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RFC 944 - Official ARPA-Internet protocols


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Network Working Group                                        J. Reynolds
Request for Comments: 944                                      J. Postel
                                                                     ISI
Obsoletes: RFCs 924, 901, 880, 840                            April 1985

                    OFFICIAL ARPA-INTERNET PROTOCOLS

STATUS OF THIS MEMO

   This memo is an official status report on the protocols used in the
   ARPA-Internet community.  Distribution of this memo is unlimited.

INTRODUCTION

   This RFC identifies the documents specifying the official protocols
   used in the Internet.  Comments indicate any revisions or changes
   planned.

   To first order, the official protocols are those in the "Internet
   Protocol Transition Workbook" (IPTW) dated March 1982.  There are
   several protocols in use that are not in the IPTW.  A few of the
   protocols in the IPTW have been revised.  Notably, the mail protocols
   have been revised and issued as a volume titled "Internet Mail
   Protocols" dated November 1982.  Telnet and the most useful Telnet
   options have been revised and issued as a volume titled "Internet
   Telnet Protocol and Options" (ITP) dated June 1983.  Some protocols
   have not been revised for many years, these are found in the old
   "ARPANET Protocol Handbook" (APH) dated January 1978.  There is also
   a volume of protocol related information called the "Internet
   Protocol Implementers Guide" (IPIG) dated August 1982.

   This document is organized as a sketchy outline.  The entries are
   protocols (e.g., Transmission Control Protocol).  In each entry there
   are notes on status, specification, comments, other references,
   dependencies, and contact.

      The STATUS is one of: required, recommended, elective, or
      experimental.

      The SPECIFICATION identifies the protocol defining documents.

      The COMMENTS describe any differences from the specification or
      problems with the protocol.

      The OTHER REFERENCES identify documents that comment on or expand
      on the protocol.

      The DEPENDENCIES indicate what other protocols are called upon by
      this protocol.

Official ARPA-Internet Protocols                                 RFC 944

      The CONTACT indicates a person who can answer questions about the
      protocol.

      In particular, the status may be:

         required

            - all hosts must implement the required protocol,

         recommended

            - all hosts are encouraged to implement the recommended
            protocol,

         elective

            - hosts may implement or not the elective protocol,

         experimental

            - hosts should not implement the experimental protocol
            unless they are participating in the experiment and have
            coordinated their use of this protocol with the contact
            person, and

         none

            - this is not a protocol.

         For further information about protocols in general, please
         contact:

            Joyce Reynolds
            USC - Information Sciences Institute
            4676 Admiralty Way
            Marina del Rey, California  90292-6695

            Phone: (213) 822-1511

            ARPA mail: JKREYNOLDS@USC-ISIF.ARPA

Official ARPA-Internet Protocols                                 RFC 944

OVERVIEW

   Catenet Model  ------------------------------------------------------

      STATUS:  None

      SPECIFICATION:  IEN 48 (in IPTW)

      COMMENTS:

         Gives an overview of the organization and principles of the
         Internet.

         Could be revised and expanded.

      OTHER REFERENCES:

         RFC 871 - A Perspective on the ARPANET Reference Model

         Padlipsky, M.A., "The Elements of Networking Style and other
         Essays and Animadversions on the Art of Intercomputer
         Networking", Prentice-Hall, New Jersey, 1985.

         Leiner, Barry, Robert Cole, Jon Postel and Dave Mills, "The
         DARPA Protocol Suite", IEEE INFOCOM 85, Washington, D.C.,
         March 1985.  Also in IEEE Communications Magazine, March 1985.

      DEPENDENCIES:

      CONTACT: Postel@USC-ISIF.ARPA

Official ARPA-Internet Protocols                                 RFC 944

NETWORK LEVEL

   Internet Protocol  --------------------------------------------- (IP)

      STATUS:  Required

      SPECIFICATION:  RFC 791 (in IPTW)

      COMMENTS:

         This is the universal protocol of the Internet.  This datagram
         protocol provides the universal addressing of hosts in the
         Internet.

         A few minor problems have been noted in this document.

         The most serious is a bit of confusion in the route options.
         The route options have a pointer that indicates which octet of
         the route is the next to be used.  The confusion is between the
         phrases "the pointer is relative to this option" and "the
         smallest legal value for the pointer is 4".  If you are
         confused, forget about the relative part, the pointer begins
         at 4.

         Another important point is the alternate reassembly procedure
         suggested in RFC 815.

         Some changes are in the works for the security option.

         Note that ICMP is defined to be an integral part of IP.  You
         have not completed an implementation of IP if it does not
         include ICMP.

      OTHER REFERENCES:

         RFC 815 (in IPIG) - IP Datagram Reassembly Algorithms

         RFC 814 (in IPIG) - Names, Addresses, Ports, and Routes

         RFC 816 (in IPIG) - Fault Isolation and Recovery

         RFC 817 (in IPIG) - Modularity and Efficiency in Protocol
         Implementation

         MIL-STD-1777 - Military Standard Internet Protocol

      DEPENDENCIES:

      CONTACT: Postel@USC-ISIF.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Internet Control Message Protocol  --------------------------- (ICMP)

      STATUS:  Required

      SPECIFICATION:  RFC 792 (in IPTW)

      COMMENTS:

         The control messages and error reports that go with the
         Internet Protocol.

         A few minor errors in the document have been noted.
         Suggestions have been made for additional types of redirect
         message and additional destination unreachable messages.

         A proposal for two additional ICMP message types is made in
         RFC 917 "Internet Subnets", Address Format Request (A1=17), and
         Address Format Reply (A2=18).  The details of these ICMP types
         are subject to change.  Use of these ICMP types is
         experimental.

         Note that ICMP is defined to be an integral part of IP.  You
         have not completed an implementation of IP if it does not
         include ICMP.

