draft-ietf-snmpv3-next-gen-arch-04.txt   draft-ietf-snmpv3-next-gen-arch-05.txt 
An Architecture for Describing INTERNET-DRAFT D. Harrington
SNMP Management Frameworks
1 August 1997
D. Harrington
Cabletron Systems, Inc. Cabletron Systems, Inc.
dbh@cabletron.com R. Presuhn
BMC Software, Inc.
B. Wijnen B. Wijnen
IBM T.J. Watson Research IBM T.J. Watson Research
wijnen@vnet.ibm.com 30 September 1997
<draft-ietf-snmpv3-next-gen-arch-04.txt> An Architecture for Describing
SNMP Management Frameworks
<draft-ietf-snmpv3-next-gen-arch-05.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft. Internet-Drafts are working This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts. working documents as Internet-Drafts.
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time. It is inappropriate to use Internet-Drafts as reference material time. It is inappropriate to use Internet-Drafts as reference
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ftp.isi.edu (US West Coast).
Abstract Abstract
This document describes an architecture for describing SNMP Management This document describes an architecture for describing SNMP
Frameworks. The architecture is designed to be modular to allow the Management Frameworks. The architecture is designed to be modular to
evolution of the SNMP protocol standards over time. The major portions allow the evolution of the SNMP protocol standards over time. The
of the architecture are an SNMP engine containing a Message Processing major portions of the architecture are an SNMP engine containing a
Subsystem, a Security Subsystem and an Access Control Subsystem, and Message Processing Subsystem, a Security Subsystem and an Access
possibly multiple SNMP applications which provide specific functional Control Subsystem, and possibly multiple SNMP applications which
processing of network management data. provide specific functional processing of management data.
Harrington/Wijnen Expires February 1998 [Page 1]
0. Issues
0.1. Resolved Issues
. contextEngineID in reportPDU = snmpEngineID of report generator
. returnResponsePDU - are all parameters needed? overrides allowed?
all parameters kept for future flexibility
overrides not supported by SNMPv3
. use of IN/OUT indicators in primitives accepted
. NT/Unix-like access control - can be defined as future model
. user-friendly names? yes, but with limits
. SnmpAdminString as index? yes, but restrict sizes
. need both MMS and maxSizeResponseScopedPDU? yes.
. synchronous vs. asynchronous primitives? synchronous preferred
. should we change MIB naming? no, it is acceptable
. is it ok that USM is bound to SNMPv3? while undesirable, it is
acceptable. A cleaner model may be defined in the future.
. should securityModel "any" be supported? for ACM use, not SNMPv3
. what defines SNMPv3? a document will be published after Munich
. Is an application-level handle needed for request/response matching?
yes. create sendPduhandle
. Is wildcard contextEngineID/pduType registration needed? No. This is
an internal interface, and wildcarding can be supported by an
implementation, but is not required in the standard.
. Should indices be integers or SnmpAdminStrings? SnmpAdminStrings
is the consensus.
. Should protocols be identified as OIDs or Integers? OIDs
. terminology:
securityLevel rather than LoS
msgXXXX to identify message fields in SNMPv3
. OID or Integer for auth/priv protocol identifiers
Consensus: use OID
. Is Glossary needed to describe primitive parameters, or is the
expanded template adequate for this purpose?
Consensus: Terms are basically all defined in section 3.
. state_reference releases
Consensus: documents checked; we think it is OK now
. new SnmpEngineID format rules to be discussed yet.
Consensus: Limit size to be 1..32
. needs changes to meet STDGUIDE guidelines
We think we're meeting them now
. we punted snmpEngineMaxMessageSize at 2nd interim because that
info travels in each SNMPv3 message. However, we may want to
re-introduce it so that SNMPv1/v2c managers can learn the value!!
Consensus: Nobody picked up on this, so it seems not needed.
. Do we need a mechanism to discover securityModels supported
Can be decided after Munich
. add a "Decision History" section (as an appendix?)
Can be decided after Munich
Harrington/Wijnen Expires February 1998 [Page 2]
0.1.1. Issues discussed at second Interim Meeting:
. A "readable" introduction supplement may be done after Munich.
. Applications are responsible for retries, but implementations may
differ.
. TCs should not be defined just to describe primitive parameters.
If they cannot be described adequately in text, they can be defined
in a Glossary. Avoid describing implementation details.
. Is SnmpAdminString appropriate for all strings, such as
securityIdentifier and context and group? These had different
sizes and semantics. size and semantics may be defined in
syntax and description of OBJECT
. AdminString has size (0..255); revisit for utf8 discussions
. securityModel #s - 00 for IETF standards; from v2* documents
. protocol IDs - integer or OID? voted 13-0 for OID.
. uniqueness of securityName
. mapping between principal and securityName is outside scope of WG.
. principals may have more than one securityName in an entity
. mappings may exist between many types of MDID and a single
securityName
. mappings may exist between different (model, Name) and the same
securityName by varying the model or the Name.
. the securityName and a MDID may be identical. This can be defined
by the Security Model.
(user,"public") may map to securityName "public"
. [securityName, securityModel] yields zero or one MDName, with
exceptions for backwards compatibility. The exception is defined
by the model, and the problems are the province of the model to
resolve.
Harrington/Wijnen Expires February 1998 [Page 3]
0.2. Change Log
[version 4.14]
. formatting
. pagination
[version 4.13]
. new acknowledgements
. updated references
. updated issues list
. ordered security, editors, acknowledgements, references sections
. checked line lengths
[version 4.12]
. cleanup
. added expectResponse to processIncomingMsg to address Levi-raised
concern
. acknowledgements
. MIB checked by SMICng
. post to snmpv3 mailing list
[version 4.11]
. Change Primitives between MP and SEC to try and address the issue
of architectural binding to message format.
. Added securityName and securityLevel to the returnResponsePdu
primitive so that architecturally it could be different for a
request and a response.
. Rename processMsg primitive to processIncomingMsg
[version 4.10]
. spell check
[version 4.9]
. editorial changes
. fix SnmpEngineID TC
. add a note to SnmpAdminString
. rename title of section 1.1
. expand description of Dispatcher a bit
[version 4.8]
. Added parameter pduVersion on primitives:
sendPdu
processPdu
returnResponsePdu
processResponsePdu
prepareDataElements
prepareOutgoingMessage
prepareResponseMessage
. Added parameter messageProcessingModel on the primitive:
processPdu
processResponsePdu
returnResponsePdu
. Removed messageProcessingModel parameter from primitives:
registerContextEngineID
Harrington/Wijnen Expires February 1998 [Page 4]
unregisterContextEngineID
. Renamed SNMP Version Multiplexer to Dispatcher
. Renamed Version Multiplexer to Message Multiplexer
. Renamed Application Multiplexer to PDU Dispatcher
. Rearranged some parameters in various Primitives so the sequence
of parameters is now more consistent.
[version 4.7]
. editorial cleanup
. changed asterisk text
. modified snmpv3 framework description to eliminate dependencies
. reorder 4.2.x to reflect transaction order
. changed SnmpEngineID size to 1..32
[version 4.6]
. Changes to use synchronous primitives where possible
. Changes to describe SNMP Version Multiplexer
. Remove (empty) glossary
. Redraw documentation figure
. Redraw Operational Overview Figure
. Remove old section 4 (Architectural Elements of Procedure)
These moved to the MP document into the SNMP Version Multiplexer
section.
. Move Overview of all primitives from Appendix to Section 4.
. Simplify Appendix A to just described Model Designer Guidelines
and refer back to section 4 for specific primitives
. Remove Appendix B (An Evolutionary Architecture - Design Goals)
. added design decision regarding security
. Included latest Snmp SecurityModel TC (as it was actually posted
to the SNMPv3 mailing list).
[version 4.5]
. start with <draft-ietf-snmpv3-next-gen-arch-03.txt>
. change vendor to implementor
. change LoS to securityLevel
. remove mention of enterprise
. change Internet Management Framework to SNMP Management Framework
. modify usage of "frameworks" to improve internal consistency.
. change Message Processing Abstract Service Interface to
Application Multiplexor
. change description of SNMP engine
. moved "one-to-one association" for entity and engine to discussion
of engine.
. changed distributing to dispatching
. added asterisks to indicate v3* items are also not required.
. changed "community access control" to "other access control"
. added TC for SnmpMessageProcessingModel
. modified Security Considerations
. modified acknowledgements
[version 4.4]
Harrington/Wijnen Expires February 1998 [Page 5]
. Fixed one error in the MIB (found with SMICng)
. Reformatted text for SnmpAdminString, no change in text.
. Changed text for SnmpEngineID.. this is still under discussion.
But this new text seems to be getting close to what we want.
. Added an issue w.r.t. snmpEngineMaxMessageSize
. adapt Primitive names and parameters to very latest (july 11) names
. removed blank lines before the .p page controls.
. publish as <draft-ietf-snmpv3-next-gen-arch-03.txt>
[version 4.3]
. some minor editing adjustments
[version 4.2]
. modify abstract so there is no requirement for one entity
to contain both a command generator and a notification receiver.
. modify Introduction list of entities which are meant to be
supported
. reorganized sections 1 through 4 for more consistency in contents.
. described section contents in Introduction:Target Audience
. move documentation descriptions to section 2
. rewrite section 4 to be more like a real elements of procedure.
. modified SnmpSecurityModel and SnmpEngineID definitions
. replaced MIB with Bert's replacement
. added Randy's TC for SnmpAdminString
. modified the example algorithm text for SnmpEngineID
. rewrote security considerations for brevity.
. modified "context" description
. moved "Threats" to Goals/Requirements
. eliminated snmpEngineMaxMessageSize object
. posted to snmpv3 (by DBH)
[version 4.1]
. Adopt "abstract" to new terminology
. Addressed all comments I (BW) made to DBH in an earlier email
. Changed Introduction section to new terminology
. changed wording for "implementation" to indicate it may contain
multiple models.
. Section 2. Started some wording on Goals and Design decisions
. Added the overview picture of a traditional agent and a
traditional manager. This is in section 2.
. Changed overview figure in section 3. to address the comments
by Dave Levi. It now lists the type of applications
. At various places ensure that text (easily) fits within 72
columns as required by RFC-editors Guidelines document.
. Section 2.3 (new section) has the documents set overview.
I verified the claims about standards. Not sure I worded the
SNMPv2 std correctly,. We'll hear it if we did it wrong.
. Section 2.4 (new section) gives overview of SNMP entities based
on modified Dave Levi figure. I (Bert) wonder however if it would
not be better to move it to after section 3.1.13
. Section 3. Added more figures... please let us know if you find
then useful and/or helpful. We could also move these back to
section 2 if such makes more sense.
