INTERNET-DRAFT Jeffrey D. Case
SNMP Research, Inc.
Russ Mundy
Trusted Information Systems, Inc.
David Partain
SNMP Research Europe
Bob Stewart
Cisco Systems
Introduction to Version 3 of the
Internet-standard Network Management Framework
1998/08/07 13:38:54
draft-ietf-snmpv3-intro-01.txt
1.3 -- 1998/08/07 13:38:54
Status of this Memo
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Abstract
The purpose of this document is to provide an overview of the third
version of the Internet-standard Management Framework, termed the
SNMP version 3 Framework (SNMPv3). This Framework is derived from
and builds upon both the original Internet-standard Management
Framework (SNMPv1) and the second Internet-standard Management
Framework (SNMPv2).
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The architecture is designed to be modular to allow the evolution of
the Framework over time.
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1. Introduction
This document is an introduction to the third version of the
Internet-standard Management Framework, termed the SNMP version 3
Management Framework (SNMPv3) and has multiple purposes.
First, it describes the relationship between the SNMP version 3
(SNMPv3) specifications and the specifications of the SNMP version 1
(SNMPv1) Management Framework, the SNMP version 2 (SNMPv2) Management
Framework, and the Community-based Administrative Framework for
SNMPv2.
Second, it provides a roadmap to the multiple documents which contain
the relevant specifications.
Third, this document provides a brief easy-to-read summary of the
contents of each of the relevant specification documents.
[Finally, this document may someday contain information regarding
what it means to be a compliant SNMPv3 implementation, i.e., a set of
applicability statements, but it does not now, and if it never does,
then this sentence will be deleted.]
This document is intentionally tutorial in nature and, as such, may
occasionally be "guilty" of oversimplification. In the event of a
conflict or contradiction between this document and the more detailed
documents for which this document is a roadmap, the specifications in
the more detailed documents shall prevail.
Further, the detailed documents attempt to maintain separation
between the various component modules in order to specify well-
defined interfaces between them. This roadmap document, however,
takes a different approach and attempts to provide an integrated view
of the various component modules in the interest of readability.
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2. The Internet Standard Management Framework
The third version of the Internet Standard Management Framework (the
SNMPv3 Framework) is derived from and builds upon both the original
Internet-standard Management Framework (SNMPv1) and the second
Internet-standard Management Framework (SNMPv2).
All versions (SNMPv1, SNMPv2, and SNMPv3) of the Internet Standard
Management Framework share the same basic structure and components.
Furthermore, all versions of the specifications of the Internet
Standard Management Framework follow the same architecture.
2.1 Basic Structure and Components
An enterprise deploying the Internet Standard Management Framework
contains four basic components:
* several (typically many) managed nodes, each with an SNMP entity
which provides remote access to management instrumentation
(traditionally called an agent);
* at least one SNMP entity with management applications (typically
called a manager),
* a management protocol used to convey management information
between the SNMP entities, and
* management information.
The management protocol is used to convey management information
between SNMP entities such as managers and agents.
This basic structure is common to all versions of the Internet
Standard Management Framework; i.e., SNMPv1, SNMPv2, and SNMPv3.
2.2 Architecture of the Internet Standard Management Framework
The specifications of the Internet Standard Management Framework are
based on a modular architecture. This framework is more than just a
protocol for moving data. It consists of:
* a data definition language,
* definitions of management information (the Management
Information Base, or MIB),
* a protocol definition, and
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* security and administration.
Over time, as the Framework has evolved from SNMPv1, through SNMPv2,
to SNMPv3, the definitions of each of these architectural components
have become richer and more clearly defined, but the fundamental
architecture has remained consistent.
One prime motivator for this modularity was to enable the ongoing
evolution of the Framework as is documented in RFC 1052 [14]. When
originally envisioned, this capability was to be used to ease the
transition from SNMP-based management of internets to management
based on OSI protocols. To this end, the framework was architected
with a protocol-independent data definition language and Management
Information Base along with a MIB-independent protocol. This
separation was designed to allow the SNMP-based protocol to be
replaced without requiring the management information to be redefined
or reinstrumented. History has shown that the selection of this
architecture was the right decision for the wrong reason -- it turned
out that this architecture has eased the transition from SNMPv1 to
SNMPv2 and from SNMPv2 to SNMPv3 rather than easing the transition
away from management based on the Simple Network Management Protocol.
