GMT may be present or omitted. A parameter
            that may be repeated is followed by an ellipsis. Mutually
            exclusive parameters are separated by a vertical bar (|)
            character. For example, ggg|<message-id> indicates that a
            group name or a <message-id> may be specified, but not both.
            Some parameters may be case or language specific. See RFC
            1036[6] for these details.

            In addition, certain commands make use of a pattern for
            selection of multiple news groups. The pattern in all cases is
            based on the WILDMAT format.  Arguments expected to be in
            wildmat format will be represented by the string wildmat. This
            format is discussed in detail in section 5 of this memo.

          7. The GREETING Step

          7.1  Initial Connection

            There is no keyword presented by the client upon initial
            connection to the server. The server MUST present an
            appropriate response code as a greeting to the client.  This
            response informs the client about what steps the client should
            take to reach the news exchange step.

            The server MUST present a 200 greeting code if the client is
            authorized to post articles though the use of the POST keyword
            on this server.

            The server MUST present a 201 greeting code if the client is
            not authorized to post articles using the POST keyword.

            The server MUST present a 502 greeting code if the client is
            not permitted under any circumstances to interact with the
            server. The server should immediately close the connection
            with the client after presenting this code.

            In all other cases, the server MUST present a 400 greeting
            code.

          7.1.1 Initial Connection Example

            Example of a normal connection from an authorized client

                    [C] Initial TCP connection completed

          Barber                                                 [Page 7]

          INTERNET DRAFT                                 November 1999

                    [S] 200 NNTP Service Ready, posting permitted

            Client can send commands at this point. In this example, the
            client jumps directly to the conclusion step (See section
            10.1).

                    [C] QUIT

                    [S] 205 NNTP Service exits normally

            Example of a normal connection from an unauthorized client

                    [C] Initial TCP connection completed

                    [S] 502 NNTP Service Unavailable

            At this point, the server closes the TCP connection.

            Example of a normal connection from an authorized client that
            is not permitted to post

                    [C] Initial TCP connection completed

                    [S] 201 NNTP Service Ready, posting prohibited

            Client can send commands at this point. In this example, the
            client jumps directly to the conclusion step (See section
            10.1).

                    [C] QUIT

                    [S] 205 NNTP Service exits normally

            Example of a connection from any client where the server is
            unable to provide service

                    [C] Initial TCP connection completed

                    [S] 400 NNTP Service temporarily unavailable

            At this point, the server closes the TCP connection.

          7.1.2 MODE READER

            MODE READER

          Barber                                                 [Page 8]

          INTERNET DRAFT                                 November 1999

            MODE READER MAY be used by the client to indicate to the
            server that it is a news reading client. This command may be
            entered at any time. The server must present a greeting code
            (as described in section 7.1.2.1) appropriate to the server's
            ability to provide service to this client in this mode.

          7.1.2.1 Responses
                 200 Hello, you can post
                 201 Hello, you can't post
                 400 Service temporarily unavailable
                 502 Service unavailable

          7.1.2.2 MODE READER Examples

            Example of use of the MODE READER command by an authorized
            client

                    [C] MODE READER

                    [S] 200 NNTP Service Ready, posting permitted

            Client can send commands at this point. In this example, the
            client jumps directly to the conclusion step (See section
            10.1).

                    [C] QUIT

                    [S] 205 NNTP Service exits normally

            Example of use of MODE READER by a client not authorized to
            receive service from the server as a news reader

                    [C] MODE READER

                    [S] 502 NNTP Service Unavailable

            At this point, the server closes the TCP connection.

            Example of a normal connection from an authorized client that
            is not permitted to post

                    [C] MODE READER

                    [S] 201 NNTP Service Ready, posting prohibited

          Barber                                                 [Page 9]

          INTERNET DRAFT                                 November 1999

            Client can send commands at this point. In this example, the
            client jumps directly to the conclusion step (See section
            10.1).

                    [C] QUIT

                    [S] 205 NNTP Service exits normally

            Example of a connection from any client where the server is
            unable to provide news reader service

                    [C] MODE READER

                    [S] 400 NNTP Service temporarily unavailable

            At this point, the server closes the TCP connection.

          8. The CAPABILITIES DISCOVERY Step

            A client NNTP supporting NNTP service extensions should query
            a server early in the session for extensions session by
            issuing the LIST EXTENSIONS command. If the NNTP server
            supports the NNTP service extensions it MUST give a successful
            response (see section 8.1.1), a failure response (see section
            8.1.2), or an error response (see section 8.1.3). If the NNTP
            server does not support any NNTP service extensions, it MUST
            generate an error response (see section 8.1.4).

          8.1 LIST EXTENSIONS

            If successful, the server NNTP MUST respond with code 202. On
            failure, the server NNTP MUST respond with code 503. On error,
            the server NNTP MUST respond with one of codes 400, 402, 500,
            501 and 502.

            This command MAY be issued at anytime during a session.  It is
            not required that the client issues this command before
            attempting to make use of any extension. The response
            generated by this command MAY change during a session because
            of other state information. However, a client NNTP MUST NOT
            cache (for use in another session) any information returned if
            the LIST EXTENSIONS command succeeds. That is, a client NNTP
            is only able to get the current and correct information
            concerning available extensions during a session by issuing a
            LIST EXTENSIONS command during that session and processing
            that response.

          Barber                                                 [Page 10]

          INTERNET DRAFT                                 November 1999

          8.1.1 Successful response

            If the server NNTP implements and is able to perform the LIST
            EXTENSIONS command, it MUST return code 202.

            Text following the return code on the first line of the reply
            is free form, and not interpreted, and has no practical use,
            as this text is not expected to be revealed to end users.  The
            syntax of other reply lines is precisely defined, and if
            present, MUST be exactly as specified.

            Each line listing an extension in the extension-listing begins
            with a single space.  That space IS NOT optional, nor does it
            indicate general white space.  This space guarantees that the
            line can never be misinterpreted as the end of the extension-
            listing, but is required even where there is no possibility of
            ambiguity.

            Each extension supported MUST be listed on a separate line to
            facilitate the possible inclusion of parameters supported by
            each extension command.  The extension-label to be used in the
            response to the LIST EXTENSIONS command will be specified as
            each new extension is added to the NNTP command set.  Often it
            will be the name of a new command added; however this IS NOT
            required.  In fact, it IS NOT required that a new feature
            actually adds a new command or keyword.  Any parameters
            included are to be specified with the definition of the
            command concerned.

            That specification SHALL also specify how any parameters
            present are to be interpreted and how each parameter is
            separated from other parameters.

            The extension-label is nominally case sensitive, however the
            definitions of specific labels and parameters specify the
            precise interpretation, and it is to be expected that those
            definitions will usually specify the label in a case
            independent manner.  Where this is done, implementations are
            recommended to use US-ASCII upper case letters when
            transmitting the extension response.

            The LIST EXTENSIONS command itself is not included in the list
            of features supported, support for the LIST EXTENSIONS command
            is indicated by return of a reply other than a 500 or 502
            reply.

            The end of the list is defined by the usual period on a line
            by itself.

            A typical example reply to the LIST EXTENSIONS command might
            be a multiline reply of the form:

          Barber                                                 [Page 11]

          INTERNET DRAFT                                 November 1999

                    [C] LIST EXTENSIONS

                    [S] 202 Extensions supported:

                    [S] OVER

                    [S] PAT

                    [S] LISTGROUP

                    [S] .

            The particular extensions shown here are simply examples of
            what may be defined in other places, no particular meaning
            should be attributed to them.  Recall also, that the extension
            names returned are not command names, as such, but simply
            indications that the server possesses some attribute or other.

            The order in which the extensions are returned is of no
            importance, NNTP server processes are not required to
            implement any particular order, or even to consistently return
            the same order when the command is repeated.

          8.1.2 Failure response

            If for some reason the server NNTP is unable to list the
            service extensions it supports, it MUST return code 503. No
            list (not even an empty one) will be returned.

            In the case of a failure response, the client NNTP may try the
            extensions either as the need arises or configure itself for
            the basic NNTP functionality defined in this document.

          8.1.3 Error responses from extended servers

            If the server NNTP recognizes the LIST EXTENSIONS command, but
            due to various conditions cannot make any extensions available
            to the client at the time the client issued the LIST
            EXTENSIONS command, it MUST return code 402. No list (not even
            an empty one) will be returned.

            The client NNTP should configure itself for the basic NNTP
            functionality defined in this document, or issue commands that
            might change the state of the server, or issue the QUIT
            command (see section 10.1) if a particular extension is
            required for the client to properly operate.

          Barber                                                 [Page 12]

          INTERNET DRAFT                                 November 1999

            If the server NNTP determines that the NNTP service is no
            longer available (e.g., due to imminent system shutdown), it
            must return code 400. Note that this is response code should
            not be generated due to an inactivity timeout as described in
            section 4.

            In the case of any error response outlined in this section,
            the client NNTP should issue the QUIT command (see section
            10.1).

          8.1.4 Responses from servers without extensions

            A server NNTP that conforms to this memo but does not support
            the extensions specified here will not recognize the LIST
            EXTENSIONS command and MUST consequently return code 500 or
            code 501. The server NNTP SHALL stay in the same state after
            returning this code. The client NNTP may try the extensions
            either as the need arises or configure itself for the basic
            NNTP functionality defined in this document.

          8.1.5 Responses from improperly implemented servers

            A server NNTP that improperly implements the LIST EXTENSIONS
            command may return an empty list. Clients SHALL accommodate
            this protocol violation and interpret it as a response code
            402.

            The client NNTP should configure itself for the basic NNTP
            functionality defined in this document, or issue commands that
            might change the state of the server, or issue the QUIT
            command (see section 10.1) if a particular extension is
            required for the client to properly operate.

