Network Working Group                           23 June 1971
Request for Comments #172                       Abhay Bhushan, MIT
NIC 6794                                        Bob Braden, UCLA
Categories: D.4, D.5, and D.7                   Will Crowther, BBN
Updates: 114                                    Eric Harslem, Rand
Obsolete: None                                  John Heafner, Rand
                                                Alex McKenzie, BBN
                                                John Melvin, SRI
                                                Bob Sundberg, Harvard
                                                Dick Watson, SRI
                                                Jim White, UCSB












                    THE FILE TRANSFER PROTOCOL




























 
NWG/RFC 172


I. INTRODUCTION

      The file transfer protocol (FTP) is a user-level protocol for file
transfer between host computers (including terminal IMP's), on the ARPA
computer network. 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 other hosts. FTP uses the data transfer
protocol described in RFC 171 to achieve transfer of data. This paper
assumes knowledge of RFC 171.

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

II. DISCUSSION

      A file is considered here to be an ordered set of arbitrary
length, consisting of computer (including instructions) data. 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 names in case of named
files. 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 he wishes to use. FTP
may be extended later to include standard conventions for pathname
structures.[1]

      A file may or may not have access controls associated with it.
The access controls designate the users' access privilege. In the
absence of access controls, the files cannot be protected from
accidental or unauthorized usage. It is the prerogative of a resident
file system to provide protection, and selective access. FTP only
provides identifier and password mechanisms for exchange of access