Network Working Group M. Peterson D. Papenthien Internet Draft Rhino Software, Inc. Intended status: Streamlined FTP Command Extensions April 4, 2008 Expires: October 2008 Streamlined FTP Command Extensions draft-peterson-streamlined-ftp-command-extensions-01.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. This document may not be modified, and derivative works of it may not be created, except to publish it as an RFC and to translate it into languages other than English. This document may only be posted in an Internet-Draft. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on October 4, 2008. Copyright Notice Copyright (C) The IETF Trust (2008). Abstract Peterson & Papenthien Expires October 4, 2008 [Page 1] Internet-Draft Streamlined FTP Command Extensions April 2008 This document specifies FTP commands to download thumbnails of remote images, remove entire directory trees, request the amount of storage space available to the user, request the size of a remote directory and its contents, and to specify an FTP host. The commands are designed to reduce the number of server / client exchanges, provide information that was not previously available, and to reduce bandwidth requirements for some higher level operations. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. This document uses previously established definitions for FTP related terms as defined in [RFC959]. In particular, the terms "data connection", "FTP command", "file", "pathname", "reply", "server-FTP process", "user", and "user-FTP process" are used as defined. The terms "server" and "client" are also used in place of "server-FTP process" and "user-FTP process", respectively, for the sake of brevity. The syntax for responses to FTP commands used in this document is explained using Augmented BNF as defined in [RFC5234]. Additional tokens defined in [RFC3659] that extend ABNF are also used, specifically the TCHAR token. In command examples, "C>" and "S>" indicate lines sent by the client and server, respectively. Table of Contents 1. Introduction...................................................3 2. Remove Directory All (RMDA)....................................3 2.1. RMDA Syntax...............................................4 2.2. RMDA Error Responses......................................4 2.3. RMDA FEAT Response........................................4 2.4. RMDA Examples.............................................5 3. Directory Size (DSIZ)..........................................5 3.1. DSIZ Syntax...............................................6 3.2. DSIZ Error Responses......................................7 3.3. DSIZ FEAT Response........................................7 3.4. DSIZ Examples.............................................7 4. Available Octets (AVBL)........................................8 4.1. AVBL Syntax...............................................8 4.2. AVBL Error Responses......................................9 Peterson & Papenthien Expires October 4, 2008 [Page 2] Internet-Draft Streamlined FTP Command Extensions April 2008 4.3. AVBL FEAT Response........................................9 4.4. AVBL Examples.............................................9 5. Change Host (HOST)............................................10 5.1. HOST Syntax..............................................10 5.2. HOST Error Responses.....................................11 5.3. HOST FEAT Response.......................................11 5.4. HOST Examples............................................11 6. Retrieve Thumbnail of Remote Image File (THMB)................12 6.1. THMB Syntax..............................................12 6.2. THMB Error Responses.....................................14 6.3. THMB FEAT Response.......................................14 6.4. THMB Examples............................................14 7. Security Considerations.......................................15 8. IANA Considerations...........................................15 9. Conclusions...................................................15 10. Acknowledgments..............................................16 Authors' Addresses...............................................18 Intellectual Property Statement..................................18 Disclaimer of Validity...........................................19 1. Introduction This document updates the File Transfer Protocol [RFC959]. It adds five new commands: "RMDA", "DSIZ", "AVBL", "HOST", and "THMB". The "HOST" command has been used in various forms for several years while the other four commands are new. These commands have been designed to streamline certain client and server communications, reduce the amount of bandwidth required to perform various operations, and allow a server-FTP process to operate multiple hosts on the same IP address and port combination. 