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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Possible downref: Non-RFC (?) normative reference: ref. 'FIPS-180-3' -- Obsolete informational reference (is this intentional?): RFC 3230 (Obsoleted by RFC 9530) Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Bryan 3 Internet-Draft T. Kosse 4 Intended status: Standards Track D. Stenberg 5 Expires: January 10, 2011 July 9, 2010 7 File Transfer Protocol HASH Command for Cryptographic Hashes 8 draft-bryan-ftp-hash-06 10 Abstract 12 The File Transfer Protocol does not offer any method to verify the 13 integrity of a transferred file, nor can two files be compared 14 against each other without actually transferring them first. 15 Cryptographic hashes are a possible solution to this problem. In the 16 past, several attempts have been made to add commands to obtain 17 checksums and hashes, however none have been formally specified, 18 leading to non-interoperability and confusion. To solve these 19 issues, this document specifies a new FTP command to be used by 20 clients to request cryptographic hashes of files. 22 Status of this Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on January 10, 2011. 39 Copyright Notice 41 Copyright (c) 2010 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 57 1.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 3 58 2. Document Conventions . . . . . . . . . . . . . . . . . . . . . 3 59 2.1. Basic Tokens . . . . . . . . . . . . . . . . . . . . . . . 4 60 2.2. Server Replies . . . . . . . . . . . . . . . . . . . . . . 4 61 3. The HASH Command (HASH) . . . . . . . . . . . . . . . . . . . 5 62 3.1. FEAT Command Response for HASH Command . . . . . . . . . . 6 63 3.2. OPTS Parameters for HASH . . . . . . . . . . . . . . . . . 6 64 3.3. User-PI usage of HASH . . . . . . . . . . . . . . . . . . 7 65 3.4. HASH Command Errors . . . . . . . . . . . . . . . . . . . 8 66 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 67 5. Implementation Requirements . . . . . . . . . . . . . . . . . 9 68 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 69 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 70 7.1. Normative References . . . . . . . . . . . . . . . . . . . 10 71 7.2. Informative References . . . . . . . . . . . . . . . . . . 10 72 Appendix A. Acknowledgements and Contributors . . . . . . . . . . 11 73 Appendix B. List of Non-standard Cryptographic Hash or 74 Checksum Commands and Implementations . . . . . . . . 11 75 Appendix C. Document History . . . . . . . . . . . . . . . . . . 13 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 78 1. Introduction 80 The File Transfer Protocol [RFC0959] does not offer any method to 81 verify the integrity of a transferred file, nor can two files be 82 compared against each other without actually transferring them first. 83 Cryptographic hashes are a possible solution to this problem. In the 84 past, several attempts have been made to add commands to obtain 85 checksums and hashes, however none have been formally specified, 86 leading to non-interoperability and confusion. (See Appendix B for 87 more information). To solve these issues, this document specifies a 88 new FTP command to be used by clients to request cryptographic hashes 89 of files. HTTP has a similar feature named Instance Digests 90 [RFC3230] which allows a client to request the cryptographic hash of 91 a file. 93 [[ Discussion of this draft should take place on ftpext@ietf.org (or 94 apps-discuss@ietf.org if necessary). ]] 96 1.1. Example 98 Example of HASH client request: 100 C> HASH filename.ext 102 HASH server response with Positive Completion code and the requested 103 hash using the currently selected algorithm: 105 S> 213 SHA-1 80bc95fd391772fa61c91ed68567f0980bb45fd9 filename.ext 107 2. Document Conventions 109 This specification describes conformance of File Transfer Protocol 110 Extension for cryptographic hashes. 112 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 113 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 114 document are to be interpreted as described in BCP 14, [RFC2119], as 115 scoped to those conformance targets. 