          9. The NEWS EXCHANGE Step

            During this step, two basic types of transactions occur:

          . article retrieval from the server
          . article posting to the server

          9.1 Article Retrieval

            News reading clients have available a variety of mechanisms to
            retrieve articles via NNTP. The news articles are stored and
            indexed using three types of keys. One key is the message id
            of an article. According to RFC 1036, this identifier should
            be globally unique. Another key is composed of the news group
            name and the article number within that news group. That key
            MUST be unique to a particular server (there will be only one

          Barber                                                 [Page 13]

          INTERNET DRAFT                                 November 1999

            article with that number within a particular news group), but
            is not required to be globally unique.  Additionally, because
            the same article can be cross-posted to multiple news groups,
            there may be multiple keys that point to the same article on
            the same server. The final key is the arrival timestamp,
            giving the time that the article arrived at the server.

            The server MUST ensure that article numbers are issued in
            order of arrival timestamp; that is, articles arriving later
            MUST have higher numbers than those that arrive earlier. The
            server SHOULD allocate the next sequential unused number to
            each new article.

            Article numbers MUST lie between 1 and 4,294,967,295
            inclusive. The client and server SHOULD NOT use leading zeroes
            in specifying article numbers, and MUST NOT use more than 16
            digits. In some situations, the value zero replaces an article
            number to show some special situation. One case involves
            responses to the ARTICLE, STAT, BODY and HEAD commands where a
            <message-id> is specified as the argument. In those cases, the
            "current article pointer" is not changed.

          9.1.1 Article Retrieval by News Group Name and Article Number

            The following commands are used to set the current news group
            name and the "current article pointer" which is used by other
            commands for article retrieval.

          9.1.1.1 GROUP

            GROUP ggg

            The required parameter ggg is the name of the news group to be
            selected (e.g. "news.software.b"). A list of valid news groups
            may be obtained by using the LIST keyword.  See section 9.4
            for more information on the LIST keyword.

            The successful selection response will return the article
            numbers of the first and last articles in the group at the
            moment of selection (these numbers are referred to as the
            "reported low water mark" and the "reported high water mark"),
            and an estimate of the number of articles on file in the
            group.

            If the group is not empty, the estimate MUST be at least the
            actual number of articles available, and MUST be no greater
            than one more than the difference between the reported low and
            high water marks. (Some implementations will actually count
            the number of articles on file. Others will just subtract the
            low water mark from the high water mark and add one to get an
            estimate.)

          Barber                                                 [Page 14]

          INTERNET DRAFT                                 November 1999

            If the group is empty, one of the following three situations
            will occur. Clients MUST accept all three cases; servers MUST
            NOT represent an empty group in any other way.

          . The high water mark will be one less than the low water mark,
            and the estimated article count will be zero. Servers SHOULD
            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.
          . All three numbers will be zero.
          . The high water mark is greater than or equal to the low water
            mark; the estimated article count might be zero or non-zero;
            if non-zero, the same requirements apply as for a non-empty
            group.

            The set of articles in a group may change after the GROUP
            command is carried out. That is:

          . articles may be removed from the group
          . articles may be reinstated in the group with the same article
            number, but those articles MUST have numbers no less than the
            reported low water mark (note that this is a reinstatement of
            the previous article, not a new article reusing the number)
          . new articles may be added with article numbers greater than
            the reported high water mark (if an article that was the one
            with the highest number has been removed, the next new article
            will not have the number one greater than the reported high
            water mark)

            Except when the group is empty and all three numbers are zero,
            whenever a subsequent GROUP command for the same news group is
            issued, either by the same client or a different client, the
            reported low water mark in the response MUST be no less than
            that in any previous response for that news group sent to any
            client. The client may make use of the low water mark to
            remove all remembered information about articles with lower
            numbers, as these will never recur. This includes the
            situation when the high water mark is one less than the low
            water mark.

            No similar assumption can be made about the high water mark,
            as this can decrease if an article is removed, and then
            increase again if it is reinstated or if new articles arrive.

            When a valid group is selected by means of this command, the
            internally maintained "current article pointer" MUST be set to
            the first article in the group and the name of the current
            news group MUST be set to the selected news group name.  If an
            invalid group is specified, the previously selected group and
            article MUST remain selected.  If an empty news group is
            selected, the "current article pointer" is in an indeterminate
            state and MUST NOT be used.

          Barber                                                 [Page 15]

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            The GROUP keyword MUST be used by a client and a successful
            response received before the any other command is used that
            depends on having the "current article pointer" be valid.

          9.1.1.1.1 Responses

                 211 n f l s group selected
                 (n = estimated number of articles in group, f = first
                    article number in the group, l = last article number in
                    the group, s = name of the group.)
                 411 no such news group

          9.1.1.1.2 GROUP Examples
            Example for a group known to the server

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

            Example for a group unknown to the server

                    [C] GROUP example.is.sob.bradner.or.barber

                    [S] 411 example.is.sob.bradner.or.barber is unknown

          9.1.1.2   LAST

            LAST

            The internally maintained "current article pointer" MUST be
            set to the previous article in the current news group.  If
            already positioned at the first article of the news group, an
            error message MUST be returned and the current article MUST
            remain selected.

            There MAY be no previous article in the group, although the
            current article number is not the reported low water mark.
            There MUST NOT be a previous article when the current article
            number is the reported low water mark.

            Because articles can be removed and added, the results of
            multiple LAST and NEXT commands MAY not be consistent over the
            life of a particular NNTP session.

            The internally-maintained "current article pointer" MUST be
            set by this command.

            A response indicating the current article number and a
            message-id string MUST be returned. No article text is sent in
            response to this command.

          Barber                                                 [Page 16]

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          9.1.1.2.1 Responses

                 223 n a article retrieved - request text separately (n =
                    article number, a = unique article id)
                 412 no news group selected
                 420 no current article has been selected
                 422 no previous article in this group

          9.1.1.2.2 LAST Examples

            Example of a successful article retrieval using LAST
                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] NEXT

                    [S] 223 3000237 <668929@domain.com> retrieved

                    [C] LAST

                    [S] 223 3000234 <45223423@to.to> retrieved

            Example of an attempt to retrieve an article without having
            selected a group (via the GROUP command) first

                    [S] 200 NNTP Service ready

                    [C] LAST

                    [S] 412 no newsgroup selected

            Example of an attempt to retrieve an article using the LAST
            command when the current article pointer is pointing at the
            first article in the group

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] LAST

                    [S] 422 No previous article to retrieve

          Barber                                                 [Page 17]

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            Example of an attempt to retrieve an article using the LAST
            command when the current group selected is empty

                    [S] 200 NNTP Service Ready

                    [C] GROUP example.empty.newsgroup

                    [S] 211 0 0 0 example.empty.newsgroup

                    [C] LAST

                    [S] 420 No current article selected

          9.1.1.3 NEXT

            NEXT

            The internally maintained "current article pointer" MUST be
            advanced to the next article in the current news group.  If no
            more articles remain in the current group, an error message
            MUST be returned and the current article MUST remain selected.

            The internally-maintained "current article pointer" MUST be
            set by this command.

            A response indicating the current article number and the
            message-id string MUST be returned.  No text is sent in
            response to this command.

          9.1.1.3.1 Responses

                 223 n a article retrieved - request text separately (n =
                    article number, a = unique article id)
                 412 no news group selected
                 420 no current article has been selected
                 421 no next article in this group

          9.1.1.3.2 NEXT Examples

            Example of a successful article retrieval using NEXT
                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] NEXT

                    [S] 223 3000237 <668929@domain.com> retrieved

          Barber                                                 [Page 18]

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            Example of an attempt to retrieve an article without having
            selected a group (via the GROUP command) first

                    [S] 200 NNTP Service ready

                    [C] NEXT

                    [S] 412 no newsgroup selected

            Example of an attempt to retrieve an article using the NEXT
            command when the current article pointer is pointing at the
            first article in the group

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] ARTICLE 3002322

                    [S] 220 3002322 <411@whitehouse.gov> retrieved

                        Path: pathost!demo!whitehouse!not-for-mail

                        From: nobody@whitehouse.gov(Demo User)

                        Newsgroups: misc.test

                        Subject: I am just a test article

                        Date: 6 Oct 1998 04:38:40 -0500

                        Organization: The White House, Washington, DC

                        Message-ID: <411@whitehouse.gov>

                        This is just a test article.

                        .

                    [C] NEXT

                    [S] 422 No next article to retrieve

            Example of an attempt to retrieve an article using the NEXT
            command when the current group selected is empty

          Barber                                                 [Page 19]

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                    [S] 200 NNTP Service Ready

                    [C] GROUP example.empty.newsgroup

                    [S] 211 0 0 0 example.empty.newsgroup

                    [C] NEXT

                    [S] 420 No current article selected

          9.2 Retrieval of Articles and Article Sections

            There are two forms to the ARTICLE command (and the related
            BODY, HEAD, and STAT commands), each using a different method
            of specifying which article is to be retrieved. When the
            ARTICLE keyword is followed by a message-id in angle brackets
            ("<" and ">"), the first form of the command MUST be used;
            when a numeric parameter or no parameter is supplied, the
            second form MUST be invoked. In the cases where the argument
            is a message-id, the article number specified in the response
            must be zero. This is one of the special cases described in
            section 9.1.

            An article, as defined by RFC 1036, consists of two parts: the
            article headers and the article body. When responding to an
            article command, the server returns the entire article
            contents and does not attempt to alter or translate them in
            any way.

          9.2.1 ARTICLE

            ARTICLE [<message-id>|nnn]

            This response displays the header, a blank line, then the body
            (text) of the specified article. The optional parameter nnn is
            the numeric id of an article in the current news group and
            SHOULD be chosen from the range of articles provided when the
            news group was selected.  If it is omitted, the current
            article is assumed. Message-id is the message id of an article
            as shown in that article's header.