      OTHER REFERENCES:  RFC 917

      DEPENDENCIES: Internet Protocol

      CONTACT: Postel@USC-ISIF.ARPA

Official ARPA-Internet Protocols                                 RFC 944

HOST LEVEL

   User Datagram Protocol  --------------------------------------- (UDP)

      STATUS:  Recommended

      SPECIFICATION:  RFC 768 (in IPTW)

      COMMENTS:

         Provides a datagram service to applications.  Adds port
         addressing to the IP services.

         The only change noted for the UDP specification is a minor
         clarification that if in computing the checksum a padding octet
         is used for the computation it is not transmitted or counted in
         the length.

      OTHER REFERENCES:

      DEPENDENCIES: Internet Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   Transmission Control Protocol  -------------------------------- (TCP)

      STATUS:  Recommended

      SPECIFICATION:  RFC 793 (in IPTW)

      COMMENTS:

         Provides reliable end-to-end data stream service.

         Many comments and corrections have been received for the TCP
         specification document.  These are primarily document bugs
         rather than protocol bugs.

         Event Processing Section:  There are many minor corrections and
         clarifications needed in this section.

         Push:  There are still some phrases in the document that give a
         "record mark" flavor to the push.  These should be further
         clarified.  The push is not a record mark.

         Urgent:  Page 17 is wrong.  The urgent pointer points to the
         last octet of urgent data (not to the first octet of non-ungent
         data).

Official ARPA-Internet Protocols                                 RFC 944

         Listening Servers:  Several comments have been received on
         difficulties with contacting listening servers.  There should
         be some discussion of implementation issues for servers, and
         some notes on alternative models of system and process
         organization for servers.

         Maximum Segment Size:  The maximum segment size option should
         be generalized and clarified.  It can be used to either
         increase or decrease the maximum segment size from the default.
         The TCP Maximum Segment Size is the IP Maximum Datagram Size
         minus forty.  The default IP Maximum Datagram Size if 576.  The
         default TCP Maximum Segment Size is 536.  For further
         discussion, see RFC 879.

         Idle Connections:  There have been questions about
         automatically closing idle connections.  Idle connections are
         ok, and should not be closed.  There are several cases where
         idle connections arise, for example, in Telnet when a user is
         thinking for a long time following a message from the server
         computer before his next input.  There is no TCP "probe"
         mechanism, and none is needed.

         Queued Receive Data on Closing:  There are several points where
         it is not clear from the description what to do about data
         received by the TCP but not yet passed to the user,
         particularly when the connection is being closed.  In general,
         the data is to be kept to give to the user if he does a RECV
         call.

         Out of Order Segments:  The description says that segments that
         arrive out of order, that is, are not exactly the next segment
         to be processed, may be kept on hand.  It should also point out
         that there is a very large performance penalty for not doing
         so.

         User Time Out:  This is the time out started on an open or send
         call.  If this user time out occurs the user should be
         notified, but the connection should not be closed or the TCB
         deleted.  The user should explicitly ABORT the connection if he
         wants to give up.

      OTHER REFERENCES:

         RFC 813 (in IPIG) - Window and Acknowledgement Strategy in TCP

         RFC 814 (in IPIG) - Names, Addresses, Ports, and Routes

         RFC 816 (in IPIG) - Fault Isolation and Recovery

Official ARPA-Internet Protocols                                 RFC 944

         RFC 817 (in IPIG) - Modularity and Efficiency in Protocol
         Implementation

         RFC 879 - TCP Maximum Segment Size

         RFC 889 - Internet Delay Experiments

         RFC 896 - TCP/IP Congestion Control

         MIL-STD-1778 - Military Standard Transmission Control Protocol

      DEPENDENCIES: Internet Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   Host Monitoring Protocol  ------------------------------------- (HMP)

      STATUS:  Elective

      SPECIFICATION:  RFC 869

      COMMENTS:

         This is a good tool for debugging protocol implementations in
         remotely located computers.

         This protocol is used to monitor Internet gateways and the
         TACs.

      OTHER REFERENCES:

      DEPENDENCIES: Internet Protocol

      CONTACT: Hinden@BBN-UNIX.ARPA

   Cross Net Debugger  ------------------------------------------ (XNET)

      STATUS:  Elective

      SPECIFICATION:  IEN 158

      COMMENTS:

         A debugging protocol, allows debugger like access to remote
         systems.

         This specification should be updated and reissued as an RFC.

      OTHER REFERENCES:  RFC 643

Official ARPA-Internet Protocols                                 RFC 944

      DEPENDENCIES: Internet Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   "Stub" Exterior Gateway Protocol  ----------------------------- (EGP)

      STATUS:  Recommended for Gateways

      SPECIFICATION:  RFC 888, RFC 904

      COMMENTS:

         The protocol used between gateways of different administrations
         to exchange routing information.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:  RFC 827, RFC 890

      DEPENDENCIES: Internet Protocol

      CONTACT: Mills@USC-ISID.ARPA

   Gateway Gateway Protocol  ------------------------------------- (GGP)

      STATUS:  Experimental

      SPECIFICATION:  RFC 823

      COMMENTS:

         The gateway protocol now used in the core gateways.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:

      DEPENDENCIES: Internet Protocol

      CONTACT: Brescia@BBN-UNIX.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Multiplexing Protocol  ---------------------------------------- (MUX)

      STATUS:  Experimental

      SPECIFICATION:  IEN 90

      COMMENTS:

         Defines a capability to combine several segments from different
         higher level protocols in one IP datagram.

         No current experiment in progress.  There is some question as
         to the extent to which the sharing this protocol envisions can
         actually take place.  Also, there are some issues about the
         information captured in the multiplexing header being (a)
         insufficient, or (b) over specific.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:

      DEPENDENCIES: Internet Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   Stream Protocol  ----------------------------------------------- (ST)

      STATUS:  Experimental

      SPECIFICATION:  IEN 119

      COMMENTS:

         A gateway resource allocation protocol designed for use in
         multihost real time applications.

