Movatterモバイル変換

Network Working Group                                         A. BhushanRequest for Comments: 414                                        MIT-MACUpdates: RFC354,RFC 385                               29 November 1972NIC: 12406FILE TRANSFER PROTOCOL (FTP) STATUS AND FURTHER COMMENTS   A number of HOSTs have working server and user FTPs now.  The   following reflects the status of FTP implementations to the best of   my knowledge:      BBN(A and B), SRI-ARC, UTAH, CASE, USC-ISI, CCA, MIT-AI MIT-      Mathlab, MIT-DMCG, CMU, AMES-67, and SU-AI have fully functionning      server and user FTPs.      MIT-Multics has user and server FTPs but the server does not      listen on socket 3 (it can be started by normal login and the      command ftp_server).  UCSB will soon have user and server FTP's.   The servers at all the TENEX systems are more or less identical   (developed by Bob Clements at BBN).  The servers at MIT-AI and MIT-ML   are also identical (developed by Pitts Jarvis of MAC).  Others   currently involved with FTP include Arvola Chan (AC@MIT-DMCG), Ken   Pogran (Multics), Greg Hicks (HICKS@UTAH), Wayne Hathaway (AMES-67),   Ralph Gorin (SU-AI), Rick Werme (CMU), and Ron Stoughton (UCSB).   The User-FTP or the user interface to FTP is where desirable and   interesting features can be put in.  An example of such a features is   the BBN (and other TENEXes) "SNDMSG USER@HOST" feature which allows a   local user to send messages (or mail) to other network users.  If the   remote host is not up, the message is stored as "--UNSENT-MAIL--   USERHOST" in the user's directory and a background job periodically   checks for such files to send mail.  MIT-AI and MIT-ML have a "TRANS"   command which allows convenient transfer of files.  At MIT-DMCG we   have developed under the "CALICO" subsystem, generalized commands   which allow local users to send mail, copy files efficiently, and   list users and directories over the network in a manner similar to   local usage (that is without having to explicitly connect, login, and   send commands to a remote HOST).  We also allow TELNET, FTP, and RJS   users to automatically "login" and perform other command sequences   from an "initial" file.   It should be noted that file transfer between PDP-10's in "Image 36"   is an order of magnitude faster (and more efficient) than in "ASCII   8".  Note also that it is useful to provide a "Quote" or "talk" mode   in user-FTP, to enable a user to input commands directly to the FTP   server (i.e. commands not implemented in user-FTP).  It is desirableBhushan                                                         [Page 1]

RFC 414             FTP Status and Further Comments        November 1972   that user and server FTP features and desirable modes of usage be   documented and reported via the RFC mechanism.   The following suggestions and additions pertain to the File Transfer   Protocol as stated in NWG/RFC 354 and NWG/RFC 385.  After receiving   comments to this RFC, I will have the three RFC's combined into a   single document and have it issued as the ARPANET Official File   Transfer Protocol, very soon.  It should however be noted that FTP is   an open-ended protocol with room for experimentation.  New commands,   reply codes, data representation types, and file structures may be   defined in future.  If two sites agree, they can define their own   experimental set of commands, data types, file structures, and/or   transfer modes.  Such additions to the protocol should be well   documented and clearly specified so that other sites can also make   use of the same.   1) The FTP assumes line-at-a-time interaction with local acho.  The      server is not obliged to provide remote echo and may ignore TELNET      control characters.  A server however should not give error or bad      response on receiving TELNET control characters.      The server does not explicitly provide any editing capability such      as character delete or line kill characters.  All editing is      assumed to be local.  TIP users should use FTP in line mode and      send both <CR> and <LF> (by TIP commands @T O L and @I L).  In      such a mode the TIP user can flush his current input line by the      flush command (@F).      The server should respond to the TELNET "SYNCH" by flushing the      current command line and waiting for user input such as an "ABOR"      command.  Other commands such as "BYE" or "STAT" may also      constitute an acceptable input.   2) Commands such as "STAT" which will produce more than one line of      output over the TELNET connection, require some way of positively      indicating the end of status information.  It is proposed that a      "200 status complete" reply give a positive indication for end of      status information.  The reply to STAT should begin with a line      starting with 1xx (where x=digit), with the following lines not      having a digit as their first character, and the status ending      with the 200 reply.  (Note that the requirement of three spaces is      dropped in favour of the less restrictive requirement of the first      character not being a digit.)  This change would make operations      much easier for both user and server FTPs.   3) A reminder that BYE<CR><LF> is legal.  A space after a command      name is not required if there is a null argument.Bhushan                                                         [Page 2]