            The internally maintained "current article pointer" MUST NOT
            be altered when the message-id argument is used. This is both
            to facilitate the presentation of articles that may be
            referenced within an article being read, and because of the
            semantic difficulties of determining the proper sequence and
            membership of an article which may have been posted to more
            than one news group.

          Barber                                                 [Page 20]

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            The internally-maintained "current article pointer" MUST be
            set when a valid article number is specified as the argument.
            This includes the case when an article number is implied by
            the use of no argument.

            A previously valid article number MAY become invalid if the
            article has been removed. A previously invalid article number
            MAY become valid if the article has been reinstated, but such
            an article number MUST be no less than the reported low water
            mark for that group.

            If there is a valid article to present in a reply to this
            command, a response indicating the current article number (or
            zero when the message-id argument is used), a message-id
            string, and that text is to follow MUST be returned.

            The message-id string is an identification string contained
            within angle brackets ("<" and ">"), which is derived from the
            header of the article itself.  The Message-ID header line
            (required by RFC 1036) from the article must be used to supply
            this information. If the message-id header line is missing
            from the article, a single digit "0" (zero) should be supplied
            within the angle brackets.

            Since the message-id field is unique for each article, it may
            be used by a news reading program to skip duplicate displays
            of articles that have been posted more than once, or to more
            than one news group.

          9.2.1.1 Responses
                 220 n <a> article retrieved - head and body follow (n =
                    article number, <a> = message-id)
                 412 no news group has been selected
                 420 no current article has been selected
                 423 no such article number in this group
                 430 no such article found
                 502 Service unavailable

          9.2.1.2 Examples
            Example of a successful retrieval of an article (using no
            article number)

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] ARTICLE

                    [S] 220 3000234 <45223423@to.to>

                        Path: pathost!demo!somewhere!not-for-mail

          Barber                                                 [Page 21]

          INTERNET DRAFT                                 November 1999

                        From: nobody@nowhere.to (Demo User)

                        Newsgroups: misc.test

                        Subject: I am just a test article

                        Date: 6 Oct 1998 04:38:40 -0500

                        Organization: Nowhere, To

                        Message-ID: <45223423@to.to>

                        This is just a test article.

                        .

            Example of a successful retrieval of an article by message-id

                    [S] 200 NNTP Service Ready

                    [C] ARTICLE <45223423@to.to>

                    [S] 220 0 <45223423@to.to>

                        Path: pathost!demo!somewhere!not-for-mail

                        From: nobody@nowhere.to (Demo User)

                        Newsgroups: misc.test

                        Subject: I am just a test article

                        Date: 6 Oct 1998 04:38:40 -0500

                        Organization: Nowhere, To

                        Message-ID: <45223423@to.to>

                        This is just a test article.

                        .

            Example of an unsuccessful retrieval of an article by message-
            id

                    [S] 200 NNTP Service Ready

                    [C] ARTICLE <i.am.not.there@nowhere.to>

                    [S] 430 No Such Article Found

          Barber                                                 [Page 22]

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            Example of an unsuccessful retrieval of an article by number

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 news.groups

                    [C] ARTICLE 300256

                    [S] 423 No such article number in this group

            Example of an unsuccessful retrieval of an article by number
            because no news group was selected first

                    [S] 200 NNTP Service Ready

                    [C] ARTICLE 300256

                    [S] 412 No news group selected

            Example of an attempt to retrieve an article when the current
            group selected is empty

                    [S] 200 NNTP Service Ready

                    [C] GROUP example.empty.newsgroup

                    [S] 211 0 0 0 example.empty.newsgroup

                    [C] ARTICLE

                    [S] 420 No current article selected

            Example of a failure due to the service being unavailable

                    [S] 200 NNTP Service Ready

                    [C] ARTICLE <i.am.a.test.article@nowhere.to>

                    [S] 500 Service unavailable

          9.2.2 HEAD
            HEAD [<message-id>|nnn]

            This response displays the header of the specified article.
            The optional parameter nnn is the numeric id of an article in
            the current news group and SHOULD be chosen from the range of
            articles provided when the news group was selected.  If it is
            omitted, the current article is assumed. Message-id is the
            message id of an article as shown in that article's header.

          Barber                                                 [Page 23]

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            The internally maintained "current article pointer" MUST NOT
            be altered when the message-id argument is used. This is both
            to facilitate the presentation of articles that may be
            referenced within an article being read, and because of the
            semantic difficulties of determining the proper sequence and
            membership of an article which may have been posted to more
            than one news group.

            The internally-maintained "current article pointer" MUST be
            set when a valid article number is specified as the argument.
            This includes the case when an article number is implied by
            the use of no argument.

            A previously valid article number MAY become invalid if the
            article has been removed. A previously invalid article number
            MAY become valid if the article has been reinstated, but such
            an article number MUST be no less than the reported low water
            mark for that group.

            If there is a valid article to present in a reply to this
            command, a response indicating the current article number (or
            zero when the message-id argument is used), a message-id
            string, and that text is to follow MUST be returned.

            The message-id string returned is an identification string
            contained within angle brackets ("<" and ">"), which is
            derived from the header of the article itself.  The Message-ID
            header line (required by RFC 1036) from the article must be
            used to supply this information. If the message-id header line
            is missing from the article, a single digit "0" (zero) should
            be supplied within the angle brackets.

            Since the message-id field is unique for each article, it may
            be used by a news reading program to skip duplicate displays
            of articles that have been posted more than once, or to more
            than one news group.

          9.2.2.1 Responses
                 221 n <a> article retrieved - head follows
                 412 no news group has been selected
                 420 no current article has been selected
                 423 no such article number in this group
                 430 no such article found
                 502 Service unavailable

          9.2.2.2 Examples
            Example of a successful retrieval of the headers in an article
            (using no article number)

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

          Barber                                                 [Page 24]

          INTERNET DRAFT                                 November 1999

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] HEAD

                    [S] 220 3000234 <45223423@to.to>

                        Path: pathost!demo!somewhere!not-for-mail

                        From: nobody@nowhere.to (Demo User)

                        Newsgroups: misc.test

                        Subject: I am just a test article

                        Date: 6 Oct 1998 04:38:40 -0500

                        Organization: Nowhere, To

                        Message-ID: <45223423@to.to>

                        .

            Example of a successful retrieval of the headers in an article
            by message-id

                    [S] 200 NNTP Service Ready

                    [C] HEAD <45223423@to.to>

                    [S] 220 0 <45223423@to.to>

                        Path: pathost!demo!somewhere!not-for-mail

                        From: nobody@nowhere.to (Demo User)

                        Newsgroups: misc.test

                        Subject: I am just a test article

                        Date: 6 Oct 1998 04:38:40 -0500

                        Organization: Nowhere, To

                        Message-ID: <45223423@to.to>

                        .

            Example of an unsuccessful retrieval of the header of an
            article by message-id

                    [S] 200 NNTP Service Ready

          Barber                                                 [Page 25]

          INTERNET DRAFT                                 November 1999

                    [C] HEAD <i.am.not.there@nowhere.to>

                    [S] 430 No Such Article Found

            Example of an unsuccessful retrieval of the header of an
            article by number

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] HEAD 300256

                    [S] 423 No such article number in this group

            Example of an unsuccessful retrieval the header of an article
            by number because no news group was selected first

                    [S] 200 NNTP Service Ready

                    [C] HEAD 300256

                    [S] 412 No news group selected

            Example of an attempt to retrieve the header of an article
            when the current group selected is empty

                    [S] 200 NNTP Service Ready

                    [C] GROUP example.empty.newsgroup

                    [S] 211 0 0 0 example.empty.newsgroup

                    [C] HEAD

                    [S] 420 No current article selected

            Example of a failure due to the service being unavailable

                    [S] 200 NNTP Service Ready

                    [C] HEAD <i.am.a.test.article@nowhere.to>

                    [S] 500 Service unavailable

          9.2.3 BODY
            BODY [<message-id>|nnn]

            This response displays the body (text) of the specified
            article. The optional parameter nnn is the numeric id of an
            article in the current news group and SHOULD be chosen from

          Barber                                                 [Page 26]

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            the range of articles provided when the news group was
            selected.  If it is omitted, the current article is assumed.
            Message-id is the message id of an article as shown in that
            article's header.

            The internally maintained "current article pointer" MUST NOT
            be altered when the message-id argument is used. This is both
            to facilitate the presentation of articles that may be
            referenced within an article being read, and because of the
            semantic difficulties of determining the proper sequence and
            membership of an article which may have been posted to more
            than one news group.

            The internally-maintained "current article pointer" MUST be
            set when a valid article number is specified as the argument.
            This includes the case when an article number is implied by
            the use of no argument.

            A previously valid article number MAY become invalid if the
            article has been removed. A previously invalid article number
            MAY become valid if the article has been reinstated, but such
            an article number MUST be no less than the reported low water
            mark for that group.

            If there is a valid article to present in a reply to this
            command, a response indicating the current article number (or
            zero when the message-id argument is used), a message-id
            string, and that text is to follow MUST be returned.

            The message-id string returned is an identification string
            contained within angle brackets ("<" and ">"), which is
            derived from the header of the article itself.  The Message-ID
            header line (required by RFC 1036) from the article must be
            used to supply this information. If the message-id header line
            is missing from the article, a single digit "0" (zero) should
            be supplied within the angle brackets.

            Since the message-id field is unique for each article, it may
            be used by a news reading program to skip duplicate displays
            of articles that have been posted more than once, or to more
            than one news group.