Harrington/Wijnen Expires February 1998 [Page 6]
. Added a picture in section 3.2.
It also shows some of access control, so not sure it really fits
here, although it does map principal to model dependent security
ID to securityName
. Replace "<" with "is lower than" in section 3.4.3 which seems
better in a text document.
. Renamed section 4.1 to "SNMP engine processing" instead of
"The Message Processing Subsystem" because the transport
mappings, mpc multiplexor and such is done in ARCH document so
it is done "in general in the engine" and it passes a specific
message to a Message Processing Subsystem.
. "bulletized" some stuff in section 4.2 and 4.3.
Dave, this is just how I (Bert) like it better. Feel free to
undo it if you strongly disagree
. Section 4.3 changed "initiate a transaction" to "originate a
notification".
. Inserted title line for section 4.4 (I think it was missing)
I have named it "Information Model" in accordance with the change
I made (after Russ's comments) in the document figure to lump SMI,
TC and Conformance together.
. Inserted a title for section 4.5 named "Operational Model" to
get in sync with the the lumping together of ProtoOps and Transport
Mappings in document overview
. Renumber section 4.4.4 to 4,5,1 and added 4.5.2 to follow the
document overview figure. If we really want to follow it, then
maybe we should also reorder some of these sections. Like
Access Control seems specifically misplaced. So I decided to move
it before applications as section 4.3, so the 4.x above should
all be read as 4.x+1
. Removed size from SnmpEngineID TC... why did you limit it to
(0..2048). Did we not decide to leave it open?
. Should we not remove snmpEngineMaxMessageSize from the MIB.
That was agreed at 2nd interim. It travels in every message and so
seems to be useless. However, I think it could indeed still help
SNMPv1 or SNMPv2c managers.
. I kept your definitions of registration-points for auth and priv
protocols, but my recollection is that they would be completely
removed from ARCH and that it would all be done in SEC document.
. Modified Security Considerations. Was still talking about LPM.
. Appendix. I am still wondering if we need to use capitals for
things like "Security Model" "Subsystem" and such. This is only
an appendix... but we better be consistent, no? Anyway
I changed it so it is consistent (at least I tried).
. Appendix, renamed imf to snmpFramework
. Appendix, changed state_reference and state_release to
stateReference and stateRelease to be consistent with other names
for abstract data and primitives.
. A.2 changed MessageEngine to SNMP engine
. Fixed ASI primitives to be in sync with SEC document.
I also thought that our ARCH document-outline wanted to at least
have the primitives listed within the main body of the text, no?
Harrington/Wijnen Expires February 1998 [Page 7]
. Adapted send_pdu to sendPdu primitive as reconciled by Randy
In fact I made sure all primitives are in-line with current
agreement on names and parameters.
. Rename title of A.2.4 and A.2.5 so it fits on 1 line in contents
. I did not look at appendix B. That is your (DBH) specialty is it
not ? ;-).
. Quick simple spell check done with "spell" on AIX
[version 4.0]
. move section 7 - Model Requirements to an appendix
. move Section 3 - Design Goals to an appendix
. modified Section 5 - Naming
. remove "possibly multiple"
. moved Section 5 to Section 3
. change orangelets to applications
. modify description of applications
. change scopedPDU-MMS and PDU-MMS to maxSizeResponseScopedPDU
. change Scoped-PDU and ScopedPDU to scopedPDU (no dash, lower case S)
. change imfxxx to snmpFrameworkxxx
. change security-entity to principal
. change securityIdentity to securityName
. change MIID to securityName
. eliminate all reference to groupName or group
. LoS ordering noAuthNoPriv < authNoPriv < authPriv
. Los TC naming - noAuthNoPriv(1), authNoPriv(2), authPriv(3)
. remove TCs not used in MIBs - securityIdentity TC etc
. changed Message Processing and Control to Message Processing
. changed future tense to present tense
. eliminate messageEngine
. added/updated primitives
. addressed issues raised on the mailing list
[version 3.1]
. change securityIdentity to MIID
. write text to explain the differences between security-identities,
model-dependent identifiers, and model-independent identifiers.
. write text to explain distinction within the LCD of the security
data, the access control data, and the orangelet data.
. identify issues
. publish as <draft-ietf-snmpv3-next-gen-arch-02.txt>
[version 3.0]
. add section on threats for message security
. add section on threats for access control
. change application to orangelet
. remove references to F-Ts
. change securityIdentity to security-identity
. change securityCookie to securityIdentity
. the format of securityIdentity is defined by the model
. add securityModel to passed parameters as needed
. eliminate group from passed parameters
. remove unused IMPORTS
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. add glossary section with initial set of words to define
. differentiate the messageEngine from the contextEngine
. eliminate the term SNMPng
. rewrote 1.1. A Note on Terminology
. eliminated assumptions about SNMP processing always being
message related
. rewrote 4.x to reflect new thinking
. rewrote 5.x to reflect new thinking
. rewrote 6.x (the MIB) to reflect new thinking
. added MIB objects at this level (previously only TCs)
. rewrote 7.x
. sent to v3edit list
Harrington/Wijnen Expires February 1998 [Page 9]
1. Introduction 1. Introduction
1.1. Overview 1.1. Overview
This document assumes an audience with varying levels of technical This document defines a vocabulary for describing SNMP Management
understanding of SNMP. Frameworks, and an architecture for describing the major portions of
SNMP Management Frameworks.
This document does not provide a general introduction to SNMP. Other This document does not provide a general introduction to SNMP. Other
documents and books can provide a much better introduction to SNMP. documents and books can provide a much better introduction to SNMP.
Nor does this document provide a history of SNMP. That also can be Nor does this document provide a history of SNMP. That also can be
found in books and other documents. found in books and other documents.
This document defines a vocabulary for describing SNMP Management Section 1 describes the purpose, goals, and design decisions of this
Frameworks, and an architecture for describing the major portions of architecture.
SNMP Management Frameworks.
Section 1 describes the purpose, goals, and design decisions of
this architecture.
Section 2 describes various types of documents which define SNMP Section 2 describes various types of documents which define SNMP
Frameworks, and how they fit into this architecture. It also provides Frameworks, and how they fit into this architecture. It also provides
a minimal roadmap to the documents which have previously defined a minimal roadmap to the documents which have previously defined
SNMP frameworks. SNMP frameworks.
Section 3 details the vocabulary of this architecture and its pieces. Section 3 details the vocabulary of this architecture and its pieces.
This section is important for understanding the remaining sections, This section is important for understanding the remaining sections,
and for understanding documents which are written to fit within this and for understanding documents which are written to fit within this
architecture. architecture.
skipping to change at page 10, line ? skipping to change at page 1, line 81
within this architecture. within this architecture.
Section 5 defines a collection of managed objects used to instrument Section 5 defines a collection of managed objects used to instrument
SNMP entities within this architecture. SNMP entities within this architecture.
Sections 6, 7, 8, and 9 are administrative in nature. Sections 6, 7, 8, and 9 are administrative in nature.
Appendix A contains guidelines for designers of Models which are Appendix A contains guidelines for designers of Models which are
expected to fit within this architecture. expected to fit within this architecture.
1.2. SNMP Management Systems The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
1.2. SNMP
An SNMP management system contains: An SNMP management system contains:
- several (potentially many) nodes, each with an SNMP entity - several (potentially many) nodes, each with an SNMP entity
containing command responder and notification originator containing command responder and notification originator
applications, which have access to management instrumentation; applications, which have access to management instrumentation
(traditionally called agents);
- at least one SNMP entity containing command generator and/or - at least one SNMP entity containing command generator and/or
notification receiver applications; and, notification receiver applications (traditionally called a
manager) and,
- a management protocol, used to convey management information - a management protocol, used to convey management information
between the SNMP entities. between the SNMP entities.
SNMP entities executing command generator and notification receiver SNMP entities executing command generator and notification receiver
applications monitor and control managed elements. Managed elements applications monitor and control managed elements. Managed elements
are devices such as hosts, routers, terminal servers, etc., which are devices such as hosts, routers, terminal servers, etc., which are
are monitored and controlled via access to their management monitored and controlled via access to their management information.
information.
It is the purpose of this document to define an architecture which It is the purpose of this document to define an architecture which
can evolve to realize effective network management in a variety can evolve to realize effective management in a variety of
of configurations and environments. The architecture has been configurations and environments. The architecture has been designed
designed to meet the needs of implementations of: to meet the needs of implementations of:
- minimal SNMP entities with command responder and/or notification
originator applications (traditionally called SNMP agents), - minimal SNMP entities with command responder and/or
notification originator applications (traditionally called SNMP
agents),
- SNMP entities with proxy forwarder applications (traditionally - SNMP entities with proxy forwarder applications (traditionally
called SNMP proxy agent), called SNMP proxy agent),
- command line driven SNMP entities with command generator and/or - command line driven SNMP entities with command generator and/or
notification receiver applications (traditionally called SNMP notification receiver applications (traditionally called SNMP
command line managers), command line managers),
- SNMP entities with command generator and/or notification - SNMP entities with command generator and/or notification
receiver, plus command responder and/or notification originator receiver, plus command responder and/or notification originator
applications (traditionally called SNMP mid-level managers or applications (traditionally called SNMP mid-level managers or
dual-role entities), dual-role entities),
- SNMP entities with command generator and/or notification - SNMP entities with command generator and/or notification
receiver and possibly other types of applications for managing receiver and possibly other types of applications for managing
a potentially very large number of managed nodes (traditionally a potentially very large number of managed nodes (traditionally
called network management stations). called (network) management stations).
1.3. Goals of this Architecture 1.3. Goals of this Architecture
This architecture was driven by the following goals: This architecture was driven by the following goals:
- Use existing materials as much as possible. It is heavily based - Use existing materials as much as possible. It is heavily based
on previous work, informally known as SNMPv2u and SNMPv2*. on previous work, informally known as SNMPv2u and SNMPv2*.
- Address the need for secure SET support, which is considered - Address the need for secure SET support, which is considered
the most important deficiency in SNMPv1 and SNMPv2c. the most important deficiency in SNMPv1 and SNMPv2c.
- Make it possible to move portions of the architecture forward - Make it possible to move portions of the architecture forward
in the standards track, even if consensus has not been reached in the standards track, even if consensus has not been reached
on all pieces. on all pieces.
- Define an architecture that allows for longevity of the SNMP - Define an architecture that allows for longevity of the SNMP
Frameworks that have been and will be defined. Frameworks that have been and will be defined.
