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Network Working Group                                     D. WysochanskiRequest for Comments: 4850                       Network Appliance, Inc.Updates:3720                                                 April 2007Category: Standards TrackDeclarative Public Extension Key forInternet Small Computer Systems Interface (iSCSI) Node ArchitectureStatus 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 IETF Trust (2007).Abstract   The Internet Small Computer Systems Interface (iSCSI) protocol,   described inRFC 3720, allows for extension items to the protocol in   the form of Private or Public Extension Keys.  This document   describes a Public Extension Key for the purpose of enhancing iSCSI   supportability.  The key accomplishes this objective by allowing   iSCSI nodes to communicate architecture details during the iSCSI   login sequence.  The receiving node can then use this information for   enhanced logging and support.  This document updatesRFC 3720 to   allow iSCSI extension items to be defined by standards track RFCs and   experimental RFCs in addition to informational RFCs.Wysochanski                 Standards Track                     [Page 1]

RFC 4850                iSCSI Node Architecture               April 20071.  Introduction1.1.  Overview   This document describes a declarative Public Extension Key, as   defined bySection 12.22 of RFC 3720 [2], that may be used to   communicate additional iSCSI node information to the peer node in a   session.  The information carried in the described key has been found   to be valuable in real iSCSI customer environments as initiator and   target vendors collaborate to resolve technical issues and better   understand the interaction of iSCSI implementations.   The key has been modeled after the HTTP "Server" and "User-Agent"   header fields as specified in Sections14.38 and14.43 ofRFC 2616   [3], with the text-value(s) of the key roughly equivalent to Product   Tokens inSection 3.8 of RFC 2616 [3].  Note, however, that the text-   value(s) in the key's list-of-values MUST conform to the Text Format   as specified inSection 5.1 of RFC 3720 [2].   The key is sent during operational parameter negotiation of an iSCSI   session's login phase.  The intended use of this key is to provide   enhanced logging and support capabilities, and to enable collection   of iSCSI implementation and usage information.1.2.  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 inRFC 2119 [1].2.  Definition   The definition of the key is as follows, conforming to Sections11   and 12 ofRFC 3720 [2], with example list-of-values conforming toSection 5.1 of RFC 3720 [2].   The key is defined with a use of "LO", making it a Leading Only key,   and does not modify Sections11 or12 ofRFC 3720 [2].  Thus, the key   MUST only be sent on the leading connection, MUST NOT be changed   after the leading connection login, and MUST only be sent after the   security negotiation login stage has completed (during operational   negotiation login stage).  The key may be sent during normal or   discovery sessions.Wysochanski                 Standards Track                     [Page 2]

RFC 4850                iSCSI Node Architecture               April 20072.1.  X#NodeArchitecture   Use: LO, Declarative   Senders: Initiator and Target   Scope: SW   X#NodeArchitecture=<list-of-values>   Examples:      X#NodeArchitecture=ExampleOS/v1234,ExampleInc_SW_Initiator/1.05a      X#NodeArchitecture=ExampleInc_HW_Initiator/4010,Firmware/2.0.0.5      X#NodeArchitecture=ExampleInc_SW_Initiator/2.1,CPU_Arch/i686   The initiator or target declares the details of its iSCSI node   architecture to the remote endpoint.  These details may include, but   are not limited to, iSCSI vendor software, firmware, or hardware   versions, the OS version, or hardware architecture.   The length of the key value (total length of the list-of-values) MUST   NOT be greater than 255 bytes.   X#NodeArchitecture MUST NOT be redeclared.3.  Implementation   Functional behavior of the iSCSI node (this includes the iSCSI   protocol logic -- the SCSI, iSCSI, and TCP/IP protocols) MUST NOT   depend on the presence, absence, or content of the key.  The key MUST   NOT be used by iSCSI nodes for interoperability, or exclusion of   other nodes.  To ensure proper use, key values SHOULD be set by the   node itself, and there SHOULD NOT be provisions for the key values to   contain user-defined text.   Nodes implementing this key MUST choose one of the following   implementation options:      o  only transmit the key,      o  only log the key values received from other nodes, or      o  both transmit and log the key values.   Each node choosing to implement transmission of the key values MUST   be prepared to handle the response ofRFC 3720 [2] compliant nodes   that do not understand the key (RFC 3720 [2] states that compliant   nodes MUST respond with X#NodeArchitecture=NotUnderstood).   Nodes that implement transmission and/or logging of the key values   may also implement administrative mechanisms that disable and/orWysochanski                 Standards Track                     [Page 3]

RFC 4850                iSCSI Node Architecture               April 2007   change the logging and key transmission detail (see Security   Considerations).  Thus, a valid behavior for this key may be that a   node is completely silent (the node does not transmit any key value,   and simply discards any key values it receives without issuing a   NotUnderstood response).4.  Security Considerations   This extension key transmits specific implementation details about   the node that sends it; such details may be considered sensitive in   some environments.  For example, if a certain software or firmware   version is known to contain security weaknesses, announcing the   presence of that version via this key may not be desirable.  The   countermeasures for this security concern are:   o  sending less detailed information in the key values,   o  not sending the extension key, or   o  using IPsec to provide confidentiality for the iSCSI connection on      which the key is sent (seeRFC 3720 [2] andRFC 3723 [4]).   To support the first and second countermeasures, all implementations   of this extension key MUST provide an administrative mechanism to   disable sending the key.  In addition, all implementations SHOULD   provide an administrative mechanism to configure a verbosity level of   the key value, thereby controlling the amount of information sent.   For example, a lower verbosity might enable transmission of node   architecture component names only, but no version numbers.   The choice of which countermeasure is most appropriate depends on the   environment.  However, sending less detailed information in the key   values may be an acceptable countermeasure in many environments,   since it provides a compromise between sending too much information   and the other more complete countermeasures of not sending the key at   all or using IPsec.   In addition to security considerations involving transmission of the   key contents, any logging method(s) used for the key values MUST keep   the information secure from intruders.  For all implementations, the   requirements to address this security concern are:   o  Display of the log MUST only be possible with administrative      rights to the node.   o  Options to disable logging to disk and to keep logs for a fixed      duration SHOULD be provided.Wysochanski                 Standards Track                     [Page 4]

