SACM N. Cam-Winget
Internet-Draft Cisco Systems
Intended status: Informational L. Lorenzin
Expires: November 10, 2015 Pulse Secure
May 9, 2015
Secure Automation and Continuous Monitoring (SACM) Requirements
draft-ietf-sacm-requirements-05
Abstract
This document defines the scope and set of requirements for the
Secure Automation and Continuous Monitoring (SACM) architecture, data
model and protocols. The requirements and scope are based on the
agreed upon use cases.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirements for SACM . . . . . . . . . . . . . . . . . . 4
2.2. Requirements for the Architecture . . . . . . . . . . . . 6
2.3. Requirements for the Information Model . . . . . . . . . 7
2.4. Requirements for the Data Model . . . . . . . . . . . . . 8
2.5. Requirements for Data Model Operations . . . . . . . . . 11
2.6. Requirements for Transport Protocols . . . . . . . . . . 12
3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
5. Security Considerations . . . . . . . . . . . . . . . . . . . 13
5.1. Trust between Provider and Requestor . . . . . . . . . . 14
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.1. Normative References . . . . . . . . . . . . . . . . . . 15
6.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
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 the enterprise, 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].
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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 data
models, 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. [EDITOR Note: Should this really be a task as I think it
may need to be pre-defined as part of the SACM information model?
This refers to comment on Mar 23 made by Jim Schaad]
2. Map the assets to an endpoint class. This requires populating
the attributes needed to exchange information pertaining to the
assets composing an endpoint. [EDITOR Note: Do we need to add
another task or subtask for the creation of such a mapping as
commented by Jim Schaad?]
3. Policy Definition: This is where an organization can express its
policy for acceptable or problematic values of an asset
attribute. The expected values of an asset attribute are
determined for later comparison against the actual asset
attribute values during the evaluation process. Expected values
may include both those values which are good as well as those
values which represent problems, such as vulnerabilities. The
organization can also specify the asset attributes that are to be
present for a given asset.
4. Evaluation task: Evaluate the actual values of the asset data
against those expressed in the policy.
5. Report results: Report the results of the evaluation for use by
other components. Examples of use of a report would be
additional evaluation, network enforcement, vulnerability
detection and license management.
6. Access Control Policy: Classes of entities and access control
policies are assigned to generic attributes as well as attributes
for specific endpoints.
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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 proposed SACM
standards:
G-001 Solution Extensibility: The data models, protocols, and
transports defined by SACM MUST be designed to allow support for
future extensions.
1. The information model and interfaces MUST support the ability to
add new operations while maintaining backwards compatibility.
2. The query language MUST allow for general inquiries, as well as
expression of specific paths to follow; the retrieval of
specific information based on an event, or on a continuous basis
and the ability to retrieve specific pieces of information,
specific types or classes of information, or the entirety of
available information. [EDITOR Note: this should be part of the
operations on data model section, but we haven't defined
routability for source paths so not sure this is even in scope
for SACM]
3. The information model MUST accommodate the addition of new data
types and/or schemas.
G-002 Interoperability: The data models, protocols, and transports
must be specified with enough details to ensure interoperability.
[EDITOR Note: Can we remove this requirement?]
G-003 Scalability: The data models, protocols, and transports MUST
be scalable. SACM needs to support a broad set of deployment
scenarios. Scalability must be addressed to support:
* Large datagrams: It is possible that the size of posture
assessment information can vary from a single assessment that is
small in size to a very large datagram or a very large set of
assessments.
* Large number of providers and consumers: A deployment may consist
of a very large number of endpoints requesting and/or producing
posture assessment information.
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* Large number of target endpoints: A deployment may be managing
information of a very large number of target endpoints.
G-004 Agility: The data model, protocols, and transports MUST be
suitably specified to enable implementations to fit into different
deployment models and scenarios, including considerations for
implementations of data models and transports operating in
constrained environments.
G-005 Information Extensibility: A method for expressing both
standard and non-standard (implementation-specific) data attributes
while avoiding collisions SHOULD be defined. For interoperability
and scope boundary, an explicit set of data attributes MUST be
defined in the information model as mandatory to implement.
G-006 Data Integrity: A method for ensuring data integrity MUST be
provided. 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. [EDITOR Note: is the intent to provide data transport
integrity only?]
G-007 Data Partitioning: A method for partitioning data MUST be
supported to accommodate considerations such as geographic,
regulatory, operational requirements, overlay boundaries and
federation where the data may be collected in multiple locations and
either centralized or kept in the local region. Where replication
of data is supported, it is required that methods exist to prevent
update loops.
G-008 Versioning and Backward Compatibility: Announcement and
negotiation of versions, inclusive of existing capabilities (such as
transport protocols, data models, specific attributes within data
models, standard attribute expression sets, etc.) MUST be
supported. Negotiation for both versioning and capability is needed
to accommodate future growth and ecosystems with mixed capabilities.