         The implementation of this protocol has evolved and may no
         longer be consistent with this specification.  The document
         should be updated and issued as an RFC.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:

      DEPENDENCIES: Internet Protocol

      CONTACT: jwf@LL-EN.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Network Voice Protocol  ------------------------------------ (NVP-II)

      STATUS:  Experimental

      SPECIFICATION:  ISI Internal Memo

      COMMENTS:

         Defines the procedures for real time voice conferencing.

         The specification is an ISI Internal Memo which should be
         updated and issued as an RFC.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:  RFC 741

      DEPENDENCIES:  Internet Protocol, Stream Protocol

      CONTACT:  Casner@USC-ISIB.ARPA

   Reliable Data Protocol  --------------------------------------- (RDP)

      STATUS:  Experimental

      SPECIFICATION:  RFC 908

      COMMENTS:

         This protocol is designed to efficiently support the bulk
         transfer of data for such host monitoring and control
         applications as loading/dumping and remote debugging.  The
         protocol is intended to be simple to implement but still be
         efficient in environments where there may be long transmission
         delays and loss or non-sequential delivery of message segments.

      OTHER REFERENCES:

      DEPENDENCIES:  Internet Protocol

      CONTACT:  CWelles@BBN-UNIX.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Internet Reliable Transaction Protocol  ---------------------- (IRTP)

      STATUS:  Experimental

      SPECIFICATION:  RFC 938

      COMMENTS:

         This protocol is a transport level host to host protocol
         designed for an internet environment.  While the issues
         discussed may not be directly relevant to the research problems
         of the DARPA community, they may be interesting to a number of
         researchers and implementors.

      OTHER REFERENCES:

      DEPENDENCIES:  Internet Protocol

      CONTACT:  Trudy@ACC.ARPA

Official ARPA-Internet Protocols                                 RFC 944

APPLICATION LEVEL

   Telnet Protocol  ------------------------------------------- (TELNET)

      STATUS:  Recommended

      SPECIFICATION:  RFC 854 (in "Internet Telnet Protocol and
      Options")

      COMMENTS:

         The protocol for remote terminal access.

         This has been revised since the IPTW.  RFC 764 in IPTW is now
         obsolete.

      OTHER REFERENCES:

         MIL-STD-1782 - Telnet Protocol

      DEPENDENCIES:  Transmission Control Protocol

      CONTACT:  Postel@USC-ISIF.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Telnet Options  ------------------------------------ (TELNET-OPTIONS)

      STATUS:  Elective

      SPECIFICATION:  General description of options:  RFC 855
      (in "Internet Telnet Protocol and Options")

      Number   Name                                RFC  NIC  ITP APH USE
      ------   ---------------------------------   --- ----- --- --- ---
         0     Binary Transmission                 856 ----- yes obs yes
         1     Echo                                857 ----- yes obs yes
         2     Reconnection                        ... 15391  no yes  no
         3     Suppress Go Ahead                   858 ----- yes obs yes
         4     Approx Message Size Negotiation     ... 15393  no yes  no
         5     Status                              859 ----- yes obs yes
         6     Timing Mark                         860 ----- yes obs yes
         7     Remote Controlled Trans and Echo    726 39237  no yes  no
         8     Output Line Width                   ... 20196  no yes  no
         9     Output Page Size                    ... 20197  no yes  no
        10     Output Carriage-Return Disposition  652 31155  no yes  no
        11     Output Horizontal Tabstops          653 31156  no yes  no
        12     Output Horizontal Tab Disposition   654 31157  no yes  no
        13     Output Formfeed Disposition         655 31158  no yes  no
        14     Output Vertical Tabstops            656 31159  no yes  no
        15     Output Vertical Tab Disposition     657 31160  no yes  no
        16     Output Linefeed Disposition         658 31161  no yes  no
        17     Extended ASCII                      698 32964  no yes  no
        18     Logout                              727 40025  no yes  no
        19     Byte Macro                          735 42083  no yes  no
        20     Data Entry Terminal                 732 41762  no yes  no
        21     SUPDUP                          734 736 42213  no yes  no
        22     SUPDUP Output                       749 45449  no  no  no
        23     Send Location                       779 -----  no  no  no
        24     Terminal Type                       930 -----  no  no  no
        25     End of Record                       885 -----  no  no  no
        26     TACACS User Identification          927 -----  no  no  no
        27     Output Marking                      933 -----  no  no  no
       255     Extended-Options-List               861 ----- yes obs yes

                                                        (obs = obsolete)

      The ITP column indicates if the specification is included in the
      Internet Telnet Protocol and Options.  The APH column indicates if
      the specification is included in the ARPANET Protocol Handbook.
      The USE column of the table above indicates which options are in
      general use.

Official ARPA-Internet Protocols                                 RFC 944

      COMMENTS:

         The Binary Transmission, Echo, Suppress Go Ahead, Status,
         Timing Mark, and Extended Options List options have been
         recently updated and reissued.  These are the most frequently
         implemented options.

         The remaining options should be reviewed and the useful ones
         should be revised and reissued.  The others should be
         eliminated.

         The following are recommended:  Binary Transmission, Echo,
         Suppress Go Ahead, Status, Timing Mark, and Extended Options
         List.

      OTHER REFERENCES:

      DEPENDENCIES: Telnet

      CONTACT: Postel@USC-ISIF.ARPA

   File Transfer Protocol  --------------------------------------- (FTP)

      STATUS:  Recommended

      SPECIFICATION:  RFC 765 (in IPTW)

      COMMENTS:

         The protocol for moving files between Internet hosts.  Provides
         for access control and negotiation of file parameters.

         There are a number of minor corrections to be made.  A major
         change is the deletion of the mail commands, and a major
         clarification is needed in the discussion of the management of
         the data connection.  Also, a suggestion has been made to
         include some directory manipulation commands (RFC 775).