- Keep SNMP as simple as possible. - Keep SNMP as simple as possible.
- Make it relatively inexpensive to deploy a minimal conformant
implementation - Make it relatively inexpensive to deploy a minimal conforming
implementation.
- Make it possible to upgrade portions of SNMP as new approaches - Make it possible to upgrade portions of SNMP as new approaches
become available, without disrupting an entire SNMP framework. become available, without disrupting an entire SNMP framework.
- Make it possible to support features required in large networks,
but make the expense of supporting a feature directly related - Make it possible to support features required in large
to the support of the feature. networks, but make the expense of supporting a feature directly
related to the support of the feature.
1.4. Security Requirements of this Architecture 1.4. Security Requirements of this Architecture
Several of the classical threats to network protocols are applicable Several of the classical threats to network protocols are applicable
to the network management problem and therefore would be applicable to the management problem and therefore would be applicable to any
to any Security Model used in an SNMP Management Framework. Other Security Model used in an SNMP Management Framework. Other threats
threats are not applicable to the network management problem. This are not applicable to the management problem. This section discusses
section discusses principal threats, secondary threats, and threats principal threats, secondary threats, and threats which are of lesser
which are of lesser importance. importance.
The principal threats against which any Security Model used within The principal threats against which any Security Model used within
this architecture SHOULD provide protection are: this architecture SHOULD provide protection are:
Modification of Information Modification of Information
The modification threat is the danger that some unauthorized SNMP The modification threat is the danger that some unauthorized SNMP
entity may alter in-transit SNMP messages generated on behalf of entity may alter in-transit SNMP messages generated on behalf of
an authorized principal in such a way as to effect unauthorized an authorized principal in such a way as to effect unauthorized
management operations, including falsifying the value of an object. management operations, including falsifying the value of an
object.
Masquerade Masquerade
The masquerade threat is the danger that management operations The masquerade threat is the danger that management operations not
not authorized for some principal may be attempted by assuming authorized for some principal may be attempted by assuming the
the identity of another principal that has the appropriate identity of another principal that has the appropriate
authorizations. authorizations.
Message Stream Modification Message Stream Modification
The SNMP protocol is typically based upon a connectionless The SNMP protocol is typically based upon a connectionless
transport service which may operate over any subnetwork service. transport service which may operate over any subnetwork service.
The re-ordering, delay or replay of messages can and does occur The re-ordering, delay or replay of messages can and does occur
through the natural operation of many such subnetwork services. through the natural operation of many such subnetwork services.
The message stream modification threat is the danger that messages The message stream modification threat is the danger that messages
may be maliciously re-ordered, delayed or replayed to an extent may be maliciously re-ordered, delayed or replayed to an extent
which is greater than can occur through the natural operation of which is greater than can occur through the natural operation of a
a subnetwork service, in order to effect unauthorized management subnetwork service, in order to effect unauthorized management
operations. operations.
Disclosure Disclosure
The disclosure threat is the danger of eavesdropping on the The disclosure threat is the danger of eavesdropping on the
exchanges between SNMP engines. Protecting against this threat exchanges between SNMP engines. Protecting against this threat
may be required as a matter of local policy. may be required as a matter of local policy.
There are at least two threats against which a Security Model within There are at least two threats against which a Security Model within
this architecture need not protect. this architecture need not protect.
Denial of Service Denial of Service
A Security Model need not attempt to address the broad range of A Security Model need not attempt to address the broad range of
attacks by which service on behalf of authorized users is denied. attacks by which service on behalf of authorized users is denied.
Indeed, such denial-of-service attacks are in many cases Indeed, such denial-of-service attacks are in many cases
indistinguishable from the type of network failures with which any indistinguishable from the type of network failures with which any
viable network management protocol must cope as a matter of course. viable management protocol must cope as a matter of course.
Traffic Analysis Traffic Analysis
A Security Model need not attempt to address traffic analysis A Security Model need not attempt to address traffic analysis
attacks. Many traffic patterns are predictable - entities may attacks. Many traffic patterns are predictable - entities may be
be managed on a regular basis by a relatively small number of managed on a regular basis by a relatively small number of
management stations - and therefore there is no significant management stations - and therefore there is no significant
advantage afforded by protecting against traffic analysis. advantage afforded by protecting against traffic analysis.
1.5. Design Decisions 1.5. Design Decisions
Various designs decision were made in support of the goals of the Various design decisions were made in support of the goals of the
architecture and the security requirements: architecture and the security requirements:
- Architecture - Architecture
An architecture should be defined which identifies the conceptual An architecture should be defined which identifies the
boundaries between the documents. Subsystems should be defined conceptual boundaries between the documents. Subsystems should
which describe the abstract services provided by specific be defined which describe the abstract services provided by
portions of an SNMP framework. Abstract service interfaces, as specific portions of an SNMP framework. Abstract service
described by service primitives, define the abstract boundaries interfaces, as described by service primitives, define the
between documents, and the abstract services that are provided abstract boundaries between documents, and the abstract
by the conceptual subsystems of an SNMP framework. services that are provided by the conceptual subsystems of an
SNMP framework.
- Self-contained Documents - Self-contained Documents
Elements of procedure plus the MIB objects which are needed for Elements of procedure plus the MIB objects which are needed for
processing for a specific portion of an SNMP framework should be processing for a specific portion of an SNMP framework should
defined in the same document, and as much as possible, should be defined in the same document, and as much as possible,
not be referenced in other documents. This allows pieces to be should not be referenced in other documents. This allows pieces
designed and documented as independent and self-contained parts, to be designed and documented as independent and self-contained
which is consistent with the general SNMP MIB module approach. parts, which is consistent with the general SNMP MIB module
As portions of SNMP change over time, the documents describing approach. As portions of SNMP change over time, the documents
other portions of SNMP are not directly impacted. This modularity describing other portions of SNMP are not directly impacted.
allows, for example, Security Models, authentication and privacy This modularity allows, for example, Security Models,
mechanisms, and message formats to be upgraded and supplemented authentication and privacy mechanisms, and message formats to
as the need arises. The self-contained documents can move along be upgraded and supplemented as the need arises. The self-
the standards track on different time-lines. contained documents can move along the standards track on
different time-lines.
- The Security Models in the Security Subsystem SHOULD protect - Threats
The Security Models in the Security Subsystem SHOULD protect
against the principal threats: modification of information, against the principal threats: modification of information,
masquerade, message stream modification and disclosure. masquerade, message stream modification and disclosure. They
They do not need to protect against denial of service and do not need to protect against denial of service and traffic
traffic analysis. analysis.
- Remote Configuration - Remote Configuration
The Security and Access Control Subsystems add a whole new set The Security and Access Control Subsystems add a whole new set
of SNMP configuration parameters. The Security Subsystem also of SNMP configuration parameters. The Security Subsystem also
requires frequent changes of secrets at the various SNMP requires frequent changes of secrets at the various SNMP
entities. To make this deployable in a large operational entities. To make this deployable in a large operational
environment, these SNMP parameters must be able to be remotely environment, these SNMP parameters must be able to be remotely
configured. configured.
- Controlled Complexity - Controlled Complexity
It is recognized that simple managed devices want to keep the It is recognized that producers of simple managed devices want
resources used by SNMP to a minimum. At the same time, there to keep the resources used by SNMP to a minimum. At the same
is a need for more complex configurations which can spend more time, there is a need for more complex configurations which can
resources for SNMP and thus provide more functionality. spend more resources for SNMP and thus provide more
The design tries to keep the competing requirements of these functionality. The design tries to keep the competing
two environments in balance and allows the more complex requirements of these two environments in balance and allows
environments to logically extend the simple environment. the more complex environments to logically extend the simple
environment.
2. Documentation Overview 2. Documentation Overview
The following figure shows the set of documents that fit within the The following figure shows the set of documents that fit within the
SNMP Architecture. SNMP Architecture.
+-------------------------- Document Set ----------------------------+ +------------------------- Document Set ----------------------------+
| | | |
| +------------+ +-----------------+ +----------------+ | | +------------+ +-----------------+ +----------------+ |
| | Document * | | Applicability * | | Coexistence * | | | | Document * | | Applicability * | | Coexistence * | |
| | Roadmap | | Statement | | & Transition | | | | Roadmap | | Statement | | & Transition | |
| +------------+ +-----------------+ +----------------+ | | +------------+ +-----------------+ +----------------+ |
| | | |
| +----------------------------------------------------------------+ | | +---------------------------------------------------------------+ |
| | Message Handling | | | | Message Handling | |
| | +-----------------+ +-----------------+ +-----------------+ | | | | +----------------+ +-----------------+ +-----------------+ | |
| | | Transport | | Message | | Security | | | | | | Transport | | Message | | Security | | |
| | | Mappings | | Processing and | | | | | | | | Mappings | | Processing and | | | | |
| | | | | Dispatching | | | | | | | | | | Dispatcher | | | | |
| | +-----------------+ +-----------------+ +-----------------+ | | | | +----------------+ +-----------------+ +-----------------+ | |
| +----------------------------------------------------------------+ | | +---------------------------------------------------------------+ |
| | | |
| +----------------------------------------------------------------+ | | +---------------------------------------------------------------+ |
| | PDU Handling | | | | PDU Handling | |
| | +-----------------+ +-----------------+ +-----------------+ | | | | +----------------+ +-----------------+ +-----------------+ | |
| | | Protocol | | Applications | | Access | | | | | | Protocol | | Applications | | Access | | |
| | | Operations | | | | Control | | | | | | Operations | | | | Control | | |
| | +-----------------+ +-----------------+ +-----------------+ | | | | +----------------+ +-----------------+ +-----------------+ | |
| +----------------------------------------------------------------+ | | +---------------------------------------------------------------+ |
| | | |
| +----------------------------------------------------------------+ | | +---------------------------------------------------------------+ |
| | Information Model | | | | Information Model | |
| | +--------------+ +--------------+ +---------------+ | | | | +--------------+ +--------------+ +---------------+ | |
| | | Structure of | | Textual | | Conformance | | | | | | Structure of | | Textual | | Conformance | | |
| | | Management | | Conventions | | Statements | | | | | | Management | | Conventions | | Statements | | |
| | | Information | | | | | | | | | | Information | | | | | | |
| | +--------------+ +--------------+ +---------------+ | | | | +--------------+ +--------------+ +---------------+ | |
| +----------------------------------------------------------------+ | | +---------------------------------------------------------------+ |
| | | |
| +----------------------------------------------------------------+ | | +---------------------------------------------------------------+ |
| | MIBs | | | | MIBs | |
| | +-------------+ +-------------+ +----------+ +----------+ | | | | +-------------+ +-------------+ +----------+ +----------+ | |
| | | Standard v1 | | Standard v1 | | Historic | | Draft v2 | | | | | | Standard v1 | | Standard v1 | | Historic | | Draft v2 | | |
| | | RFC1157 | | RFC1212 | | RFC14xx | | RFC19xx | | | | | | RFC1157 | | RFC1212 | | RFC14xx | | RFC19xx | | |
| | | format | | format | | format | | format | | | | | | format | | format | | format | | format | | |
| | +-------------+ +-------------+ +----------+ +----------+ | | | | +-------------+ +-------------+ +----------+ +----------+ | |
| +----------------------------------------------------------------+ | | +---------------------------------------------------------------+ |
| | | |
+--------------------------------------------------------------------+ +-------------------------------------------------------------------+
Those marked with an asterisk (*) are expected to be written in the Those marked with an asterisk (*) are expected to be written in the
future. Each of these documents may be replaced or supplemented. future. Each of these documents may be replaced or supplemented.