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-010 Endpoint Discovery: SACM MUST define the means by which
endpoints may be discovered. Use Case 2.1.2 describes the need to
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discover endpoints and their composition. [EDITOR Note: should we
make this a sub-requirement to G-009 as suggested by Jim Schaad?]
G-011 Push and Pull Access: Three methods of data access MUST be
supported: the standard Pull model as well as solicited and
unsolicited Push models. All of the methods of data access MUST
support the ability for the initiator to filter the set of posture
assessment information to be delivered. Additionally, the provider
of the information MUST be able to filter the set of posture
assessment information based on the permissions of the recipient.
This requirement is driven by use cases 2.1.3, 2.1.4 and 2.1.5.
G-012 Device Interface: the interfaces by which SACM components
communicate to share endpoint posture information MUST be well
defined. [EDITOR Note: to address Chris' comment, we can clarify by
changing the term interface to communication transport both at the
network and data layer]
G-013 Device location and network topology: the SACM architecture
and interfaces MUST allow for the target endpoint (network) location
and network topology to be modeled and understood. Where
appropriate, the data model and the interfaces SHOULD allow for
discovery of the target endpoint location or network topology or
both.
G-014 Target Endpoint Identity: the SACM architecture and interfaces
MUST support the ability of components to provide attributes that
can be used to compose an identity for a target endpoint. These
identities MAY be composed of attributes from one or more SACM
components.
G-015 Data Access Control: Methods of access control MUST be
supported to accommodate considerations such as geographic,
regulatory, operational and federations. Entities accessing or
publishing data MUST identify themselves and pass access policy.
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
to the SACM's architecture include:
ARCH-001 Scalability: The architectural components MUST account for
a range of deployments, from very small sets of endpoints to very
large deployments.
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ARCH-002 Flexibility: The architectural components MUST account for
different deployment scenarios where the architectural components
may be implemented, deployed, or used within a single application,
service, or 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. The fact that a centralized or
decentralized deployment is used SHOULD be invisible to a Posture
Information Consumer.
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.
ARCH-006 Role-based Authorization: The SACM architecture MUST be
capable of effecting 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 effecting context based authorization. Different
policies (e.g. business, regulatory, etc.) may specify what data may
be exposed to, or shared by consumers based on one or more
attributes of the consumer. The policy may specify that consumers
are required to share specific information either back to the the
system or to administrators.
2.3. Requirements for the Information Model
The SACM information represents the abstracted representation for the
Posture Assessment information to be communicated. SACM data models
must adhere and comply to the SACM Information Model. The
requirements for the SACM information model include:
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IM-001 Extensible Attribute Dictionary: the Information Model MUST
define a minimum set of attributes for communicating Posture
Information, to ensure interoperability between data models.
(Individual data models may define attributes beyond the mandatory-
to-implement minimum set.) The attributes should be defined with a
clear mechanism for extensibility to enable data models to adhere to
SACM's required attributes as well as allow for their own
extensions. The attribute dictionary should be defined with a clear
mechanism for extensibility to enable future versions of the
information model to be expanded with new attributes.
IM-002 Posture Data Publication: The Information Model SHOULD allow
for the data to be provided by an endpoint either solicited or
unsolicited. That is, data models MUST support at least one or both
means to publish data: solicited or unsolicited. For example, a
compliance-server provider may publish endpoint posture information
in response to a request from a consumer (solicited), or it may
publish posture information driven by a change in the posture of the
endpoint (unsolicited).
IM-003 Data model negotiation: SACM's Information Model MUST allow
support for different data models, data model versions and different
versions of the operations (and network layer transport). The SACM
Information Model MUST include the ability to discover and negotiate
the use of a particular or any data model.
IM-004 Data Model Identification: The Information model MUST provide
a means to uniquely identify each Data Model uniquely. The
identifier MUST contain both an identifier of the model and a
version indicator for the model. The identifiers SHOULD be
decomposable so that a customer can query for any version of a
specific model and compare returned values for older or newer than a
desired version.
IM-005 Data lifetime management: The information model MUST provide
a means to allow data models to include data lifetime management.
The information model must identify attributes that can allow data
models to at minimum, identify the data's origination time and
expected time of next update or data longevity (how long should the
data be assumed to still be valid).
2.4. Requirements for the Data Model
The SACM information model represents an abstraction for "what"
information can be communicated and "how" it is to be represented and
shared.
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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 the SACM information model and meets the requirements
defined in this section.
The specific requirements for candidate data models include:
DM-001 The data model MUST define the data attributes as objects
that MUST be uniquely referenced (e.g. endpoint, IP address, asset).
DM-002 The data model MAY 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).
DM-003 Search Flexibility: The search interfaces and actions MUST
include the ability to start a search anywhere within a data model
structure, and the ability to search based on patterns ("wildcard
searches") as well as specific data elements. .
DM-004 Full versus partial updates: The data model SHOULD include
the ability to allow providers of data to provide the data as a
whole or when updates occur. For example, a consumer can request a
full update on initial engagement, then request to receive deltas
(updates containing only the changes since the last update) on an
ongoing basis as new data is generated.
