Internet Draft Mark Bakke Cisco Standards Track Expires December 2002 June 2002 String Profile for iSCSI Names Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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. Copyright Notice Copyright (C) The Internet Society (2001). All Rights Reserved. Abstract The iSCSI protocol provides a way for hosts to access SCSI devices over an IP network. The iSCSI end-points, called initiators and targets, each have a globally-unique name that must be transcribable, as well as easily compared. This document describes how to prepare internationlized iSCSI names to increase the likelihood that name input and comparison work in ways that make sense for typical users throughout the world. Bakke Expires December 2002 [Page 1] Internet Draft String Profile for iSCSI Names June 2002 Acknowledgements This draft was produced as a result of discussions on iSCSI name formats with Joe Czap, Jim Hafner, Howard Hall, Jack Harwood, John Hufferd, Marjorie Krueger, Lawrence Lamers, Todd Sperry, Joshua Tseng, and Kaladhar Voruganti, as well as discussions on the normalization of names into identifiers with Paul Hoffman and Marc Blanchet. Thanks also to Bob Snively for suggesting the use of the nameprep process for iSCSI name normalization. Most of this draft was copied from the stringprep profile for nameprep [NAMEPREP], written by Paul Hoffman and Marc Blanchet. 1. Introduction The iSCSI protocol [ISCSI] provides a way for hosts to access SCSI [SAM2] devices over an IP network. The iSCSI end-points, called initiators and targets, each have a globally-unique name, defined in [NDT]. An iSCSI name is a string of UTF-8 [RFC2044] characters that includes a type designator, a naming authority based on domain names, and a unique part within the naming authority. The unique part may be generated based on anything the naming authority deems useful, and may include user input. These names may need to be transcribed (sent between two administrators via email, voice, paper, etc), so a case- insensitive comparison would be desirable. However, these names must often be compared by initiator and target implementations, most of which are done in simple, embedded software. This makes case-sensitive comparison highly desirable for these implementors. However, a completely case-sensitive implementation would result in identifiers such as "example-name" and "Example-Name" being different, which could lead to confusion as these names are transcribed. The goal, then, is to generate iSCSI names that can be transcribed and entered by users, and also compared byte-for-byte, with minimal confusion. To attain these goals, iSCSI names are generalized using a normalized character set (converted to lower case or equivalent), with no white space allowed, and very limited punctuation. For those using only ASCII characters (U+0000 to U+007F), the Bakke Expires December 2002 [Page 2] Internet Draft String Profile for iSCSI Names June 2002 following characters are allowed: - ASCII dash character ('-' = U+002d) - ASCII dot character ('.' = U+002e) - ASCII colon character (':' = U+003a) - ASCII lower-case characters ('a'..'z' = U+0061..U+007a) - ASCII digit characters ('0'..'9' = U+0030..U+0039) In addition, any upper-case characters input via a user interface should be mapped to their lower-case equivalents. This document specifies the valid character set for iSCSI names, along with the rules for normalizing and generating iSCSI names based on user inport or other information that contains international characters. In particular, it defines the following, as required by [STRINGPREP]: - The intended applicability of the profile: internationalized iSCSI names. - The character repertoire that is the input and output to stringprep: Unicode 3.1, specified in section 2. - The mappings used: specified in section 3. - The Unicode normalization used: specified in section 4. - The characters that are prohibited as output: specified in section 5. This profile MUST be used with the iSCSI protocol. 2. Terminology 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]. Examples in this document use the notation for code points and names from the Unicode Standard [Unicode3.1] and ISO/IEC 10646 [ISO10646]. For example, the letter "a" may be represented as either "U+0061" or "LATIN SMALL LETTER A". In the lists of prohibited characters, the "U+" is left off to make the lists easier to read. The comments for character ranges are shown in square brackets (such as "[SYMBOLS]") and do not come from the standards. Bakke Expires December 2002 [Page 3] Internet Draft String Profile for iSCSI Names June 2002 3. Character Repertoire This profile uses Unicode 3.1, as defined in [STRINGPREP] Appendix A.1. 