          9.2.3.1 Responses
                 222 n <a> article retrieved - body follows
                 412 no news group has been selected
                 420 no current article has been selected
                 423 no such article number in this group
                 430 no such article found
                 502 Service unavailable

          9.2.3.2 Examples
            Example of a successful retrieval of the body of an article
            (using no article number)

          Barber                                                 [Page 27]

          INTERNET DRAFT                                 November 1999

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] BODY

                    [S] 222 3000234 <45223423@to.to>

                        This is just a test article.

                        .

            Example of a successful retrieval of the body of an article by
            message-id

                    [S] 200 NNTP Service Ready

                    [C] BODY <45223423@to.to>

                    [S] 222 0 <45223423@to.to>

                        This is just a test article.

                        .

            Example of an unsuccessful retrieval of the body of an article
            by message-id

                    [S] 200 NNTP Service Ready

                    [C] BODY <i.am.not.there@nowhere.to>

                    [S] 430 No Such Article Found

            Example of an unsuccessful retrieval of the body of an article
            by number

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] BODY 300256

                    [S] 423 No such article number in this group

            Example of an unsuccessful retrieval of the body of an article
            by number because no news group was selected first

                    [S] 200 NNTP Service Ready

          Barber                                                 [Page 28]

          INTERNET DRAFT                                 November 1999

                    [C] BODY 300256

                    [S] 412 No news group selected

            Example of an attempt to retrieve the body of an article when
            the current group selected is empty

                    [S] 200 NNTP Service Ready

                    [C] GROUP example.empty.newsgroup

                    [S] 211 0 0 0 example.empty.newsgroup

                    [C] BODY

                    [S] 420 No current article selected

            Example of a failure due to the service being unavailable

                    [S] 200 NNTP Service Ready

                    [C] BODY <i.am.a.test.article@nowhere.to>

                    [S] 500 Service unavailable

          9.2.4 STAT
            STAT [<message-id>|nnn]

            This response returns only status information; no article
            contents are returned. The optional parameter nnn is the
            numeric id of an article in the current news group and SHOULD
            be chosen from the range of articles provided when the news
            group was selected.  If it is omitted, the current article is
            assumed. Message-id is the message id of an article as shown
            in that article's header.

            The internally maintained "current article pointer" MUST NOT
            be altered when the message-id argument is used. This is both
            to facilitate the presentation of articles that may be
            referenced within an article being read, and because of the
            semantic difficulties of determining the proper sequence and
            membership of an article which may have been posted to more
            than one news group.

            The internally-maintained "current article pointer" MUST be
            set when a valid article number is specified as the argument.
            This includes the case when an article number is implied by
            the use of no argument.

            A previously valid article number MAY become invalid if the
            article has been removed. A previously invalid article number
            MAY become valid if the article has been reinstated, but such
            an article number MUST be no less than the reported low water
            mark for that group.

          Barber                                                 [Page 29]

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            If there is a valid article to present in a reply to this
            command, a response indicating the current article number (or
            zero when the message-id argument is used) and a message-id
            string MUST be returned.

            The message-id string returned is an identification string
            contained within angle brackets ("<" and ">"), which is
            derived from the header of the article itself.  The Message-ID
            header line (required by RFC 1036) from the article must be
            used to supply this information. If the message-id header line
            is missing from the article, a single digit "0" (zero) should
            be supplied within the angle brackets.

            Since the message-id field is unique for each article, it may
            be used by a news reading program to skip duplicate displays
            of articles that have been posted more than once, or to more
            than one news group.

          9.2.4.1 Responses
                 223 n <a> article retrieved - request text separately
                 412 no news group has been selected
                 420 no current article has been selected
                 423 no such article number in this group
                 430 no such article found
                 502 Service unavailable

          9.2.4.2 Examples
            Example of STAT on an existing article (using no article
            number)

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] STAT

                    [S] 223 3000234 <45223423@to.to>

            Example of a STAT of an existing article by message-id

                    [S] 200 NNTP Service Ready

                    [C] STAT <45223423@to.to>

                    [S] 223 0 <45223423@to.to>

          Barber                                                 [Page 30]

          INTERNET DRAFT                                 November 1999

            Example of an STAT of an article not on the server by message-
            id

                    [S] 200 NNTP Service Ready

                    [C] STAT <i.am.not.there@nowhere.to>

                    [S] 430 No Such Article Found

            Example of STAT of an article not in the server by number

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] STAT 300256

                    [S] 423 No such article number in this group

            Example of STAT of an article by number when no news group was
            selected first

                    [S] 200 NNTP Service Ready

                    [C] STAT 300256

                    [S] 412 No news group selected

            Example of STAT of an article when the current group selected
            is empty

                    [S] 200 NNTP Service Ready

                    [C] GROUP example.empty.newsgroup

                    [S] 211 0 0 0 example.empty.newsgroup

                    [C] STAT

                    [S] 420 No current article selected

            Example of a failure due to the service being unavailable

                    [S] 200 NNTP Service Ready

                    [C] STAT <i.am.a.test.article@nowhere.to>

                    [S] 500 Service unavailable

          9.3 Article Posting

          Barber                                                 [Page 31]

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            Article posting is done in one of two modes: individual
            article posting from news reading clients and article transfer
            from other news servers.

          9.3.1 POST

            POST

            If posting is allowed, response code 340 MUST be returned to
            indicate that the article to be posted should be sent.
            Response code 440 MUST be sent if that posting is prohibited
            for some installation-dependent reason.

            If posting is permitted, the article MUST be presented to the
            server by the client in the format specified by RFC 1036. The
            text forming the header and body of the message to be posted
            MUST be sent by the client using the conventions for text
            received from the news server: A single period (".") on a line
            indicates the end of the text, with lines starting with a
            period in the original text having that period doubled during
            transmission.

            Following the presentation of the termination sequence by the
            client, the server MUST return a response code indicating
            success or failure of the article transfer.

            No attempt shall be made by the server to filter characters,
            fold or limit lines, or otherwise process incoming text. The
            intent is that the server just passes the incoming message to
            be posted to the server installation's news posting software,
            which is not part of this specification.

          9.3.1.1 Responses

                 240 article received ok
                 340 send article to be posted. End with <CR-LF>.<CR-LF>
                 440 posting not allowed
                 441 posting failed

          9.3.1.2 Examples
            Example of a successful posting

                    [S] 200 NNTP Service Ready

                    [C] POST

                    [S] 340 Input article. End with <CR-LF>.<CR-LF>

                    [C] From: demo@testdomain.com(Demo User)

                        Newsgroups: misc.test

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                        Subject: I am just a test article

                        Organization: Testdomain, USA

                        This is just a test article.

                        .

                    [S] 240 Article received ok

            Example of an unsuccessful posting

                    [S] 200 NNTP Service Ready

                    [C] POST

                    [S] 340 Input article. End with <CR-LF>.<CR-LF>

                    [C] From: demo@testdomain.com(Demo User)

                        Newsgroups: misc.test

                        Subject: I am just a test article

                        Organization: Testdomain, USA

                        This is just a test article.

                        .

                    [S] 441 Posting failed

            Example of an attempt to posting when posting is not allowed

                    [S] 201 NNTP Service Ready, read-only

                    [C] POST

                    [S] 440 Posting not permitted

          9.3.2 IHAVE

            IHAVE <message-id>

            The IHAVE command informs the server that the client has an
            article whose id is <message-id>. If the server desires a copy
            of that article, it MUST return a response instructing the
            client to send the entire article. If the server does not want

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            the article (if, for example, the server already has a copy of
            it), a response indicating that the article is not wanted MUST
            be returned.

            If transmission of the article is requested, the client MUST
            send the entire article, including header and body, in the
            manner specified for text transmission from the server. The
            server MUST return a response code indicating success or
            failure of the transferal of the article.

            This function differs from the POST command in that it is
            intended for use in transferring already-posted articles
            between hosts. It SHOULD NOT be used when the client is a
            personal news reading program. In particular, this function
            will invoke the server's news posting program with the
            appropriate settings (flags, options, etc.) to indicate that
            the forthcoming article is being forwarded from another host.

            However, the server MAY elect not to post or forward the
            article if after further examination of the article it deems
            it inappropriate to do so. Reasons for such subsequent
            rejection of an article may include such problems as
            inappropriate news groups or distributions, disk space
            limitations, article lengths, garbled headers, and the like.
            These are typically restrictions enforced by the server host's
            news software and not necessarily the NNTP server itself.

          9.3.2.1 Responses

                 235 article transferred ok
                 335 send article to be transferred.  End with <CR-
                 LF>.<CR-LF>
                 435 article not wanted - do not send it
                 436 transfer failed - try again later
                 437 article rejected - do not try again

            Because some host news posting software may not be able to
            immediately render status on the whether an article is
            inappropriate for posting or forwarding, an NNTP server MAY
            acknowledge the successful transfer of the article and later
            silently discard it. Thus, an NNTP server MAY return the 235
            acknowledgment code and later discard the received article.

          9.3.2.2 Examples
            Example of successfully sending an article to another site

                    [S] 200 NNTP Service Ready

                    [C] IHAVE <i.am.an.article.you.will.want@nowhere.to>

                    [S] 335 Send it. End with <CR-LF>.<CR-LF>

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                    [C] Path: pathost!demo!somewhere!not-for-mail

                        From: nobody@nowhere.to (Demo User)

                        Newsgroups: misc.test

                        Subject: I am just a test article

                        Date: 6 Oct 1998 04:38:40 -0500

                        Organization: Nowhere, To

                        Message-ID: <i.am.a.test.article@nowhere.to>

                        This is just a test article.

                        .

