TFTP Option Negotiation Analysis (RFC1785)

IP.com Disclosure Number: IPCOM000004038D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2000-Sep-13

Document File: 2 page(s) / 3K

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Internet Society Requests For Comment (RFCs)

Related People

G. Malkin: AUTHOR [+1][-]

Abstract

The TFTP option negotiation mechanism, proposed in [1], is a backward-compatible extension to the TFTP protocol, defined in [2]. It allows file transfer options to be negotiated prior to the transfer using a mechanism which is consistent with TFTP's Request Packet format. The mechanism is kept simple by enforcing a request- respond-acknowledge sequence, similar to the lock-step approach taken by TFTP itself.

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United States

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English (United States)

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Network Working Group G. Malkin

Request for Comments: 1785 Xylogics, Inc.

Updates: 1350 A. Harkin

Category: Informational Hewlett Packard Co.

March 1995

TFTP Option Negotiation Analysis

Status of this Memo

This memo provides information for the Internet community. This memo

does not specify an Internet standard of any kind. Distribution of

this memo is unlimited.

Abstract

The TFTP option negotiation mechanism, proposed in [1], is a

backward-compatible extension to the TFTP protocol, defined in [2].

It allows file transfer options to be negotiated prior to the

transfer using a mechanism which is consistent with TFTP's Request

Packet format. The mechanism is kept simple by enforcing a request-

respond-acknowledge sequence, similar to the lock-step approach taken

by TFTP itself.

This document was written to allay concerns that the presence of

options in a TFTP Request packet might cause pathological behavior on

servers which do not support TFTP option negotiation.

Test Results

A TFTP client, modified to send TFTP options, was tested against five

unmodified servers:

DEC DEC 3000/400 alpha OSF1 V3.0

SGI IP17 mips IRIX 5.2

SUN sun4c sparc SunOS 5.1

IBM RS/6000 Model 320 AIX 3.4

SUN sun4m SunOS 4.1.3

In each case, the servers ignored the option information in the

Request packet and the transfer proceeded as though no option

negotiation had been attempted. In addition, the standard BSD4.3

source for TFTPD, the starting point for many implementations, was

examined. The code clearly ignores any extraneous information in

Request packets.

From these results and examinations, it is clear that the TFTP option

negotiation mechanism is fully backward-compatible with unmodified

TFTP servers.

Security Considerations

Security issues are not discussed in this memo.

References

[1] Malkin, G., and A. Harkin, "TFTP Option Extension", RFC 1782,

Xylogics, Inc., Hewlett Packard Co., March 1995.

[2] Sollins, K., "The TFTP Protocol (Revision 2)", STD 33, RFC 1350,

MIT, July 1992.