The SNMPv3 Framework builds and extends these architectural
principles by:
* building on these four basic architectural components, in some
cases incorporating them from the SNMPv2 Framework by reference,
and
* by using these same layering principles in the definition of new
capabilities in the security and administration portion of the
architecture.
Those who are familiar with the architecture of the SNMPv1 Management
Framework and the SNMPv2 Management Framework will find many familiar
concepts in the architecture of the SNMPv3 Management Framework.
However, in some cases, the terminology may be somewhat different.
3. The SNMPv1 Management Framework
The original Internet-standard Network Management Framework (SNMPv1)
is defined in the following documents:
* STD 16, RFC 1155 [1] which defines the Structure of Management
Information (SMI), the mechanisms used for describing and naming
objects for the purpose of management.
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* STD 16, RFC 1212 [2] which defines a more concise description
mechanism for describing and naming management information objects,
but which is wholly consistent with the SMI.
* STD 15, RFC 1157 [3] which defines the Simple Network Management
Protocol (SNMP), the protocol used for network access to managed
objects and event notification. Note this document also defines an
initial set of event notifications.
Additionally, two documents are generally considered to be companions
to these three:
* STD 17, RFC 1213 [13] which contains definitions for the base
set of management information
* RFC 1215 [25] defines a concise description mechanism for
defining event notifications, which are called traps in the SNMPv1
protocol. It also specifies the generic traps from RFC 1157 in the
concise notation.
These documents describe the four parts of the first version of the
SNMP Framework.
3.1 The SNMPv1 Data Definition Language.
The first two and the last document describe the SNMPv1 data
definition language. Note that due to the initial requirement that
the SMI be protocol-independent, the first two SMI documents do not
provide a means for defining event notifications (traps). Instead,
the SNMP protocol document defines a few standardized event
notifications (generic traps) and provides a means for additional
event notifications to be defined. The last document specifies a
straight-forward approach towards defining event notifications used
with the SNMPv1 protocol. At the time that it was written, use of
traps in the Internet-standard network management framework was
controversial. As such, RFC 1215 was put forward with the status of
"Informational", which was never updated because it was believed that
the second version of the SNMP Framework would replace the first
version. Note that the SNMPv1 data definition language is sometimes
refered to as SMIv1.
3.2 Management Information.
The data definition language described in the first two documents was
first used to define the now-historic MIB-I as specified in RFC 1066
[12], and was subsequently used to define MIB-II as specified in RFC
1213 [13].
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Later, after the publication of MIB-II, a different approach to
management information definition was taken from the earlier approach
of having a single committee staffed by generalists work on a single
document to define the Internet-standard MIB. Rather, many mini-MIB
documents were produced in a parallel and distributed fashion by
groups chartered to produce a specification for a focused portion of
the Internet-standard MIB and staffed by personnel with expertise in
those particular areas ranging from various aspects of network
management, to system management, and application management.
3.3 Protocol Operations.
The third document, STD 15, describes the SNMPv1 protocol operations
performed by protocol data units (PDUs) on lists of variable bindings
and describes the format of SNMPv1 messages. The operators defined by
SNMPv1 are: get, get-next, get-response, set-request, and trap.
Typical layering of SNMP on a connectionless transport service is
also defined.
3.4 SNMPv1 Security and Administration.
STD 15 also describes an approach to security and administration.
Many of these concepts are carried forward into the SNMPv3 Framework.
The SNMPv1 Framework describes the encapsulation of SNMPv1 PDUs in
SNMP messages between SNMP entities and distinguishes between
application entities and protocol entities. In SNMPv3, these are
renamed applications and engines, respectively.