                    [S] 235 Article transferred ok

            Example of sending an article to another site that rejects it

                    [S] 200 NNTP Service Ready

                    [C] IHAVE <i.am.an.article.you.will.want@nowhere.to>

                    [S] 335 Send it. End with <CR-LF>.<CR-LF>

                    [C] Path: pathost!demo!somewhere!not-for-mail

                        From: nobody@nowhere.to (Demo User)

                        Newsgroups: misc.test

                        Subject: I am just a test article

                        Date: 6 Oct 1998 04:38:40 -0500

                        Organization: Nowhere, To

                        Message-ID: <i.am.a.test.article@nowhere.to>

                        This is just a test article.

                        .

                    [S] 437 Article rejected. Don't send again

            Example of sending an article to another site where the
            transfer fails

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                    [S] 200 NNTP Service Ready

                    [C] IHAVE <i.am.an.article.you.will.want@nowhere.to>

                    [S] 335 Send it. End with <CR-LF>.<CR-LF>

                    [C] Path: pathost!demo!somewhere!not-for-mail

                        From: nobody@nowhere.to (Demo User)

                        Newsgroups: misc.test

                        Subject: I am just a test article

                        Date: 6 Oct 1998 04:38:40 -0500

                        Organization: Nowhere, To

                        Message-ID: <i.am.a.test.article@nowhere.to>

                        This is just a test article.

                        .

                    [S] 436 Transfer failed

            Example of sending an article to another site that rejects it

                    [S] 200 NNTP Service Ready

                    [C] IHAVE <i.am.an.article.you.will.want@nowhere.to>

                    [S] 335 Send it. End with <CR-LF>.<CR-LF>

                    [C] Path: pathost!demo!somewhere!not-for-mail

                        From: nobody@nowhere.to (Demo User)

                        Newsgroups: misc.test

                        Subject: I am just a test article

                        Date: 6 Oct 1998 04:38:40 -0500

                        Organization: Nowhere, To

                        Message-ID: <i.am.a.test.article@nowhere.to>

                        This is just a test article.

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                        .

                    [S] 435 Don't send it again

          9.4 The LIST Keyword

          9.4.1 LIST

            LIST [ACTIVE [wildmat]]

            The response to the LIST keyword with no parameters returns a
            list of valid news groups and associated information.  Each
            news group is sent as a line of text in the following format:

               group first last status

            where <group> is the name of the news group, <last> is the
            number of the last known article currently in that news group,
            <first> is the number of the first article currently in the
            news group, and <status> indicates the current status of the
            group on this server. Typically, the <status> will be consist
            of the US-ASCII character `y' where posting is permitted, `n'
            where posting is not permitted and `m' where postings will be
            forwarded to the news group moderator by the news server.
            Other status strings may exist. The definition of these other
            values is covered in other specifications.

            The <first> and <last> fields will always be numeric.  They
            may have leading zeros. The <first> field corresponds to the
            "reported low water mark" and the <last> field corresponds to
            the "reported high water mark" described in the GROUP command
            (see Section 9.1.1.1).

            Note that posting may still be prohibited to a client although
            the LIST command indicates that posting is permitted to a
            particular news group. See the POST command for an explanation
            of client prohibitions. The posting flag exists for each news
            group because some news groups are moderated or are digests,
            and therefore cannot be posted to; that is, articles posted to
            them must be mailed to a moderator who will post them for the
            original poster.  This is independent of the posting
            permission granted to a client by the NNTP server.

            Please note that an empty list (i.e., the text body returned
            by this command consists only of the terminating period) is a
            possible valid response, and indicates that there are
            currently no valid news groups.

            If the optional matching parameter is specified, the list is
            limited to only the groups that match the pattern.

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            Specifying a single group is usually very efficient for the
            server. Multiple groups may be specified by using wildmat
            patterns (described in section 5), not regular expressions.

          9.4.1.1 Responses
                 215 list of news groups follows

          9.4.1.2 Examples
          Example of LIST returning a list of news groups
                    [S] 200 NNTP Service Ready

                    [C] LIST

                    [S] 215 list of news groups follows

                        misc.test 3000234 3002322 y

                        alt.fc-writers.recovery 1 4 y

                        tx.natives.recovery 56 89 y

                        .

            Example of LIST returning no news groups

                    [S] 200 NNTP Service Ready

                    [C] LIST

                    [S] 215 list of news groups follows

                        .

          9.4.2 LIST ACTIVE.TIMES

            LIST ACTIVE.TIMES [wildmat]

            The active.times file is maintained by some news transport
            systems to contain information about when and who created a
            particular news group. The format of this file generally
            includes three fields. The first field is the name of the news
            group. The second is the time when this group was created on
            this news server measured in seconds since the start of
            January 1, 1970.  The third is the email address of the entity
            that created the news group. When executed, the information is
            displayed following the 215 response. When display is
            completed, the server will send a period on a line by itself.
            If the information is not available, the server will return
            the 503 error response.

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            If the optional matching parameter is specified, the list is
            limited to only the groups that match the pattern.

            Specifying a single group is usually very efficient for the
            server. Multiple groups may be specified by using wildmat
            patterns (described in section 5), not regular expression

          9.4.2.1 Responses

                 215 information follows
                 503 program error, function not performed

          9.4.2.2 Examples
          Example of LIST ACTIVE.TIMES returning a list of news groups
                    [S] 200 NNTP Service Ready

                    [C] LIST ACTIVE.TIMES

                    [S] 215 information follows

                        misc.test 930445408 <creatme@isc.org>

                        alt.rfc-writers.recovery 930562309 <m@nowhere.to>

                        tx.natives.recovery 930678923 <sob@academ.com>

                        .

            Example of LIST ACTIVE.TIMES returning an error

                    [S] 200 NNTP Service Ready

                    [C] LIST ACTIVE.TIMES

                    [S] 503 program error, function not performed



          9.4.3 LIST DISTRIBUTIONS

            LIST DISTRIBUTIONS

            The distributions file is maintained by some news transport
            systems to contain information about valid values for the
            Distribution: line in a news article header and about what the
            values mean. Each line contains two fields, the value and a
            short explanation on the meaning of the value. When executed,
            the information is displayed following the 215 response. When
            display is completed, the server will send a period on a line
            by itself. If the information is not available, the server
            will return the 503 error response.

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          9.4.3.1 Responses

                 215 information follows
                 503 program error, function not performed

          9.4.3.2 Examples
          Example of LIST DISTRIBUTIONS returning a list of news groups
                    [S] 200 NNTP Service Ready

                    [C] LIST DISTRIBUTIONS

                    [S] 215 information follows

                        usa United States of America

                        na North America

                        world All over the World

                        .

            Example of LIST DISTRIBUTIONS returning an error

                    [S] 200 NNTP Service Ready

                    [C] LIST DISTRIBUTIONS

                    [S] 503 program error, function not performed

          9.4.4 LIST DISTRIB.PATS

            LIST DISTRIB.PATS

            The distrib.pats file is maintained by some news transport
            systems to contain default values for the Distribution: line
            in a news article header when posting to particular news
            groups. This information could be used to provide a default
            value for the Distribution: line in the header when posting an
            article. The information returned contains three fields
            separated by colons. The first column is a weight.  The second
            is a group name or a wildmat pattern that can be used to match
            a group name.  The third is the value of the Distribution:
            line that should be used when the group name matches and the
            weight value is the highest. All this processing is done by
            the news posting client and not by the server itself. The
            server provides this information to the client for it to use
            or ignore as it chooses. When executed, the information is
            displayed following the 215 response.  When display is
            completed, the server will send a period on a line by itself.
            If the information is not available, the server will return
            the 503 error response.

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          9.4.4.1 Responses

                 215 information follows
                 503 program error, function not performed

          9.4.4.2 Examples
          Example of LIST DISTRIB.PATS returning a list of news groups
                    [S] 200 NNTP Service Ready

                    [C] LIST DISTRIB.PATS

                    [S] 215 information follows

                        10:local.*:local

                        .

            Example of LIST DISTRIB.PATS returning an error

                    [S] 200 NNTP Service Ready

                    [C] LIST DISTRIB.PATS

                    [S] 503 program error, function not performed

          9.4.5 LIST NEWSGROUPS

               LIST NEWSGROUPS [wildmat]

               The newsgroups file is maintained by some news transport
               systems to contain the name of each news group that is
               active on the server and a short description about the
               purpose of each news group. Each line in the file contains
               two fields, the news group name and a short explanation of
               the purpose of that news group. When executed, the
               information is displayed following the 215 response. When
               display is completed, the server will send a period on a
               line by itself. If the information is not available, the
               server will return the 503 response.  If the optional
               matching parameter is specified, the list is limited to only
               the groups that match the pattern (no matching is done on
               the group descriptions).  Specifying a single group is
               usually very efficient for the server, and multiple groups
               may be specified by using wildmat patterns (see section 5),
               not regular expressions. If nothing is matched an empty list
               is returned, not an error.

          9.4.5.1 Responses

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                 215 information follows
                 503 program error, function not performed

          9.4.5.2 Examples
             Example of LIST NEWSGROUPS returning a list of news groups

                    [S] 200 NNTP Service Ready

                    [C] LIST NEWSGROUPS

                    [S] 215 information follows

                        misc.test General Usenet testing

                        alt.rfc-writers.recovery RFC Writers Recovery

                        tx.natives.recovery Texas Natives Recovery

                        .

            Example of LIST NEWSGROUPS returning an error

                    [S] 200 NNTP Service Ready

                    [C] LIST NEWSGROUPS

                    [S] 503 program error, function not performed

          9.4.6 LIST OVERVIEW.FMT

            LIST OVERVIEW.FMT

            The overview.fmt file is maintained by some news transport
            systems to contain the order in which header information is
            stored in the overview databases for each news group.  When
            executed, news article header fields are displayed one line at
            a time in the order in which they are stored in the overview
            database[7] following the 215 response.  When display is
            completed, the server will send a period on a line by itself.
            If the information is not available, the server will return
            the 503 response.