         Even though the MAIL features are defined in this document,
         they are not to be used.  The SMTP protocol is to be used for
         all mail service in the Internet.

         Data Connection Management:

            a.  Default Data Connection Ports:  All FTP implementations
            must support use of the default data connection ports, and
            only the User-PI may initiate the use of non-default ports.

            b.  Negotiating Non-Default Data Ports:   The User-PI may

Official ARPA-Internet Protocols                                 RFC 944

            specify a non-default user side data port with the PORT
            command.  The User-PI may request the server side to
            identify a non-default server side data port with the PASV
            command.  Since a connection is defined by the pair of
            addresses, either of these actions is enough to get a
            different data connection, still it is permitted to do both
            commands to use new ports on both ends of the data
            connection.

            c.  Reuse of the Data Connection:  When using the stream
            mode of data transfer the end of the file must be indicated
            by closing the connection.  This causes a problem if
            multiple files are to be transfered in the session, due to
            need for TCP to hold the connection record for a time out
            period to guarantee the reliable communication.  Thus the
            connection can not be reopened at once.

               There are two solutions to this problem.  The first is to
               negotiate a non-default port (as in (b) above).  The
               second is to use another transfer mode.

               A comment on transfer modes.  The stream transfer mode is
               inherently unreliable, since one can not determine if the
               connection closed prematurely or not.  The other transfer
               modes (Block, Compressed) do not close the connection to
               indicate the end of file.  They have enough FTP encoding
               that the data connection can be parsed to determine the
               end of the file.  Thus using these modes one can leave
               the data connection open for multiple file transfers.

               Why this was not a problem with the old NCP FTP:

                  The NCP was designed with only the ARPANET in mind.
                  The ARPANET provides very reliable service, and the
                  NCP counted on it.  If any packet of data from an NCP
                  connection were lost or damaged by the network the NCP
                  could not recover.  It is a tribute to the ARPANET
                  designers that the NCP FTP worked so well.

                  The TCP is designed to provide reliable connections
                  over many different types of networks and
                  interconnections of networks.  TCP must cope with a
                  set of networks that can not promise to work as well
                  as the ARPANET.  TCP must make its own provisions for
                  end-to-end recovery from lost or damaged packets.
                  This leads to the need for the connection phase-down
                  time-out.  The NCP never had to deal with
                  acknowledgements or retransmissions or many other

Official ARPA-Internet Protocols                                 RFC 944

                  things the TCP must do to make connection reliable in
                  a more complex world.

         LIST and NLST:

            There is some confusion about the LIST an NLST commands, and
            what is appropriate to return.  Some clarification and
            motivation for these commands should be added to the
            specification.

         Multiple 1xx Replies:

            There is some difference of opinion about the use of
            multiple 1xx responses during command processing.  This
            issue comes up particularly in processing the RETR and STOR
            commands.  The two opinions are summarized below.

            For Exactly One 1xx Response:

               When a RETR or SEND command is started, the server is
               supposed to give an "intermediate reply" of 1xx when it
               is opening the data connection.  Currently, some FTP
               servers give two 1xx messages.  This causes problems for
               single-thread FTP user implementations.  After reading
               the first intermediate reply, they go off to do the
               transfer.  The second 1xx message is not seen until the
               end of the transfer.  The RFC gives a state diagram of
               the form:

                  --------->Wait--------->
                          /      \
                          ^      |
                          |      V
                          \      /
                           <-----

               This implies any number of 1xx's (including 0).  There is
               a suspicion that this is just sloppy diagraming, and that
               the intent is clear from other parts of the RFC.

               The FTP specification states that the reason for
               intermediate replies is to allow implementations that
               can't do any better to know when to stop listening to the
               control channel and switch their attention to the data
               channel.  Given this intent, it seems clear that there
               should be exactly one 1xx reply at the start of the
               transfer.

               The FTP specification is ambiguous in this regard.  The

Official ARPA-Internet Protocols                                 RFC 944

               state diagrams appear to sanction any number of
               responses.  But the charts before them do not.  And from
               the intent, it seems obvious that exactly one is the
               right thing.

               Consider an implementation on a PC.  It is fairly hard to
               do parallel processing there.  It should be possible for
               a PC implementation to stop paying attention to the
               control channel and start reading the file from the data
               channel when he sees the 1xx response.  The only way this
               can work is if there is only one 1xx response.

               Of course, one could make it a requirement that every FTP
               implementation must be based on good enough interrupt
               technology so that it can field extra responses during
               the transfer.  But what would such a constraint buy?
               Just the ability to have both a 125 and a 150 response.
               It doesn't seem worth the price.  You could just as well
               combine the information in those responses into a single
               one.

            For Multiple 1xx Responses:

               The multiple 1xx messages arose because the new TCP
               specification omitted the 050 spontaneous reply code.  A
               solution was to change an 050 informational message to a
               1xx message, creating both a 125 and a 150.

               The state diagrams clearly allow this, and the
               "Command-Reply Sequences" section does not contradict it.
               A multiple 1xx implementation is in accord with the
               formal reply specifications.

               A multiple 1xx implementation works with the TOPS-20
               FTP's and with a number of different UNIX
               implementations, and the LOCUS system.  So, a lot of
               implementors must follow state diagrams in preference to
               prose.

               However, the observation is certainly correct that
               page 34 of the specification suggests that 1xx replies
               can be used by single-thread user implementations to
               switch attention to the data connection.  This would
               allow only a single 1xx message, in contradiction to the
               state diagrams.  It seems a bit strong, however, to call
               the one sentence on page 34 "the intent" of the
               specification, since it is contradicted by the format
               specification of replies.