2. Remove Directory All (RMDA) The FTP command REMOVE DIRECTORY ALL (RMDA) removes a directory from the server and all of its contents including all files and subdirectories. The RMDA command is considered analogous to recursively deleting all files and directories contained in a given remote directory (including the directory itself) one at a time. The primary advantage to using this command is the elimination of the additional commands usually required to perform the equivalent action. For directories containing a large number of files and subdirectories, using RMDA eliminates the overhead of querying for subdirectory listings. The end result is a more responsive operation for both the client and server. Peterson & Papenthien Expires October 4, 2008 [Page 3] Internet-Draft Streamlined FTP Command Extensions April 2008 Depending on the content being deleted (files and subdirectories) this can be a very lengthy operation for the server. Servers that implement this command are encouraged to do so in a way that does not block operations for other client connections. 2.1. RMDA Syntax The syntax of the RMDA command is: rmda = "RMDA" SP pathname CRLF All FTP commands, including RMDA, are case insensitive. However, the "pathname" variable provided with the command may be case sensitive as dictated by the server's operating system. The "pathname" specifies a remote directory that should be deleted along with all of its contents. rmda-response = "250" SP *TCHAR CRLF / error-response Responses should be the same as those for the RMD command. If processing fails at any point during the operation, the specified pathname is not to be removed. Any cached information about the pathname is considered invalid when RMDA returns an error. 2.2. RMDA Error Responses The RMDA command can return any error response listed for the RMD command in [RFC959]. The most common of these responses occurs in the event of an error while deleting a file or subdirectory, in which case the server should return a 550 reply. A 550 reply should also be sent if the provided path is a file instead of a directory. In the event that a nested file or subdirectory cannot be deleted for any reason, the parent directories of that file or subdirectory should not be deleted. When the server encounters this situation, it should attempt to delete all other files and subdirectories before stopping or responding to the client. Once the server has attempted to delete all files and subdirectories, the server MUST report failure to the client if even a single file or subdirectory could not be deleted. 2.3. RMDA FEAT Response When replying to the FEAT command, a server-FTP process that supports the RMDA command MUST include a line starting with the word "RMDA". Peterson & Papenthien Expires October 4, 2008 [Page 4] Internet-Draft Streamlined FTP Command Extensions April 2008 If descriptive text is optionally desired, a space MUST immediately follow the "RMDA" word. C> FEAT S> 211- S> ... S> RMDA [ ] S> ... S> 211 End The ellipses indicate placeholders where other features may be included, and are not required. The one space indentation of the feature lines is mandatory per [RFC2389]. 2.4. RMDA Examples This example assumes that the server contains a directory named "A" and that the client has the necessary access to delete "A" and its contents. The client-server exchange for using RMDA to accomplish this would be: C> RMDA A S> 250 RMDA command successful. If deletion of the directory, any contained file, or subdirectory fails the client-server exchange would be: C> RMDA A S> 550 A: Cannot delete directory. If deletion fails due to inadequate permissions for the directory, any contained file, or subdirectory for the connected client, the client-server exchange would be: C> RMDA A S> 550 A: Permission denied. 3. Directory Size (DSIZ) The FTP command DIRECTORY SIZE (DSIZ) returns the number of octets (8-bit bytes) on the remote file system occupied by a given directory and its contents. The parameter to this command MUST represent a directory path, not a file path. While a method already exists to retrieve similar information by recursively issuing the SIZE command as defined in [RFC3659] and tallying the results, the SIZE command returns the number of transfer Peterson & Papenthien Expires October 4, 2008 [Page 5] Internet-Draft Streamlined FTP Command Extensions April 2008 octets for a specified file, which means that it considers the current data representation type in its calculated response. The DSIZ command should not consider this in its response, instead leaving it up to the underlying file system to determine the number of octets occupied by the files. In addition, issuing a single DSIZ command saves on the number of required commands and the overhead associated with recursively querying for the SIZE of each individual file. This results in a more responsive and conservative communication exchange between the client and server. Depending on the size of the path being queried and its location relative to the server, this can be a very lengthy operation. Servers that implement this command are encouraged to do so in a way that does not block operations for other client connections. 