SACM                                                       N. Cam-Winget
Internet-Draft                                             Cisco Systems
Intended status: Informational                               L. Lorenzin
Expires: April 27, July 6, 2015                                       Pulse Secure
                                                        October 24, 2014
                                                         January 2, 2015

    Secure Automation and Continuous Monitoring (SACM) Requirements
                    draft-ietf-sacm-requirements-02
                    draft-ietf-sacm-requirements-03

Abstract

   This document defines the scope and set of requirements for the
   Secure Automation and Continuous Monitoring working group.  The
   requirements and scope are based on the agreed upon use cases.

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   This Internet-Draft will expire on April 27, July 6, 2015.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   2
     2.1.  Requirements for SACM . . . . . . . . . . . . . . . . . .   3
     2.2.  Requirements based on Use Cases . for the Architecture . . . . . . . . . . . .   5
     2.3.  Requirements for the Architecture . . . . . . . . Data Model . . . .   7
     2.4.  Requirements for the Information Model . . . . . . . . .   7
     2.5.   6
     2.4.  Requirements for Transport Protocols  . . . . . . . . . .  10   9
   3.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10   9
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
     5.1.  Trust between Provider and Requestor  . . . . . . . . . .  10
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11  12
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  11  12
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  11  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11  12

1.  Introduction

   Today's environment of rapidly-evolving security threats highlights
   the need to automate the sharing of such information while protecting
   user information as well as the systems that store, process, and
   transmit this information.  Security threats can be detected in a
   number of ways.  SACM's charter focuses on how to collect and share
   this information based on use cases that involve posture assessment
   of endpoints.

   Scalable and sustainable collection, expression, and evaluation of
   endpoint information is foundational to SACM's objectives.  To secure
   and defend a network one must reliably determine what devices are on
   the network, how those devices are configured from a hardware
   perspective, what software products are installed on those devices,
   and how those products are configured.  We need to be able to
   determine, share, and use this information in a secure, timely,
   consistent, and automated manner to perform endpoint posture
   assessments.

   This document focuses on describing the requirements for facilitating
   the exchange of posture assessment information, in particular, for
   the use cases as exemplified in [I-D.ietf-sacm-use-cases].Also, this
   document uses terminology defined in [I-D.ietf-sacm-terminology].

2.  Requirements

   This document defines requirements based on the SACM use cases
   defined in [I-D.ietf-sacm-use-cases].  This section describes the
   requirements used by SACM to assess and compare candidate information
   models data
   models, their interfaces and protocols to suit the SACM architecture.

   These requirements express characteristics or features that a
   candidate protocol or data model must be capable of offering to
   ensure security and interoperability.

   In order to address the needs for determining, sharing and using
   posture information, the following tasks should be considered:

   1.  Define the assets.  This is what we want to know about an asset.
       For instance, organizations will want to know what software is
       installed and its many critical security attributes such as patch
       level.

   2.  Resolve what assets actually compose an endpoint.  This requires
       populating the data elements and attributes needed to exchange
       information pertaining to the assets composing an endpoint.

   3.  Determine the expected values for the data elements and
       attributes that need to be evaluated against the actual collected
       instances of asset data.  This is how an organization can express
       its policy for an acceptable data element or attribute value.  A
       system administrator can also identify specific data elements and
       attributes that represent problems, such as vulnerabilities, that
       need to be detected on an endpoint.

   4.  Evaluate the collected instances of the asset data against those
       expressed in the policy.

   5.  Report the results of the evaluation.

2.1.  Requirements for SACM

   Many deployment scenarios can be instantiated to address the above
   tasks and use cases defined in [I-D.ietf-sacm-use-cases].  To ensure
   interoperability, scalability and flexibility in any of these
   deployments, the following requirements are defined for all use
   cases: proposed SACM
   standards:

   G-001  Solution Extensibility: The data models, protocols and
    transports defined by SACM must MUST be extensible to allow support for
    non-standard and future extensions.

    1.  The transport protocol must MUST support easily adding the ability to add new
        operations while maintaining backwards compatibility.

    2.  The query language must allow general inquiries as well as
        expression of specific paths to follow; retrieval of specific
        information based on an event, as well as on a continuous basis;
        and the ability to retrieve specific pieces of information,
        specific types or classes of information, and/or the entirety of
        available information.

