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5.1 MINIMUM IMPLEMENTATION

In order to make FTP workable without needless error messages, the following minimum implementation is required for all servers:

Required Data Types​

  • TYPE - ASCII Non-print
  • MODE - Stream
  • STRUCTURE - File, Record

Required Commands​

The server protocol interpreter shall "listen" on Port L. User protocol interpreters shall initiate control connections.

For the Control Connection​

The server protocol interpreter must recognize and process the following commands:

  • USER
  • QUIT
  • PORT
  • TYPE - ASCII Non-print only
  • MODE - Stream only
  • STRU - File only
  • RETR
  • STOR
  • NOOP

The optional commands ACCT, CWD, CDUP, SMNT, REIN, PASV, STOU, APPE, ALLO, REST, RNFR, RNTO, ABOR, DELE, RMD, MKD, PWD, LIST, NLST, SITE, SYST, STAT, and HELP are not required. However, implementation of these commands is highly recommended.

All servers must support page files. An implementation may simply stream the page data.

The default values for transfer parameters are:

  • TYPE - ASCII Non-print
  • MODE - Stream
  • STRU - File

All hosts must accept the above as the standard defaults.