This Architecture document specifically describes how new documents This Architecture document specifically describes how new documents
fit into the set of documents in the area of Message and PDU handling. fit into the set of documents in the area of Message and PDU
handling.
2.1. Document Roadmap 2.1. Document Roadmap
One or more documents may be written to describe how sets of documents One or more documents may be written to describe how sets of
taken together form specific Frameworks. The configuration of document documents taken together form specific Frameworks. The configuration
sets might change over time, so the "roadmap" should be maintained in of document sets might change over time, so the "road map" should be
a document separate from the standards documents themselves. maintained in a document separate from the standards documents
themselves.
2.2. Applicability Statement 2.2. Applicability Statement
SNMP is used in networks that vary widely in size and complexity, SNMP is used in networks that vary widely in size and complexity, by
by organizations that vary widely in their requirements of network organizations that vary widely in their requirements of management.
management. Some models will be designed to address specific problems Some models will be designed to address specific problems of
of network management, such as message security. management, such as message security.
One or more documents may be written to describe the environments One or more documents may be written to describe the environments to
to which certain versions of SNMP or models within SNMP would be which certain versions of SNMP or models within SNMP would be
appropriately applied, and those to which a given model might be appropriately applied, and those to which a given model might be
inappropriately applied. inappropriately applied.
2.3. Coexistence and Transition 2.3. Coexistence and Transition
The purpose of an evolutionary architecture is to permit new models The purpose of an evolutionary architecture is to permit new models
to replace or supplement existing models. The interactions between to replace or supplement existing models. The interactions between
models could result in incompatibilities, security "holes", and models could result in incompatibilities, security "holes", and other
other undesirable effects. undesirable effects.
The purpose of Coexistence documents is to detail recognized anomalies
and to describe required and recommended behaviors for resolving the
interactions between models within the architecture.
It would be very difficult to document all the possible interactions The purpose of Coexistence documents is to detail recognized
between a model and all other previously existing models while in the anomalies and to describe required and recommended behaviors for
process of developing a new model. resolving the interactions between models within the architecture.
Coexistence documents are therefore expected to be prepared separately Coexistence documents may be prepared separately from model
from model definition documents, to describe and resolve interaction definition documents, to describe and resolve interaction anomalies
anomalies between a model definition and one or more other model between a model definition and one or more other model definitions.
definitions.
Additionally, recommendations for transitions between models may Additionally, recommendations for transitions between models may also
also be described, either in a coexistence document or in a separate be described, either in a coexistence document or in a separate
document. document.
2.4. Transport Mappings 2.4. Transport Mappings
SNMP messages are sent over various transports. It is the purpose of SNMP messages are sent over various transports. It is the purpose of
Transport Mapping documents to define how the mapping between SNMP Transport Mapping documents to define how the mapping between SNMP
and the transport is done. and the transport is done.
2.5. Message Processing 2.5. Message Processing
A Message Processing Model document defines a message format, which is A Message Processing Model document defines a message format, which
typically identified by a version field in an SNMP message header. is typically identified by a version field in an SNMP message header.
The document may also define a MIB module for use in message The document may also define a MIB module for use in message
processing and for instrumentation of version-specific interactions. processing and for instrumentation of version-specific interactions.
An SNMP engine includes one or more Message Processing Models, and thus An SNMP engine includes one or more Message Processing Models, and
may support sending and receiving multiple versions of SNMP messages. thus may support sending and receiving multiple versions of SNMP
messages.
2.6. Security 2.6. Security
Some environments require secure protocol interactions. Security is Some environments require secure protocol interactions. Security is
normally applied at two different stages: normally applied at two different stages:
- in the transmission/receipt of messages, and - in the transmission/receipt of messages, and
- in the processing of the contents of messages. - in the processing of the contents of messages.
For purposes of this document, "security" refers to message-level For purposes of this document, "security" refers to message-level
security; "access control" refers to the security applied to protocol security; "access control" refers to the security applied to protocol
operations. operations.
Authentication, encryption, and timeliness checking are common Authentication, encryption, and timeliness checking are common
functions of message level security. functions of message level security.
A security document describes a Security Model, the threats against A security document describes a Security Model, the threats against
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which the model protects, the goals of the Security Model, the which the model protects, the goals of the Security Model, the
protocols which it uses to meet those goals, and it may define a MIB protocols which it uses to meet those goals, and it may define a MIB
module to describe the data used during processing, and to allow the module to describe the data used during processing, and to allow the
remote configuration of message-level security parameters, such as remote configuration of message-level security parameters, such as
passwords. passwords.
An SNMP engine may support multiple Security Models concurrently. An SNMP engine may support multiple Security Models concurrently.
2.7. Access Control 2.7. Access Control
During processing, it may be required to control access to certain During processing, it may be required to control access to managed
instrumentation for certain operations. An Access Control Model objects for operations.
determines whether access to an object should be allowed. The
mechanism by which access control is checked is defined by the
Access Control Model.
An Access Control Model document defines the mechanisms used to
determine whether access to a managed object should be allowed,
and may define a MIB module used during processing, and to allow
the remote configuration of access control policies. An Access Control Model defines mechanisms to determine whether
access to a managed object should be allowed. An Access Control
Model may define a MIB module used during processing and to allow the
remote configuration of access control policies.
2.8. Protocol Operations 2.8. Protocol Operations
SNMP messages encapsulate an SNMP Protocol Data Unit (PDU). It is the SNMP messages encapsulate an SNMP Protocol Data Unit (PDU). It is the
purpose of a Protocol Operations document to define the operations purpose of a Protocol Operations document to define the operations of
of the protocol with respect to the processing of the PDUs. the protocol with respect to the processing of the PDUs.
An application document defines which Protocol Operations documents An application document defines which Protocol Operations documents
are supported by the application. are supported by the application.
2.9. Applications 2.9. Applications
An SNMP entity normally includes a number of applications. An SNMP entity normally includes a number of applications.
Applications use the services of an SNMP engine to accomplish Applications use the services of an SNMP engine to accomplish
specific tasks. They coordinate the processing of management specific tasks. They coordinate the processing of management
information operations, and may use SNMP messages to communicate information operations, and may use SNMP messages to communicate with
with other SNMP entities. other SNMP entities.
Applications documents describe the purpose of an application, the Applications documents describe the purpose of an application, the
services required of the associated SNMP engine, and the protocol services required of the associated SNMP engine, and the protocol
operations and informational model that the application uses to operations and informational model that the application uses to
perform network management operations. perform management operations.
An application document defines which set of documents are used to An application document defines which set of documents are used to
specifically define the structure of management information, textual specifically define the structure of management information, textual
conventions, conformance requirements, and operations supported by conventions, conformance requirements, and operations supported by
the application. the application.
2.10. Structure of Management Information 2.10. Structure of Management Information
Management information is viewed as a collection of managed objects, Management information is viewed as a collection of managed objects,
residing in a virtual information store, termed the Management residing in a virtual information store, termed the Management
Information Base (MIB). Collections of related objects are defined Information Base (MIB). Collections of related objects are defined in
in MIB modules. MIB modules.
It is the purpose of a Structure of Management Information document It is the purpose of a Structure of Management Information document
to establish the syntax for defining objects, modules, and other to establish the syntax for defining objects, modules, and other
elements of managed information. elements of managed information.
2.11. Textual Conventions 2.11. Textual Conventions
When designing a MIB module, it is often useful to define new types When designing a MIB module, it is often useful to define new types
similar to those defined in the SMI, but with more precise semantics, similar to those defined in the SMI, but with more precise semantics,
or which have special semantics associated with them. These newly or which have special semantics associated with them. These newly
defined types are termed textual conventions, and may defined in defined types are termed textual conventions, and may defined in
separate documents, or within a MIB module. separate documents, or within a MIB module.
2.12. Conformance Statements 2.12. Conformance Statements
It may be useful to define the acceptable lower-bounds of It may be useful to define the acceptable lower-bounds of
implementation, along with the actual level of implementation implementation, along with the actual level of implementation
achieved. It is the purpose of Conformance Statements to define achieved. It is the purpose of Conformance Statements to define the
the notation used for these purposes. notation used for these purposes.
2.13. Management Information Base Modules 2.13. Management Information Base Modules
MIB documents describe collections of managed objects which instrument MIB documents describe collections of managed objects which
some aspect of a managed node. instrument some aspect of a managed node.
2.13.1. SNMP Instrumentation MIBs 2.13.1. SNMP Instrumentation MIBs
An SNMP MIB document may define a collection of managed objects which An SNMP MIB document may define a collection of managed objects which
instrument the SNMP protocol itself. In addition, MIB modules may be instrument the SNMP protocol itself. In addition, MIB modules may be
defined within the documents which describe portions of the SNMP defined within the documents which describe portions of the SNMP
architecture, such as the documents for Message processing Models, architecture, such as the documents for Message processing Models,
Security Models, etc. for the purpose of instrumenting those Models, Security Models, etc. for the purpose of instrumenting those Models,
and for the purpose of allowing remote configuration of the Model. and for the purpose of allowing remote configuration of the Model.
2.14. SNMP Framework Documents 2.14. SNMP Framework Documents
This architecture is designed to allow an orderly evolution of This architecture is designed to allow an orderly evolution of
portions of SNMP Frameworks. portions of SNMP Frameworks.
Throughout the rest of this document, the term "subsystem" refers Throughout the rest of this document, the term "subsystem" refers to
to an abstract and incomplete specification of a portion of an abstract and incomplete specification of a portion of a Framework,
a Framework, that is further refined by a model specification. that is further refined by a model specification.