The SNMPv1 Framework also introduces the concept of an authentication
service supporting one or more authentication schemes. In SNMPv3,
the concept of an authentication service is expanded to include other
services, such as privacy.
Finally, the SNMPv1 Framework introduces access control based on a
concept called an SNMP MIB view. The SNMPv3 Framework specifies a
fundamentally similar concept called view-based access control.
However, while the SNMPv1 Framework anticipated the definition of
multiple authentication schemes, it did not define any such schemes
other than a trivial authentication scheme based on community
strings. This was a known fundamental weakness in the SNMPv1
Framework but it was thought at that time that the definition of
commercial grade security might be contentious in its design and
difficult to get approved because "security" means many different
things to different people. To that end, and because some users do
not require strong authentication, the SNMPv1 architected an
authentication service as a separate block to be defined "later" and
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the SNMPv3 Framework provides an architecture for use within that
block as well as a definition for its subsystems.
4. The SNMPv2 Management Framework
The SNMPv2 Management Framework is fully described in [4-9] and
coexistence and transition issues relating to SNMPv1 and SNMPv2 are
discussed in [10].
SNMPv2 provides several advantages over SNMPv1, including:
* expanded data types (e.g., 64 bit counter)
* improved efficiency and performance (get-bulk operator)
* confirmed event notification (inform operator)
* richer error handling (errors and exceptions)
* improved sets, especially row creation and deletion
* fine tuning of the data definition language
However, the SNMPv2 Framework, as described in these documents, is
incomplete in that it does not meet the original design goals of the
SNMPv2 project. The unmet goals included provision of security and
administration delivering so-called "commercial grade" security with
* authentication: origin identification, message integrity,
and some aspects of replay protection;
* privacy: confidentiality;
* authorization and access control; and
* suitable remote configuration and administration capabilities
for these features.
The SNMPv3 Management Framework, as described in this document and
the companion documents, addresses these significant deficiencies.
5. The SNMPv3 Working Group
This document, and its companion documents, were produced by the
SNMPv3 Working Group of the Internet Engineering Task Force (IETF).
The SNMPv3 Working Group was chartered to prepare recommendations for
the next generation of SNMP. The goal of the Working Group was to
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produce the necessary set of documents that provide a single standard
for the next generation of core SNMP functions. The single, most
critical need in the next generation is a definition of security and
administration that makes SNMP-based management transactions secure
in a way which is useful for users who wish to use SNMPv3 to manage
networks, the systems that make up those networks, and the
applications which reside on those systems, including manager-to-
agent, agent-to-manager, and manager-to-manager transactions.
In the several years prior to the chartering of the Working Group,
there were a number of activities aimed at incorporating security and
other improvements to SNMP. These efforts included:
* "SNMP Security" circa 1991-1992 [RFC 1351 - RFC 1353],
* "SMP" circa 1992-1993,
* "The Party-based SNMPv2" circa 1993-1995 [RFC 1441 - RFC 1452].
Each of these efforts incorporated commercial grade, industrial
strength security including authentication, privacy, authorization,
view-based access control, and administration, including remote
configuration.
These efforts fed the development of the SNMPv2 Management Framework
as described in RFCs 1902 - 1908. However, the Framework described
in those RFCs had no standards-based security and administrative
framework of its own; rather, it was associated with multiple
security and administrative frameworks, including:
* "The Community-based SNMPv2" (SNMPv2c) [RFC 1901],
* "SNMPv2u" [RFCs 1909 - 1910] and
* "SNMPv2*."
SNMPv2c had the endorsement of the IETF but no security and
administration whereas both SNMPv2u and SNMPv2* had security but
lacked the endorsement of the IETF.
The SNMPv3 Working Group was chartered to produce a single set of
specifications for the next generation of SNMP, based upon a
convergence of the concepts and technical elements of SNMPv2u and
SNMPv2*, as was suggested by an advisory team which was formed to
provide a single recommended approach for SNMP evolution.
In so doing, the Working Group charter defined the following
objectives:
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* accommodate the wide range of operational environments with
differing management demands;
* facilitate the need to transition from previous, multiple
protocols to SNMPv3;
* facilitate the ease of setup and maintenance activities.