RFC 4850                iSCSI Node Architecture               April 2007   Finally, it is important to note that different nodes may have   different levels of risk, and these differences may affect the   implementation.  The components of risk include assets, threats, and   vulnerabilities.  Consider the following example iSCSI nodes, which   demonstrate differences in assets and vulnerabilities of the nodes,   and as a result, differences in implementation:   o  One iSCSI target based on a special-purpose operating system.      Since the iSCSI target controls access to the data storage      containing company assets, the asset level is seen as very high.      Also, because of the special-purpose operating system, in which      vulnerabilities are less well-known, the vulnerability level is      viewed as low.   o  Multiple iSCSI initiators in a blade farm, each running a general-      purpose operating system.  The asset level of each node is viewed      as low, since blades are replaceable and low cost.  However, the      vulnerability level is viewed as high, since there are many well-      known vulnerabilities to the general-purpose operating system.   For the above target, an appropriate implementation might be logging   of received key values, but no transmission of the key.  For the   initiators, an appropriate implementation might be transmission of   the key, but no logging of received key values.5.  IANA Considerations   The standards action of this document updatesRFC 3720 to allow any   iSCSI extension item, specifically X# extension text keys, Y# digest   algorithms, and Z# authentication methods, to be defined by a   standards track, experimental, or informational RFC.  This document   is a standards track RFC that defines an X# extension text key.   IANA registered this key as follows:   o  Key Name: X#NodeArchitecture   o  Description: Node architecture details   o  Reference: [RFC4850]   The update toRFC 3720 to allow additional types of RFCs for iSCSI   Extension items has the same effect as if the following changes were   made to the text ofRFC 3720 (RFC text cannot be changed after   publication):Wysochanski                 Standards Track                     [Page 5]

RFC 4850                iSCSI Node Architecture               April 2007   1) InSection 11.1, the requirement that Z# Authentication methods      "MUST be described by an informational RFC." is changed to "MUST      be described by a standards track RFC, an experimental RFC, or an      informational RFC."   2) InSection 12.1, the requirement that Y# Digest algorithms "MUST      be described by an informational RFC." is changed to "MUST be      described by a standards track RFC, an experimental RFC, or an      informational RFC."   3) InSection 12.22, the requirement that X# text keys "MUST be      described by an informational RFC." is changed to "MUST be      described by a standards track RFC, an experimental RFC, or an      informational RFC."   4) InSection 13.3, the description of allowed RFC types for      extension items is changed from "The RFC may be informational      rather than Standards-Track," to "The RFC MUST be standards track,      experimental, or informational,"   5) InSection 13.5.2, the phrase "standards track" is changed to      "standards track or experimental" in the last sentence of the      first paragraph, so that the sentence reads: "If the specification      is a standards track or experimental document, the usual IETF      procedures for such documents are followed."   The registries for iSCSI extension items should be managed as if   these changes had been made to the text ofRFC 3720.6.  References6.1.  Normative References   [1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement        Levels",BCP 14,RFC 2119, March 1997.   [2]  Satran, J., Meth, K., Sapuntzakis, C., Chadalapaka, M., and E.        Zeidner, "Internet Small Computer Systems Interface (iSCSI)",RFC 3720, April 2004.Wysochanski                 Standards Track                     [Page 6]

RFC 4850                iSCSI Node Architecture               April 20076.2.  Informative References   [3]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L.,        Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol --        HTTP/1.1",RFC 2616, June 1999.   [4]  Aboba, B., Tseng, J., Walker, J., Rangan, V., and F. Travostino,        "Securing Block Storage Protocols over IP",RFC 3723, April        2004.Wysochanski                 Standards Track                     [Page 7]

RFC 4850                iSCSI Node Architecture               April 2007Appendix A.  Acknowledgments   The IP Storage (ips) Working Group in the Transport Area of IETF has   been responsible for defining the iSCSI protocol (apart from a host   of other relevant IP Storage protocols).  The author acknowledges the   contributions of the entire working group.   The following individuals directly contributed to identifying issues   and/or suggesting resolutions to the issues found in this document:   David Black, Mallikarjun Chadalapaka, Paul Koning, Julian Satran,   John Hufferd, Claire Kraft, Ranga Sankar, Joseph Pittman, Greg Berg,   John Forte, Jim Yuill, William Studenmund, and Ken Sandars.  This   document benefited from all these contributions.   Finally, the author recognizes Network Appliance, Inc. for   sponsorship and support during the development of this work.Author's Address   Dave Wysochanski   8311 Brier Creek Parkway   Suite 105-296   Raleigh, NC  27617   US   Phone: +1 919 696 8130   EMail: wysochanski@pobox.comWysochanski                 Standards Track                     [Page 8]

RFC 4850                iSCSI Node Architecture               April 2007Full Copyright Statement   Copyright (C) The IETF Trust (2007).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   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.Intellectual Property   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 inBCP 78 andBCP 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 athttp://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.Acknowledgement   Funding for the RFC Editor function is currently provided by the   Internet Society.Wysochanski                 Standards Track                     [Page 9]