    3.  The information model must accommodate the addition of new data
        types and/or schemas in a backwards compatible fashion.

   G-002  Interoperability: The data models, protocols and transports
    must be specified with enough details and state machine to ensure interoperability.

   G-003  Scalability: The data models, protocols and transports must be
    scalable.  SACM must support a broad set of deployment scenarios.
    As such, it is possible that the size of posture assessment
    information can vary from a single assessment that is small in
    (record or datagram) size to a very large datagram or a very large
    set of assessments.  This must be defined by the SACM
    specifications.

   G-004  Agility: The agility requirement is to ensure that the data
    model, protocols, and transports are suitably specified to implemented enable
    implementions to fit into the different deployment models and
    scenarios.  Considerations for
    the lightweight implementations of data
    models and transports is required.  Use cases, especially in the vulnerability assessment and
    threat defense applications, require time criticality in both
    obtaining the information as well as consuming (e.g. parsing) the
    data.

   G-005 / T-001  Transport variability: Moved to the Section 2.5.

   G-006 / GN-005  Information Extensibility: A method for expressing both
    standard and non-standard (implemention-specific) data attributes
    while avoiding collisions should SHOULD be defined.  For interoperability
    and scope boundary, an explicit set of data attributes as MUST be
    defined mandatory to implement.

   G-007 / GN-006/ T-002

   G-006  Data Integrity: A method for ensuring data integrity must MUST be
    provided.  This method is required to be available (i.e. all data-handling data-
    handling components must support it), but is not required to be used
    in all cases.

   G-008 / T-003  Data Protection: Moved to the Section 2.5.

   G-009 / ARCH-004  Topology Flexibility: Moved to the Section 2.3.

   G-010 / GN-007

   G-007  Data Isolation: A method for partitioning data must MUST be
    supported, to accommodate considerations such as geographic,
    regulatory, overlay boundaries and federation, where an organization
    may want to differentiate between information that can be shared
    outside its own domain and information that cannot.  As with the
    requirement for data integrity, this method is required to be
    available (i.e. all data-handling components must support it), but
    is not required to be used in all cases.

   G-011 / ARCH-005  Modularity: has been moved to the Section 2.3.

   G-012 / GN-008

   G-008  Versioning and Backward Compatibility: Announcement and
    negotiation of versions, inclusive of exisiting capabilities (such
    as transport protocols, data models, specific attributes within data
    models, standard attribute expression sets, etc.) must  MUST be
    supported.  Negotiation for both versioning and capability is needed
    to accommodate future growth and ecosystems with mixed capabilities.

   G-013 / GN-009

   G-009  Discovery: There must be a mechanism for components to
    discover what information is available across the ecosystem (i.e. a
    method for cataloging data available in the ecosystem and
    advertising it to consumers), and where to go to get a specific
    piece of that information.  For example, providing a method by which
    a node can locate the advertised information so that consumers are
    not required to have a priori knowledge to find available
    information.

   G-014 / IM-013  Synchronization: has been moved to the Section 2.4.

   G-015 / IM-014  Collection separation: has been moved to the
    Section 2.4.

   G-016 / IM-015  Collection composition has been moved to

   G-010  Endpoint Discovery: SACM MUST define the
    Section 2.4.

2.2.  Requirements based on means by which
    endpoints may be discovered.  Use Cases

   This section Case 2.1.2 describes the requirements that may apply need to information
   models, data models, protocols or transports as identified by the use
   cases in [I-D.ietf-sacm-use-cases]
    discover endpoints and referenced by the section
   numbers from that draft.

   REQ-001  Attribute Dictionary: their composition.

   G-011  Unsolicited publication, updates or change modifications with
    filtering: Use Cases in the whole of Section 2
    describe the need for an Attribute Dictionary.  With SACM's scope
    focused on Posture Assessment, the attribute collection and
    aggregation must have a well understood set of attributes inclusive
    of their meaning or usage intent.

   REQ-002  Information Model: Use Case 2.1.1 describes the need for an
    Information Model to drive content definition.  As SACM endeavors to
    reuse already existing standards which may have their own data
    models defined by instantiating an information model, the data
    models can be mapped to SACM's information model.  See [RFC3444] for
    a description and distinctions between an information and data
    model.