RFC 414             FTP Status and Further Comments        November 1972   4) The following response are proposed to the "STAT" and "LIST"      commands (this was not clearly specified specially for the null      argument case).  Responses to "STAT" and "LIST" shall always be      over the TELNET and Data connections, respectively.  The "LIST"      command with null argument should produce a list of files in      user's current working or default directory.  The "STAT" command      with null argument should (as suggested by Wayne Hathaway) produce      tha status of all file transfer parameters (user, byte, size, data      type, transfer mode, and file structure) if used between file      transfers (i.e. no transfer in progress).  If STAT is sent during      a file transfer operation (accompanied with TELNET synch), the      server should respond with the status of the operation in      progress.  If the argument of the "LIST" and "STAT" commands is a      pathname, then a list associated with that pathname should be      sent.   5) Two new commands are hereby proposed.  First is a "HELP" command      which should send to the user helpful hints about using the server      and its implementation status (news).  The information will be      sent over the TELNET connection starting with type 100 reply and      ending with  a type 200 reply (completion).  It is suggested that      the use of this command and the "MAIL" and "BYE" commands be      allowed without the user having to "login" (i.e., supplying valid      user, password, and account).      The other command (suggested by Bob Clements) is a new directory      listing command called "NLST" which sends only the names of files      (as valid pathname strings separated by CRLF) and no other useful      but confusing information, so that it is possible to copy a whole      directory automatically using this command and the store and      retrieve commands.  The syntax and format of this command is      identical to the "LIST" command (for some HOSTs they may be      identical commands).   6) Although the minimum implementation does not require the TYPE,      BYTE, MODE, and STRU commands, it is suggested that these commands      be accepted with the default values by even those having a minimum      implementation.  This would avoid some of the "ugly" error      responses to input such as "TYPE A" and "STRU F", when these are      perfectly acceptable to the server.   7) In using the "MLFL" and "LIST" commands, it is the user's (or      user-FTP's) responsibility to ensure that the TYPE is ASCII (8-bit      bytes).  If the TYPE is other than ASCII, the server may send an      error response and refuse the command.  The user (or user-FTP)      should therefore send the server "TYPE A" command if type is other      than ASCII before sending the "MLFL" or "LIST" type commands.Bhushan                                                         [Page 3]

RFC 414             FTP Status and Further Comments        November 1972   8) A useful suggestion is to allow multiple user names in the "MAIL"      and "MLFL" commands.  Often a user wishes to send the same mail to      a number of users at particular site.  It would be very convenient      if he can do this by doing a single transfer and command.  It is      strongly urged that server sites implement this option.   9) Another suggestion that has been made is to standardize pathname      syntax in FTP.  It appears that subdirectories will soon be      introduced in the TENEX system.  Perhaps that will have some      bearing on the standard pathname syntax.  The requirements of any      pathname standard scheme are that it should allow convenient use      of local pathname conventions, and not conflict with it.  A      reasonable proposal seems to be to have the standard pathname      start with a special character such as ">" (as in Multics), and to      use this special character to separate the elements of a pathname.      If the special character happens to ba valid part of a pathname      element, use the literal quote convention of "'>" (single quote to      precede the special character).      Examples of pathnames under this convention would be:         >udd>CNet>Doe>foo_bar                       (for Multics)         >DSK>JFD>foo bar                            (for ITS)         >DOE>foo.bar1    (for TENEX)   10) The requirement of account numbers by TENEXes has caused a       certain problems for automatons using FTP, under the present       reply code sequences.  Therefore two new reply codes are defined       to handle the account requirement.  A reply code of "331 Enter       Account" shall be used if an account is required as part of user       "login" sequence.  A reply code of "433 Cannot store files       without valid account.  Enter account."  be used if an account is       required only for a particular operation such as store.   11) The following suggestions made by Wayne Hathaway (RFC       forthcoming) seem reasonable and should be included in the       Protocol:       i) The following End-of-Record condition should be explicit on       last record, and not implied in an End-of-File.  This change       would simplify server implementation and improve reliability       (better error control).       ii) Implementors of user-FTP's should note that it is trivial for       them to implement record structures in ASCII type and Stream mode       (the default CRLF convention for end-of-record).  All user-FTPs       should allow store or retrieve of record structured files with       ASCII type and stream mode.Bhushan                                                         [Page 4]

RFC 414             FTP Status and Further Comments        November 1972       iii) It is possible to send record strutured "print-file" types       (in addition to ASCII type) in either stream or text modes.  (RFC354 was not clear on this issue).       iv) The TELNET synch mechanism should be extended to other       commands such as BYE and STAT in addition to ABOR.       v) Comments are invited on the desirability of NOOP, CLSE, and       SRVR commands.  In my opinion a STAT command with null argument       serves the purpose of NOOP (to see if server is still alive), and       BYE serves the purpose of CLSE (USER command should be used to       change user name).  SRVR is a useful command.   12) Bob Clements raised the old issued of error detection and control       again.  To handle this we can define two new descriptor codes in       the Block mode, one that signals start of block check, and the       other that indicates end of block check (and includes the block       check bytes).  These codes may be ignored by any site not wishing       to implement the error detection scheme.  Your comments on the       error check scheme and the desirability of its inclusion in FTP       are solicited.            [This RFC was put into machine readable form for entry]       [into the online RFC archives by Helene Morin, Via Genie, 12/99]Bhushan                                                         [Page 5]