In the initial work of the SNMPv3 Working Group, the group focused on
security and administration, including
* authentication and privacy,
* authorization and view-based access control, and
* standards-based remote configuration of the above.
The SNMPv3 Working Group did not "reinvent the wheel," but reused the
SNMPv2 Draft Standard documents, i.e., RFCs 1902 through 1908.
The SNMPv3 Working Group produced a design based on a modular
architecture with evolutionary capabilities with emphasis on
layering. As a result, SNMPv3 is SNMPv2 plus security and
administration.
In doing so, the Working Group achieved the goal of producing a
single specification which has both the endorsement of the IETF and
security and administration.
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6. SNMPv3 Framework Module Specifications
The specification of the SNMPv3 Management Framework is partitioned
in a modular fashion among several documents. It is the intention of
the SNMPv3 Working Group that, with proper care, any or all of the
individual documents can be revised, upgraded, or replaced as
requirements change, new understandings are obtained, and new
technologies become available.
Whenever feasible, the initial document set which defines the SNMPv3
Management Framework leverages prior investments defining and
implementing the SNMPv2 Management Framework by incorporating by
reference each of the specifications of the SNMPv2 Management
Framework.
The SNMPv3 Framework augments those specifications with
specifications for security and administration for SNMPv3.
The documents which specify the SNMPv3 Management Framework follow
the same architecture as those of the prior versions and can be
organized for expository purposes into four main categories as
follows:
* the data definition language,
* Management Information Base (MIB) modules,
* protocol operations, and
* security and administration.
The first three sets of documents are incorporated from SNMPv2. The
fourth set of documents are new to SNMPv3, but, as described
previously, build on significant prior related works.
6.1 Data Definition Language
The specifications of the data definition language includes RFC 1902,
"The Structure of Management Information for Version 2 of the Simple
Network Management Protocol (SNMPv2)" [4], and related
specifications. The Structure of Management Information (SMI)
defines fundamental data types, an object model, and the rules for
writing and revising MIB modules. Related specifications include RFC
1903 and RFC 1904. The updated data definition language is sometimes
refered to as SMIv2.
RFC 1903, "Textual Conventions for Version 2 of the Simple Network
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Management Protocol (SNMPv2)" [5], defines an initial set of
shorthand abbreviations which are available for use within all MIB
modules for the convenience of human readers and writers.
RFC 1904, "Conformance Statements for Version 2 of the Simple Network
Management Protocol (SNMPv2)" [6], defines the format for compliance
statements which are used for describing requirements for agent
implementations and capability statements which can be used to
document the characteristics of particular implementations.
6.2 MIB Modules
MIB modules usually contain object definitions, may contain
definitions of event notifications, and sometimes include compliance
statements specified in terms of appropriate object and event
notification groups. As such, MIB modules define the management
information maintained by the instrumentation in managed nodes, made
remotely accessible by management agents, conveyed by the management
protocol, and manipulated by management applications.
MIB modules are defined according the rules defined in the documents
which specify the data definition language, principally the SMI as
supplemented by the related specifications.
There is a large and growing number of standards-based MIB modules,
as defined in the periodically updated list of standard protocols
[STD 0001, RFC 2000]. As of this writing, there are nearly 100
standards-based MIB modules with a total number of defined objects
approaching 10,000. In addition, there is an even larger and growing
number of enterprise-specific MIB modules defined unilaterally by
various vendors, research groups, consortia, and the like resulting
in an unknown and virtually uncountable number of defined objects.
In general, management information defined in any MIB module,
regardless of the version of the data definition language used, can
be used with any version of the protocol. For example, MIB modules
defined in terms of the SNMPv1 SMI (SMIv1) are compatible with the
SNMPv3 Management Framework and can be conveyed by the protocols
specified therein. Furthermore, MIB modules defined in terms of the
SNMPv2 SMI (SMIv2) are compatible with SNMPv1 protocol operations and
can be conveyed by it. However, there is one noteworthy exception:
the Counter64 datatype which can be defined in a MIB module defined
in SMIv2 format but which cannot be conveyed by an SNMPv1 protocol
engine.