   REQ-003  Data Model to Protocol mapping: Use Case 2.1.1 describes the
    need to instantiate a data model that can map to the SACM protocols
    for posture content operations such as publication, query, change
    detection and asynchronous notifications.

   REQ-004  Endpoint Discovery: Use Case 2.1.2 describes the need to
    discover endpoints and their composition.

   REQ-005  Attribute based query: Use Case 2.1.2 describes the need for
    the data model to support a query operation based on a set of
    attributes to facilitate collection of information such as posture
    assessment, inventory (of endpoints or endpoint components) and
    configuration checklist. .

   REQ-006  Information based query with filtering: Use Case 2.1.3
    describes the need for the data model to support the means for the
    information to be collected through a query mechanism.  Furthermore,
    the query operation requires filtering capabilities to allow for
    only a subset of information to be retrieved.  The query operation
    may be a synchronous request or asynchronous request.

   REQ-007  Asynchronous publication, updates or change modifications
    with filtering: Use Cases 2.1.3, 2.1.4 and 2.1.5 2.1.3, 2.1.4 and 2.1.5 describe the need for
    the data model to support the means for the information to be
    published asynchronously. unsolicited.  Similarly, the data model must support the
    means for a requestor to obtain updates or change modifications
    asynchronously.
    without constant querying (or polling).  Like the query operation,
    these update notifications can be set up with a filter to allow for
    only a subset of posture assessment information to be obtained.

   REQ-008  Data model scalability: Use Cases 2.1.4 and 2.1.5 describes
    the need for the data model to support scalability.  For example,
    the query operation may result in a very large set of attributes as
    well as a large set of targets.

   REQ-009  Separation of Collection Request and Collection Action: The
    data model should distinguish the request for a data attribute for
    collection versus a request to process, execute or apply the data
    attributes for evaluation or analysis.  N.B.  This requirement is
    based on most of the Use Cases in Section of

    [I-D.ietf-sacm-use-cases] and defines a requirement about the
    Information Model, thus this is the same as IM-014.

2.3.  Requirements

2.2.  Requirements for the Architecture

   At the simplest abstraction, the SACM architecture represents the
   core components and interfaces needed to perform the production and
   consumption of posture assessment information.  Requirements relating
   the SACM's architecture include:

   ARCH-001  Scalability: The architectural components must account for
    a range of deployments, from very small set of endpoints are used to
    very large deployments.

   ARCH-002  Agility: The architectural components must account for
    different deployment scenarios where the architectural components
    may be implemented, deployed or used within a single application,
    service, network or may comprise a federated system.

   ARCH-003  Separation of Data and Management functions: SACM must
    define both the configuration and management of the SACM data models
    and protocols used to transport and share posture assessment
    information.

   ARCH-004  Topology Flexibility: Both centralized and decentralized
    (peer-to-peer) information exchange must be supported.  Centralized
    data exchange enables use of a common data format to bridge together
    data exchange between diverse systems, and can leverage a virtual
    data store that centralizes and offloads all data access, storage,
    and maintenance to a dedicated resource.  Decentralized data
    exchange enables simplicity of sharing data between relatively
    uniform systems, and between small numbers of systems, especially
    within a single enterprise domain.

   ARCH-005  Modularity: Announcement and negotiation of functional
    capabilities (such as authentication protocols, authorization
    schemes, data models, transport protocols, etc.) must be supported,
    enabling a SACM component to make inquiries about the capabilities
    of other components in the SACM ecosystem.

2.4.

   ARCH-006  Role based Authorization: The SACM architecture MUST be
    capable of affecting role based authorization.  Distinction of
    endpoints capable and authorized to provide or consume information
    is required to address appropriate access controls.

   ARCH-007  Context based Authorization: The SACM architecture MUST be
    capable of affecting a context based authorization.  Different
    policies (e.g. business, regulatory, etc) may specify what data may
    be exposed or shared by particular consumers as well as how
    consumers may be required to share the information.  The context
    defines the composite set of guidelines provided by policy for
    affecting what posture data is allowed to be communicated from
    providers to consumers.

2.3.  Requirements for the Information Data Model

   The SACM information model represents an abstraction for "what"
   information can be communicated and "how" it is to be represented and
   shared.