Official ARPA-Internet Protocols                                 RFC 944

               A side discussion favoring more status information:

                  One view has always assumed a two-thread
                  implementation.  In this view, most user
                  implementations are deficient because they do not
                  allow the user to enter a STATUS command during data
                  transfer.  A cynic might say that is because the
                  Computer Scientists who did these implementations only
                  do "Toy" file transfers, and often use "Toy" operating
                  systems.

                  There has been some complaints from the Toy systems
                  crowd recently that FTP is too complicated.  Well, it
                  may be too complicated for Toy systems, but in fact it
                  is too simple for many Real file systems.  For
                  example, it has no way to encode a "library" (i.e., a
                  named collection of subfiles).  It is (barely)
                  adequate for shipping around files of text, but not
                  much more.

                  With the notable exception of Multics and UNIX, many
                  operating systems support complex file structures of
                  which the user must be aware.  One is not doing the
                  user a favor by hiding details that may reach out and
                  bite him.  That is the reason some FTPs put out a
                  large informative message at the beginning of the
                  transfer, specifying the file baroqueness that is
                  involved.  As a Computer Scientist, you may find that
                  message annoying, but if you had to use MVS very much,
                  you would find it helpful, informative, and maybe even
                  reassuring.  Some believe that as DARPA technology
                  moves into the production environment of DDN, there
                  will be user requirements for such informative
                  messages for a variety of vendor operating systems.

               To provide important information to the user the
               specification should either allow multiple 1xx messages,
               or restore the old spontaneous reply category.  In fact,
               the latter is preferable; this information should be
               displayed to the user, but a user FTP might swallow 1xx
               messages without displaying their text.

            The Answer:

               Following the Robustness Principle (a protocol
               implementation ought to inflict minimal pain and accept
               maximal pain) there should be only one 1xx response.
               That is, those FTP servers that now issue two 1xx
               responses should combine them.

Official ARPA-Internet Protocols                                 RFC 944

      OTHER REFERENCES:

         RFC 678 - Document File Format Standards

         MIL-STD-1780 - File Transfer Protocol

      DEPENDENCIES: Transmission Control Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   Trivial File Transfer Protocol  ------------------------------ (TFTP)

      STATUS:  Elective

      SPECIFICATION:  RFC 783 (in IPTW)

      COMMENTS:

         A very simple file moving protocol, no access control is
         provided.

         This is in use in several local networks.

         Ambiguities in the interpretation of several of the transfer
         modes should be  clarified, and additional transfer modes could
         be defined.  Additional error codes could be defined to more
         clearly identify problems.

      OTHER REFERENCES:

      DEPENDENCIES: User Datagram Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   Simple File Transfer Protocol  ------------------------------- (SFTP)

      STATUS:  Experimental

      SPECIFICATION:  RFC 913

      COMMENTS:

         SFTP is a simple file transfer protocol.  It fills the need of
         people wanting a protocol that is more useful than TFTP but
         easier to implement (and less powerful) than FTP.  SFTP
         supports user access control, file transfers, directory
         listing, directory changing, file renaming and deleting.

         SFTP can be implemented with any reliable 8-bit byte stream

Official ARPA-Internet Protocols                                 RFC 944

         oriented protocol, this document describes its TCP
         specification.  SFTP uses only one TCP connection; whereas TFTP
         implements a connection over UDP, and FTP uses two TCP
         connections (one using the TELNET protocol).

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:

      DEPENDENCIES: Transmission Control Protocol

      CONTACT: MKL@MIT-XX.ARPA

   Simple Mail Transfer Protocol  ------------------------------- (SMTP)

      STATUS:  Recommended

      SPECIFICATION:  RFC 821 (in "Internet Mail Protocols")

      COMMENTS:

         The procedure for transmitting computer mail between hosts.

         This has been revised since the IPTW, it is in the "Internet
         Mail Protocols" volume of November 1982.  RFC 788 (in IPTW) is
         obsolete.

         There have been many misunderstandings and errors in the early
         implementations.  Some documentation of these problems can be
         found in the file [ISIF]<SMTP>MAIL.ERRORS.

         Some minor differences between RFC 821 and RFC 822 should be
         resolved.

      OTHER REFERENCES:

         RFC 822 - Mail Header Format Standards

            This has been revised since the IPTW, it is in the "Internet
            Mail Protocols" volume of November 1982.  RFC 733 (in IPTW)
            is obsolete.  Further revision of RFC 822 is needed to
            correct some minor errors in the details of the
            specification.

         MIL-STD-1781 - Simple Mail Transfer Protocol (SMTP)

      DEPENDENCIES: Transmission Control Protocol

Official ARPA-Internet Protocols                                 RFC 944

      CONTACT: Postel@USC-ISIF.ARPA

   Resource Location Protocol  ----------------------------------- (RLP)

      STATUS:   Elective

      SPECIFICATION:   RFC 887

      COMMENTS:

         A resource location protocol for use in the ARPA-Internet.
         This protocol utilizes the User Datagram Protocol (UDP) which
         in turn calls on the Internet Protocol to deliver its
         datagrams.

      OTHER REFERENCES:

      DEPENDENCIES: User Datagram Protocol

      CONTACT:   Accetta@CMU-CS-A.ARPA

   Loader Debugger Protocol  ------------------------------------- (LDP)

      STATUS:  Experimental

      SPECIFICATION:  RFC 909

      COMMENTS:

         Specifies a protocol for loading, dumping and debugging target
         machines from hosts in a network environment.  It is also
         designed to accommodate a variety of target CPU types.  It
         provides a powerful set of debugging services, while at the
         same time, it is structured so that a simple subset may be
         implemented in applications like boot loading where efficiency
         and space are at a premium.

      OTHER REFERENCES:

      DEPENDENCIES:  Reliable Data Protocol

      CONTACT:  Hinden@BBN-UNIX.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Remote Job Entry  --------------------------------------------- (RJE)

      STATUS:  Elective

      SPECIFICATION:  RFC 407 (in APH)

      COMMENTS:

         The general protocol for submitting batch jobs and retrieving
         the results.