            If the header has the word "full" (without quotes) after the
            colon, the header's name is prepended to its field in the
            output returned by the server.

            This is command is part of the optional OVER extension which
            includes the OVER command defined in section 9.4.8. If the
            OVER extension is not implemented, then this command MUST NOT
            be implemented.

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          9.4.6.1 Responses

                 215 information follows
                 503 program error, function not performed

          9.4.6.2 Examples
            Example of LIST OVERVIEW.FMT returning a list of news groups

                    [S] 200 NNTP Service Ready

                    [C] LIST OVERVIEW.FMT

                    [S] 215 Order of fields in overview database.

                        Subject:

                        From:

                        Date:

                        Message-ID:

                        .

            Example of LIST OVERVIEW.FMT returning an error

                    [S] 200 NNTP Service Ready

                    [C] LIST OVERVIEW.FMT

                    [S] 503 program error, function not performed

          9.4.7 LISTGROUP

               LISTGROUP [ggg]

               The LISTGROUP command is used to get a listing of all the
               article numbers in a particular news group.

               The optional parameter ggg is the name of the news group to
               be selected (e.g. "news.software.b").  A list of valid news
               groups may be obtained from the LIST command. If no group is
               specified, the current group is used as the default
               argument.

               The successful selection response will be a list of the
               article numbers in the group followed by a period on a line
               by itself. The list starts on the next line following the
               211 response code.

               When a valid group is selected by means of this command, the
               internally maintained "current article pointer" MUST be set
               to the first article in the group.  If an invalid group is
               specified, the previously selected group and article remain

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               selected.  If an empty news group is selected, the "current
               article pointer" may be in an indeterminate state and should
               not be used.

               The group name MUST match a news group obtained from the
               LIST command or an error will result, else the server will
               respond with the 411 error code.

               The LISTGROUP command is an optional extension. It MAY be
               implemented. If it is not implemented, then the LISTGROUP
               label MUST NOT be included in the response to the LIST
               EXTENSIONS command.

          9.4.7.1 Responses

                 211 list of article numbers follow
                 411 No such group
                 412 Not currently in news group

          9.4.7.2 Examples
            Example of a successful execution with a group that exists on
            the server

                    [S] 200 NNTP Service Ready

                    [C] LISTGROUP misc.test

                    [S] 211 list of article numbers follow

                        3000234

                        3000237

                        3000238

                        3000239

                        3002322

                        .

            Example of an unsuccessful execution with a group that does
            not exist on the server

                    [S] 200 NNTP Service Ready

                    [C] LISTGROUP this.group.is.not.here

                    [S] 411 no such group

            Example of an attempt to retrieve an article when the current
            group selected is empty

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                    [S] 200 NNTP Service Ready

                    [C] LISTGROUP example.empty.newsgroup

                    [S] 412 No current article selected

          9.4.8 OVER

            OVER [range]

            The OVER command returns information from the overview
            database for the article(s) specified. The information
            returned in the response to this command can be used by
            clients to follow discussion threads.

            The optional range argument may be any of the following:

          . an article number
          . an article number followed by a dash to indicate all following
          . an article number followed by a dash followed by another
            article number

            If no argument is specified, then information from the current
            article is displayed. Successful responses start with a 224
            response followed by the overview information for all matched
            messages. Once the output is complete, a period is sent on a
            line by itself. If no argument is specified, the information
            for the current article is returned.  A news group must have
            been selected earlier, else a 412 error response is returned.
            If no articles are in the range specified, the server returns
            a 420 error response. A 502 response will be returned if the
            client only has permission to transfer articles.

            Each line of output MUST be formatted with the article number,
            followed by each of the headers in the overview database or
            the article itself (when the data is not available in the
            overview database) for that article separated by a US-ASCII
            tab character.  The sequence of fields must be in this order:
            subject, author, date, message-id, references, byte count, and
            line count. Other optional fields may follow line count. These
            fields are specified by examining the response to the LIST
            OVERVIEW.FMT command. Where no data exists, a null field must
            be provided (i.e. the output will have two tab characters
            adjacent to each other). Servers should not output fields for
            articles that have been removed since the overview database
            was created.

            Note that all US-ASCII tab characters in any header data that
            is returned will be converted to a single US-ASCII space
            character. A contiguous sequence of US-ASCII non-printing

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            characters will be compressed to a single US-ASCII space
            character in any output response.

            The OVER command is part of the OVER extension, which includes
            the LIST OVERVIEW.FMT command. The OVER extension is optional.
            If it is not implemented, the response to the LIST EXTENSIONS
            command must not include the OVER label.

          9.4.8.1 Responses

                 224 Overview information follows
                 412 No news group current selected
                 420 No article(s) selected
                 502 Service Unavailable

          9.4.8.2 Examples
            Example of a successful retrieval of overview information for
            an article (using no article number)

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] OVER

                    [S] 224 Overview information follows

                        300234|I am just a test article|nobody@nowhere.to

                        (Demo User)|6 Oct 1998 04:38:40 -0500|

                        <45223423@to.to>

                        .

            [Please note that the line that begins with 200234 is all one
            line that has been wrapped for readability. A vertical bar has
            been inserted to show where the US-ASCII TAB should actually
            be.]

            Example of an unsuccessful retrieval of overview information
            on an article by number

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] OVER 300256

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                    [S] 420 No such article in this group

            Example of an unsuccessful retrieval of overview information
            by number because no news group was selected first

                    [S] 200 NNTP Service Ready

                    [C] OVER

                    [S] 412 No news group selected

            Example of an attempt to retrieve an article when the current
            group selected is empty

                    [S] 200 NNTP Service Ready

                    [C] GROUP example.empty.newsgroup

                    [S] 211 0 0 0 example.empty.newsgroup

                    [C] OVER

                    [S] 420 No current article selected

          9.4.9 PAT

            PAT header range|<message-id> [wildmat[ wildmat"]]

            The PAT command is used to retrieve specific headers from
            specific articles, based on pattern matching on the contents
            of the header.

            The required header parameter is the name of a header line
            (e.g.  "subject") in a news group article. See RFC-1036 for a
            list of valid header lines. The required range argument may be
            any of the following:

          . an article number
          . an article number followed by a dash to indicate all following
          . an article number followed by a dash followed by another
            article number.
            The required message-id argument indicates a specific article.
            The range and message-id arguments are mutually exclusive. An
            additional argument consisting of one wildmat or two or more
            wildmats separated by a space may be specified. If there are
            no additional argument, a wildmat "*" is the default.
            Successful responses start with a 221 response followed by
            article number, an US-ASCII space, and the header from that
            message in which the argument pattern matches the contents of
            the specified header line. A valid response includes an empty
            list (indicating that there were no matches). Once the output
            is complete, a period is sent on a line by itself. If the
            optional argument is a message-id and no such article exists,

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            a 430 error response shall be returned. A 502 response shall
            be returned if the client only has permission to transfer
            articles.

            The PAT command is optional. If it is not implemented, the
            response to the LIST EXTENSIONS command must not include the
            PAT label.

          9.4.9.1 Responses

                 221 Header follows
                 412 no newsgroup selected
                 430 no such article
                 502 Service Unavailable

          9.4.9.2 Examples
            Example of a successful retrieval of subject lines from a
            range of articles

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] PAT Subject 3000234-300238

                    [S] 221 Header Follows

                        3000234 I am just a test article

                        3000237 Re: I am just a test article

                        3000238 Ditto

                        .

            Example of a successful retrieval of subject lines from a
            range of articles with header pattern matching

                    [S] 200 NNTP Service Ready

                    [C] GROUP misc.test

                    [S] 211 1234 3000234 3002322 misc.test

                    [C] PAT Subject 3000234-300238 j* ? *est

                    [S] 221 Header Follows

                        3000234 I am just a test article

                        3000237 Re: I am just a test article

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                        .

            Example of a successful retrieval of header from an article by
            message-id

                    [S] 200 NNTP Service Ready

                    [C] PAT subject <i.am.a.test.article@nowhere.to>

                    [S] 221 Header information follows

                        3000345 I am just a test article

                        .

            Example of an unsuccessful retrieval of a header from an
            article by message-id

                    [S] 200 NNTP Service Ready

                    [C] PAT subject <i.am.not.there@nowhere.to>

                    [S] 430 No Such Article Found

            Example of an unsuccessful retrieval of headers from articles
            by number because no news group was selected first

                    [S] 200 NNTP Service Ready

                    [C] PAT subject 300256-

                    [S] 412 No news group selected

            Example of retrieving header information when the current
            group selected is empty

                    [S] 200 NNTP Service Ready

                    [C] GROUP example.empty.newsgroup

                    [S] 211 0 0 0 example.empty.newsgroup

                    [C] PAT subject 0-

                    [S] 221 Headers follow

                        .

            Example of a failure due to restrictions configured into the
            server

                    [S] 200 NNTP Service Ready

                    [C] GROUP news.group

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                    [S] 211 1234 3000234 3002322 misc.test

                    [C] PAT Subject 3000234-300238

                    [S] 502 Service Unavailable

          10. The CONCLUSION Step

          10.1 QUIT

            QUIT

            The server process MUST acknowledge the QUIT command and then
            closes the connection to the client.  This is the preferred
            method for a client to indicate that it has finished all its
            transactions with the NNTP server.

            If a client simply disconnects (or the connection times out or
            some other fault occurs), the server SHALL gracefully cease
            its attempts to service the client.

          10.1.1 Responses

                 205 closing connection - goodbye!

          10.1.2 Example
                    [S] 200 NNTP Service Ready

                    [C] QUIT

                    [S] 205 closing connection

          11. Other Keywords

            There are other keywords that may be used at any time between
            the beginning of a session and its termination.  Using these
            keywords do not alter any state information, but the response
            generated from the use of these keywords may provide useful
            information to clients that use them.

