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FTP Extensions for IPv6 and NATs (RFC2428) Disclosure Number: IPCOM000003005D
Original Publication Date: 1998-Sep-01
Included in the Prior Art Database: 2019-Feb-11
Document File: 8 page(s) / 11K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

M. Allman: AUTHOR [+2]

Related Documents

10.17487/RFC2428: DOI


This paper specifies extensions to FTP that will allow the protocol to work over IPv4 and IPv6. [STANDARDS-TRACK]

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 23% of the total text.

Network Working Group M. Allman Request for Comments: 2428 NASA Lewis/Sterling Software Category: Standards Track S. Ostermann Ohio University C. Metz The Inner Net September 1998

FTP Extensions for IPv6 and NATs

Status of this Memo

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (1998). All Rights Reserved.


The specification for the File Transfer Protocol assumes that the underlying network protocol uses a 32-bit network address (specifically IP version 4). With the deployment of version 6 of the Internet Protocol, network addresses will no longer be 32-bits. This paper specifies extensions to FTP that will allow the protocol to work over IPv4 and IPv6. In addition, the framework defined can support additional network protocols in the future.

1. Introduction

The keywords, such as MUST and SHOULD, found in this document are used as defined in RFC 2119 [Bra97].

The File Transfer Protocol [PR85] only provides the ability to communicate information about IPv4 data connections. FTP assumes network addresses will be 32 bits in length. However, with the deployment of version 6 of the Internet Protocol [DH96] addresses will no longer be 32 bits long. RFC 1639 [Pis94] specifies extensions to FTP to enable its use over various network protocols. Unfortunately, the mechanism can fail in a multi-protocol environment. During the transition between IPv4 and IPv6, FTP needs the ability to negotiate the network protocol that will be used for data transfer.

Allman, et. al. Standards Track [Page 1]

RFC 2428 FTP Extensions for IPv6 and NATs September 1998

This document provides a specification for a way that FTP can communicate data connection endpoint information for network protocols other than IPv4. In this specification, the FTP commands PORT and PASV are replaced with EPRT and EPSV, respectively. This document is organized as follows. Section 2 outlines the EPRT command and Section 3 outlines the EPSV command. Section 4 defines the utilization of these two new FTP commands. Section 5 briefly presents security considerations. Finally, Section 6 provides conclusions.

2. The EPRT Command

The EPRT command allows for the specification of an extended address for the data connection. The extended address MUST consist of the network protocol as well as the network and transport addresses. The format of EPRT is:


The EPRT command keyword MUST be followed by a single space (ASCII 32). Following the space, a delimiter character (<d>) MUST be specified. The delimiter character MUST be one of the ASCII characters in range 33-126 inclusive. The character "|" (ASCII 124) is re...