         Some changes needed for use with TCP.

         No known active implementations.

      OTHER REFERENCES:

      DEPENDENCIES: File Transfer Protocol
                    Transmission Control Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   Remote Job Service  ---------------------------------------- (NETRJS)

      STATUS:  Elective

      SPECIFICATION:  RFC 740 (in APH)

      COMMENTS:

         A special protocol for submitting batch jobs and retrieving the
         results used with the UCLA IBM OS system.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

         Revision in progress.

      OTHER REFERENCES:

      DEPENDENCIES: Transmission Control Protocol

      CONTACT: Braden@UCLA-CCN.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Remote Telnet Service  ------------------------------------ (RTELNET)

      STATUS:  Elective

      SPECIFICATION:  RFC 818

      COMMENTS:

         Provides special access to user Telnet on a remote system.

      OTHER REFERENCES:

      DEPENDENCIES: Telnet, Transmission Control Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   Graphics Protocol  --------------------------------------- (GRAPHICS)

      STATUS:  Elective

      SPECIFICATION:  NIC 24308 (in APH)

      COMMENTS:

         The protocol for vector graphics.

         Very minor changes needed for use with TCP.

         No known active implementations.

      OTHER REFERENCES:

      DEPENDENCIES: Telnet, Transmission Control Protocol

      CONTACT: Postel@USC-ISIF.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Echo Protocol  ----------------------------------------------- (ECHO)

      STATUS:  Recommended

      SPECIFICATION:  RFC 862

      COMMENTS:

         Debugging protocol, sends back whatever you send it.

      OTHER REFERENCES:

      DEPENDENCIES: Transmission Control Protocol
                    or User Datagram Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   Discard Protocol  ----------------------------------------- (DISCARD)

      STATUS:  Elective

      SPECIFICATION:  RFC 863

      COMMENTS:

         Debugging protocol, throws away whatever you send it.

      OTHER REFERENCES:

      DEPENDENCIES: Transmission Control Protocol
                    or User Datagram Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   Character Generator Protocol  ----------------------------- (CHARGEN)

      STATUS:  Elective

      SPECIFICATION:  RFC 864

      COMMENTS:

         Debugging protocol, sends you ASCII data.

      OTHER REFERENCES:

      DEPENDENCIES: Transmission Control Protocol
                    or User Datagram Protocol

Official ARPA-Internet Protocols                                 RFC 944

      CONTACT: Postel@USC-ISIF.ARPA

   Quote of the Day Protocol  ---------------------------------- (QUOTE)

      STATUS:  Elective

      SPECIFICATION:  RFC 865

      COMMENTS:

         Debugging protocol, sends you a short ASCII message.

      OTHER REFERENCES:

      DEPENDENCIES: Transmission Control Protocol
                    or User Datagram Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   Active Users Protocol  -------------------------------------- (USERS)

      STATUS:  Elective

      SPECIFICATION:  RFC 866

      COMMENTS:

         Lists the currently active users.

      OTHER REFERENCES:

      DEPENDENCIES: Transmission Control Protocol
                    or User Datagram Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   Finger Protocol  ------------------------------------------- (FINGER)

      STATUS:  Elective

      SPECIFICATION:  RFC 742 (in APH)

      COMMENTS:

         Provides information on the current or most recent activity of
         a user.

         Some extensions have been suggested.

Official ARPA-Internet Protocols                                 RFC 944

         Some changes are are needed for TCP.

      OTHER REFERENCES:

      DEPENDENCIES: Transmission Control Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   WhoIs Protocol  ------------------------------------------- (NICNAME)

      STATUS:  Elective

      SPECIFICATION:  RFC 812 (in IPTW)

      COMMENTS:

         Accesses the ARPANET Directory database.  Provides a way to
         find out about people, their addresses, phone numbers,
         organizations, and mailboxes.

      OTHER REFERENCES:

      DEPENDENCIES: Transmission Control Protocol

      CONTACT: Feinler@SRI-NIC.ARPA

   Domain Name Protocol  -------------------------------------- (DOMAIN)

      STATUS:  Experimental

      SPECIFICATION:  RFC 881, 882, 883

      COMMENTS:

      OTHER REFERENCES:

         RFC 920 - Domain Requirements

         RFC 921 - Domain Name Implementation Schedule - Revised

      DEPENDENCIES: Transmission Control Protocol
                    or User Datagram Protocol

      CONTACT: Mockapetris@USC-ISIF.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   HOSTNAME Protocol  --------------------------------------- (HOSTNAME)

      STATUS:  Elective

      SPECIFICATION:  RFC 811 (in IPTW)

      COMMENTS:

         Accesses the Registered Internet Hosts database (HOSTS.TXT).
         Provides a way to find out about a host in the Internet, its
         Internet Address, and the protocols it implements.

      OTHER REFERENCES:

         RFC 810 - Host Table Specification

      DEPENDENCIES: Transmission Control Protocol

      CONTACT: Feinler@SRI-NIC.ARPA

   Host Name Server Protocol  ----------------------------- (NAMESERVER)

      STATUS:  Experimental

      SPECIFICATION:  IEN 116 (in IPTW)

      COMMENTS:

         Provides machine oriented procedure for translating a host name
         to an Internet Address.

         This specification has significant problems:  1) The name
         syntax is out of date.  2) The protocol details are ambiguous,
         in particular, the length octet either does or doesn't include
         itself and the op code.  3) The extensions are not supported by
         any known implementation.