          11.1 DATE

            DATE

            This command exists to help clients find out the current time
            from the server's perspective.  This command SHOULD NOT be
            used as a substitute for NTP[8], but to provide information
            that might be useful when using the NEWNEWS command (see
            section 0).

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            This command returns a one-line response code of 111 followed
            by the UTC (or GMT) date and time on the server in the form
            YYYYMMDDhhmmss.

          11.1.1 Responses

                 111 YYYYMMDDhhmmss

          11.1.2 Example
                    [S] 200 NNTP Service Ready

                    [C] DATE

                    [S] 19990623135624

          11.2 The HELP Command

            HELP

            This command provides a short summary of commands that are
            understood by this implementation of the server. The help text
            will be presented as a textual response terminated by a single
            period on a line by itself.

            This text is not guaranteed to be in any particular format and
            SHALL NOT be used by clients as a replacement for the LIST
            EXTENSIONS command described in section 8.1.

          11.2.1 Responses

                 100 help text follows

          11.2.2 Example
                    [S] 200 NNTP Service Ready

                    [C] HELP

                    [S] 100 Help text follows

                        This is some help text. There is no specific

                        formatting requirement for this test, though

                        it is customary for it to list the valid commands

                        and give a brief definition of what they do

                        .

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          11.3 NEWGROUPS

            NEWGROUPS date time [GMT|UTC]

            A list of newsgroups created since <date and time> MUST be
            listed in the same format as the LIST command.

            The date is sent as 6 or 8 digits in the format [XX]YYMMDD,
            where XX is the first two digits of the year, YY is the last
            two digits of the year, MM is the two digits of the month
            (with leading zero, if appropriate), and DD is the day of the
            month (with leading zero, if appropriate). If the first two
            digits of the year are not specified, the year is to be taken
            from the current century if YY is smaller than or equal to the
            current year, otherwise the year is from the previous century.

            Time must also be specified.  It must be as 6 digits HHMMSS
            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. The
            tokens "GMT" and "UTC" specifies that the date and time are
            given in UTC. If the tokens "GMT" and "UTC" are omitted then
            the date and time are specified in the server's local
            timezone. Note that there is no way within this specification
            of NNTP to establish the server's local timezone.

            Note that an empty list (i.e., the text body returned by this
            command consists only of the terminating period) is a possible
            valid response, and indicates that there are currently no new
            newsgroups.

            Clients SHOULD make all queries using GMT/UTC time when
            possible.

          11.3.1 Responses

                 231 list of new newsgroups follows

          11.3.2 Examples
            Example where there are new groups

                    [S] 200 NNTP Service Ready

                    [C] NEWGROUPS 19990624 000000 UTC

                    [S] 230 list of new newsgroups follows

                        alt.rfc-writers.recovery

                        tx.natives.recovery

                        .

            Example where there are no new groups

          Barber                                                 [Page 52]

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                    [S] 200 NNTP Service Ready

                    [C] NEWGROUPS 19990624 000000 UTC

                    [S] 230 list of new newsgroups follows

                        .

          11.4 NEWNEWS

            NEWNEWS newsgroups date time [GMT]

            A list of message-ids of articles posted or received to the
            specified news group since "date" will be listed. The format
            of the listing will be one message-id per line, as though text
            were being sent.  A single line consisting solely of one
            period followed by CR-LF will terminate the list.

            Date and time are in the same format as the NEWGROUPS command.
            The newsgroups parameter MUST be in wildmat format and MAY
            consist of multiple wildmat constructs separated by an US-
            ASCII comma character.

            Note that an empty list (i.e., the text body returned by this
            command consists only of the terminating period) is a possible
            valid response, and indicates that there is currently no new
            news.

            Clients SHOULD make all queries in GMT/UTC time when possible.

          11.4.1 Responses

               230 list of new articles by message-id follows

          11.4.2 Examples
            Example where there are new articles

                    [S] 200 NNTP Service Ready

                    [C] NEWNEWS news.*,sci.* 19990624 000000

                    [S] 230 list of new articles by message-id follows

                        <i.am.a.new.article@nowhere.to>

                        <i.am.another.new.article@nowhere.to>

                        .

            Example where there are no new articles

          Barber                                                 [Page 53]

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                    [S] 200 NNTP Service Ready

                    [C] NEWNEWS alt.* 19990624 000000

                    [S] 230 list of new articles by message-id follows

                        .

          12. Framework for NNTP Extensions

            Although NNTP is widely and robustly deployed, some parts of
            the Internet community might wish to extend the NNTP service.
            This memo defines a means whereby an extended NNTP client may
            query the server to determine the service extensions that it
            supports.

            It must be emphasized that any extension to the NNTP service
            should not be considered lightly. NNTP's strength comes
            primarily from its simplicity.  Experience with many protocols
            has shown that:

            Protocols with few options tend towards ubiquity, whilst
            protocols with many options tend towards obscurity.

            This means that each and every extension, regardless of its
            benefits, must be carefully scrutinized with respect to its
            implementation, deployment, and interoperability costs. In
            many cases, the cost of extending the NNTP service will likely
            outweigh the benefit.

            Given this environment, the framework for the extensions
            described in this memo consists of:

            a)   a mechanism for clients to determine a server's available
               extensions
            b)   a registry of NNTP service extensions

            The LIST EXTENSIONS command is described in section 8.1 of
            this memo and is the mechanism for clients to use to determine
            what extensions are available for client use.

            The IANA shall maintain a registry of NNTP service extensions.

            Associated with each such extension is a corresponding NNTP
            keyword value. Each service extension registered with the IANA
            MUST be defined in an RFC. Such RFCs either must be on the
            standards-track or must define an IESG-approved experimental
            protocol.  The definition must include:

          . the textual name of the NNTP service extension
          . the label that is returned by LIST EXTENSIONS that would
            indicate to the client that the server supports this
            particular extension

          Barber                                                 [Page 54]

          INTERNET DRAFT                                 November 1999

          . any new NNTP keywords associated with the extension
          . the syntax and possible values of parameters associated with
            the new NNTP keywords
          . any new parameters the extension associates with any other
            pre-existing NNTP verbs
          . how support for the extension affects the behavior of a server
            and client NNTP
          . the increment by which the extension is increasing the maximum
            length of the any commands over that specified in this
            document.

            In addition, any NNTP keyword value that starts with an upper
            or lower case "X" refers to a local NNTP service extension,
            which is used through bilateral, rather than standardized,
            agreement. Keywords beginning with "X" MUST NOT be used in a
            registered service extension.

            Any keyword values presented in the NNTP response that do not
            begin with "X" must correspond to a standard, standards-track,
            or IESG-approved experimental NNTP service extension
            registered with IANA.  A conforming server MUST NOT offer non
            "X" prefixed keyword values that are not described in a
            registered extension.

            Additional verbs are bound by the same rules as NNTP keywords;
            specifically, verbs beginning with "X" are local extensions
            that MUST NOT be registered or standardized and verbs not
            beginning with "X" must always be registered.

          12.1 Initial IANA Registry

            The IANA's initial registry of NNTP service extensions
            consists of these entries:

          Service Extension     NNTP Extension Label  Added Behavior

          Overview Support      OVER                  Defined in this
                                                      document

          Specific Article      LISTGROUP             Defined in this
          Numbers                                     document

          Header Pattern        PAT                   Defined in this
          Matching                                    document

          13. Augmented BNF[9] Syntax for NNTP Commands

          Barber                                                 [Page 55]

          INTERNET DRAFT                                 November 1999

          This syntax defines the non-terminal "command". The non-terminal
          "parameter" is used for command parameters whose syntax is
          specified elsewhere. The syntax is in alphabetical order. Note
          that ABNF strings are case insensitive.

            article-command = "ARTICLE" [1*WSP (msg-id / article-number)]
               *WSP CRLF
            article-number = 1*16DIGIT
            augument = parameter ; excluding sequence ".."
            body-command = "BODY" [1*WSP (msg-id / article-number)] *WSP
               CRLF
            command = article-command /
               body-command /
               date-command /
               group-command /
               head-command /
               help-command /
               ihave-command /
               last-command /
               list-active-times-command /
               list-distrib-pats-command /
               list-distributions-command /
               list-extensions-command /
               list-newsgroups-command /
               list-overview-fmt-command /
               list-command /
               listgroup-command /
               mode-reader-command /
               newgroups-command /
               newnews-command /
               next-command /
               over-command /
               pat-command /
               post-command /
               quit-command /
               stat-command
            CR = %x0D
            CRLF = CR LF
            date-command = "DATE" *WSP CRLF
            date = 6*8DIGIT
            DIGIT = %x30-39
            group-command = "GROUP" 1*WSP newsgroup *WSP CRLF
            head-command = "HEAD" [1*WSP (msg-id / article-number)] *WSP
               CRLF
            header = parameter
            help-command = "HELP" *WSP CRLF
            HT = %x09
            ihave-command = "IHAVE" 1*WSP msg-id *WSP CRLF
            last-command = "LAST" *WSP CRLF
            LF = %x0A
            list-active-times-command = "LIST" 1*WSP "ACTIVE.TIMES"
               [1*WSP wildmat] *WSP CRLF
            list-command = "LIST" [1*WSP "ACTIVE" [1*WSP wildmat]] *WSP
               CRLF

          Barber                                                 [Page 56]