DM-005 The data model SHOULD allow for a loose coupling between the
provider and the requestor.
DM-006 Provider identification: The interfaces and actions in the
data model MUST include the ability to identify data from a specific
provider. For example, a SACM consumer should be able to request
all data to come from a specific provider (e.g. Provider A) as
there can be a larger set of providers.
DM-007 Data cardinality: The data model MUST 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.
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DM-008 Data model negotiation: The interfaces and actions in the
data model MUST include capability negotiation to enable discovery
of supported and available data types and schemas.
DM-009 Data source: The data model MUST include the ability for
providers to identify the data origin. For example, a provider
endpoint could share self-reported data vs. data collected from a
different SACM endpoint or by some externally-observed data.
DM-010 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. [EDITOR Note: Per Jim
Schaad`s comment, this is really subsumed by IM-001. Should we
remove it or incorporate into IM-001?]
DM-011 The data model SHOULD allow the provider to include the
information's origination time.
DM-012 The data model SHOULD allow the provider to include
attributes defining how the data was generated (e.g. self-reported,
reported by aggregator, scan result, etc.).
DM-013 The data model SHOULD allow the provider to include
attributes defining the data source (e.g. hostname, domain (DNS)
name or application name.)"
DM-014 The data model SHOULD allow the provider to include
attributes defining whether the information provided is a delta,
partial, or full set of information.
DM-015 The data model MUST support the collection of attributes by a
variety of collectors, including internal collectors, external
collectors with an authenticated relationship with the endpoint, and
external collectors based on network and other observers.
DM-016 Solicited vs. Unsolicited Updates: The data model SHOULD
enable a provider to publish data either solicited (in response to a
request from a from a consumer) or unsolicited (as new data is
generated, without a request required). For example, an external
collector can publish data in response to a request by a consumer
for information about an endpoint, or can publish data as it
observes new information about an endpoint, without any specific
consumer request triggering the publication.
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2.5. Requirements for Data Model Operations
Posture information data adhering to a Data Model must also provide
interfaces that include operations for access and production of the
data. The specific requirements for such operations include:
OP-001 Time Synchronization: Request and response operations SHOULD
be timestamped, and published information 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 SHOULD be provided.
OP-002 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.
OP-003 Collection composition: A collection request MAY be composed
of multiple collection requests (which yield collected values). The
desire for multiple values MUST 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.
OP-004 Attribute-based query: A query operation SHOULD be based on a
set of attributes. 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.
OP-005 Information-based query with filtering: The query operation
MUST support 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.
OP-006 Data model scalability: The data model MUST be scalable. 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.
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OP-007 The data model MUST allow a SACM component to communicate
what data was used to construct the target endpoint's identity, so
other SACM components can determine whether they are constructing an
equivalent target enpoint (and their identity) and whether they have
confidence in that identity. SACM components SHOULD have interfaces
defined to transmit this data directly or to refer to where the
information can be retrieved.
2.6. Requirements for Transport Protocols
EDITOR Note: this section is meant to relate to Network tranport
layer protocols. For the data, I pesumed the transport would fall as
an operation on the data model. But we need group consensus and
terminology to clarify this.
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 the data link layer, network, transport, or
application layers.
T-002 Data Integrity: Transport protocols MUST be able to ensure
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 to detect replays.
T-006 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.).
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3. Acknowledgements
The authors would like to thank Barbara Fraser, Jim Bieda, and Adam
Montville for reviewing and contributing to this draft. In addition,
we recognize valuable comments and suggestions made by Jim Schaad and
Chris Inacio.
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.
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 important to note that participating
endpoints may not be cooperative or trustworthy.
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5.1. Trust between Provider and Requestor
The information given from 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 describe the different
considerations that may 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 possible for
these proxies and brokers to inject and affect man-in-the-middle
attacks.
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 received 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. Providing non-
repudiation in SACM is out of scope. However, SACM specifications
should provide the means for allowing non-repudiation possible and at
minimum, provide endpoint authentication and 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 based on its
currency and/or age.
It is also important to note that endpoint assessment reports,
especially as they may be provided by the target endpoint may pose
untrustworthy information. The considerations for this is described
in Section 8 of [RFC5209].
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The trustworthiness of the posture information given by the provider
to one or many requestors is dependent on several considerations.
Some of these include the 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 of the provider.
o Either or both confidentiality and 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., Cam-Winget,
N., Lu, J., Ford, B., and M. Kaeo, "Terminology for
Security Assessment", draft-ietf-sacm-terminology-06 (work
in progress), February 2015.
[I-D.ietf-sacm-use-cases]
Waltermire, D. and D. Harrington, "Endpoint Security
Posture Assessment - Enterprise Use Cases", draft-ietf-
sacm-use-cases-09 (work in progress), March 2015.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[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
Cam-Winget & Lorenzin Expires November 10, 2015 [Page 15]
Internet-Draft Abbreviated Title May 2015
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
Cam-Winget & Lorenzin Expires November 10, 2015 [Page 16]