         This protocol is now abandon in favor of the DOMAIN protocol.
         Further implementations of this protocol are not advised.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:

      DEPENDENCIES: User Datagram Protocol

      CONTACT: Postel@USC-ISIF.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   CSNET Mailbox Name Server Protocol  ---------------------- (CSNET-NS)

      STATUS:  Experimental

      SPECIFICATION:  CS-DN-2

      COMMENTS:

         Provides access to the CSNET data base of users to give
         information about users names, affiliations, and mailboxes.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:

      DEPENDENCIES: Transmission Control Protocol

      CONTACT: Solomon@UWISC.ARPA

   Daytime Protocol  ----------------------------------------- (DAYTIME)

      STATUS:  Elective

      SPECIFICATION:  RFC 867

      COMMENTS:

         Provides the day and time in ASCII character string.

      OTHER REFERENCES:

      DEPENDENCIES: Transmission Control Protocol
                    or User Datagram Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   Time Server Protocol  ---------------------------------------- (TIME)

      STATUS:  Elective

      SPECIFICATION:  RFC 868

      COMMENTS:

         Provides the time as the number of seconds from a specified
         reference time.

      OTHER REFERENCES:

Official ARPA-Internet Protocols                                 RFC 944

      DEPENDENCIES: Transmission Control Protocol
                    or User Datagram Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   DCNET Time Server Protocol  --------------------------------- (CLOCK)

      STATUS:  Elective

      SPECIFICATION:  RFC 778

      COMMENTS:

         Provides a mechanism for keeping synchronized clocks.

      OTHER REFERENCES:

      DEPENDENCIES: Internet Control Message Protocol

      CONTACT: Mills@USC-ISID.ARPA

   SUPDUP Protocol  ------------------------------------------- (SUPDUP)

      STATUS:  Elective

      SPECIFICATION:  RFC 734 (in APH)

      COMMENTS:

         A special Telnet like protocol for display terminals.

      OTHER REFERENCES:

      DEPENDENCIES: Transmission Control Protocol

      CONTACT: Crispin@SU-SCORE.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Internet Message Protocol  ------------------------------------ (MPM)

      STATUS:  Experimental

      SPECIFICATION:  RFC 759

      COMMENTS:

         This is an experimental multimedia mail transfer protocol.  The
         implementation is called a Message Processing Module or MPM.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:

         RFC 767 - Structured Document Formats

      DEPENDENCIES: Transmission Control Protocol

      CONTACT: Postel@USC-ISIF.ARPA

   Post Office Protocol - Version 2  ---------------------------- (POP2)

      STATUS:  Experimental

      SPECIFICATION:  RFC 937

      COMMENTS:

         The intent of the Post Office Protocol - Version 2 (POP2) is to
         allow a user's workstation to access mail from a mailbox
         server.  It is expected that mail will be posted from the
         workstation to the mailbox server via the Simple Mail Transfer
         Protocol (SMTP).

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:  Obsoletes RFC 918

      DEPENDENCIES: Transmission Control Protocol

      CONTACT: JKReynolds@USC-ISIF.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Network Standard Text Editor  ------------------------------- (NETED)

      STATUS:  Elective

      SPECIFICATION:  RFC 569

      COMMENTS:

         Describes a simple line editor which could be provided by every
         Internet host.

      OTHER REFERENCES:

      DEPENDENCIES:

      CONTACT:  Postel@USC-ISIF.ARPA

   Authentication Service  -------------------------------------- (AUTH)

      STATUS:  Experimental

      SPECIFICATION:  RFC 931

      COMMENTS:

         This server provides a means to determine the identity of a
         user of a particular TCP connection.  Given a TCP port number
         pair, it returns a character string which identifies the owner
         of that connection on the server's system.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:  Supercedes RFC 912

      DEPENDENCIES: Transmission Control Protocol

      CONTACT: StJohns@MIT-Multics.ARPA

Official ARPA-Internet Protocols                                 RFC 944

APPENDICES

   Assigned Numbers  ---------------------------------------------------

      STATUS:  None

      SPECIFICATION:  RFC 943

      COMMENTS:

         Describes the fields of various protocols that are assigned
         specific values for actual use, and lists the currently
         assigned values.

         Issued April 1985, replaces RFC 923, RFC 790 in IPTW, and
         RFC 900.

      OTHER REFERENCES:

      CONTACT: JKReynolds@USC-ISIF.ARPA

   Pre-emption  --------------------------------------------------------

      STATUS:  Elective

      SPECIFICATION:  RFC 794 (in IPTW)

      COMMENTS:

         Describes how to do pre-emption of TCP connections.

      OTHER REFERENCES:

      CONTACT: Postel@USC-ISIF.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Service Mappings  ---------------------------------------------------

      STATUS:  None

      SPECIFICATION:  RFC 795 (in IPTW)

      COMMENTS:

         Describes the mapping of the IP type of service field onto the
         parameters of some specific networks.

         Out of date, needs revision.

      OTHER REFERENCES:

      CONTACT: Postel@USC-ISIF.ARPA

   Address Mappings  ---------------------------------------------------

      STATUS:  None

      SPECIFICATION:  RFC 796 (in IPTW)

      COMMENTS:

         Describes the mapping between Internet Addresses and the
         addresses of some specific networks.

         Out of date, needs revision.

      OTHER REFERENCES:

      CONTACT:  Postel@USC-ISIF.ARPA

   Document Formats  ---------------------------------------------------

      STATUS:  None

      SPECIFICATION:  RFC 678

      COMMENTS:

         Describes standard format rules for several types of documents.

      OTHER REFERENCES:

      CONTACT:  Postel@USC-ISIF.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Bitmap Formats  -----------------------------------------------------

      STATUS:  None

      SPECIFICATION:  RFC 797

      COMMENTS:

         Describes a standard format for bitmap data.

      OTHER REFERENCES:

      CONTACT:  Postel@USC-ISIF.ARPA

   Facsimile Formats  --------------------------------------------------

      STATUS:  None

      SPECIFICATION:  RFC 804

      COMMENTS:

         Describes a standard format for facsimile data.