          INTERNET DRAFT                                 November 1999

            list-distrib-pats-command = "LIST" 1*WSP "DISTRIB.PATS" *WSP
               CRLF
            list-distributions-command = "LIST" 1*WSP "DISTRIBUTIONS" *WSP
               CRLF
            list-extensions-command = "LIST" 1*WSP "EXTENSIONS" *WSP CRLF
            list-newsgroups-command = "LIST" 1*WSP "NEWSGROUPS" [1*WSP
               wildmat]
               *WSP CRLF
            list-overview-fmt-command = "LIST" 1*WSP "OVERVIEW.FMT" *WSP
               CRLF
            listgroup-command = "LISTGROUP" [1*WSP newsgroup] *WSP CRLF
            mode-reader-command = "MODE" 1*WSP "READER" *WSP CRLF
            msg-id = <defined in RFC822>
            newgroups-command = "NEWGROUPS" 1*WSP date 1*WSP time [1*WSP
               "GMT"/"UTC"] *WSP CRLF
            newnews-command = "NEWNEWS" 1*WSP newsgroup *("," newsgroup)
               1*WSP date 1*WSP time [1*WSP "GMT"/"UTC"]
               *WSP CRLF
            newsgroup = parameter
            next-command = "NEXT" *WSP CRLF
            over-command = "OVER" [1*WSP range] *WSP CRLF
            parameter = 1*(%x21-FF) ; generic command parameter
            pat-command = "PAT" 1*WSP header 1*WSP (range / msg-id)
               *(1*WSP wildmat) *WSP CRLF
            post-command = "POST" *WSP CRLF
            quit-command = "QUIT" *WSP CRLF
            range = article-number ["-" [article-number]]
            SP = %x20
            stat-command = "STAT" [1*WSP (msg-id / article-number)] *WSP
               CRLF
            time = 6DIGIT
            UTF-8-non-ascii = UTF8-2 / UTF8-3 / UTF8-4 / UTF8-5 / UTF8-6
            UTF8-1 = %x80-BF
            UTF8-2 = %xC0-DF UTF8-1
            UTF8-3 = %xE0-EF 2UTF8-1
            UTF8-4 = %xF0-F7 3UTF8-1
            UTF8-5 = %xF8-FB 4UTF8-1
            UTF8-6 = %xFC-FD 5UTF8-1
            wildmat = ["!"]1*("*" / "?" / wildmat-exact / wildmat-set /
            "\" (%x22-7F / UTF-8-non-ascii))
            wildmat-exact = %x22-29 / %x2B-3E / %x40-5A / %x5D-7F / UTF-8-
               non-ascii ; exclude space ! * ? [ \
            wildmat-non-hyphen = %x21-2C / %x2E-7F / UTF-8-non-ascii ;
               exclude space -
            wildmat-set = "[" ["^"] ["]" / "-"] *(wildmat-non-hyphen"["-"
               wildmat-non-hyphen]) ["-"]
            WSP = SP / HT

          14. Security Considerations

            This section is meant to inform application developers,
            information providers, and users of the security limitations
            in NNTP as described by this document. The discussion does not

          Barber                                                 [Page 57]

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            include definitive solutions to the problems revealed, though
            it does make some suggestions for reducing security risks.

          14.1 Personal and Proprietary Information

            NNTP, because it was created to distribute network news
            articles, will forward whatever information is stored in those
            articles. Specification of that information is outside this
            scope of this document, but it is likely that some personal
            and/or proprietary information is available in some of those
            articles. It is very important that designers and implementors
            provide informative warnings to users so personal and/or
            proprietary information is not disclosed inadvertently.
            Additionally, effective and easily understood mechanisms to
            manage the distribution of news articles must be provided to
            NNTP Server administrators, so that they are able to report
            with confidence what information is and is not being forwarded
            in news articles passing though their servers.

          14.2 Abuse of Server Log Information

            A server is in the position to save session data about a
            user's requests which might identify their reading patterns or
            subjects of interest. This information is clearly confidential
            in nature and its handling can be constrained by law in
            certain countries. People using the NNTP protocol to provide
            data are responsible for ensuring that such material is not
            distributed without the permission of any individuals that are
            identifiable by the published results.

          14.3 DNS Spoofing

            Clients and Servers using NNTP rely heavily on the Domain Name
            Service, and are thus generally prone to security attacks
            based on the deliberate mis-association of IP addresses and
            DNS names. Clients and Servers need to be cautious in assuming
            the continuing validity of an IP number/DNS name association.

            In particular, NNTP clients and servers SHOULD rely on their
            name resolver for confirmation of an IP number/DNS name
            association, rather than caching the result of previous host
            name lookups. Many platforms already can cache host name
            lookups locally when appropriate, and they SHOULD be
            configured to do so. It is proper for these lookups to be
            cached, however, only when the TTL (Time To Live) information
            reported by the name server makes it likely that the cached
            information will remain useful.

            If NNTP clients or servers cache the results of host name
            lookups in order to achieve a performance improvement, they
            MUST observe the TTL information reported by DNS.

            If NNTP clients or servers do not observe this rule, they
            could be spoofed when a previously-accessed server's IP

          Barber                                                 [Page 58]

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            address changes. As network renumbering is expected to become
            increasingly common, the possibility of this form of attack
            will grow. Observing this requirement thus reduces this
            potential security vulnerability.

            This requirement also improves the load-balancing behavior of
            clients for replicated servers using the same DNS name and
            reduces the likelihood of a user's experiencing failure in
            accessing sites which use that strategy.

          14.4 Weak Authentication and Access Control

            There is no user-based or token-based authentication in the
            basic NNTP specification. Access is normally controlled by
            server configuration files. Those files specify access by
            using domain names or ip addresses. However, this
            specification does permit the creation of extensions to the
            NNTP protocol itself for such purposes. While including such
            mechanisms is optional, doing so is strongly encouraged.

            Other mechanisms are also available. For example, a proxy
            server could be put in place that requires authentication
            before connecting via the proxy to the NNTP server.

          15. Notes

            UNIX is a registered trademark of the X/Open Consortium.

          16. References

            1 Kantor, B and P. Lapsley, "Network News Transfer Protocol",
            RFC-977, U.C. San Diego and U.C. Berkeley.

            2 Yergeau, F., "UTF-8, a transformation format of ISO 10646",
            RFC 2278, Alis Technologies.

            3 Coded Character Set-7-bit American Standard Code for
            Information Interchange, ANSI x3.4-1986.

            4 Bradner, Scott, "Key words for use in RFCs to Indicate
            Requirement Levels", RFC-2119, Harvard University.

            5 Salz, Rich, Manual Page for wildmat(3) from the INN 1.4
            distribution, UUNET Technologies, Revision 1.10, April, 1992.

            6 Horton, M.R. and R. Adams, "Standard for interchange of
            USENET messages",  RFC-1036, AT&T Bell Laboratories and Center
            for Seismic Studies, December, 1987.

            7 Robertson, Rob, "FAQ: Overview database / NOV General
            Information", ftp://ftp.uu.net/networking/news/nntp/inn/faq-
            nov.Z, January, 1995.

            8 Mills, David L., "Network Time Protocol (Version 3),
            Specification, Implementation and Analysis", RFC-1305,
            University of Delaware, March 1992.

            9 Crocker, D.  and Overell, P., "Augmented BNF for Syntax
            Specifications: ABNF", RFC-2234, Internet Mail Consortium and
            Demon Internet, Ltd.

          Barber                                                 [Page 59]

          INTERNET DRAFT                                 November 1999

          17. Acknowledgments

            The author acknowledges the original authors of NNTP as
            documented in RFC 977: Brian Kantor and Phil Lapsey.

            The author gratefully acknowledges the work of the NNTP
            committee chaired by Eliot Lear. The organization of this
            document was influenced by the last available draft from this
            working group. A special thanks to Eliot for generously
            providing the original machine readable sources for that
            document.

            The author gratefully acknowledges the work of the Marshall
            Rose & John G. Meyers in RFC 1939 and the work of the DRUMS
            working group, specifically RFC 1869, which is the basis of
            the NNTP extensions mechanism detailed in this document.

            The author gratefully acknowledges the authors of RFC 2616 for
            providing specific and relevant examples of security issues
            that should be considered for HTTP. Since many of the same
            considerations exist for NNTP, those examples that are
            relevant have been included here with some minor rewrites.

            The author gratefully acknowledges the comments and additional
            information provided by the following individuals in preparing
            one of the progenitors of this document:

          . Wayne Davison <davison@armory.com>
          . Clive D.W. Feather <clive@demon.net>
          . Chris Lewis <clewis@bnr.ca>
          . Tom Limoncelli <tal@mars.superlink.net>
          . Eric Schnoebelen <eric@egsner.cirr.com>
          . Rich Salz <rsalz@osf.org>

            This work was precipitated by the work of various newsreader
            authors and newsserver authors, which includes those listed
            below:

          . Rick Adams -- Original author of the NNTP extensions to the RN
            newsreader and last maintainer of Bnews
          . Stan Barber -- Original author of the NNTP extensions to the
            newsreaders that are part of Bnews.
          . Geoff Collyer -- Original author of the OVERVIEW database
            proposal and one of the original authors of CNEWS
          . Dan Curry -- Original author of the xvnews newsreader
          . Wayne Davision -- Author of the first threading extensions to
the
            RN newsreader (commonly called TRN).
          . Geoff Huston -- Original author of ANU NEWS
          . Phil Lapsey -- Original author of the UNIX reference
            implementation
          . Ian Lea -- Long time maintainer of the TIN newsreader
          . Chris Lewis -- First known implementor of the AUTHINFO GENERIC
            extension
          . Rich Salz -- Original author of INN
          . Henry Spencer -- One of the original authors of CNEWS
          . Kim Storm -- Original author of the NN newsreader

          18. Author's Address

            Stan Barber
            P.O. Box 300481
            Houston, Texas 77230
            Email: <sob@academ.com>

            This document expires May 15, 2000.

          Barber                                                 [Page 60]


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