3.1. DSIZ Syntax The syntax of the DSIZ command is: dsiz = "DSIZ" [SP pathname] CRLF All FTP commands, including DSIZ, are case insensitive. However, the "pathname" variable provided with the command may be case sensitive as dictated by the server's operating system. If the "pathname" variable is not present in the received DSIZ command, its value is assumed to be the current directory (i.e., the path that would be returned in response to a Print Working Directory (PWD) command). The "pathname" specifies a remote directory that should be queried to retrieve the total storage space occupied by its contents on the server's file system. The "pathname" MUST be a valid directory path; it cannot be a path to a file or a system device. dsiz-response = "213" SP 1*DIGIT CRLF / error-response The 213 reply is formatted in such a way that the returned size value can be machine parsed. A successful response includes a numeric value indicating the number of octets on the server's file system occupied by the provided pathname and its contents. Peterson & Papenthien Expires October 4, 2008 [Page 6] Internet-Draft Streamlined FTP Command Extensions April 2008 3.2. DSIZ Error Responses In the event that the pathname is not a directory, the server MUST return a permanent 550 error reply. Where the command cannot be parsed, a 500 or 501 reply SHOULD be sent. The client MUST NOT assume that the presence of a 550 reply indicates that it cannot access the directory or its contents. The server may generate this error for other reasons, for example the overhead required for the operation is too great. 3.3. DSIZ FEAT Response When replying to the FEAT command, a server-FTP process that supports the DSIZ command MUST include a line starting with the word "DSIZ". If descriptive text is optionally desired, a space MUST immediately follow the "DSIZ" word. C> FEAT S> 211- S> ... S> DSIZ [ ] S> ... S> 211 End The ellipses indicate placeholders where other features may be included, and are not required. The one space indentation of the feature lines is mandatory per [RFC2389]. 3.4. DSIZ Examples Assuming the presence of directory "A" on the server and that the client has the necessary permissions to access and list it, a typical DSIZ client-server exchange would be: C> DSIZ A S> 213 123456 Where 123456 is the number of octets on the server's file system occupied by the directory "A" and its contents. Assuming directory "A" cannot be listed due to client permissions, the client-server exchange would be: C> DSIZ A S> 550 A: Permission denied. Peterson & Papenthien Expires October 4, 2008 [Page 7] Internet-Draft Streamlined FTP Command Extensions April 2008 Assuming the client provides the parameter "file.fid" where "file.fid" is an existing file, the client-server exchange would be: C> DSIZ file.fid S> 550 A: Is a file. 4. Available Octets (AVBL) The FTP command AVAILABLE OCTETS (AVBL) can be used to retrieve the number of octets available to receive uploads in a specified remote directory. Many server-FTP processes have implemented proprietary methods for restricting the amount of space available, either to the user as a whole or within a specified remote location. The AVBL command offers an interface for retrieving this value in a way that can be machine parsed. 4.1. AVBL Syntax The syntax of the AVBL command is: avbl = "AVBL" [SP pathname] CRLF All FTP commands, including AVBL, are case insensitive. However, the optional "pathname" variable provided with the command may be case sensitive as dictated by the server's operating system. If the "pathname" variable is not present in the received AVBL command, its value is assumed to be the current directory (i.e., the path that would be returned in response to a Print Working Directory (PWD) command). The "pathname" variable specifies the remote directory that the client wants to know how many octets are available to the user for uploads. The "pathname" MUST be a valid directory path; it cannot be a path to a file or a system device. avbl-response = "213" SP 1*DIGIT CRLF / error-response The 213 reply is formatted in such a way that the returned size can be machine parsed. A successful response includes a numeric value that may be the number of octets available as dictated by the physical limitations of the underlying storage mechanism. It may also be a limit imposed upon "pathname" or even the user that issued the command. The exact method for calculating this numeric value is up to the specific server-FTP process implementation. Peterson & Papenthien Expires October 4, 2008 [Page 8] Internet-Draft Streamlined FTP Command Extensions April 2008 4.2. AVBL Error Responses In the event that the pathname is not a directory, the server MUST return a permanent 550 error reply. Where the command cannot be parsed, a 500 or 501 reply should be sent. The client MUST NOT assume that the presence of a 550 reply indicates that it cannot access the directory or its contents. The server may generate this error for other reasons, for example the overhead required for the operation is too great. 