4. Mapping This profile specifies mapping using the following tables from [STRINGPREP]. The following mapping tables MUST be used when generating iSCSI names from Unicode characters. Table B.1 Table B.2 5. Normalization Unicode normalization form KC MUST be used with this profile, as described in [STRINGPREP]. 6. Prohibited Output This profile specifies prohibiting using the following tables from [stringprep]. Characters appearing within these tables MUST NOT be used within an iSCSI name. Table C.1 Table C.2 Table C.3 Table C.4 Table C.5 Table C.6 Table C.7 Table C.8 Table C.9 Important note: this profile MUST be used with the iSCSI protocol. The iSCSI protocol has additional naming rules that are checked outside of this profile. In addition, this profile adds the following prohibitions. The full set of prohibited characters are those from the tables above plus those listed individually below. Bakke Expires December 2002 [Page 4] Internet Draft String Profile for iSCSI Names June 2002 6.1. Inappropriate Characters from Common Input Mechanisms u+3002 is used as if it were u+002e in many domain name input mechanisms used by applications, particularly in asia. The character u+3002 MUST NOT be used in an iSCSI name. 3002; ideographic full stop 6.2. Currently-prohibited ASCII characters Some of the ASCII characters that are currently prohibited in iSCSI names by [NDT] are also used in protocol elements such as URIs [URI]. The other characters in the range U+0000 to U+007F that are not currently allowed are prohibited in iSCSI names to reserve them for future use in protocol elements. Note that the dash (U+002D), dot (U+002E), and colon (U+003A) are not prohibited. The following characters MUST NOT be used in iSCSI names: 0000-002C; [ASCII CONTROL CHARACTERS and SPACE through ,] 002F; [ASCII /] 003B-0040; [ASCII ; through @] 005B-0060; [ASCII [ through `] 007B-007F; [ASCII { through DEL] 7. Unassigned Code Points in Internationalized Domain Names If the processing in [iSCSI] specifies that a list of unassigned code points be used, the system uses table A.1 from [STRINGPREP] as its list of unassigned code points. 8. Security Considerations ISO/IEC 10646 has many characters that look similar. In many cases, users of security protocols might do visual matching, such as when comparing the names of trusted third parties. This profile does nothing to map similar-looking characters together. iSCSI names may be used by an initiator to verify that a target it has discovered is the correct one, and by a target to verify that an initiator is to be allowed access. If these names are interpreted and compared differently by different iSCSI implementations, an initiator could gain access to the wrong target, or could be denied access to a legitimate target. Bakke Expires December 2002 [Page 5] Internet Draft String Profile for iSCSI Names June 2002 9. IANA Considerations This is a profile of stringprep. When it becomes an RFC, it should be registered in the stringprep profile registry. 10. Summary This document describes a stringprep profile to be used with programs generating names for iSCSI initiators and targets. 11. Normative References [STRINGPREP] Paul Hoffman and Marc Blanchet, "Preparation of Internationalized Strings ("stringprep")", draft-hoffman- stringprep-03, May 2002. [ISCSI] J. Satran, et. al. "iSCSI", draft-ietf-ips-iscsi-12.txt, June 2002. 12. Informative References [NDT] K. Voruganti, et. al. "iSCSI Naming and Discovery Requirements", draft-ietf-ips-iscsi-name-disc-05, May 2002. [NAMEPREP] Paul Hoffman and Marc Blanchet. Nameprep: A Stringprep Profile for Internationalized Domain Names. draft-ietf-idn- nameprep-10, May 2002. [RFC2119] Scott Bradner, "Key words for use in RFCs to Indicate Requirement Levels", March 1997, RFC 2119. [SAM2] ANSI T10. "SCSI Architectural Model 2", March 2000. [RFC2044] F. Yergeau, "UTF-8, a transformation format of Unicode and ISO 10646", October 1996, RFC 2044. [Unicode3.1] The Unicode Standard, Version 3.1.0: The Unicode Consortium. The Unicode Standard, Version 3.0. Reading, MA, Addison- Wesley Developers Press, 2000. ISBN 0-201-61633-5, as amended by: Unicode Standard Annex #27: Unicode 3.1 . Bakke Expires December 2002 [Page 6] Internet Draft String Profile for iSCSI Names June 2002 [ISO10646] ISO/IEC 10646-1:2000. International Standard -- Information technology -- Universal Multiple-Octet Coded Character Set (UCS) -- Part 1: Architecture and Basic Multilingual Plane. [URI] For example: Roy Fielding et al., "Uniform Resource Identifiers: Generic Syntax", August 1998, RFC 2396; Robert Hinden et. al, "IPv6 Literal Addresses in URL's", December 1999, RFC 2732. Note that there are many other RFCs that define additional URI schemes. Author Contact Information Mark Bakke Cisco Systems, Inc. 6450 Wedgwood Road Maple Grove, MN USA 55311 Voice: +1 763-398-1000 E-Mail: mbakke@cisco.com 13. Full Copyright Statement Copyright (C) The Internet Society (2001). All Rights Reserved. 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