6.3 Protocol Operations and Transport Mappings
The specifications for the protocol operations and transport mappings
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of the SNMPv3 Framework are incorporated by reference to the two
SNMPv2 Framework documents.
The specification for protocol operations is found in RFC 1905,
"Protocol Operations for Version 2 of the Simple Network Management
Protocol (SNMPv2)" [7].
The specification of transport mappings is found in RFC 1906,
"Transport Mappings for Version 2 of the Simple Network Management
Protocol (SNMPv2)" [8].
6.4 SNMPv3 Security and Administration
The SNMPv3 document series defined by the SNMPv3 Working Group
consists of six [seven] documents at this time:
RFC xxxx, "Introduction to the Third Version of the Internet
Standard Management Framework (SNMPv3)," which is this document.
RFC 2271, "An Architecture for Describing SNMP Management
Frameworks" [15], describes the overall architecture with special
emphasis on the architecture for security and administration.
RFC 2272, "Message Processing and Dispatching for the Simple
Network Management Protocol (SNMP)" [16], describes the possibly
multiple message processing models and the dispatcher portion that
can be a part of an SNMP protocol engine.
RFC 2273, "SNMPv3 Applications" [17], describes the five types of
applications that can be associated with an SNMPv3 engine and
their elements of procedure.
RFC 2274, "The User-Based Security Model for Version 3 of the
Simple Network Management Protocol (SNMPv3)" [18], describes the
threats, mechanisms, protocols, and supporting data used to
provide SNMP message-level security.
RFC 2275, "View-based Access Control Model for the Simple Network
Management Protocol (SNMP)" [19], describes how view-based access
control can be applied within command responder and notification
originator applications.
RFC yyyy, "SNMPv3 Coexistence and Transition" [20], does not exist
yet and is still in development.
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7. Document Summaries
The following sections provide brief summaries of each document with
slightly more detail than is provided in the overviews, above.
7.1 Structure of Management Information
Management information is viewed as a collection of managed objects,
residing in a virtual information store, termed the Management
Information Base (MIB). Collections of related objects are defined
in MIB modules. These modules are written in the SNMP MIB module
language, which contains elements of OSI's Abstract Syntax Notation
One (ASN.1) [11] language. RFC 1902, RFC 1903, and RFC 1904 together
define the MIB module language, specify the base data types for
objects, specify a core set of short-hand specifications for data
types called textual conventions, and specify a few administrative
assignments of object identifier (OID) values.
The SMI is divided into three parts: module definitions, object
definitions, and, trap definitions.
(1) Module definitions are used when describing information modules.
An ASN.1 macro, MODULE-IDENTITY, is used to convey concisely the
semantics of an information module.
(2) Object definitions are used when describing managed objects. An
ASN.1 macro, OBJECT-TYPE, is used to convey concisely the syntax
and semantics of a managed object.
(3) Notification definitions are used when describing unsolicited
transmissions of management information. An ASN.1 macro,
NOTIFICATION-TYPE, is used to convey concisely the syntax and
semantics of a notification.
7.1.1 Base SMI Specification
RFC 1902 specifies the base data types for the MIB module language,
which include: Integer32, enumerated integers, Unsigned32, Gauge32,
Counter32, Counter64, TimeTicks, OCTET STRING, OBJECT IDENTIFIER,
IpAddress, Opaque, and BITS. It also assigns values to several object
identifiers. RFC 1902 further defines the following constructs of
the MIB module language:
* IMPORTS to allow the specification of items that are used
in a MIB module, but defined in another MIB module.
* MODULE-IDENTITY to specify for a MIB module a description
and administrative information such as contact and revision
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history.
* OBJECT-IDENTITY and OID value assignments to specify a
an OID value.
* OBJECT-TYPE to specify the data type, status, and the semantics
of managed objects.