117 This document also uses notation defined in STD 9, [RFC0959]. In 118 particular, the terms or commands "reply", "user", "file", "FTP 119 commands", "user-PI" (user protocol interpreter), "server-FTP 120 process", "server-PI", "mode", "type", "STOR", "RETR", and "ASCII", 121 are all used here as defined there. The term "pathname" is used as 122 defined in Section 2.2 of [RFC3659]. 124 In the examples of FTP dialogs presented in this document, lines that 125 begin "C> " were sent over the control connection from the user-PI to 126 the server-PI, and lines that begin "S> " were sent over the control 127 connection from the server-PI to the user-PI. In all cases, the 128 prefixes shown above, including the one space, have been added for 129 the purposes of this document, and are not a part of the data 130 exchanged between client and server. 132 Syntax required is defined using the Augmented BNF defined in 133 [RFC5234]. 135 2.1. Basic Tokens 137 This document imports the core definitions given in Appendix B of 138 [RFC5234]. There definitions will be found for basic ABNF elements 139 like ALPHA, DIGIT, SP, etc. To that, the following term is added for 140 use in this document. 142 TCHAR = VCHAR / SP / HTAB ; visible plus white space 144 The VCHAR (from [RFC5234]) and TCHAR rules give basic character types 145 from varying sub-sets of the ASCII character set for use in various 146 commands and responses. 148 Note that in ABNF, string literals are case insensitive. That 149 convention is preserved in this document, and implies that FTP 150 commands and parameters that are added by this specification have 151 values that can be represented in any case. That is, "HASH" is the 152 same as "hash", "Hash", "HaSh", etc., and "ftp.example.com" is the 153 same as "Ftp.Example.Com", "fTp.eXample.cOm", etc. 155 2.2. Server Replies 157 Section 4.2 of [RFC0959] defines the format and meaning of replies by 158 the server-PI to FTP commands from the user-PI. Those reply 159 conventions are used here without change. 161 error-response = error-code SP *TCHAR CRLF 162 error-code = ("4" / "5") 2DIGIT 164 Implementers should note that the ABNF syntax (which was not used in 165 [RFC0959]) used in this document, and other FTP related documents, 166 sometimes shows replies using the one line format. Unless otherwise 167 explicitly stated, that is not intended to imply that multi-line 168 responses are not permitted. Implementers should assume that, unless 169 stated to the contrary, any reply to any FTP command (including QUIT) 170 can be of the multi-line format described in [RFC0959]. 172 Throughout this document, replies will be identified by the three 173 digit code that is their first element. Thus the term "500 reply" 174 means a reply from the server-PI using the three digit code "500". 176 3. The HASH Command (HASH) 178 A new command "HASH" is added to the FTP command set to allow the 179 client to request the cryptographic hash of a file from a server-FTP 180 process. 182 The syntax for the HASH command is: 184 hash-command = "HASH" SP 186 As with all FTP commands, the "HASH" command word is case 187 independent, and MAY be specified in any character case desired. 189 The HASH command keyword MUST be followed by a single space (ASCII 190 32) followed by the pathname. 192 The pathname argument should reference the same file as other file 193 based commands such as STOR or RETR which the same argument would 194 reference. The pathname argument MUST represent a file path, not a 195 directory path. 197 The text returned in response to the HASH command MUST be: 199 hash-response = hash-ok / error-response 200 hash-ok = "213" SP hashname SP 1*HEXDIGIT SP CRLF 202 All hash values MUST be encoded in lowercase hexadecimal format. 