One document matched: draft-montville-mile-enum-reference-format-00.txt


 



INTERNET-DRAFT                                         Adam W. Montville
Intended Status: Informational                          (Tripwire, Inc.)
Expires: March 5, 2013                                 September 1, 2012



                  IODEF Enumeration Reference Format 
             draft-montville-mile-enum-reference-format-00


Abstract

   Some standards, such as the Incident Object Description Exchange
   Format [IODEF], provide classes used to reference external entities
   (such as enumeration identifiers).  At the time of standardization,
   however, needed references may not be known, and the method of
   external entity identification is often left unstructured.  This
   document describes, using [IODEF] as an example, a method to provide
   structure after the fact.


Status of this Memo

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Copyright and License Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors. All rights reserved.

 


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   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of
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   described in the Simplified BSD License.



Table of Contents

   1  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1  Terminology . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Referencing External Enumerations  . . . . . . . . . . . . . .  3
   3  Security Considerations . . . . . . . . . . . . . . . . . . . .  5
   4  IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  5
   5  References  . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     5.1  Normative References  . . . . . . . . . . . . . . . . . . .  5
     5.2  Informative References  . . . . . . . . . . . . . . . . . .  6
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  6

























 


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1  Introduction

   There is an identified need to specify a format to include relevant
   enumeration values in an IODEF document.  It is anticipated that this
   requirement will exist in other standardization efforts within
   several IETF Working Groups, but this document uses IODEF as the
   primary example.

1.1  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 RFC 2119 [RFC2119].


2.  Referencing External Enumerations

   The need is to place enumeration values and their references in
   [IODEF]'s Reference class.  There are several ways to accomplish this
   goal, but one that seems the most appropriate at this point in time
   is to require a specific format for the ReferenceName string of the
   Reference class, such that an IANA table can be used to catalog a
   variety of reference types.

      +------------------+
      | Reference        |
      +------------------+
      |                  |<>----------[ ReferenceName ]
      |                  |<>--{0..*}--[ URL           ]
      |                  |<>--{0..*}--[ Description   ]
      +------------------+

                    FIGURE 1: IODEF Reference Class 

   Per [IODEF] the ReferenceName is of type ML_STRING.  This becomes
   problematic when specific references, especially enumerations such as
   CEE, CVE, CCE, and so on, are referenced - how is an implementer to
   know which type of reference this is, and thus how to parse it? One
   solution, presented here, is to require that ReferenceName follow a
   particular format. 

 2.1 Reference Name Format

   The format of the ReferenceName MUST follow the form of

      id_type:id

   Where id_type is an IANA-registered type.  By requiring that a
 


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   specific type be prepended to the identifier, an implementer can look
   up the type in an IANA table to understand exactly what the
   identifier in ReferenceName is.


 2.2 Reference Example

   The operation of this method can be described using a fictitious
   example.  Assume a Reference class as described in the Section 2
   introduction and an enumeration of formatted strings used to identify
   Concept X.  Then, the string format of Concept X Identifiers would be
   registered with IANA (see Section 4), such that implementations of
   the Reference class understand how to handle the formatted string.


      <Reference>
         <ReferenceName>CXI:CXI-1234-XYZ</ReferenceName>
         <URL>http://cxi.example.com</URL>
         <Description>Foo</Description>
      </Reference>

   Information in the IANA table (see Section 4) would include:

      Name: Concept X Identifier
      Version: x.y
      Specification URI: http://cxi.example.com/spec_url
      Reference: Foo.

 2.3 Reference Method Applicability

      It should be readily apparent that any standard, not just [IODEF]
      needing to reference an enumeration identified by a specially
      formatted string can use this method of providing structure after
      the standard has been published.  In effect, this method provides
      a standardized interface for enumerations, thus allowing a loose
      coupling between a given standard and the enumerations it needs to
      reference now and in the future.











 


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3  Security Considerations

      None.


4  IANA Considerations

      This document specifies an identifier format for the [IODEF]
      ReferenceName string of the Reference class.

      The following registry has been created and is now managed by
      IANA:

      Name of the Registry: "Enumeration Reference Type Identifiers"

      The registry is intended to enable enumeration value additions to
      attributes of a given reference class of an IETF standard, for
      example, the Reference class of the IODEF schema.

      Fields to record in the registry: Name, Version, Specification
      URI, Reference

      Initial registry contents: None.

      Allocation Policy: Expert Review [RFC5226].

   The Designated Expert is expected to consult with the MILE (Managed
   Incident Lightweight Exchange) working group or its successor if any
   such WG exists (e.g., via email to the working group's mailing list).
   The Designated Expert is expected to review the request and validate
   the appropriateness of the enumeration for the attribute.  If a
   specification is associated with the request, it MUST be reviewed by
   the Designated Expert.


5  References

5.1  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [IODEF]    Danyliw, R., Meijer, J., and Y. Demchenko, "The Incident
              Object Description Exchange Format", RFC 5070, December
              2007.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
 


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              May 2008.


5.2  Informative References

              None.



Authors' Addresses


   Adam W. Montville
   Tripwire, Inc.
   101 SW Main Street
   Suite 1500
   Portland, OR 97204

   EMail: amontville@tripwire.com
































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