📄 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.Rinne [Page 6]RFC 1756 Remote Write Protocol January 1995 110 Ok to forward. or 110 Ok to forward <user@host.domain>. 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.Rinne [Page 7]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.Rinne [Page 8]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 <user@host.domain>. 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.Rinne [Page 9]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.Rinne [Page 10]RFC 1756 Remote Write Protocol January 19957. 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 rwrited8. 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' -> =099. 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: Timo.Rinne@hut.fiRinne [Page 11]
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