* SEQUENCE type assignement to list the columnar objects in
a table.
* NOTIFICATION-TYPE construct to describe an event notification.
7.1.2 Textual Conventions
When designing a MIB module, it is often useful to specify in a
short-hand way the semantics for a set of objects with similar
behavior. This is done by defining a new data type using a base data
type specified in the SMI. Each new type has a different name, and
specifies a base type with more restrictive semantics. These newly
defined types are termed textual conventions, and are used for the
convenience of humans reading a MIB module and potentially by
"intelligent" management applications. It is the purpose of RFC
1903, Textual Conventions for SNMPv2 [5], to define the construct,
TEXTUAL-CONVENTION, of the MIB module language used to define such
new types and to specify an initial set of textual conventions
available to all MIB modules.
7.1.3 Conformance Statements
It may be useful to define the acceptable lower-bounds of
implementation, along with the actual level of implementation
achieved. It is the purpose of RFC 1904, Conformance Statements for
SNMPv2 [6], to define the constructs of the MIB module language used
for these purposes. There are two kinds of constructs:
(1) Compliance statements are used when describing requirements for
agents with respect to object and event notification definitions.
The MODULE-COMPLIANCE construct is used to convey concisely
such requirements.
(2) Capability statements are used when describing capabilities of
agents with respect to object and event notification definitions.
The AGENT-CAPABILITIES construct is used to convey concisely such
capabilities.
Finally, collections of related objects and collections of related
event notifications are grouped together to form a unit of
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conformance. The OBJECT-GROUP construct is used to convey concisely
the objects in and the semantics of an object group. The
NOTIFICATION-GROUP construct is used to convey concisely the event
notifications in and the semantics of an event notification group.
7.2 Protocol Operations
The management protocol provides for the exchange of messages which
convey management information between the agents and the management
stations. The form of these messages is a message "wrapper" which
encapsulates a Protocol Data Unit (PDU).
It is the purpose of RFC 1905, Protocol Operations for SNMPv2 [7], to
define the operations of the protocol with respect to the sending and
receiving of the PDUs.
7.3 Transport Mappings
SNMP Messages may be used over a variety of protocol suites. It is
the purpose of RFC 1906, Transport Mappings for SNMPv2 [8], to define
how SNMP messages maps onto an initial set of transport domains.
Other mappings may be defined in the future.
Although several mappings are defined, the mapping onto UDP is the
preferred mapping. As such, to provide for the greatest level of
interoperability, systems which choose to deploy other mappings
should also provide for proxy service to the UDP mapping.
7.4 Protocol Instrumentation
It is the purpose of RFC 1907, the Management Information Base for
SNMPv2 document [9] to define managed objects which describe the
behavior of an SNMPv2 entity.
7.5 Architecture / Security and Administration
It is the purpose of RFC 2271, "SNMPv3 Architecture" [15], to define
an architecture for defining SNMP Management Frameworks. While
addressing general architectural issues, it focuses on aspects
related to security and administration. It defines a number of terms
used throughout the SNMPv3 Management Framework and, in so doing,
clarifies and extends the naming of
* engines and applications,
* entities (service providers such as the engines in agents
and managers),
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* identities (service users), and
* management information, including support for multiple
logical contexts.
The document contains a small MIB module which is implemented by all
authoritative SNMPv3 protocol engines.
7.6 Message Processing and Dispatch (MPD)
RFC 2272, "Message Processing and Dispatching for the Simple Network
Management Protocol (SNMP)" [16], describes the Message Processing
and Dispatching for SNMP messages within the SNMP architecture. It
defines the procedures for dispatching potentially multiple versions
of SNMP messages to the proper SNMP Message Processing Models, and
for dispatching PDUs to SNMP applications. This document also
describes one Message Processing Model - the SNMPv3 Message
Processing Model.
It is expected that an SNMPv3 protocol engine MUST support at least
one Message Processing Model. An SNMPv3 protocol engine MAY support
more than one, for example in a multilingual system which provides
simultaneous support of SNMPv3 and SNMPv1 and/or SNMPv2c.
