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Network Working Group                                          G. MalkinRequest for Commments: 2349                                 Bay NetworksUpdates:1350                                                  A. HarkinObsoletes:1784                                      Hewlett Packard Co.Category: Standards Track                                       May 1998TFTP Timeout Interval and Transfer Size OptionsStatus 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.Abstract   The Trivial File Transfer Protocol [1] is a simple, lock-step, file   transfer protocol which allows a client to get or put a file onto a   remote host.   This document describes two TFTP options. The first allows the client   and server to negotiate the Timeout Interval.  The second allows the   side receiving the file to determine the ultimate size of the   transfer before it begins.  The TFTP Option Extension mechanism is   described in [2].Timeout Interval Option Specification   The TFTP Read Request or Write Request packet is modified to include   the timeout option as follows:      +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+      |  opc  |filename| 0 |  mode  | 0 | timeout| 0 |  #secs | 0 |      +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+      opc         The opcode field contains either a 1, for Read Requests, or 2,         for Write Requests, as defined in [1].Malkin & Harkin             Standards Track                     [Page 1]

RFC 2349    TFTP Timeout Interval and Transfer Size Options     May 1998      filename         The name of the file to be read or written, as defined in [1].         This is a NULL-terminated field.      mode         The mode of the file transfer: "netascii", "octet", or "mail",         as defined in [1].  This is a NULL-terminated field.      timeout         The Timeout Interval option, "timeout" (case in-sensitive).         This is a NULL-terminated field.      #secs         The number of seconds to wait before retransmitting, specified         in ASCII.  Valid values range between "1" and "255" seconds,         inclusive.  This is a NULL-terminated field.   For example:      +-------+--------+---+--------+---+--------+---+-------+---+      |   1   | foobar | 0 | octet  | 0 | timeout| 0 |   1   | 0 |      +-------+--------+---+--------+---+--------+---+-------+---+   is a Read Request, for the file named "foobar", in octet (binary)   transfer mode, with a timeout interval of 1 second.   If the server is willing to accept the timeout option, it sends an   Option Acknowledgment (OACK) to the client.  The specified timeout   value must match the value specified by the client.Transfer Size Option Specification   The TFTP Read Request or Write Request packet is modified to include   the tsize option as follows:      +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+      |  opc  |filename| 0 |  mode  | 0 | tsize  | 0 |  size  | 0 |      +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+      opc         The opcode field contains either a 1, for Read Requests, or 2,         for Write Requests, as defined in [1].      filename         The name of the file to be read or written, as defined in [1].         This is a NULL-terminated field.Malkin & Harkin             Standards Track                     [Page 2]

RFC 2349    TFTP Timeout Interval and Transfer Size Options     May 1998      mode         The mode of the file transfer: "netascii", "octet", or "mail",         as defined in [1].  This is a NULL-terminated field.      tsize         The Transfer Size option, "tsize" (case in-sensitive).  This is         a NULL-terminated field.      size         The size of the file to be transfered.  This is a NULL-         terminated field.   For example:      +-------+--------+---+--------+---+--------+---+--------+---+      |   2   | foobar | 0 | octet  | 0 | tsize  | 0 | 673312 | 0 |      +-------+--------+---+--------+---+--------+---+--------+---+   is a Write Request, with the 673312-octet file named "foobar", in   octet (binary) transfer mode.   In Read Request packets, a size of "0" is specified in the request   and the size of the file, in octets, is returned in the OACK.  If the   file is too large for the client to handle, it may abort the transfer   with an Error packet (error code 3).  In Write Request packets, the   size of the file, in octets, is specified in the request and echoed   back in the OACK.  If the file is too large for the server to handle,   it may abort the transfer with an Error packet (error code 3).Security Considerations   The basic TFTP protocol has no security mechanism.  This is why it   has no rename, delete, or file overwrite capabilities.  This document   does not add any security to TFTP; however, the specified extensions   do not add any additional security risks.References   [1] Sollins, K., "The TFTP Protocol (Revision 2)", STD 33,RFC 1350,       October 92.   [2] Malkin, G., and A. Harkin, "TFTP Option Extension",RFC 2347,       May 1998.Malkin & Harkin             Standards Track                     [Page 3]

RFC 2349    TFTP Timeout Interval and Transfer Size Options     May 1998Authors' Addresses   Gary Scott Malkin   Bay Networks   8 Federal Street   Billerica, MA  01821   Phone:  (978) 916-4237   EMail:  gmalkin@baynetworks.com   Art Harkin   Internet Services Project   Information Networks Division   19420 Homestead Road MS 43LN   Cupertino, CA  95014   Phone: (408) 447-3755   EMail: ash@cup.hp.comMalkin & Harkin             Standards Track                     [Page 4]

RFC 2349    TFTP Timeout Interval and Transfer Size Options     May 1998Full Copyright Statement   Copyright (C) The Internet Society (1998).  All Rights Reserved.   This document and translations of it may be copied and furnished to   others, and derivative works that comment on or otherwise explain it   or assist in its implementation may be prepared, copied, published   and distributed, in whole or in part, without restriction of any   kind, provided that the above copyright notice and this paragraph are   included on all such copies and derivative works.  However, this   document itself may not be modified in any way, such as by removing   the copyright notice or references to the Internet Society or other   Internet organizations, except as needed for the purpose of   developing Internet standards in which case the procedures for   copyrights defined in the Internet Standards process must be   followed, or as required to translate it into languages other than   English.   The limited permissions granted above are perpetual and will not be   revoked by the Internet Society or its successors or assigns.   This document and the information contained herein is provided on an   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Malkin & Harkin             Standards Track                     [Page 5]