   It is expected that as applications may produce Posture assessment
   information, they may share it using a specific data model.
   Similarly, applications consuming or requesting Posture Assessment
   information, may require it be based on a specific data model.  Thus,
   while there may exist different data models and schemas, they should
   adhere to a SACM information model that meets a set of the requirements
   defined in this section.

   The specific requirements for candidate data models include:

   IM-001  The information data model MUST define the data attributes as objects
    that MUST be uniquely referenced (e.g. endpoint, IP address, asset).

   IM-002  The information data model may structure data models be structured into modules and submodules
    to allow for data references within a module.  For example, an
    endpoint may be defined as a module that references one or more
    submodules that further describe the one or more assets.
    Constraints and interfaces may further be defined to resolve or
    tolerate ambiguity in the references (e.g. same IP address used in
    two separate networks).

   IM-003  The interfaces and actions in the information data model MUST include
    support for rootless searches and wildcard searches

   IM-004  The search interfaces and actions MUST include the ability to
    start a search anywhere within a data model structure.

   IM-005  The information data model SHOULD include management of the data,
    including data lifetime management (longevity or expiration of
    data).

   IM-006  Ephemerality: The information model SHOULD include the
    ability to allow providers of data to provide the data as a whole or
    when updates occur.  The data ephemerality
    (update vs. notify). may be provided by a requestor either
    solicited or unsolicited.

   IM-007  The information data model SHOULD allow for a loose coupling between producer the
    provider and consumer. the requestor.

   IM-008  The interfaces and actions in the information data model MUST include the
    ability to identify data from a specific producer. provider.

   IM-009  Data cardinality: The structures in the information data model MUST account for
    metadata cardinality. describe their
    constraints (e.g. cardinality).  As Posture information and the
    tasks for collection, aggregation or evaluation could comprise one
    or more attributes, interfaces and actions must allow and account
    for such cardinality as well as whether the attributes are
    conditional, optional or mandatory.

   IM-010  Data model negotiation: The interfaces and actions in the
    information model MUST include capability negotiation to enable
    discovery of supported and available data types and schemas.

   IM-011  Provenance of data -

    *  Publisher identity, classification, trustworthiness,
       authoritativeness

    *  Freshness of data

    *  Method by which  The data was generated (i.e. self-reported, reported
       by aggregator, result of scan, etc.)

    *  Location of model SHOULD include the ability for providers to
    identify the data

    *  Delta results vs. total results origin.

   IM-012  Freshness: Published data must be associated with the time of
    origination - separately from the time of publication required in
    IM-013.  This allows consumers can make decisions about the
    relevance of the data based on its currency and/or age.

   IM-013  Synchronization: Request and response operations must SHOULD be
    timestamped, and published information must SHOULD capture time of
    publication.  Actions or decisions based on time-sensitive data
    (such as user logon/logoff, endpoint connection/disconnection,
    endpoint behavior events, etc.) are all predicated on a synchronized
    understanding of time.  A method for detecting and reporting time
    discrepancies must SHOULD be provided.

   IM-014

   IM-013  Collection separation: The request for a data item must
    include enough information to properly identify the item to collect,
    but the request shall not be a command to directly execute nor
    directly be applied as arguments to a command.  The purpose of this
    requirement is primarily to reduce the potential attack vectors, but
    has the additional benefit of abstracting the request for collection
    from the collection method thereby allowing more flexibility in how
    collection is implemented.

   IM-015

   IM-014  Collection composition composition: A collection request can be composed
    of multiple collection requests (which yield collected values).
    This must be able to be expressed as part of the collection request
    so that the aggregation can be resolved at the point of collection
    without having to interact with the requester.

2.5.  Requirements for Transport Protocols

   The requirements for transport protocols include:

   T-001  Transport variability: Different transports must be supported
    to address different deployment and time constraints.  Supporting
    transports may be at

   IM-015  Attribute based query: Use Case 2.1.2 describes the Layer 2, Layer 3 and higher application
    layers.

   T-002  Data Integrity: A method need for ensuring data integrity must be
    provided if required at
    the transport layer.

   T-003  Data Protection: Transport protocols must ensure data
    protection for data in transit by encryption model to support a query operation based on a set of
    attributes to facilitate collection of information such as posture
    assessment, inventory (of endpoints or endpoint components) and robustness against
    protocol-based attacks.  Protection
    configuration checklist.