7.7 SNMPv3 Applications
It is the purpose of RFC 2273, "SNMPv3 Applications" to describe the
five types of applications which can be associated with an SNMP
engine. They are: Command Generators, Command Responders,
Notification Originators, Notification Receivers, and Proxy
Forwarders.
The document also defines MIB modules for specifying targets of
management operations (including notifications), for notification
filtering, and for proxy forwarding.
7.8 User-based Security Model (USM)
RFC 2274, the "User-based Security Model (USM) for version 3 of the
Simple Network Management Protocol (SNMPv3)" describes the User-based
Security Model for SNMPv3. It defines the Elements of Procedure for
providing SNMP message-level security.
The document describes the two primary and two secondary threats
which are defended against by the User-based Security Model. They
are: modification of information, masquerade, message stream
modification, and [optionally] disclosure.
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The USM utilizes MD5 [21] and the Secure Hash Algorithm [22] as keyed
hashing algorithms [22] for digest computation to provide data
integrity
* to directly protect against data modification attacks,
* to indirectly provide data origin authentication, and
* to defend against masquerade attacks.
The USM uses loosely synchronized monotonically increasing time
indicators to defend against certain message stream modification
attacks. Automatic clock synchronization mechanisms based on the
protocol are specified without dependence on third-party time sources
and concomitant security considerations.
The USM uses the Data Encryption Standard (DES) [24] in the cipher
block chaining mode (CBC) [optionally] to protect against disclosure.
The document also includes a MIB suitable for remotely monitoring and
managing the configuration parameters for the USM, including key
distribution and key management.
A single protocol entity may provide simultaneous support for
multiple security models as well as multiple authentication and
privacy protocols. All of the protocols used by the USM are based on
symmetric cryptography, i.e., private key mechanisms. The SNMPv3
architecture admits the use of public key cryptography, but as of
this writing, no SNMPv3 security models utilizing public key
cryptography have been published.
7.9 View-based Access Control (VACM)
The purpose of RFC 2275, the "View-based Access Control Model (VACM)
for the Simple Network Management Protocol (SNMP)" is to describe the
View-based Access Control Model for use in the SNMP architecture.
The VACM can simultaneously be associated in a single engine
implementation with multiple Message Processing Models and multiple
Security Models.
It is architecturally possible to have multiple, different, Access
Control Models active and present simultaneously in a single engine
implementation, but this is expected to be *_very_* rare in practice
and *_far_* less common than simultaneous support for multiple
Message Processing Models and/or multiple Security Models.
7.10 SNMPv3 Coexistence and Transition
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This document does not exist yet. It needs to contain:
background of 2 approaches to coexistence and transition
multilingual approach
proxy approach
mapping functions derived from rfc 2089 but incorporated by value
rather than by reference in order to get these functions onto the
standards track and to fix up any lingering problems
a community-based security model consistent with the architecture
and containing a suitable MIB module for remote configuration thereof
for use by multilingual engines supporting snmpv1 and snmpv2c in
addition to snmpv3
This could be multiple documents, but it really isn't necessary to have more
than one and fewer are better than many.
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8. Security Considerations
As this document is primarily a roadmap document, it introduces no
new security considerations. The reader is referred to the relevant
sections of each of the referenced documents for information about
security considerations.
9. Editors' Addresses
Jeffrey Case
SNMP Research, Inc.
3001 Kimberlin Heights Road
Knoxville, TN 37920-9716
USA
Phone: +1 423 573 1434
EMail: case@snmp.com
Russ Mundy
Trusted Information Systems
3060 Washington Rd
Glenwood, MD 21738
USA
Phone: +1 301 854 6889
Email: mundy@tis.com
David Partain
SNMP Research Europe
Teknikringen 1
S-583 30 Linkoping
Sweden
Phone: +46 13 21 18 81
Email: partain@europe.snmp.com
Bob Stewart
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
U.S.A.
Phone: +1 603 654 6923
EMail: bstewart@cisco.com
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10. Full Copyright Statement
Copyright (C) The Internet Society (1998). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implmentation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS 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."