4.3. AVBL FEAT Response When replying to the FEAT command, a server-FTP process that supports the AVBL command MUST include a line starting with the word "AVBL". If descriptive text is optionally desired, a space MUST immediately follow the "AVBL" word. C> FEAT S> 211- S> ... S> AVBL [ ] S> ... S> 211 End The ellipses indicate placeholders where other features may be included, and are not required. The one space indentation of the feature lines is mandatory per [RFC2389]. 4.4. AVBL Examples A typical client-server exchange using the AVBL command may look like this: C> AVBL S> 213 123456 Where 123456 is the number of octets the user has available for file uploads. In this example, no pathname is provided with the AVBL command. Therefore, the server has used the current working directory when processing its response. Assuming the presence of directory "A" on the server and that the client has the necessary permissions to access and list it: C> AVBL A S> 213 123456 Peterson & Papenthien Expires October 4, 2008 [Page 9] Internet-Draft Streamlined FTP Command Extensions April 2008 Assuming directory "A" cannot be listed due to client permissions, the client-server exchange would be: C> AVBL A S> 550 A: Permission denied. Assuming the client provides the parameter "file.fid" where "file.fid" is an existing file, the client-server exchange would be: C> AVBL file.fid S> 550 A: Is a file. 5. Change Host (HOST) The FTP command CHANGE HOST (HOST) allows the client to identify the name used to connect to the server. This command allows the server to host many unique domains within the server-FTP process that make use of the same IP address and port number combination, much like the "Host" header field of the HTTP protocol as defined in [RFC2616] allows a web server to do the same. 5.1. HOST Syntax The syntax of the HOST command is: host = "HOST" SP host_name CRLF All FTP commands, including HOST, are case insensitive. The specified "host_name" is also case insensitive to provide compatibility with domain names, which are case insensitive as well [RFC1035]. The "host_name" parameter can be any arbitrary text that uniquely identifies the client's desired domain to the server-FTP process. The most common and appropriate application of a "host_name" would be to specify a Fully Qualified Domain Name (FQDN) as this meets the criteria of being unique. However, by not restricting this parameter to a FQDN, other usages become available such as one not defined at the time of this document's writing or a proprietary naming convention employed within a large internal network. host-response = "220" SP *TCHAR CRLF / error-response The HOST command MUST be sent prior to issuing the USER command or logging into the server. If the specified host is valid, the server Peterson & Papenthien Expires October 4, 2008 [Page 10] Internet-Draft Streamlined FTP Command Extensions April 2008 responds with the usual 220 welcome response, returning the connect message specified for the host. 5.2. HOST Error Responses If the parameter is invalid, the server MUST use the 504 reply code. If the client session is already logged in (successfully issued USER and PASS commands), the server MUST use the 530 reply code. If the host_name is unrecognized by the server, the server MUST use the 530 reply code. If the server does not accept a host_name parameter, the server MUST continue with login to the default host on the IP address and port. 5.3. HOST FEAT Response When replying to the FEAT command, a server-FTP process that supports the HOST command SHOULD include a line starting with the word "HOST". If descriptive text is optionally desired, a space MUST immediately follow the "HOST" word. C> FEAT S> 211- S> ... S> HOST [ ] S> ... S> 211 End The ellipses indicate placeholders where other features may be included, and are not required. The one space indentation of the feature lines is mandatory per [RFC2389]. NOTE: Some servers do not allow the FEAT command to be issued prior to the occurrence of a successful login. Because the HOST command is required prior to login, a FEAT response code for HOST is optional depending on the server's implementation of FEAT. 5.4. HOST Examples Assuming host "ftp.domain.com" is defined for the server-FTP process, the client-server exchange would be: C> HOST ftp.domain.com S> 220 Welcome to ftp.domain.com, proceed... When the domain name (host) does not exist, the client-server exchange would be: Peterson & Papenthien Expires October 4, 2008 [Page 11] Internet-Draft Streamlined FTP Command Extensions April 2008 C> HOST ftp.domain-x.com S> 550 Host not found. When invalid syntax is specified, the client-server exchange would be: C> HOST ftp domain com S> 504 Invalid parameter. 