rfc1756.txt

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        The SEND command is completed and message is forwarded to the
        user.

    105 Sender ok.

        The FROM command successful.

    106 Recipient ok.

        The TO command successful.

    107 Message ok.

        The DATA command successful.

    108 Recipient ok to send.

        The VRFY command successful and direct message delivery is
        possible.

    109 RSET ok.

        The RWP server has received the RSET command and reset itself.



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RFC 1756                 Remote Write Protocol              January 1995


    110 Ok to forward.

        or

    110 Ok to forward <[e-mail]>.

        The VRFY command successful and direct message delivery by
        forwarding is possible.  If response has also forwarding
        address the client can either forward the message itself or
        give it to server for forwarding.

    111 Original sender host ok.

        The FHST command successful and original sender host is set as
        given by the client.

    200 Enter message.  Single dot '.' on line terminates.

        The RWP server is ready to receive the message. Single dot on
        message line terminates the message.


    300 |I'm not in right now but I'll be back tomorrow
    300 |at 8 o'clock a.m.

        Automatical response to the delivered message.  Every line of
        this user defined reply message is delivered in its own 300
        line.  Response code 300 lines may appear only after SEND
        command before response code 103 (message delivered).  Client
        receiving autoreply 300 should show the text of the autoreply
        to the user.  Actual autoreply line begins after the '|'
        -character in the line.

    500 Hello remote.host.  This is local.host speaking.

        Response to the HELO command.  This message can also occur in
        the beginning of the conversation without the VER command and
        it can be ignored.

    501 Rwrited version X.X.

        Response to the VER command.  This message can also occur in
        the beginning of the conversation without the VER command and
        it can be ignored.







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RFC 1756                 Remote Write Protocol              January 1995


    502 RWP version 1.0.

        Response to the VER command.  This message can also occur in
        the beginning of the conversation without the VER command and
        it can be ignored.

    510 Valid commands are:
    510     BYE,    DATA,   HELP,   HELO,
    510     RSET,   SEND,   PROT,   QUIT,
    510     VRFY,   VER
    510     FROM senderlogin
    510     FHST senderhost
    510     TO   recipentlogin
    510     FWDS current_hop_count

        Response to the HELP command.

    511 Information to the user.

        Server specific informational response.  These responses may
        occur anytime during the conversation.  The client can ignore
        them.

    512 Debug information to the user.

        Server specific informational response.  Reserved for server
        debugging.  These messages may occur anytime during the
        conversation.  The client can ignore them.

    666 FATAL ERROR!

        The RWP server got into the fatal error situation and is about
        to exit immediately.  Client programs are strongly encouraged
        to close the connection.

    668 Syntax error.

        The RWP server has received an invalid command.

    669 Permission denied.

        The RWP server is unable to deliver the message because the
        target user has denied the send permission.

    670 User not logged in.

        The RWP server is unable to deliver the message because the
        target user is not logged in.



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RFC 1756                 Remote Write Protocol              January 1995


    671 No such user.

        The RWP server is unable to deliver the message because the
        target user does not exist.  Error code 670 can be used to
        replace this message.

    672 No message.

        The DATA command is terminated with empty message body.  No
        SEND command can be executed before a new DATA command is
        given.

    673 FROM command required.

        Tried to give the SEND command before FROM.

    674 TO command required.

        Tried to give the SEND command before TO.

    675 DATA command required.

        Tried to give the SEND command before DATA.

    676 Forward limit exceeded.

        Response to the FWDS command that had an argument that
        exceeded the server specific limit of message forwarding
        steps.

    677 Unable to forward message.

        or

    677 Unable to forward message to <[e-mail]>.

        Response to the SEND or VRFY command if message forwarding is
        attempted and the server specific limit of message forwarding
        steps has been exceeded or if message forwarding has otherwise
        failed.  If message forwarding fails with message 669, 670 or
        671, server will not use response 667 but gives response but
        instead it gives the response analogous with the error
        occured.  If message 677 includes address the message was to
        be forwarded, the client may try to deliver it itself.

    698 Unknown error.

        RWP server has faced an internal error that is not fatal.



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RFC 1756                 Remote Write Protocol              January 1995


    699 Unknown error.

        RWP server has faced an unknown error that is not fatal.

5. RWP Compliant Software

   Simple RWP 1.0 compliant server and client software RWrite-1.1 will
   be available during the fall 1994.

6. Security of RWP

   RWP version 1.0 does not offer any mean to verify the identity of the
   user connecting the RWP server program.  It's possible to identify
   the sender using ident-service, but not all hosts currently support
   that.  This vulnerability is analogous with the weakness of the SMTP
   protocol.  Cryptographic user verification and message hiding method
   is under development and is to be defined in RWP version 2.0 during
   the year 1995.

   RWP server also may offer a way to the intruder to get to know user
   ids within the target host by trying the TO and VRFY commands.  This
   vulnerability is also present in SMTP.  It is however possible to
   build servers so that they never give message 671 (no such user) but
   use response 670 (user not logged in) instead.

   Another way to increase security even within RWP-1.0 described in the
   document is to design RWP servers so that they do not deliver
   messages directly to user but instead connect to some kind of RWP
   agent process that is executed by each user willing to receive RWP
   messages.  This user configurable message agent could then decide
   whether to deliver the message to the user and which way of delivery
   to use.  Message agent is the best way to prevent hostile user from
   sending uncontrolled message flood to the user's terminal.

   Sample implementation (RWrite-1.0) of the RWP server includes the
   support for user configuration files in which each user can either
   allow or deny messages from some user(s), host(s) or network
   domains(s).  Support for message agents is currently under
   development.

   The user that is receiving the message should be able to define
   characters to be stripped from the incoming messages to prevent
   terminal mess-up.








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RFC 1756                 Remote Write Protocol              January 1995


7. RWP Connection Type

   It is suggested that tcp (and udp) port 18 should be allocated for
   rwp in future versions of RFCs listing the reserved tcp/udp/rpc
   ports.  Currently port 18 is assigned to the service called Message
   Send Protocol (msp) that is not known to be implemented.  Actually
   port 18 is not currently defined at all in the /etc/services -file of
   the any common UNIX-like system.  Entry for /etc/services -file is as
   follows

       rwrite    18/udp       # RWP rwrite
       rwrite    18/tcp       # RWP rwrite

   Given that RWP compliant daemon program is /usr/sbin/rwrited the
   entry for /etc/inetd.conf -file would be:

       rwrite  stream  tcp  nowait  nobody  /usr/sbin/rwrited rwrited

8. Character quotation

   To offer a safe method to transfer various character sets RWP defines
   a method to quote characters in both message and autoreply.  RWP uses
   quotation similar to MIME `quoted-printable' encoding.  Quoted
   character is presented as a '=' -sign followed by a two character hex
   code.  This means also that all '='-signs have to be quoted.
   Quotation is also needed when message contains a line with only a
   single dot '.' in it.

    For example:
                    '.'  ->  =2E
                    '='  ->  =3D
                    '\a' ->  =07
                    '\t' ->  =09

9. Security Considerations

   Security issues are not discussed in this memo.

10. Author's Address

   Timo J. Rinne
   Helsinki University of Technology.
   Cirion oy
   PO-BOX 250
   FIN-00121
   Helsinki, Finland

   EMail: [e-mail]



Rinne                                                          [Page 11]