11. References
[1] Rose, M., and K. McCloghrie, "Structure and Identification of
Management Information for TCP/IP-based internets", STD 16, RFC
1155, May 1990.
[2] Rose, M., and K. McCloghrie, "Concise MIB Definitions", STD 16,
RFC 1212, March 1991.
[3] Case, J., Fedor, M., Schoffstall, M., Davin, J., "Simple Network
Management Protocol", STD 15, RFC 1157, SNMP Research, Performance
Systems International, MIT Laboratory for Computer Science, May
1990.
[4] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
S. Waldbusser, "Structure of Management Information for Version 2
of the Simple Network Management Protocol (SNMPv2)", RFC 1902,
January 1996.
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[5] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
S. Waldbusser, "Textual Conventions for Version 2 of the Simple
Network Management Protocol (SNMPv2)", RFC 1903, January 1996.
[6] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
S. Waldbusser, "Conformance Statements for Version 2 of the Simple
Network Management Protocol (SNMPv2)", RFC 1904, January 1996.
[7] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
S. Waldbusser, "Protocol Operations for Version 2 of the Simple
Network Management Protocol (SNMPv2)", RFC 1905, January 1996.
[8] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
S. Waldbusser, "Transport Mappings for Version 2 of the Simple
Network Management Protocol (SNMPv2)", RFC 1906, January 1996.
[9] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
S. Waldbusser, "Management Information Base for Version 2 of the
Simple Network Management Protocol (SNMPv2)", RFC 1907,
January 1996.
[10] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
S. Waldbusser, "Coexistence between Version 1 and Version 2 of the
Internet-standard Network Management Framework", RFC 1908,
January 1996.
[11] Information processing systems - Open Systems Interconnection -
Specification of Abstract Syntax Notation One (ASN.1),
International Organization for Standardization. International
Standard 8824, (December, 1987).
[12] McCloghrie, K., and M. Rose, "Management Information Base for
Network Management of TCP/IP-based Internets", RFC 1066, August 1988.
[13] McCloghrie, K., and M. Rose, "Management Information Base for
Network Management of TCP/IP-based internets: MIB-II, RFC 1213,
March 1991.
[14] Cerf, V., "IAB Recommendations for the Development of Internet
Network Management Standards", RFC 1052, April 1988.
[15] Harrington, D, R. Presuhn, and B. Wijnen, "An Architecture for
Describing SNMP Management Frameworks, RFC 2271, January, 1998.
[16] Case, J., Harrington, D., Presuhn, R., and B. Wijnen, "Message
Processing and Dispatching for the Simple Network Management
Protocol (SNMP)", RFC 2272, January 1998.
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[17] Levi, D., Meyer, P., and B. Stewart, "SNMPv3 Applications", RFC 2273,
January 1998.
[18] Blumenthal, U., and B. Wijnen, "The User-Based Security Model for
Version 3 of the Simple Network Management Protocol (SNMPv3)",
RFC 2274, January 1998.
[19] Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based Access Control
Model for the Simple Network Management Protocol (SNMP)", RFC 2275,
January 1998.
[20] TBD, "SNMPv3 Coexistence and Transition", RFC yyyy, Work in progress,
date TBD.
[21] Rivest, R., "Message Digest Algorithm MD5", RFC 1321, April 1992.
[22] Secure Hash Algorithm. NIST FIPS 180-1, (April, 1995)
http://csrc.nist.gov/fips/fip180-1.txt (ASCII)
http://csrc.nist.gov/fips/fip180-1.ps (Postscript)
[23] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC:
Keyed-Hashing for Message Authentication", RFC 2104, February
1997.
[24] Data Encryption Standard, National Institute of Standards
and Technology. Federal Information Processing Standard (FIPS)
Publication 46-1. Supersedes FIPS Publication 46, (January, 1977;
reaffirmed January, 1988).
[25] M.T. Rose, "A Convention for Defining Traps for use with the
SNMP", RFC 1215, March 1991.
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