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.

Abstract

The File Transfer Protocol is, from time to time, extended with new commands, or facilities. Implementations of the FTP protocol cannot be assumed to all immediately implement all newly defined mechanisms. This document provides a mechanism by which clients of the FTP protocol can discover which new features are supported by a particular FTP server.

1. Introduction

This document amends the File Transfer Protocol (FTP) [1]. Two new commands are added: "FEAT" and "OPTS".

These commands allow a client to discover which optional commands a server supports, and how they are supported, and to select among various options that any FTP command may support.

2. Document Conventions

This document makes use of the document conventions defined in BCP14 [2]. That provides the interpretation of some capitalized words like MUST, SHOULD, etc.

Terms defined in [1] will be used here as defined there. These include ASCII, reply, server-FTP process, user-FTP process, server-PI, user-PI, and user.

Syntax required is defined using the Augmented BNF defined in [3]. Some general ABNF definitions are required throughout the document,...