6. Retrieve Thumbnail of Remote Image File (THMB) Many user-FTP processes have implemented a view of the remote directory contents that allows for a size-reduced representation of remote files recognized as image types to be displayed. This size- reduced representation of the image is commonly referred to as a thumbnail. This view of the remote file system usually requires a large amount of resources, in the form of time and bandwidth, in order to be properly represented. The THMB FTP command allows the server-FTP process to locally generate a thumbnail of a requested image type and transfer the resulting image instead of the entire contents of the original image file. This facilitates a faster and more efficient method of fulfilling a user-FTP process's implementation of a "thumbnail view". Depending on the size of the image file being processed and the CPU resources available to the server-FTP process, this can be a lengthy operation. Servers that implement this command are encouraged to do so in a way that does not block operations for other client connections. 6.1. THMB Syntax The THMB FTP command initiates a file transfer of the generated thumbnail image in much the same way that the Retrieve (RETR) FTP command initiates a download of a remote file. As such, thumbnail transfer occurs over a previously established data connection as indicated in [RFC959]. When the THMB command is received, an initial response is sent over the command connection, the thumbnail is transferred over the data connection, the data connection is closed, and the final response is sent over the command connection. The syntax of the THMB command is: thmb = "THMB" SP fmt SP 1*DIGIT SP 1*DIGIT SP pathname CRLF Peterson & Papenthien Expires October 4, 2008 [Page 12] Internet-Draft Streamlined FTP Command Extensions April 2008 All FTP commands, including THMB, are case insensitive. However, the "pathname" variable provided with the command may be case sensitive as dictated by the server's operating system. The "fmt" parameter indicates an image format recognized by the server-FTP process that should be used to generate the thumbnail image. Its value corresponds to the commonly accepted file extension used for the requested image format. Image formats supported by the server are listed in the THMB FEAT Response [6.3]. The requested thumbnail format does not necessarily conform to the existing format of the image. For example, a client-FTP process may request a PNG thumbnail of a JPEG image. The two digits following "fmt" are the requested maximum width and maximum height in pixels, respectively, that the client is willing to accept for the generated thumbnail image. The server SHOULD preserve the original aspect ratio of the image to avoid distortion while ensuring these maximum values are not exceeded by the generated thumbnail image. The "pathname" specifies a remote file, of a supported image type, that should be sent to the client in thumbnail form according to the other parameters. The syntax of a positive response is: Host-response = "150" SP *TCHAR (1*DIGIT 1*TCHAR) CRLF / error-response (1*DIGIT) represents the size in octets of the forthcoming file transfer. The value within the parentheses MAY include descriptive text, for example (123456 Bytes). By providing this information to the client, the client can determine the required file size and transfer status information. The potential responses to the THMB command that should be expected over the command channel correspond to the list of acceptable responses to the RETR command as defined in [RFC959]. As the THMB command initiates a data transfer over a previously negotiated data connection, the binary image data for the server generated thumbnail image is transferred over this data connection. Because image data is always binary in nature, the server-FTP process will always receive this data as if the current data representation type is BINARY, regardless of the setting that was established through the last received TYPE command. After the THMB command is Peterson & Papenthien Expires October 4, 2008 [Page 13] Internet-Draft Streamlined FTP Command Extensions April 2008 fully processed, the server-FTP process reverts back to using the previously established data representation type. 6.2. THMB Error Responses If an error is encountered while attempting to process or generate the thumbnail image, the server MUST use the 550 reply code. If an error is encountered while allocating resources for temporary storage of the generated thumbnail, the server MUST use the 550 reply code. 6.3. THMB FEAT Response When replying to the FEAT command, a server-FTP process that supports the THMB command MUST include a line starting with the word "THMB". If descriptive text is optionally desired, a space MUST immediately follow the required "fmt" parameter. C> FEAT S> 211- S> ... S> THMB fmt [ ] S> ... S> 211 End The "fmt" variable represents the supported image format(s); multiple format abbreviations can be given separated by the "|" character. Each format abbreviation must be the media subtype name of an 'image' media type that is IANA-registered under the provisions established in [RFC4288] describing a unique file storage format and giving a specific file name extension. Supporting servers must support at least JPEG or PNG formats. An example THMB response to the FEAT command might be: THMB JPEG|GIF|TIFF|PNG This response identifies JPEG, GIF, TIFF, and PNG formats as image types supported by the server for thumbnail generation. The ellipses indicate placeholders where other features may be included, and are not required. The one space indentation of the feature lines is mandatory per [RFC2389]. 