File Transfer Protocol
RFC 542

Document Type RFC - Unknown (August 1973; Errata)
Obsoleted by RFC 765
Updated by RFC 640, RFC 614
Obsoletes RFC 354
Last updated 2013-03-02
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File Transfer Protocol
                                                         (Aug. 12, 1973)
                                                       RFC 542 NIC 17759

Nancy J. Neigus                            See Also:  RFCs 354, 454, 495
Bolt Beranek and Newman, Inc.
Cambridge, Mass.

              File Transfer Protocol for the ARPA Network


                                                  File Transfer Protocol
                                                         (Aug. 12, 1973)
                                                       RFC 542 NIC 17759

                                PREFACE

This document is the result of several months discussion via RFC
(relevant numbers are 430, 448, 454, 463, 468, 478, 480), followed by a
meeting of the FTP committee at BBN on March 16, followed by further
communication among committee members.  There are a considerable number
of changes for the last "official" version, see RFCs 354, 385, but the
gross structure remains the same.  The places to look for differences
are (1) in the definitions pf types and modes, (2) in the specification
of the data connection and data sockets, (3) in the command-reply
sequences, (4) in the functions dependent on the TELNET protocol (FTP
has been altered to correspond to the new TELNET spec).  The model has
been clarified and enlarged to allow inter-server file transfer, and
several new commands have been added to accommodate more specialized (or
site-specific) functions.  It is my belief that this new specificiation
reflects the views expressed by the committee at the above-mentioned
meeting and in subsequent conversations.

The large number of incompatibilities would complicate a phased
implementation schedule, such as is in effect for the TELNET protocol.
Therefore we have assigned a new socket, decimal 21, as a temporary
logger socket for the new version and a change-over date of 1 February
1974.  Until that date the old (354, 385) version of FTP will be
available on Socket 3 and the new version (attached) should be
implemented on Socket 21.  On 1 February the new version will shift to
Socket 3 and the old disappear from view.

The File Transfer protocol should be considered stable at least until
February, though one should feel free to propose further changes via
RFC.  (Implementation of new commands on an experimental basis is
encouraged and should also be reported by RFC.)  In addition, members of
the FTP committee may be contacted directly about changes.  Based on
attendance at the March 16 meeting, they are:

   Abhay Bhushan MIT-DMCG
   Bob Braden UCLA-CCN
   Bob Bressler BBN-NET
   Bob Clements BBN-TENEX
   John Day ILL-ANTS
   Peter Deutsch PARC-MAXC
   Wayne Hathaway AMES-67
   Mike Kudlick SRI-ARC
   Alex McKenzie BBN-NET
   Bob Merryman UCSD-CC
   Nancy Neigus BBN-NET
   Mike Padlipsky MIT-Multics
   Jim Pepin USC-44
   Ken Pogran MIT-Multics
   Jon Postel UCLA-NMC

                                   1


                                                  File Transfer Protocol
                                                         (Aug. 12, 1973)
                                                       RFC 542 NIC 17759
                                                                        
                                                                        
   Milton Reese FNWC
   Brad Reussow HARV-10
   Marc Seriff MIT-DMCG
   Ed Taft HARV-10
   Bob Thomas BBN-TENEX
   Ric Werme CMU-10
   Jim White SRI-ARC

I would especially like to thank Bob Braden, Ken Pogran, Wayne Hathaway,
Jon Postel, Ed Taft and Alex McKenzie for their help in preparing this
document.

NJN/jm

                                   2


                                                  File Transfer Protocol
                                                         (Aug. 12, 1973)
                                                       RFC 542 NIC 17759
                                                                        
                                                                        
                         FILE TRANSFER PROTOCOL

INTRODUCTION

   The File Transfer Protocol (FTP) is a protocol for file transfer
   between Hosts (including Terminal Interface Message Processors
   (TIPs)) on the ARPA Computer Network (ARPANET).  The primary function
   of FTP is to transfer files efficiently and reliably among Hosts and
   to allow the convenient use of remote file storage capabilities.

   The objectives of FTP are 1) to promote sharing of files (computer
   programs and/or data), 2) to encourage indirect or implicit (via
   programs) use of remote computers, 3) to shield a user from
   variations in file storage systems among Hosts, and 4) to transfer
   data reliably and efficiently.  FTP, though usable directly by a user
   at a terminal, is designed mainly for use by programs.

   The attempt in this specification is to satisfy the diverse needs of
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