A "model" describes a specific design of a subsystem, defining A "model" describes a specific design of a subsystem, defining
additional constraints and rules for conformance to the model. additional constraints and rules for conformance to the model. A
A model is sufficiently detailed to make it possible to implement model is sufficiently detailed to make it possible to implement the
the specification. specification.
An "implementation" is an instantiation of a subsystem, conforming An "implementation" is an instantiation of a subsystem, conforming to
to one or more specific models. one or more specific models.
SNMP version 1 (SNMPv1), is the original Internet-standard Network SNMP version 1 (SNMPv1), is the original Internet-standard Network
Management Framework, as described in RFCs 1155, 1157, and 1212. Management Framework, as described in RFCs 1155, 1157, and 1212.
SNMP version 2 (SNMPv2), is the SNMPv2 Framework as derived from the SNMP version 2 (SNMPv2), is the SNMPv2 Framework as derived from the
SNMPv1 Framework. It is described in RFCs 1902-1907. SNMPv2 has no SNMPv1 Framework. It is described in RFCs 1902-1907. SNMPv2 has no
message definition. message definition.
Community-based SNMP version 2 (SNMPv2c), is an experimental SNMP The Community-based SNMP version 2 (SNMPv2c), is an experimental SNMP
Framework which supplements the SNMPv2 Framework, as described in Framework which supplements the SNMPv2 Framework, as described in
RFC1901. It adds the SNMPv2c message format, which is similar to the
message format. SNMPv1 message format.
SNMP version 3 (SNMPv3), is an extensible SNMP Framework which SNMP version 3 (SNMPv3), is an extensible SNMP Framework which
supplements the SNMPv2 Framework, by supporting the following: supplements the SNMPv2 Framework, by supporting the following:
- a new SNMP message format,
- Security for Messages, and
- Access Control.
Other SNMP Frameworks, i.e. other configurations of implemented - a new SNMP message format,
subsystems, are expected to also be consistent with this architecture.
2.15. Operational Overview - Security for Messages, and
The following pictures show two communicating SNMP entities using - Access Control.
the conceptual modularity described by this SNMP Architecture.
The pictures represent SNMP entities that have traditionally been
called SNMP manager and SNMP agent respectively.
* One or more models may be present.
(traditional SNMP manager) Other SNMP Frameworks, i.e., other configurations of implemented
+--------------------------------------------------------------------+ subsystems, are expected to also be consistent with this
| +--------------+ +--------------+ +--------------+ SNMP entity | architecture.
| | NOTIFICATION | | NOTIFICATION | | COMMAND | |
| | ORIGINATOR | | RECEIVER | | GENERATOR | |
| | applications | | applications | | applications | |
| +--------------+ +--------------+ +--------------+ |
| ^ ^ ^ |
| | | | |
| v v v |
| +-------+--------+-----------------+ |
| ^ |
| | +---------------------+ +-----------------+ |
| | | Message Processing | | Security | |
| Dispatcher v | Subsystem | | Subsystem | |
| +-------------------+ | +------------+ | | | |
| | PDU Dispatcher | | +->| v1MP * |<--->| +-------------+ | |
| | | | | +------------+ | | | Other | | |
| | | | | +------------+ | | | Security | | |
| | | | +->| v2cMP * |<--->| | Model | | |
| | Message | | | +------------+ | | +-------------+ | |
| | Dispatcher <--------->+ | | | |
| | | | | +------------+ | | +-------------+ | |
| | | | +->| v3MP * |<--->| | User-based | | |
| | Transport | | | +------------+ | | | Security | | |
| | Mapping | | | +------------+ | | | Model | | |
| | (e.g RFC1906) | | +->| otherMP * |<--->| +-------------+ | |
| +-------------------+ | +------------+ | | | |
| ^ +---------------------+ +-----------------+ |
| | |
| v |
+--------------------------------------------------------------------+
+-----+ +-----+ +-------+
| UDP | | IPX | . . . | other |
+-----+ +-----+ +-------+
^ ^ ^
| | |
v v v
+------------------------------+
| Network |
+------------------------------+
+------------------------------+
| Network |
+------------------------------+
^ ^ ^
| | |
v v v
+-----+ +-----+ +-------+
| UDP | | IPX | . . . | other |
+-----+ +-----+ +-------+ (traditional SNMP agent)
+--------------------------------------------------------------------+
| ^ |
| | +---------------------+ +-----------------+ |
| | | Message Processing | | Security | |
| Dispatcher v | Subsystem | | Subsystem | |
| +-------------------+ | +------------+ | | | |
| | Transport | | +->| v1MP * |<--->| +-------------+ | |
| | Mapping | | | +------------+ | | | Other | | |
| | (e.g. RFC1906) | | | +------------+ | | | Security | | |
| | | | +->| v2cMP * |<--->| | Model | | |
| | Message | | | +------------+ | | +-------------+ | |
| | Dispatcher <--------->+ | | | |
| | | | | +------------+ | | +-------------+ | |
| | | | +->| v3MP * |<--->| | User-based | | |
| | | | | +------------+ | | | Security | | |
| | | | | +------------+ | | | Model | | |
| | PDU Dispatcher | | +->| otherMP * |<--->| +-------------+ | |
| +-------------------+ | +------------+ | | | |
| ^ +---------------------+ +-----------------+ |
| | |
| v |
| +-------+-------------------------+----------------+ |
| ^ ^ ^ |
| | | | |
| v v v |
| +-------------+ +---------+ +--------------+ +-------------+ |
| | COMMAND | | ACCESS | | NOTIFICATION | | PROXY * | |
| | RESPONDER |<->| CONTROL |<->| ORIGINATOR | | FORWARDER | |
| | application | | | | applications | | application | |
| +-------------+ +---------+ +--------------+ +-------------+ |
| ^ ^ |
| | | |
| v v |
| +----------------------------------------------+ |
| | MIB instrumentation | SNMP entity |
+--------------------------------------------------------------------+
3. Elements of the Architecture 3. Elements of the Architecture
This section describes the various elements of the architecture and This section describes the various elements of the architecture and
how they are named. There are three kinds of naming: how they are named. There are three kinds of naming:
1) the naming of entities, 1) the naming of entities,
2) the naming of identities, and 2) the naming of identities, and
3) the naming of management information. 3) the naming of management information.
This architecture also defines some names for other constructs that This architecture also defines some names for other constructs that
are used in the documentation. are used in the documentation.
3.1. The Naming of Entities 3.1. The Naming of Entities
The following picture shows detail about an SNMP entity and how The following figure shows detail about an SNMP entity and how
components within it are named. components within it are named.
+--------------------------------------------------------------------+ +-------------------------------------------------------------------+
| SNMP entity | | SNMP entity |
| | | |
| +--------------------------------------------------------------+ | | +-------------------------------------------------------------+ |
| | SNMP engine (identified by snmpEngineID) | | | | SNMP engine (identified by snmpEngineID) | |
| | | | | | | |
| | +-------------+ +------------+ +-----------+ +-----------+ | | | | +------------+ +------------+ +-----------+ +-----------+ | |
| | | | | | | | | | | | | | | | | | | | | | | |
| | | Dispatcher | | Message | | Security | | Access | | | | | | Dispatcher | | Message | | Security | | Access | | |
| | | | | Processing | | Subsystem | | Control | | | | | | | | Processing | | Subsystem | | Control | | |
| | | | | Subsystem | | | | Subsystem | | | | | | | | Subsystem | | | | Subsystem | | |
| | | | | | | | | | | | | | | | | | | | | | | |
| | +-------------+ +------------+ +-----------+ +-----------+ | | | | +------------+ +------------+ +-----------+ +-----------+ | |
| | | | | | | |
| +--------------------------------------------------------------+ | | +-------------------------------------------------------------+ |
| | | |
| +--------------------------------------------------------------+ | | +-------------------------------------------------------------+ |
| | Application(s) | | | | Application(s) | |
| | | | | | | |
| | +-------------+ +--------------+ +--------------+ | | | | +-------------+ +--------------+ +--------------+ | |
| | | Command | | Notification | | Proxy | | | | | | Command | | Notification | | Proxy | | |
| | | Generator | | Receiver | | Forwarder | | | | | | Generator | | Receiver | | Forwarder | | |
| | +-------------+ +--------------+ +--------------+ | | | | +-------------+ +--------------+ +--------------+ | |
| | | | | | | |
| | +-------------+ +--------------+ +--------------+ | | | | +-------------+ +--------------+ +--------------+ | |
| | | Command | | Notification | | Other | | | | | | Command | | Notification | | Other | | |
| | | Responder | | Originator | | | | | | | | Responder | | Originator | | | | |
| | +-------------+ +--------------+ +--------------+ | | | | +-------------+ +--------------+ +--------------+ | |
| | | | | | | |
| +--------------------------------------------------------------+ | | +-------------------------------------------------------------+ |
| | | |
+--------------------------------------------------------------------+ +-------------------------------------------------------------------+
3.1.1. SNMP entity 3.1.1. SNMP entity
An SNMP entity is an implementation of this architecture. Each such An SNMP entity is an implementation of this architecture. Each such
SNMP entity consists of an SNMP engine and one or more associated SNMP entity consists of an SNMP engine and one or more associated
applications. applications.
3.1.2. SNMP engine 3.1.2. SNMP engine
An SNMP engine provides services for sending and receiving messages, An SNMP engine provides services for sending and receiving messages,
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3.1.2. SNMP engine 3.1.2. SNMP engine
An SNMP engine provides services for sending and receiving messages, An SNMP engine provides services for sending and receiving messages,
authenticating and encrypting messages, and controlling access to authenticating and encrypting messages, and controlling access to
managed objects. There is a one-to-one association between an SNMP managed objects. There is a one-to-one association between an SNMP
engine and the SNMP entity which contains it. engine and the SNMP entity which contains it.
The engine contains: The engine contains:
1) a Dispatcher, 1) a Dispatcher,
2) a Message Processing Subsystem, 2) a Message Processing Subsystem,
3) a Security Subsystem, and 3) a Security Subsystem, and
4) an Access Control Subsystem. 4) an Access Control Subsystem.
3.1.3. snmpEngineID 3.1.3. snmpEngineID
Within an administrative domain, an snmpEngineID is the unique Within an administrative domain, an snmpEngineID is the unique and
and unambiguous identifier of an SNMP engine. Since there is a unambiguous identifier of an SNMP engine. Since there is a one-to-one
one-to-one association between SNMP engines and SNMP entities, association between SNMP engines and SNMP entities, it also uniquely
it also uniquely and unambiguously identifies the SNMP entity. and unambiguously identifies the SNMP entity.
