INTERNET-DRAFT Adam W. Montville
Intended Status: Standards Track (Tripwire, Inc.)
Expires: June 17, 2013 December 14, 2012
IODEF Enumeration Reference Format
draft-montville-mile-enum-reference-format-02
Abstract
The Incident Object Description Exchange Format [IODEF] provides a
Reference class used to reference external entities (such as
enumeration identifiers). However, the method of external entity
identification has been left unstructured. This document describes a
method to provide structure for referencing external entities for the
[IODEF] Reference class.
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.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Referencing External Enumerations . . . . . . . . . . . . . . 3
3 Security Considerations . . . . . . . . . . . . . . . . . . . . 6
4 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
5 References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1 Normative References . . . . . . . . . . . . . . . . . . . 7
5.2 Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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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 the scope of this document pertains
solely to [IODEF].
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 identifiers 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 is to
require a specific format for the ReferenceName string of the [IODEF]
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:version:id
Where id_type is an IANA-registered type having the form
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<Abbreviation>
And where version is an IANA-registered type having the form
<Version>
And where id is the actual enumeration identifier string.
The IANA Considerations section of this document provides details for
<Abbreviation> and <Version>. This format allows the <Version> to be
associated with the id rather than the id_type. By requiring that a
specific type and version be associated with the identifier, an
implementer can look up the type in an IANA table to understand
exactly what the identifier in ReferenceName is and how s/he may
expect that identifier to be structured.
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:1.0:CXI-1234-XYZ</ReferenceName>
<URL>http://cxi.example.com</URL>
<Description>Foo</Description>
</Reference>
Information in the IANA table (see Section 4) would include:
Full Name: Concept X Identifier
Abbreviation: CXI
Version: 1.0
Specification URI: http://cxi.example.com/spec_url
2.3 Reference Method Applicability
While the scope of this document pertains to [IODEF], it should be
readily apparent that any standard 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
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a given standard and the enumeration identifiers 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.
Registration request for the IODEF Enumeration Reference Format:
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. Note that
certain name requests should not be permitted as either Full Name
or Abbreviation entries for the requested IANA table. For
example, the following list should not be permitted: foo, bar,
example.com. It is anticipated that the Expert Review process
will flag any additional undesired Full Name or Abbreviation
issues.
Fields to record in the registry:
Full Name: The full name of the enumeration as a string
Abbreviation: The abbreviation of the enumeration as a string,
e.g. a short initialization is encouraged
Version: The version of the enumeration as a string, e.g. dot-
separated numbers are a good idea
Specification URI: A list of one or more URIs [RFC3986] from
which the registered specification can be obtained. The
registered specification MUST be readily and publicly available
from that URI.
Initial registry contents: None.
Allocation Policy: Expert Review [RFC5226] and Specification
Required [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
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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.
[3986] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
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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