      OTHER REFERENCES:

      CONTACT:  Postel@USC-ISIF.ARPA

   Host-Front End Protocol  ------------------------------------- (HFEP)

      STATUS:  Experimental

      SPECIFICATION:  RFC 929

      COMMENTS:

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:  RFC 928

      DEPENDENCIES:

      CONTACT: Padlipsky@USC-ISI.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Internet Protocol on X.25 Networks  ------------------------ (IP-X25)

      STATUS:  Recommended

      SPECIFICATION:  RFC 877

      COMMENTS:

         Describes a standard for the transmission of IP Datagrams over
         Public Data Networks.

      OTHER REFERENCES:

      CONTACT:  jtk@PURDUE.ARPA

   Internet Protocol on DC Networks  --------------------------- (IP-DC)

      STATUS:  Elective

      SPECIFICATION: RFC 891

      COMMENTS:

      OTHER REFERENCES:

         RFC 778 - DCNET Internet Clock Service

      CONTACT:  Mills@USC-ISID.ARPA

   Internet Protocol on Ethernet Networks  ---------------------- (IP-E)

      STATUS:  Recommended

      SPECIFICATION: RFC 894

      COMMENTS:

      OTHER REFERENCES:  RFC 893

      CONTACT:  Postel@USC-ISIF.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Internet Protocol on Experimental Ethernet Networks  -------- (IP-EE)

      STATUS:  Recommended

      SPECIFICATION: RFC 895

      COMMENTS:

      OTHER REFERENCES:

      CONTACT:  Postel@USC-ISIF.ARPA

   Internet Subnets Protocol  --------------------------------- (IP-SUB)

      STATUS:  Experimental

      SPECIFICATION: RFC 940

      COMMENTS:

         Discussion of the various problems and potential solutions of
         "explicit subnets" in a multi-LAN environment.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:  RFC 917, RFC 925, RFC 932, RFC 936, RFC 922

      DEPENDENCIES:

      CONTACT:  Mills@USC-ISID.ARPA

   Broadcasting Internet Datagrams  ------------------------- (IP-BROAD)

      STATUS:  Experimental

      SPECIFICATION:  RFC 919

      COMMENTS:

         A proposed protocol of simple rules for broadcasting Internet
         datagrams on local networks that support broadcast, for
         addressing broadcasts, and for how gateways should handle them.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:  RFC 922

Official ARPA-Internet Protocols                                 RFC 944

      DEPENDENCIES:

      CONTACT: Mogul@SU-SCORE.ARPA

   Address Resolution Protocol  ---------------------------------- (ARP)

      STATUS:  Recommended

      SPECIFICATION: RFC 826

      COMMENTS:

         This is a procedure for finding the network hardware address
         corresponding to an Internet Address.

      OTHER REFERENCES:

      CONTACT:  Postel@USC-ISIF.ARPA

   A Reverse Address Resolution Protocol  ----------------------- (RARP)

      STATUS:  Elective

      SPECIFICATION: RFC 903

      COMMENTS:

         This is a procedure for workstations to dynamically find their
         protocol address (e.g., their Internet Address), when they only
         only know their hardware address (e.g., their attached physical
         network address).

      OTHER REFERENCES:

      CONTACT:  Mogul@SU-SCORE.ARPA

   Multi-LAN Address Resolution Protocol  ----------------------- (MARP)

      STATUS:  Experimental

      SPECIFICATION: RFC 925

      COMMENTS:

         Discussion of the various problems and potential solutions of
         "transparent subnets" in a multi-LAN environment.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

Official ARPA-Internet Protocols                                 RFC 944

      OTHER REFERENCES:  RFC 917, RFC 826

      DEPENDENCIES:

      CONTACT:  Postel@USC-ISIF.ARPA

   Broadcasting Internet Datagrams with Subnets --------- (IP-SUB-BROAD)

      STATUS:  Experimental

      SPECIFICATION:  RFC 922

      COMMENTS:

         A proposed protocol of simple rules for broadcasting Internet
         datagrams on local networks that support broadcast, for
         addressing broadcasts, and for how gateways should handle them.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:

      DEPENDENCIES:

      CONTACT: Mogul@SU-SCORE.ARPA

   Host Access Protocol  ----------------------------------------- (HAP)

      STATUS:  Recommended

      SPECIFICATION:  RFC 907

      COMMENTS:

         This protocol specifies the network-access level communication
         between an arbitrary computer, called a host, and a
         packet-switched satellite network, e.g., SATNET or WBNET.

         Note:  Implementations of HAP should be performed in
         coordination with satellite network development and operations
         personnel.

      OTHER REFERENCES:

      DEPENDENCIES:

      CONTACT: Schoen@BBN-UNIX.ARPA

Official ARPA-Internet Protocols                                 RFC 944

   Reliable Asynchronous Transfer Protocol  --------------------- (RATP)

      STATUS:  Experimental

      SPECIFICATION:  RFC 916

      COMMENTS:

         This paper specifies a protocol which allows two programs to
         reliably communicate over a communication link.  It ensures
         that the data entering one end of the link if received arrives
         at the other end intact and unaltered.  This proposed protocol
         is designed to operate over a full duplex point-to-point
         connection.  It contains some features which tailor it to the
         RS-232 links now in current use.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:

      DEPENDENCIES: Transmission Control Protocol

      CONTACT: Finn@USC-ISIF.ARPA

   Thinwire Protocol  --------------------------------------- (THINWIRE)

      STATUS:  Experimental

      SPECIFICATION:  RFC 914

      COMMENTS:

         This paper discusses a Thinwire Protocol for connecting
         personal computers to the ARPA-Internet.  It primarily focuses
         on the particular problems in the ARPA-Internet of low speed
         network interconnection with personal computers, and possible
         methods of solution.

         Please discuss any plans for implementation or use of this
         protocol with the contact.

      OTHER REFERENCES:

      DEPENDENCIES:

      CONTACT: Farber@ROCHESTER.ARPA

 

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