3.1.4. Dispatcher 3.1.4. Dispatcher
There is only one Dispatcher in an SNMP engine. It allows for There is only one Dispatcher in an SNMP engine. It allows for
concurrent support of multiple versions of SNMP messages in the concurrent support of multiple versions of SNMP messages in the SNMP
SNMP engine. It does so by: engine. It does so by:
- sending and receiving SNMP messages to/from the network, - sending and receiving SNMP messages to/from the network,
- determining the version of an SNMP message and interact - determining the version of an SNMP message and interact with
with the corresponding Message Processing Model, the corresponding Message Processing Model,
- providing an abstract interface to SNMP applications for - providing an abstract interface to SNMP applications for
dispatching a PDU to an application. delivery of a PDU to an application.
- providing an abstract interface for SNMP applications that - providing an abstract interface for SNMP applications that
allows them to send a PDU to a remote SNMP entity. allows them to send a PDU to a remote SNMP entity.
3.1.5. Message Processing Subsystem 3.1.5. Message Processing Subsystem
The Message Processing Subsystem is responsible for preparing The Message Processing Subsystem is responsible for preparing
messages for sending, and extracting data from received messages. messages for sending, and extracting data from received messages.
The Message Processing Subsystem potentially contains multiple The Message Processing Subsystem potentially contains multiple
Message Processing Models as shown in the next picture. Message Processing Models as shown in the next figure.
* One or more Message Processing Models may be present. * One or more Message Processing Models may be present.
+------------------------------------------------------------------+ +------------------------------------------------------------------+
| | | |
| Message Processing Subsystem | | Message Processing Subsystem |
| | | |
| +------------+ +------------+ +------------+ +------------+ | | +------------+ +------------+ +------------+ +------------+ |
| | * | | * | | * | | * | | | | * | | * | | * | | * | |
| | SNMPv3 | | SNMPv1 | | SNMPv2c | | Other | | | | SNMPv3 | | SNMPv1 | | SNMPv2c | | Other | |
| | Message | | Message | | Message | | Message | | | | Message | | Message | | Message | | Message | |
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3.1.6. Message Processing Model 3.1.6. Message Processing Model
Each Message Processing Model defines the format of a particular Each Message Processing Model defines the format of a particular
version of an SNMP message and coordinates the preparation and version of an SNMP message and coordinates the preparation and
extraction of each such version-specific messages. extraction of each such version-specific messages.
3.1.7. Security Subsystem 3.1.7. Security Subsystem
The Security Subsystem provides security services such as the The Security Subsystem provides security services such as the
authentication and privacy of messages and potentially contains authentication and privacy of messages and potentially contains
multiple Security Models as shown in the next picture. multiple Security Models as shown in the following figure
* One or more Security Models may be present. * One or more Security Models may be present.
+------------------------------------------------------------------+ +------------------------------------------------------------------+
| | | |
| Security Subsystem | | Security Subsystem |
| | | |
| +----------------+ +-----------------+ +-------------------+ | | +----------------+ +-----------------+ +-------------------+ |
| | * | | * | | * | | | | * | | * | | * | |
| | User-Based | | Other | | Other | | | | User-Based | | Other | | Other | |
| | Security | | Security | | Security | | | | Security | | Security | | Security | |
| | Model | | Model | | Model | | | | Model | | Model | | Model | |
| | | | | | | | | | | | | | | |
| +----------------+ +-----------------+ +-------------------+ | | +----------------+ +-----------------+ +-------------------+ |
| | | |
+------------------------------------------------------------------+ +------------------------------------------------------------------+
3.1.8. Security Model 3.1.8. Security Model
A Security Model defines the threats against which it protects, A Security Model defines the threats against which it protects, the
the goals of its services, and the security protocols used to provide goals of its services, and the security protocols used to provide
security services such as authentication and privacy. security services such as authentication and privacy.
3.1.9. Security Protocol 3.1.9. Security Protocol
A Security Protocol defines the mechanisms, procedures, and MIB A Security Protocol defines the mechanisms, procedures, and MIB data
data used to provide a security service such as authentication used to provide a security service such as authentication or privacy.
or privacy.
3.1.10. Access Control Subsystem 3.1.10. Access Control Subsystem
The Access Control Subsystem provides authorization services by The Access Control Subsystem provides authorization services by means
means of one or more Access Control Models. of one or more Access Control Models.
+------------------------------------------------------------------+ +------------------------------------------------------------------+
| | | |
| Access Control Subsystem | | Access Control Subsystem |
| | | |
| +---------------+ +-----------------+ +------------------+ | | +---------------+ +-----------------+ +------------------+ |
| | * | | * | | * | | | | * | | * | | * | |
| | View-Based | | Other | | Other | | | | View-Based | | Other | | Other | |
| | Access | | Access | | Access | | | | Access | | Access | | Access | |
| | Control | | Control | | Control | | | | Control | | Control | | Control | |
skipping to change at page 28, line 9 skipping to change at page 1, line 721
3.1.11. Access Control Model 3.1.11. Access Control Model
An Access Control Model defines a particular access decision function An Access Control Model defines a particular access decision function
in order to support decisions regarding access rights. in order to support decisions regarding access rights.
3.1.12. Applications 3.1.12. Applications
There are several types of applications, including: There are several types of applications, including:
- command generators, which monitor and manipulate management data, - command generators, which monitor and manipulate management
data,
- command responders, which provide access to management data, - command responders, which provide access to management data,
- notification originators, which initiate asynchronous messages, - notification originators, which initiate asynchronous messages,
- notification receivers, which process asynchronous messages, and
- notification receivers, which process asynchronous messages,
and
- proxy forwarders, which forward messages between entities. - proxy forwarders, which forward messages between entities.
These applications make use of the services provided by the SNMP These applications make use of the services provided by the SNMP
engine. engine.
3.1.13. SNMP Agent 3.1.13. SNMP Manager
An SNMP entity containing one or more command generator and/or
notification receiver applications (along with their associated SNMP
engine) has traditionally been called an SNMP manager.
* One or more models may be present.
(traditional SNMP manager)
+-------------------------------------------------------------------+
| +--------------+ +--------------+ +--------------+ SNMP entity |
| | NOTIFICATION | | NOTIFICATION | | COMMAND | |
| | ORIGINATOR | | RECEIVER | | GENERATOR | |
| | applications | | applications | | applications | |
| +--------------+ +--------------+ +--------------+ |
| ^ ^ ^ |
| | | | |
| v v v |
| +-------+--------+-----------------+ |
| ^ |
| | +---------------------+ +----------------+ |
| | | Message Processing | | Security | |
| Dispatcher v | Subsystem | | Subsystem | |
| +-------------------+ | +------------+ | | | |
| | PDU Dispatcher | | +->| v1MP * |<--->| +------------+ | |
| | | | | +------------+ | | | Other | | |
| | | | | +------------+ | | | Security | | |
| | | | +->| v2cMP * |<--->| | Model | | |
| | Message | | | +------------+ | | +------------+ | |
| | Dispatcher <--------->+ | | | |
| | | | | +------------+ | | +------------+ | |
| | | | +->| v3MP * |<--->| | User-based | | |
| | Transport | | | +------------+ | | | Security | | |
| | Mapping | | | +------------+ | | | Model | | |
| | (e.g RFC1906) | | +->| otherMP * |<--->| +------------+ | |
| +-------------------+ | +------------+ | | | |
| ^ +---------------------+ +----------------+ |
| | |
| v |
+-------------------------------------------------------------------+
+-----+ +-----+ +-------+
| UDP | | IPX | . . . | other |
+-----+ +-----+ +-------+
^ ^ ^
| | |
v v v
+------------------------------+
| Network |
+------------------------------+
3.1.14. SNMP Agent
An SNMP entity containing one or more command responder and/or An SNMP entity containing one or more command responder and/or
notification originator applications (along with their associated notification originator applications (along with their associated
SNMP engine) has traditionally been called an SNMP agent. SNMP engine) has traditionally been called an SNMP agent.
+------------------------------+
3.1.14. SNMP Manager | Network |
+------------------------------+
An SNMP entity containing one or more command generator and/or ^ ^ ^
notification receiver applications (along with their associated | | |
SNMP engine) has traditionally been called an SNMP manager. v v v
+-----+ +-----+ +-------+
| UDP | | IPX | . . . | other |
+-----+ +-----+ +-------+ (traditional SNMP agent)
+-------------------------------------------------------------------+
| ^ |
| | +---------------------+ +----------------+ |
| | | Message Processing | | Security | |
| Dispatcher v | Subsystem | | Subsystem | |
| +-------------------+ | +------------+ | | | |
| | Transport | | +->| v1MP * |<--->| +------------+ | |
| | Mapping | | | +------------+ | | | Other | | |
| | (e.g. RFC1906) | | | +------------+ | | | Security | | |
| | | | +->| v2cMP * |<--->| | Model | | |
| | Message | | | +------------+ | | +------------+ | |
| | Dispatcher <--------->| +------------+ | | +------------+ | |
| | | | +->| v3MP * |<--->| | User-based | | |
| | | | | +------------+ | | | Security | | |
| | PDU Dispatcher | | | +------------+ | | | Model | | |
| +-------------------+ | +->| otherMP * |<--->| +------------+ | |
| ^ | +------------+ | | | |
| | +---------------------+ +----------------+ |
| v |
| +-------+-------------------------+---------------+ |
| ^ ^ ^ |
| | | | |
| v v v |
| +-------------+ +---------+ +--------------+ +-------------+ |
| | COMMAND | | ACCESS | | NOTIFICATION | | PROXY * | |
| | RESPONDER |<->| CONTROL |<->| ORIGINATOR | | FORWARDER | |
| | application | | | | applications | | application | |
| +-------------+ +---------+ +--------------+ +-------------+ |
| ^ ^ |
| | | |
| v v |
| +----------------------------------------------+ |
| | MIB instrumentation | SNMP entity |
+-------------------------------------------------------------------+
3.2. The Naming of Identities 3.2. The Naming of Identities
principal <---------------------------------+ principal
^
| |
+-------------------------------------|-----+ |
| SNMP engine | | +----------------------------|-------------+
| | | | SNMP engine v |
| +-----------------------+ | | | +--------------+ |
| | Security Model | | |
| | +-------------+ | | |
wire | | | Model | +------------+--+ |
<----------->| Dependent |<-->| | securityName| |
| | | Security ID | +---------------+ |
| | +-------------+ | |
| | | | | | | |
| +-----------------------+ | | +-----------------| securityName |---+ |
| | | | Security Model | | | |
| | | | +--------------+ | |
+-------------------------------------------+ | | ^ | |
| | | | |
| | v | |
| | +------------------------------+ | |
| | | | | |
| | | Model | | |
| | | Dependent | | |
| | | Security ID | | |
| | | | | |
| | +------------------------------+ | |
| | ^ | |
| | | | |
| +-------------------------|----------+ |
| | |
| | |
+----------------------------|-------------+
|
v
wire
3.2.1. Principal 3.2.1. Principal
A principal is the "who" on whose behalf services are provided A principal is the "who" on whose behalf services are provided or
or processing takes place. processing takes place.