6.4. THMB Examples Assuming the existence of image file "widget.png" on the server and that the client has all necessary permissions to access and transfer Peterson & Papenthien Expires October 4, 2008 [Page 14] Internet-Draft Streamlined FTP Command Extensions April 2008 the "widget.png" file, a request for a "widget.png" thumbnail might look like this: C> THMB PNG 80 80 widget.png S> 150 Starting thumbnail transfer (1234 Bytes) for widget.png S> 226 Transfer complete. In between the 150 and 226 server responses, the thumbnail image has been transferred over a negotiated data connection. If the client requests a thumbnail for an unsupported image type, the exchange would be: C> THMB PSP 80 80 widget.psp S> 501 Syntax error in parameters or arguments. 7. Security Considerations This document does not explicitly address security issues as they pertain to the FTP protocol in general. The commands introduced in this document do not affect the security of the FTP protocol nor do they address any of the security considerations described in [RFC2577]. Implementation of the RMDA, DSIZ, AVBL, and THMB commands can require significant server resources to process. This knowledge could be used by attackers in a denial of service attack. However, this issue has been addressed before with others commands, such as SIZE, and is traditionally mitigated by the server-FTP process's implementation of the command. The FTP server is encouraged to take specific care when implementing the RMDA command to avoid bypassing permissions. While it may be tempting to take advantage of a method made available by the platform to delete an entire tree of the file system at once, doing so could allow for the possibility of bypassing permissions that apply to specific files. Consequently, the contents of the path being deleted by RMDA must be individually evaluated. 8. IANA Considerations None. 9. Conclusions Inclusion of these commands both for servers and client can significantly reduce bandwidth requirements for many operations as Peterson & Papenthien Expires October 4, 2008 [Page 15] Internet-Draft Streamlined FTP Command Extensions April 2008 well as improving the client-side experience by reducing the amount of time needed to perform these operations via other methods. 10. Acknowledgments We would like to thank Alfred Hoenes for reviewing this document and providing thorough and thoughtful suggestions on how to make it better. This document was prepared using 2-Word-v2.0.template.dot. Funding for the RFC Editor function is currently provided by the Internet Society. Peterson & Papenthien Expires October 4, 2008 [Page 16] Internet-Draft Streamlined FTP Command Extensions April 2008 Normative References [RFC959] Postel, J. and J. Reynolds, "File Transfer Protocol (FTP)", STD 9, RFC 959, October 1985. [RFC1035] Mockapetris, P., "Domain Names - Implementation and Specification", STD 13, RFC 1035, November 1987. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2389] Hethmon, P. and R. Elz, "Feature negotiation mechanism for the File Transfer Protocol", RFC 2389, August 1998. [RFC2577] Allman, M. and S. Ostermann, "FTP Security Considerations", RFC 2577, May 1999. [RFC3659] Hethmon, P., "Extensions to FTP", RFC 3659, March 2007. [RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and Registration Procedures", BCP 13, RFC 4288, December 2005. [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. Informative References [RFC2616] Fielding, R., et al., "Hypertext Transfer Protocol - HTTP/1.1", RFC 2616, June 1999. Peterson & Papenthien Expires October 4, 2008 [Page 17] Internet-Draft Streamlined FTP Command Extensions April 2008 Authors' Addresses Mark P. Peterson Rhino Software, Inc. P.O. Box 53 Helenville, WI 53137 U.S.A. Phone: +1 (262) 560-9627 FAX: +1 (262) 560-9628 Email: mark.peterson@rhinosoft.com Douglas J. Papenthien Rhino Software, Inc. P.O. Box 53 Helenville, WI 53137 U.S.A. Phone: +1 (262) 560-9627 FAX: +1 (262) 560-9628 Email: douglas.papenthien@rhinosoft.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Peterson & Papenthien Expires October 4, 2008 [Page 18] Internet-Draft Streamlined FTP Command Extensions April 2008 Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Peterson & Papenthien Expires October 4, 2008 [Page 19]