RFC 1545 (rfc1545) - Page 3 of 5
FTP Operation Over Big Address Records (FOOBAR)
Alternative Format: Original Text Document
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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