   IM-016  Information based query with filtering: Use Case 2.1.3
    describes the need for the data at rest is not in scope model to support the means for SACM.  Data protection may the
    information to be used for both privacy and non-
    privacy scenarios.

3.  Acknowledgements

   The authors would like collected through a query mechanism.  Furthermore,
    the query operation requires filtering capabilities to thank Barbara Fraser, Jim Bieda and Adam
   Montville allow for reviewing and contributing
    only a subset of information to this draft.

4.  IANA Considerations

   This memo includes no be retrieved.  The query operation
    MAY be a synchronous request to IANA.

5.  Security Considerations

   This document defines or asynchronous request.

   IM-017  Data model scalability: Use Cases 2.1.4 and 2.1.5 describes
    the need for the data model to support scalability.  For example,
    the query operation may result in a very large set of attributes as
    well as a large set of targets.

   IM-018  Attribute Dictionary: Use Cases in the whole of Section 2
    describe the need for an Attribute Dictionary.  With SACM's scope
    focused on Posture Assessment, the data model attribute collection
    and aggregation MUST have a well understood set of attributes
    inclusive of their meaning or usage intent.

   IM-019  Transport Agnostic: the data model SHOULD be transport
    agnostic, to allow for the data operations to leverage the most
    appropriate transport Internet layer (e.g.  Link Layer, TCP, UDP,
    etc.).

   IM-020  The data model SHOULD allow the provider to include the
    information's origination time.

   IM-021  The data model SHOULD allow the provider to include attributs
    defining how the data was generated (e.g. self-reported, reported by
    aggregator, scan result, etc.).

   IM-022  The data model SHOULD allow the provider to include
    attributes defining the location of the data source.

   IM-023  The data model SHOULD allow the provider to include
    attributes defining whether the information provided is a delta,
    partial or full set of information.

2.4.  Requirements for Transport Protocols

   The requirements for SACM.  As such, transport protocols include:

   T-001  Transport variability: Different transports must be supported
    to address different deployment and time constraints.  Supporting
    transports MAY be at the data link layer, network transport layer or
    the application layers.

   T-002  Data Integrity: Transport protocols MUST be able to support
    data integrity.

   T-003  Data Confidentiality: Transport protocols MUST be able to
    support data confidentiality.  Transport protocols SHOULD ensure
    data protection for data in transit by encryption to provide
    confidentiality, integrity and robustness against protocol-based
    attacks.  Note that while the transport MUST be able to support data
    confidentiality, implementations MAY choose to make confidentiality
    optional.  Protection for data at rest is not in scope for SACM.
    Data protection MAY be used for both privacy and non-privacy
    scenarios.

   T-004  Transport protection: Transport protocols MUST be capable of
    supporting mutual authentication and replay protection.

   T-005  Transport reliability: Transport protocols MUST provide
    reliable delivery of data.  This includes the ability to perform
    fragmentation and reassembly, and detect replays.

3.  Acknowledgements

   The authors would like to thank Barbara Fraser, Jim Bieda and Adam
   Montville for reviewing and contributing to this draft.

4.  IANA Considerations

   This memo includes no request to IANA.

5.  Security Considerations

   This document defines the requirements for SACM.  As such, it is
   expected that several data models, protocols and transports may be
   defined or reused from already existing standards.  This section will
   highlight security considerations that may apply to SACM based on the
   architecture and standards applied in SACM.  In particular,
   highlights to security considerations that may apply to the SACM
   reference architecture and standard data models and transports will
   be discussed

   To address security and privacy considerations, the data model,
   protocols and transport must consider authorization based on consumer
   function and privileges, to only allow authorized consumers and
   providers to access specific information being requested or
   published.

   To enable federation across multiple entities (such as across
   organizational or geographic boundaries) authorization must also
   extend to infrastructure elements themselves, such as central
   controllers / brokers / data repositories.

   In addition, authorization needs to extend to specific information or
   resources available in the environment.  In other words,
   authorization should be based on both subject (the information
   requestor) and object (the information requested).  The method by
   which this authorization is applied is unspecified.

   With SACM's charter focus on the sharing of posture information for
   improving efficacy of security applications such as compliance,
   configuration, assurance and other threat and vulnerability reporting
   and remediation systems.  While the goal is to facilitate the flow of
   information securely, it is
   expected important to note that several data models, protocols and transports participating
   endpoints may not be
   defined cooperative or reused trustworthy.