A principal can be, among other things, an individual acting in A principal can be, among other things, an individual acting in a
a particular role; a set of individuals, with each acting in a particular role; a set of individuals, with each acting in a
particular role; an application; or a set of applications; particular role; an application or a set of applications; and
and combinations thereof. combinations thereof.
3.2.2. securityName 3.2.2. securityName
A securityName is a human readable string representing a principal. A securityName is a human readable string representing a principal.
It has a model independent format, and can be used outside a It has a model-independent
particular Security Model. format, and can be used outside a particular Security Model.
3.2.3. Model dependent security ID 3.2.3. Model-dependent security ID
A model dependent security ID is the model specific representation A model-dependent security ID is the model-specific representation of
of a securityName within a particular Security Model. a securityName within a particular Security Model.
Model dependent security IDs may or may not be human readable, and Model-dependent security IDs may or may not be human readable, and
have a model dependent syntax. Examples include community names, have a model-dependent syntax. Examples include community names, user
user names, and parties. names, and parties.
The transformation of model dependent security IDs into securityNames The transformation of model-dependent security IDs into securityNames
and vice versa is the responsibility of the relevant Security Model. and vice versa is the responsibility of the relevant Security Model.
3.3. The Naming of Management Information 3.3. The Naming of Management Information
Management information resides at an SNMP entity where a Command Management information resides at an SNMP entity where a Command
Responder Application has local access to potentially multiple Responder Application has local access to potentially multiple
contexts. Such a Command Responder application uses a contextEngineID contexts. Such a Command Responder application uses a contextEngineID
equal to the snmpEngineID of its associated SNMP engine. equal to the snmpEngineID of its associated SNMP engine.
+-----------------------------------------------------------------+ +-----------------------------------------------------------------+
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| | | | | | | | | | | | | | | | | | | |
+-----------------------------------------------------------------+ +-----------------------------------------------------------------+
3.3.1. An SNMP Context 3.3.1. An SNMP Context
An SNMP context, or just "context" for short, is a collection of An SNMP context, or just "context" for short, is a collection of
management information accessible by an SNMP entity. An item of management information accessible by an SNMP entity. An item of
management information may exist in more than one context. An SNMP management information may exist in more than one context. An SNMP
engine potentially has access to many contexts. engine potentially has access to many contexts.
Typically, there are many instances of each managed object type within Typically, there are many instances of each managed object type
a management domain. For simplicity, the method for identifying within a management domain. For simplicity, the method for
instances specified by the MIB module does not allow each instance to identifying instances specified by the MIB module does not allow each
be distinguished amongst the set of all instances within a management instance to be distinguished amongst the set of all instances within
domain; rather, it allows each instance to be identified only within a management domain; rather, it allows each instance to be identified
some scope or "context", where there are multiple such contexts within only within some scope or "context", where there are multiple such
the management domain. Often, a context is a physical device, or contexts within the management domain. Often, a context is a
perhaps, a logical device, although a context can also encompass physical device, or perhaps, a logical device, although a context can
multiple devices, or a subset of a single device, or even a subset of also encompass multiple devices, or a subset of a single device, or
multiple devices, but a context is always defined as a subset of a even a subset of multiple devices, but a context is always defined as
single SNMP entity. Thus, in order to identify an individual item of a subset of a single SNMP entity. Thus, in order to identify an
management information within the management domain, its contextName individual item of management information within the management
and contextEngineID must be identified in addition to its object type domain, its contextName and contextEngineID must be identified in
and its instance. addition to its object type and its instance.
For example, the managed object type ifDescr [RFC1573], is defined as For example, the managed object type ifDescr [RFC1573], is defined as
the description of a network interface. To identify the description the description of a network interface. To identify the description
of device-X's first network interface, four pieces of information are of device-X's first network interface, four pieces of information are
needed: the snmpEngineID of the SNMP entity which provides access to needed: the snmpEngineID of the SNMP entity which provides access to
the management information at device-X, the contextName (device-X), the management information at device-X, the contextName (device-X),
the managed object type (ifDescr), and the instance ("1"). the managed object type (ifDescr), and the instance ("1").
Each context has (at least) one unique identification within the Each context has (at least) one unique identification within the
management domain. The same item of management information can exist management domain. The same item of management information can exist
in multiple contexts. So, an item of management information can have in multiple contexts. An item of management information may have
multiple unique identifications, either because it exists in multiple multiple unique identifications. This occurs when an item of
contexts, and/or because each such context has multiple unique management information exists in multiple contexts, and this also
identifications. occurs when a context has multiple unique identifications.
The combination of a contextEngineID and a contextName unambiguously The combination of a contextEngineID and a contextName unambiguously
identifies a context within an administrative domain. identifies a context within an administrative domain; note that there
may be multiple unique combinations of contextEngineID and
contextName that unambiguously identify the same context.
3.3.2. contextEngineID 3.3.2. contextEngineID
Within an administrative domain, a contextEngineID uniquely Within an administrative domain, a contextEngineID uniquely
identifies an SNMP entity that may realize an instance of a identifies an SNMP entity that may realize an instance of a context
context with a particular contextName. with a particular contextName.
3.3.3. contextName 3.3.3. contextName
A contextName is used to name a context. Each contextName A contextName is used to name a context. Each contextName MUST be
MUST be unique within an SNMP entity. unique within an SNMP entity.
3.3.4. scopedPDU 3.3.4. scopedPDU
A scopedPDU is a block of data containing a contextEngineID, A scopedPDU is a block of data containing a contextEngineID, a
a contextName, and a PDU. contextName, and a PDU.
The PDU is an SNMP Protocol Data Unit containing information The PDU is an SNMP Protocol Data Unit containing information named in
named in the context which is unambiguously identified within the context which is unambiguously identified within an
an administrative domain by the combination of the contextEngineID administrative domain by the combination of the contextEngineID and
and the contextName. See, for example, RFC1905 for more information the contextName. See, for example, RFC1905 for more information about
about SNMP PDUs. SNMP PDUs.
3.4. Other Constructs 3.4. Other Constructs
3.4.1. maxSizeResponseScopedPDU 3.4.1. maxSizeResponseScopedPDU
The maxSizeResponseScopedPDU is the maximum size of a scopedPDU to The maxSizeResponseScopedPDU is the maximum size of a scopedPDU to be
be included in a response message, making allowance for the message included in a response message. Note that the size of a scopedPDU
header. does not include the size of the SNMP message header.
3.4.2. Local Configuration Datastore 3.4.2. Local Configuration Datastore
The subsystems, models, and applications within an SNMP entity may The subsystems, models, and applications within an SNMP entity may
need to retain their own sets of configuration information. need to retain their own sets of configuration information.
Portions of the configuration information may be accessible as Portions of the configuration information may be accessible as
managed objects. managed objects.
The collection of these sets of information is referred to The collection of these sets of information is referred to as an
as an entity's Local Configuration Datastore (LCD). entity's Local Configuration Datastore (LCD).
3.4.3. securityLevel 3.4.3. securityLevel
This architecture recognizes three levels of security: This architecture recognizes three levels of security:
- without authentication and without privacy (noAuthNoPriv) - without authentication and without privacy (noAuthNoPriv)
- with authentication but without privacy (authNoPriv) - with authentication but without privacy (authNoPriv)
- with authentication and with privacy (authPriv) - with authentication and with privacy (authPriv)
These three values are ordered such that noAuthNoPriv is less than These three values are ordered such that noAuthNoPriv is less than
authNoPriv and authNoPriv is less than authPriv. authNoPriv and authNoPriv is less than authPriv.
Every message has an associated securityLevel. All Subsystems (Message Every message has an associated securityLevel. All Subsystems
Processing, Security, Access Control) and applications are required (Message Processing, Security, Access Control) and applications are
to either supply a value of securityLevel or to abide by the supplied required to either supply a value of securityLevel or to abide by the
value of securityLevel while processing the message and its contents. supplied value of securityLevel while processing the message and its
contents.
4. Abstract Service Interfaces. 4. Abstract Service Interfaces.
Abstract service interfaces have been defined to describe the Abstract service interfaces have been defined to describe the
conceptual interfaces between the various subsystems within an SNMP conceptual interfaces between the various subsystems within an SNMP
entity. entity.
These abstract service interfaces are defined by a set of primitives These abstract service interfaces are defined by a set of primitives
that define the services provided and the abstract data elements that that define the services provided and the abstract data elements that
are to be passed when the services are invoked. This section lists are to be passed when the services are invoked. This section lists
skipping to change at page 33, line 32 skipping to change at page 1, line 1072
All Subsystems which pass stateReference information also provide a All Subsystems which pass stateReference information also provide a
primitive to release the memory that holds the referenced state primitive to release the memory that holds the referenced state
information: information:
stateRelease( stateRelease(
IN stateReference -- handle of reference to be released IN stateReference -- handle of reference to be released
) )
4.2. Dispatcher Primitives 4.2. Dispatcher Primitives
The Dispatcher typically provides services to the SNMP applications via The Dispatcher typically provides services to the SNMP applications
its PDU Dispatcher. This section describes the primitives provided by via its PDU Dispatcher. This section describes the primitives
the PDU Dispatcher. provided by the PDU Dispatcher.