204 The HASH command uses the currently selected hash algorithm. The 205 currently selected hash algorithm can be determined with FEAT or OPTS 206 HASH, and changed with OPTS HASH. 208 The HASH command is meant to be used for files transmitted in Image 209 type mode (TYPE I) and Stream transfer mode (MODE S). The returned 210 hash MUST be calculated as if a client were to download the full file 211 using TYPE I and MODE S and were to calculate the hash on the 212 received octet data. In other words, if a client were to download a 213 full file using TYPE I and MODE S and were to calculate the hash on 214 the received octet data, it would be identical to the hash returned 215 by HASH. 217 3.1. FEAT Command Response for HASH Command 219 When replying to the FEAT command [RFC2389], a server-FTP process 220 that supports the HASH command MUST include a feature line indicating 221 that the HASH command is supported, along with a list of all 222 supported hash algorithms in a semicolon separated list. The hash 223 algorithm that is currently selected MUST be marked with an asterisk. 224 The order of hash algorithms is insignificant. This command word is 225 case insensitive, and MAY be sent in any mixture of upper or lower 226 case, however it SHOULD be sent in upper case. That is, the response 227 SHOULD be: 229 C> FEAT 230 S> 211-Extensions supported: 231 S> ... 232 S> HASH SHA-256;SHA-512;SHA-1*;MD5 233 S> ... 234 S> 211 END 236 The ellipses indicate place holders where other features may be 237 included, and are not required. The one-space indentation of the 238 feature lines is mandatory [RFC2389]. 240 The IANA registry named "Hash Function Textual Names" defines values 241 for hash algorithms. Hash names should be presented in uppercase, 242 but comparisons should be case-insensitive, e.g. MD5, md5, Md5 are 243 all the same. 245 hash-feat = SP "HASH" SP hashlist CRLF 246 hashlist = 1*( hashname ["*"] ";" ) 247 hashname = 1*( hchar ) 248 hchar = ALPHA / DIGIT / "-" / "_" / "/" / "." / "," 250 3.2. OPTS Parameters for HASH 252 To query the current hash algorithm and to change it, the OPTS 253 command as defined in [RFC2389] is used with HASH as the first 254 argument. 256 If no second argument is passed, OPTS HASH simply returns the 257 currently selected hash algorithm. 259 C> OPTS HASH 260 S> 200 SHA-1 262 To change the algorithm, a valid hash algorithm MUST be given as 263 second argument. A list of valid hash algorithms is available via 264 the FEAT command. If the command is successful, all future calls to 265 HASH until the next successful OPTS HASH command or until the session 266 is reinitialized (REIN) will use the selected hash algorithm. 268 C> OPTS HASH SHA-512 269 S> 200 SHA-512 271 Requesting unknown or unsupported algorithms produces an error 272 response. 274 C> OPTS HASH CRC-37 275 S> 501 Unknown algorithm, current selection not changed 277 The syntax for OPTS HASH: 279 hashopts-cmd = "OPTS HASH" [ SP hashname ] CRLF 280 hashopts-response = hashopts-ok / error-response 281 hashopts-ok = "200" SP hashname CRLF 283 3.3. User-PI usage of HASH 285 The user-PI issues the FEAT command to query the server-PI about 286 which algorithm is currently selected. This also reveals the other 287 algorithms that the server supports. In this example, the SHA-1 288 algorithm is currently selected. 290 C> FEAT 291 S> 211-Extensions supported: 292 S> ... 293 S> HASH SHA-256;SHA-512;SHA-1*;MD5 294 S> ... 295 S> 211 END 297 OPTS HASH is an alternative method for the user-PI to query the 298 server-PI about which algorithm is currently selected. 300 C> OPTS HASH 301 S> 200 SHA-1 303 In this example, we wish to select SHA-256, a different algorithm. 305 C> OPTS HASH SHA-256 306 S> 200 SHA-256 308 The user-PI requests the cryptographic hash of a file with HASH 309 command. Server-PI replies with cryptographic hash of file. 311 C> HASH filename.ext 312 S> 213 SHA-256 f0ad929cd259957e160ea442eb80986b5f... filename.ext 314 Client downloads file. Client hashes the downloaded file and 315 compares its hash to the hash obtained from the server. The HASH 316 command could also be used to verify that an uploaded file has the 317 same hash as the local file. 319 3.4. HASH Command Errors 321 The server-PI SHOULD reply with a 500 reply if the HASH command is 322 unrecognized or unimplemented. 