RFC 1639 (rfc1639) - Page 2 of 5
FTP Operation Over Big Address Records (FOOBAR)
Alternative Format: Original Text Document
RFC 1639 FTP Over Big Address June 1994
1. Background
The PORT command of File Transfer Protocol allows users to specify an
address other than the default data port for the transport connection
over which data are transferred. The PORT command syntax is:
PORT
The argument is the concatenation of a 32-bit internet
and a 16-bit TCP . This address
information is broken into 8-bit fields and the value of each field
is transmitted as a decimal number (in character string
representation). The fields are separated by commas. A PORT command
is thus of the general form "PORT h1,h2,h3,h4,p1,p2", where h1 is the
high order 8 bits of the internet host address.
The argument is also used by the PASV reply, and in
certain negative completion replies.
To accommodate larger network addresses anticipated for all IP "next
generation" alternatives, and to accommodate FTP operation over
network and transport protocols other than IP, new commands and reply
codes are needed for FTP.
2. The LPRT Command
The LPRT command allows users to specify a "long" address for the
transport connection over which data are transferred. The LPRT
command syntax is:
LPRT
The argument is the concatenation of the following
fields;
o an 8-bit argument (af)
o an 8-bit argument (hal)
o a of (h1, h2, ...)
o an 8-bit (pal)
o a of (p1, p2, ...)
The initial values assigned to the argument take the
value of the version number of IP (see Assigned Numbers, STD 2, RFC
1340); values in the range of 0-15 decimal are thus reserved for IP
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