5.1.  Trust between Provider and Requestor

   The information given from already existing standards. the provider to a requestor may come with
   different levels of trustworthiness given the different potential
   deployment scenarios and compromise either at the provider, the
   requestor or devices that are involved in the transport between the
   provider and requestor.  This section will
   highlight security describe the different
   considerations that may apply reduce the level of trustworthiness of the
   information provided.

   In the information transport flow, it is possible that some of the
   devices may serve as proxies or brokers and as such, may be able to
   observe the communications flowing between an information provider
   and requester.  Without appropriate protections

   It is common to, in general, distrust the network service provider,
   unless the full hop by hop communications process flow is well
   understood.  As such, the posture information provider should protect
   the posture information data it provides as well as the transport it
   uses.  Similarly, while there may be providers whose goal is to
   openly share its information, there may also be providers whose
   policy is to grant access to certain posture information based on its
   business or regulatory policy.  In those situations, a provider may
   require full authentication and authorization of the requestor (or
   set of requestors) and share only the authorized information to the
   authenticated and authorized requestors.

   A requestor beyond distrusting the network service provider, must
   also account that the information recieved from the provider may have
   been communicated through an undetermined network communications
   system.  That is, the posture information may have traversed through
   many devices before reaching the requestor.  As such, providing non-
   repudiation in SACM based on is out of scope.  However, SACM specifications
   should provide the
   architecture means for allowing non-repudiation possible and standards applied in SACM.

   To address security at
   minimum, provide endpoint authentication and privacy considerations, transport integrity.

   A requestor may require data freshness indications, both knowledge of
   data origination as well as time of publication so that it can make
   more informed decisions about the relevance of the data model,
   protocols and transport must consider authorization based on consumer
   function and privileges, to only allow authorized consumers and
   providers to access specific information being requested or
   published.

   To enable federation across multiple entities (such as across
   organizational or geographic boundaries) authorization must its
   currency and/or age.

   It is also
   extend important to infrastructure elements themselves, such note that endpoint assessment reports,
   especially as central
   controllers / brokers / data repositories.

   In addition, authorization needs to extend to specific they may be provided by the target endpoint may pose
   untrustworthy information.  The considerations for this is described
   in Section 8 of [RFC5209].

   The trustworthiness of the posture information given by the provider
   to one or
   resources available in many requestors is dependent on several considerations.
   Some of these include the environment.  In other words, requestor requiring:

   o  Full disclosure of the network topology path to the provider(s).

   o  Direct (peer to peer) communication with the provider.

   o  Authentication and authorization should be based on of the provider.

   o  Either or both subject (the information
   requestor) confidentiality and object (the information requested).  The method by
   which this authorization is applied is unspecified. integrity at the transport
      layer.

   o  Either or both confidentiality and integrity at the data layer.

6.  References

6.1.  Normative References

   [I-D.ietf-sacm-terminology]
              Waltermire, D., Montville, A., Harrington, D., and N. Cam-
              Winget, "Terminology for Security Assessment", draft-ietf-
              sacm-terminology-05 (work in progress), August 2014.

   [I-D.ietf-sacm-use-cases]
              Waltermire, D. and D. Harrington, "Endpoint Security
              Posture Assessment - Enterprise Use Cases", draft-ietf-
              sacm-use-cases-07 (work in progress), April 2014.

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

6.2.  Informative References

   [RFC3444]  Pras, A. and J. Schoenwaelder, "On the Difference between
              Information Models and Data Models", RFC 3444, January
              2003.

   [RFC5209]  Sangster, P., Khosravi, H., Mani, M., Narayan, K., and J.
              Tardo, "Network Endpoint Assessment (NEA): Overview and
              Requirements", RFC 5209, June 2008.

6.2.  Informative References

   [RFC3444]  Pras, A. and J. Schoenwaelder, "On the Difference between
              Information Models and Data Models", RFC 3444, January
              2003.

Authors' Addresses

   Nancy Cam-Winget
   Cisco Systems
   3550 Cisco Way
   San Jose, CA  95134
   US

   Email: ncamwing@cisco.com

   Lisa Lorenzin
   Pulse Secure
   2700 Zanker Rd., Suite 200
   San Jose, CA  95134
   US

   Email: llorenzin@pulsesecure.net