324 The server-PI SHOULD reply with a 501 reply to the OPTS HASH command 325 if the user-PI has requested an unknown or unsupported algorithm. 327 The server-PI SHOULD reply with a 550 reply if the HASH command is 328 used on a file that can not be found. 330 The server-PI SHOULD reply with a 551 reply if the server-PI can not 331 calculate the hash of a file because it is unable to deliver the file 332 with TYPE I and MODE S. 334 The server-PI SHOULD reply with a 552 reply if the user is not 335 allowed to use the HASH command. 337 The server-PI SHOULD reply with a 450 reply if the server is busy, 338 e.g. already hashing other files yet inviting the client to retry in 339 the future. 341 4. IANA Considerations 343 This new command is added to the "FTP Commands and Extensions" 344 registry created by [RFC5797]. 346 Command Name: HASH 348 Description: Cryptographic Hash of a file 350 FEAT String: HASH 352 Command Type: Service execution 354 Conformance Requirements: Optional 356 Reference: This specification 358 5. Implementation Requirements 360 All conforming implementations MUST at least support the SHA-1 361 algorithm [FIPS-180-3]. Implementations SHOULD NOT make any 362 algorithm the default that is known to be weaker than SHA-1. Support 363 for any additional algorithms is OPTIONAL. 365 6. Security Considerations 367 The server MUST only allow the HASH command to be processable for 368 files which the logged in user has a right to access. 370 Implementing the HASH command may impose a considerable load on the 371 server, which could lead to denial-of-service attacks. Servers have, 372 however, implemented this for many years, without significant 373 reported difficulties. On an affected server a malicious user could, 374 for example, continuously send HASH commands over multiple 375 connections and thus consume most of the FTP server's resources, 376 leaving little room for other operations. To mitigate this risk, a 377 server MAY cache the calculated hashes so that the hash of a file is 378 only calculated once even if multiple hash requests are sent for that 379 file, provided it updates or invalidates the cached hash when the 380 content of the corresponding file changes. A server may refuse to 381 process a HASH command for many reasons, one of which may be a 382 suspected denial-of-service attack. A client MUST be able to 383 understand that refusal to process HASH commands may be transient (if 384 indicated by a 4xy response) and MAY be honoured later if the server 385 so decides. A client MUST allow that a HASH command might take a 386 reasonably long time to complete. 388 In addition, the HASH command can be used to draw conclusions about 389 the contents of a file. If the hash of a file on some server matches 390 the hash of some known file, then both files are likely identical. 391 By uploading a file, running HASH against it and running HASH against 392 another file location, the client could infer some filesystem 393 deployment information (e.g. that there is a logical link between a 394 pair of directories in the tree). This is probably not an issue if 395 the user has access to both branches of the directory tree, there is 396 the possibility that this information is exposable. To prevent this 397 scenario it suffices to limit use of the HASH command to users who 398 would already be able to download the file. 400 This mechanism simply allows the FTP protocol to expose HASH values 401 of files, using the currently chosen mechanism, accessible to the 402 server by the client. The suitability or otherwise of a specific 403 hash algorithm for a specific purpose is an implementation decision. 405 7. References 407 7.1. Normative References 409 [FIPS-180-3] 410 National Institute of Standards and Technology (NIST), 411 "Secure Hash Standard (SHS)", FIPS PUB 180-3, 412 October 2008. 414 [RFC0959] Postel, J. and J. Reynolds, "File Transfer Protocol", 415 STD 9, RFC 0959, October 1985. 417 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 418 Requirement Levels", BCP 14, RFC 2119, March 1997. 