RFC 1545 (rfc1545) - Page 3 of 5

FTP Operation Over Big Address Records (FOOBAR)

RFC 1545                  FTP Over Big Address             November 1993


   The value of each field is broken into 8-bit fields and the value of
   each field is transmitted as an unsigned decimal number (in character
   string representation, note that negative numbers are explicitly not
   permitted).  The fields are separated by commas.

   A LPRT command is thus of the general form

      LPRT af,hal,h1,h2,h3,h4...,pal,p1,p2...

   where h1 is the high order 8 bits of the internet host address, and
   p1 is the high order 8 bits of the port number (transport address).

3.  The LPSV Command

   The L(ONG) PASSIVE command requests the server-DTP to listen on a
   data port other than its default data port and to wait for a
   connection rather than initiate one upon receipt of a transfer
   command.  The response to this command includes the address family,
   host address length indicator, host address, port address length, and
   port address this server is listening on.  The reply code and text
   for entering the passive mode using a long address is 228
   (Interpretation according to FTP is: positive completion reply 2yz,
   connections x2z, passive mode entered using long address xy8).  The
   suggested textual message to accompany this reply code is:

      228 Entering Long Passive Mode (af,hal,h1,h2,h3,h4...,pal,p1,p2...)

4.  Permanent Negative Completion Reply Codes

   The negative completion reply codes that are associated with syntax
   errors in the PORT and PASV commands are appropriate for the LPRT and
   LPSV commands (500, 501).  An additional negative completion reply
   code is needed to distinguish the case where a host supports the LPRT
   or LPSV command, but does not support the address family specified.
   Of the FTP function groupings currently defined for reply codes
   (syntax, information, connections, authentication and accounting, and
   file system), "connections" seems the most logical choice; thus, an
   additional negative command completion reply code, 521 is added, with
   the following suggested textual message:

      521 Supported address families are (af1, af2, ..., afn)

   Where (af1, af2, ..., afn) are the values of the version numbers of
   the "next generation" or other protocol families supported.  IP
   address noted earlier.






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