FTP Operation Over Big Address Records (FOOBAR)
RFC 1545
Document | Type |
RFC - Experimental
(November 1993; No errata)
Obsoleted by RFC 1639
Was draft-piscitello-ftp-bigports (individual)
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Author | David Piscitello | ||
Last updated | 2013-03-02 | ||
Stream | Legacy | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 1545 (Experimental) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group D. Piscitello Request for Comments: 1545 Bellcore Category: Experimental November 1993 FTP Operation Over Big Address Records (FOOBAR) Status of this Memo This memo defines an Experimental Protocol for the Internet community. This memo does not specify an Internet standard of any kind. Discussion and suggestions for improvement are requested. Distribution of this memo is unlimited. Abstract This paper describes a convention for specifying longer addresses in the PORT command. Introduction This RFC specifies a method for assigning long addresses in the HOST-PORT specification for the data port to be used in establishing a data connection for File Transfer Protocol, FTP (STD 9, RFC 959). This is a general solution, applicable for all "next generation" IP alternatives, and can also be extended to allow FTP operation over transport interfaces other than TCP. Acknowledgments Many thanks to all the folks in the IETF who casually mentioned how to do this, but who left it to me to write this RFC. Special thanks to Rich Colella, Bob Ullmann, Shawn Ostermann, Steve Lunt, and Brian Carpenter who had the time and decency to comment on the initial draft. :-) 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 <SP> <host-port> <CRLF> The <host-port> argument is the concatenation of a 32-bit internet <host-address> and a 16-bit TCP <port-address>. This address information is broken into 8-bit fields and the value of each field is transmitted as a decimal number (in character string Piscitello [Page 1] RFC 1545 FTP Over Big Address November 1993 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. To accommodate larger network addresses anticipated for all IP "next generation" alternatives, new commands and reply codes are needed for FTP. This memo addresses these needs. 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 <SP> <long-host-port> <CRLF> The <long-host-port> argument is the concatenation of the following fields; o an 8-bit <address-family> argument (af) o an 8-bit <host-address-length> argument (hal) o a <host-address> of <host-address-length> (h1, h2, ...) o an 8-bit <port-address-length> (pal) o a <port-address> of <port-address-length> (p1, p2, ...) The <address-family> argument takes the value of the version number of IP (see Assigned Numbers, STD 2, RFC 1340), or generally speaking, an Internet layer protocol. Relevant assigned IPng version numbers are: Decimal Keyword ------ ------- 0 reserved 1-3 unassigned 4 Internet Protocol (IP) 5 ST Datagram Mode 6 SIP 7 TP/IX 8 PIP 9 TUBA 10-14 unassigned 15 reserved Piscitello [Page 2] 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...)Show full document text