420 [RFC2389] Hethmon, P. and R. Elz, "Feature negotiation mechanism for 421 the File Transfer Protocol", RFC 2389, August 1998. 423 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 424 Specifications: ABNF", STD 68, RFC 5234, January 2008. 426 7.2. Informative References 428 [RFC3230] Mogul, J. and A. Van Hoff, "Instance Digests in HTTP", 429 RFC 3230, January 2002. 431 [RFC3659] Hethmon, P., "Extensions to FTP", RFC 3659, March 2007. 433 [RFC5797] Klensin, J. and A. Hoenes, "FTP Command and Extension 434 Registry", RFC 5797, March 2010. 436 [draft-twine-ftpmd5] 437 Twine, J., "The MD5 and MMD5 FTP Command Extensions", 438 draft-twine-ftpmd5-00 (work in progress), May 2002. 440 Appendix A. Acknowledgements and Contributors 442 Thanks to John C. Klensin, Alfred Hoenes, James Twine, Robert 443 McMurray, Mathias Berchtold, Tatsuhiro Tsujikawa, and Paul Ford- 444 Hutchinson. 446 Portions of [RFC3659] were wholly reused in this document. 448 Appendix B. List of Non-standard Cryptographic Hash or Checksum 449 Commands and Implementations 451 [[ to be removed by the RFC editor before publication as an RFC. ]] 453 A number of similar checksum or hash commands exist, but are not 454 formally specified, leading to non-interoperability and confusion. 455 The commands, any specifications, and relevant details: 457 o CKSM: GridFTP v2 Protocol Description 458 http://www.ogf.org/documents/GFD.47.pdf Usage: OPTS CKSM 459 CRLF. Supports ADLER32, MD5, CRC32. 460 o MD5/MMD5: Expired Internet Draft [draft-twine-ftpmd5] from 2002. 461 Usage: MD5 Algorithm specific command. Response codes: 462 251 positive completion, 500 Command Not Recognized, 502 Command 463 Not Implemented, 504 Command Not Implemented for the Specified 464 Argument. 465 o SITE CHECKSUM: Usage: SITE check_login SP CHECKSUM SP pathname 466 CRLF. Supports CRC32 and MD5. 467 o SITE SHOHASH: Usage: site shohash [filename]. Supports MD5. 468 Response codes: 200 positive completion. 469 o XCRC: By GlobalSCAPE in 2001. http://help.globalscape.com/help/ 470 secureserver2/File_Integrity_Checking.htm Usage: XCRC 471 SP EP. SP is starting point and EP is ending point in bytes and 472 are optional parameters. Algorithm specific command. Response 473 codes: 250 positive completion, 450 Requested file action not 474 taken. (File is busy), 550 Requested action not taken. (File not 475 found, no read permission, SP or EP not correct). 476 o XMD5: XMD5 SP EP. Similar to XCRC. Algorithm specific 477 command. 478 o XSHA, XSHA1, XSHA256, XSHA512: Usage similar to XCRC, although 479 SP/EP usage unknown. Algorithm specific commands. 481 An incomplete list of FTP clients and servers that have implemented 482 these commands: 484 o Akamai NetStorage (supports SITE CHKHSH/SITE SHOHASH) p17-18 485 http://pigdogslow.dyndns.org/NetStorage_UserGuide.pdf 487 o Apache Ftp Server (supports MD5/MMD5 from draft-twine-ftpmd5) 488 http://cwiki.apache.org/FTPSERVER/documentation.html 489 o Backup4all Pro (supports XCRC) 490 o Backup to FTP (supports XCRC) 491 o BlackMoon FTP Server (supports XCRC) 492 http://www.blackmoonftpserver.com/portal/readmore/features.html 493 o C.P.A. Secure (supports XCRC) 494 http://www.cpasecure.com/CPASecureVsSecureFTP.html 495 o Cerberus FTP server (supports XCRC, XMD5, XSHA1, XSHA256, XSHA512) 496 http://www.softpedia.com/progChangelog/ 497 Cerberus-FTP-Server-Changelog-1904.html 498 o Core FTP Pro (supports XCRC) 499 o Cross FTP Server (supports MD5/MMD5) 500 o FileCOPA FTP Server (supports XCRC, XMD5, XSHA1) 501 http://www.filecopa-ftpserver.com/features.html 502 o File Watchdogs FTP Server (supports XCRC, XMD5, XSHA1, XSHA256, 503 XSHA512) 504 http://www.filewatchdogs.com/ftpsitehosting/help/15559.htm 505 o FireFTP (supports XMD5, XSHA1) 506 http://fireftp.mozdev.org/features.html 507 o FTP Daemon (supports SITE CHECKMETHOD/SITE CHECKSUM) 508 http://www.pro-bono-publico.de/projects/ftpd.html 509 o FTP Voyager (supports XCRC) http://www.ftpvoyager.com/XCRC.asp 510 o Gene6 FTP Server 511 http://www.g6ftpserver.com/en/information#features 512 o GlobalSCAPE's Secure FTP Server / EFT Server / CuteFTP clients 513 (supports XCRC) 514 o Globus FTP client / Globus Toolkit(supports CKSM) http:// 515 www.globus.org/toolkit/releasenotes/3.2.0/gridftp_notes.html 516 o GoldenGate FTP (Ftp Full Java Server) (supports XCRC, XMD5, XSHA1) 517 o IceWarp FTP Server http://www.icewarp.com/products/ftp_server/ 518 o ICS FTP client (supports XCRC, XMD5) 519 http://www.magsys.co.uk/delphi/magics.asp 520 o ioFTPD (supports XCRC) 521 o JAFS (supports XCRC and MD5) 522 http://www.sbbi.net/site/jafs/features.html 523 o Kellerman FTP (supports XCRC) 524 http://sharptoolbox.com/tools/kellerman-ftp 525 o Limagito FTP server (supports XCRC, XMD5, XSHA1) 526 http://www.limagito.com/file-mover-features.html 527 o MOVEit DMZ (supports XSHA1) 528 o Nofeel FTP server (supports XCRC, XMD5, XSHA1) 529 http://www.nftpserver.com/history.php 530 o Null FTP (supports XCRC, XMD5, XSHA) 531 http://www.sharewareconnection.com/null-ftp-client-pro.htm 532 o Orenosv FTP Client (supports XCRC, XMD5) 533 http://www.orenosv.com/orenosv/ftpcli_en.html 535 o ProFTPD module mod_digest (supports XCRC, XMD5, XSHA1, SHA256) 536 http://www.smartftp.com/oss/proftpd/mod_digest.html 537 o PSFTPd Secure FTP Server (supports XCRC, XMD5, XSHA) 538 http://www.psftp.de/psftpd_fo.php 539 o Quick 'n Easy FTP Server (supports XCRC) http:// 540 www.pablosoftwaresolutions.com/html/ 541 quick__n_easy_ftp_server_pro.html 542 o RaidenFTPD32 FTP server (supports XCRC, XMD5) 543 o Robo-FTP Server (supports XCRC, XMD5, XSHA1) 544 http://kb.robo-ftp.com/change_log/show/61 545 o SyncBackPro and SyncBackSE (supports XCRC) 546 http://www.2brightsparks.com/syncback/sbpro-changes.html 547 o Secure FTP Factory (supports XCRC) 548 o Serv-U FTP Server (supports XCRC) http://www.serv-u.com/help/ 549 serv_u_help/additional_ftp_commands_supported_by_serv_u.htm 550 o SmartFTP client (supports XCRC, XMD5, XSHA, CKSM) 551 http://www.smartftp.com/features/ 552 o Starksoft Ftp Component for .NET / Mono (supports XCRC, XMD5, 553 XSHA1) http://www.starksoft.com/prod_ftp.html 554 o Titan FTP Server (supports XCRC) 555 o Turbo FTP (supports XCRC) 556 o WISE-FTP (supports XCRC) http://www.wise-ftp.com/news/ 557 o WS_FTP client / server (supports XSHA1, server also XMD5, XSHA1, 558 XSHA256, XSHA512) http://ipswitchft.custhelp.com/app/answers/ 559 detail/a_id/671/kw/xmd5/r_id/166/sno/1 560 o wuftpd (supports SITE CHECKMETHOD/SITE CHECKSUM) 561 o wzdFTPd (supports XCRC, XMD5) 562 http://www.wzdftpd.net/wiki/index.php/Commands 563 o Zalman FTP Client (supports XCRC) 564 http://www.zalmansoftware.com/download.html 565 o zFTPServer 567 Appendix C. Document History 569 [[ to be removed by the RFC editor before publication as an RFC. ]] 571 Known issues concerning this draft: 572 o Should HASH support partial file hashes, similar to the Content- 573 MD5 HTTP Header. 574 o Section needs improvement: which files should a server process a 575 HASH command for a logged in user? 576 o What should happen if somebody attempts to HASH something that 577 isn't a file (e.g. it's a directory)? 579 -06 : July, 2010. 581 o Change server reply format. 583 -05 : June 29, 2010. 584 o Add Basic Tokens and Server Replies subsections from RFC 3659. 586 -04 : June 11, 2010. 587 o User-PI usage and command errors sections updated. 589 -03 : May 21, 2010. 590 o List of non-standard checksum and hash commands and their 591 implementations. 593 -02 : April 16, 2010. 594 o Error codes section. 596 -01 : April 7, 2010. 597 o Changing HASH algorithm with OPTS. 598 o Reference RFC 5797 and add IANA Considerations section. 599 o Informative Reference to expired Internet Draft 600 (draft-twine-ftpmd5) which attempted to address this issue (it 601 only supported one hash, MD5). 603 -00 : October 19, 2009. 604 o Initial draft. 606 Authors' Addresses 608 Anthony Bryan 609 Pompano Beach, FL 610 USA 612 Email: anthonybryan@gmail.com 613 URI: http://www.metalinker.org 615 Tim Kosse 617 Email: tim.kosse@filezilla-project.org 618 URI: http://filezilla-project.org/ 620 Daniel Stenberg 622 Email: daniel@haxx.se 623 URI: http://www.haxx.se/