The File Transfer Protocol
RFC 265

Document Type RFC - Unknown (November 1971; No errata)
Obsoleted by RFC 354
Updated by RFC 310, RFC 281, RFC 294
Obsoletes RFC 172
Last updated 2013-03-02
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Network Working Group                             17 November 1971
Request for Comments #265                         Abbay Bhushan, MIT
NIC 781                                           Bob Braden, UCLA
Categories D.4, D.5, and D.7                      Will Crowther, BBN
                                                  Eric Narslem, Rand
Obsoletes: 172                                    John Heafner, Rand
                                                  Alex McKenzie, BBH
                                                  John Melvin, SRI
                                                  Bob Sundberg, Harvard
                                                  Dick Watson, SRI
                                                  Jim White, UOSB

                       THE FILE TRANSFER PROTOCOL

    This Paper is a revision of RF 172, Mic 6794. The changes
to RFC 172 are given below. The protocol is then restated for
your ocnvenience.

                           CHANGES TO RFC 172

1) Two new file transfer requests have been added. These are

2) The op code assignements in control transactions have been
changed to include the above requests.

3) Two new error codes indicating 'incorrect or missing
indentifier' and 'file already exists' have been added. New error
code assignements reflect this change.

4) Editorial changes to clarify specifications.

                                                                [Page 1]
File Transfer Protocol          RFC 265                 17 November 1971


    The file transfer protocol (FTP) is a userlevel procotocol for
file transfer between host computers (including terminal IMPs), on the
ARPA computer network (ARPANET). The primary function of FTP is to
facilitate transfer of files between hosts and to allow convenient use
of storage and file handling capabilities of remote hosts. FTP uses
the Data Transfer Protocol described in RFC 264 to achieve transfer of
data. This paper assumes knowledge of RFC 264.

    The objectives of FTP are to promote sharing of files (computer
programs and/or data) encourage implicit (without explicit login) use
of computers, and shield the user from variations in file and storage
systems of different hosts. These objetives are achieved by specifying
a standard file transfer socket and initial connection protocol for
implicit use, and using standard conventions for file transfer and
related operations.


    A file is considered here to be an ordered set of arbitrary
length, consisting of computer data (including programs). Files are
uniquely identified in a system by their pathnames. A pathname is
(loosely) defined to be the data string which must be input to the
file system by a network user in order to identify a file. Pathname
usually contains device and/or directory names, and file name. FTP
specifications provide standard file system commands, but do not
provide standard naming convention at this time. Each user must follow
the naming convention of the file system be wishing to use. FTP may be
extended later to include standard conventions of pathname structures.

    A file may or may not have access control associated with it The
access controls designate users access privileges. In absence of
access controls, files cannot be protected from accidental or
unauthorized usage. It is the prerogative of a serving file system to
provide protection, and selective access.  FTP provides identifier and
password mechanisms for exchange of access control information. it
should however ve noted, that for file sharing, it is necessary that a
user be allowed (subject to access controls) to access files not
created by him.

    FTP does not restrict the nature of information in files.  For
example, a file could contain ASCII text, binary data, computer
program, or any other information. A provision for indicating data
structure (type and byte size) exists in FTP to aid in parsing,
interpretation, and storage of data.

                                                                [Page 2]
File Transfer Protocol          RFC 265                 17 November 1971

    To facilitate impliict usage, a serving file transfer process my
be a disowned "demon" process which "listens" to an agreed-upon
socket, and follows the standard initial connection protocol for
establishing a fill-duplex connection. It should be noted that FTP my
also be used directly by logging into a remote host, and arranging for
file transfer over specific sockets.

    FTP is readily extendable, in that additional commands and data
types may be defined by those agreeing to implement them.
Implementation of a subset of commands is specifically permitted, and
an initial subset for implementation is recommended. (*)The protocol
may also be extended to enable remote execution of programs, but no
standard procedure is suggested.

    For transferring data, FTP uses the data transfer protocol
specified in RFC 264. As the data transfer protool does not specify
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