4.2.1. Generate Outgoing Request or Notification 4.2.1. Generate Outgoing Request or Notification
The PDU Dispatcher provides the following primitive for an application The PDU Dispatcher provides the following primitive for an
to send an SNMP Request or Notification to another SNMP entity: application to send an SNMP Request or Notification to another SNMP
entity:
statusInformation = -- sendPduHandle if success statusInformation = -- sendPduHandle if success
-- errorIndication if failure -- errorIndication if failure
sendPdu( sendPdu(
IN transportDomain -- transport domain to be used IN transportDomain -- transport domain to be used
IN transportAddress -- transport address to be used IN transportAddress -- transport address to be used
IN messageProcessingModel -- typically, SNMP version IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model to use IN securityModel -- Security Model to use
IN securityName -- on behalf of this principal IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security requested IN securityLevel -- Level of Security requested
IN contextEngineID -- data from/at this entity IN contextEngineID -- data from/at this entity
IN contextName -- data from/in this context IN contextName -- data from/in this context
IN pduVersion -- the version of the PDU IN pduVersion -- the version of the PDU
IN PDU -- SNMP Protocol Data Unit IN PDU -- SNMP Protocol Data Unit
IN expectResponse -- TRUE or FALSE IN expectResponse -- TRUE or FALSE
) )
4.2.2. Process Incoming Request or Notification PDU 4.2.2. Process Incoming Request or Notification PDU
The PDU Dispatcher provides the following primitive to pass an incoming The PDU Dispatcher provides the following primitive to pass an
SNMP PDU to an application: incoming SNMP PDU to an application:
processPdu( -- process Request/Notification PDU processPdu( -- process Request/Notification PDU
IN messageProcessingModel -- typically, SNMP version IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model in use IN securityModel -- Security Model in use
IN securityName -- on behalf of this principal IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security IN securityLevel -- Level of Security
IN contextEngineID -- data from/at this SNMP entity IN contextEngineID -- data from/at this SNMP entity
IN contextName -- data from/in this context IN contextName -- data from/in this context
IN pduVersion -- the version of the PDU IN pduVersion -- the version of the PDU
IN PDU -- SNMP Protocol Data Unit IN PDU -- SNMP Protocol Data Unit
IN maxSizeResponseScopedPDU -- maximum size of the Response PDU IN maxSizeResponseScopedPDU -- maximum size of the Response PDU
IN stateReference -- reference to state information IN stateReference -- reference to state information
) -- needed when sending a response ) -- needed when sending a response
4.2.3. Generate Outgoing Response 4.2.3. Generate Outgoing Response
The PDU Dispatcher provides the following primitive for an application The PDU Dispatcher provides the following primitive for an
to return an SNMP Response PDU to the PDU Dispatcher: application to return an SNMP Response PDU to the PDU Dispatcher:
returnResponsePdu( returnResponsePdu(
IN messageProcessingModel -- typically, SNMP version IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model in use IN securityModel -- Security Model in use
IN securityName -- on behalf of this principal IN securityName -- on behalf of this principal
IN securityLevel -- same as on incoming request IN securityLevel -- same as on incoming request
IN contextEngineID -- data from/at this SNMP entity IN contextEngineID -- data from/at this SNMP entity
IN contextName -- data from/in this context IN contextName -- data from/in this context
IN pduVersion -- the version of the PDU IN pduVersion -- the version of the PDU
IN PDU -- SNMP Protocol Data Unit IN PDU -- SNMP Protocol Data Unit
IN maxSizeResponseScopedPDU -- maximum size of the Response PDU IN maxSizeResponseScopedPDU -- maximum size of the Response PDU
IN stateReference -- reference to state information IN stateReference -- reference to state information
-- as presented with the request -- as presented with the request
IN statusInformation -- success or errorIndication IN statusInformation -- success or errorIndication
) -- error counter OID/value if error ) -- error counter OID/value if error
4.2.4. Process Incoming Response PDU 4.2.4. Process Incoming Response PDU
The PDU Dispatcher provides the following primitive to pass an incoming The PDU Dispatcher provides the following primitive to pass an
SNMP Response PDU to an application: incoming SNMP Response PDU to an application:
processResponsePdu( -- process Response PDU processResponsePdu( -- process Response PDU
IN messageProcessingModel -- typically, SNMP version IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model in use IN securityModel -- Security Model in use
IN securityName -- on behalf of this principal IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security IN securityLevel -- Level of Security
IN contextEngineID -- data from/at this SNMP entity IN contextEngineID -- data from/at this SNMP entity
IN contextName -- data from/in this context IN contextName -- data from/in this context
IN pduVersion -- the version of the PDU IN pduVersion -- the version of the PDU
IN PDU -- SNMP Protocol Data Unit IN PDU -- SNMP Protocol Data Unit
IN statusInformation -- success or errorIndication IN statusInformation -- success or errorIndication
IN sendPduHandle -- handle from sendPDU IN sendPduHandle -- handle from sendPdu
) )
4.2.5. Registering Responsibility for Handling SNMP PDUs. 4.2.5. Registering Responsibility for Handling SNMP PDUs.
Applications can register/unregister responsibility for a specific Applications can register/unregister responsibility for a specific
contextEngineID, for specific pduTypes, with the PDU Dispatcher contextEngineID, for specific pduTypes, with the PDU Dispatcher
according to these primitives: according to these primitives:
statusInformation = -- success or errorIndication statusInformation = -- success or errorIndication
registerContextEngineID( registerContextEngineID(
IN contextEngineID -- take responsibility for this one IN contextEngineID -- take responsibility for this one
IN pduType -- the pduType(s) to be registered IN pduType -- the pduType(s) to be registered
) )
unregisterContextEngineID( unregisterContextEngineID(
IN contextEngineID -- give up responsibility for this one IN contextEngineID -- give up responsibility for this one
IN pduType -- the pduType(s) to be unregistered IN pduType -- the pduType(s) to be unregistered
) )
Note that realizations of the registerContextEngineID and
unregisterContextEngineID abstract service interfaces may provide
implementation-specific ways for applications to register/deregister
responsiblity for all possible values of the contextEngineID or
pduType parameters.
4.3. Message Processing Subsystem Primitives 4.3. Message Processing Subsystem Primitives
The Dispatcher interacts with a Message Processing Model to process a The Dispatcher interacts with a Message Processing Model to process a
specific version of an SNMP Message. This section describes the specific version of an SNMP Message. This section describes the
primitives provided by the Message Processing Subsystem. primitives provided by the Message Processing Subsystem.
4.3.1. Prepare an Outgoing SNMP Request or Notification Message 4.3.1. Prepare Outgoing SNMP Request or Notification Message
The Message Processing Subsystem provides this service primitive for The Message Processing Subsystem provides this service primitive for
preparing an outgoing SNMP Request or Notification Message: preparing an outgoing SNMP Request or Notification Message:
statusInformation = -- success or errorIndication statusInformation = -- success or errorIndication
prepareOutgoingMessage( prepareOutgoingMessage(
IN transportDomain -- transport domain to be used IN transportDomain -- transport domain to be used
IN transportAddress -- transport address to be used IN transportAddress -- transport address to be used
IN messageProcessingModel -- typically, SNMP version IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model to use IN securityModel -- Security Model to use
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4.3.3. Prepare Data Elements from an Incoming SNMP Message 4.3.3. Prepare Data Elements from an Incoming SNMP Message
The Message Processing Subsystem provides this service primitive for The Message Processing Subsystem provides this service primitive for
preparing the abstract data elements from an incoming SNMP message: preparing the abstract data elements from an incoming SNMP message:
result = -- SUCCESS or errorIndication result = -- SUCCESS or errorIndication
prepareDataElements( prepareDataElements(
IN transportDomain -- origin transport domain IN transportDomain -- origin transport domain
IN transportAddress -- origin transport address IN transportAddress -- origin transport address
IN wholeMsg -- as received from the network IN wholeMsg -- as received from the network
IN wholeMsglength -- as received from the network IN wholeMsgLength -- as received from the network
OUT messageProcessingModel -- typically, SNMP version OUT messageProcessingModel -- typically, SNMP version
OUT securityModel -- Security Model to use OUT securityModel -- Security Model to use
OUT securityName -- on behalf of this principal OUT securityName -- on behalf of this principal
OUT securityLevel -- Level of Security requested OUT securityLevel -- Level of Security requested
OUT contextEngineID -- data from/at this entity OUT contextEngineID -- data from/at this entity
OUT contextName -- data from/in this context OUT contextName -- data from/in this context
OUT pduVersion -- the version of the PDU OUT pduVersion -- the version of the PDU
OUT PDU -- SNMP Protocol Data Unit OUT PDU -- SNMP Protocol Data Unit
OUT pduType -- SNMP PDU type OUT pduType -- SNMP PDU type
OUT sendPduHandle -- handle for matched request OUT sendPduHandle -- handle for matched request
OUT maxSizeResponseScopedPDU -- maximum size of the Response PDU OUT maxSizeResponseScopedPDU -- maximum size of the Response PDU
OUT statusInformation -- success or errorIndication OUT statusInformation -- success or errorIndication
-- error counter OID/value if error -- error counter OID/value if error
OUT stateReference -- reference to state information OUT stateReference -- reference to state information
-- to be used for a possible Response -- to be used for possible Response
) )
4.4. Access Control Subsystem Primitives 4.4. Access Control Subsystem Primitives
Applications are the typical clients of the service(s) of the Access Applications are the typical clients of the service(s) of the Access
Control Subsystem. Control Subsystem.
The following primitive is provided by the Access Control Subsystem The following primitive is provided by the Access Control Subsystem
to check if access is allowed: to check if access is allowed:
skipping to change at page 37, line 31 skipping to change at page 1, line 1283
IN securityModel -- Security Model in use IN securityModel -- Security Model in use
IN securityName -- principal who wants to access IN securityName -- principal who wants to access
IN securityLevel -- Level of Security IN securityLevel -- Level of Security
IN viewType -- read, write, or notify view IN viewType -- read, write, or notify view
IN contextName -- context containing variableName IN contextName -- context containing variableName
IN variableName -- OID for the managed object IN variableName -- OID for the managed object
) )
4.5. Security Subsystem Primitives 4.5. Security Subsystem Primitives
The Message Processing Subsystem is the typical client of the services The Message Processing Subsystem is the typical client of the
of the Security Subsystem. services of the Security Subsystem.
4.5.1. Generate a Request or Notification Message 4.5.1. Generate a Request or Notification Message
The Security Subsystem provides the following primitive to generate The Security Subsystem provides the following primitive to generate a
a Request or Notification message: Request or Notification message:
statusInformation = statusInformation =
generateRequestMsg( generateRequestMsg(
IN messageProcessingModel -- typically, SNMP version IN messageProcessingModel -- typically, SNMP version
IN globalData -- message header, admin data IN globalData -- message header, admin data
IN maxMessageSize -- of the sending SNMP entity IN maxMessageSize -- of the sending SNMP entity
IN securityModel -- for the outgoing message IN securityModel -- for the outgoing message
IN securityEngineID -- authoritative SNMP entity IN securityEngineID -- authoritative SNMP entity
IN securityName -- on behalf of this principal IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security requested IN securityLevel -- Level of Security requested
IN scopedPDU -- message (plaintext) payload IN scopedPDU -- message (plaintext) payload
OUT securityParameters -- filled in by Security Module OUT securityParameters -- filled in by Security Module
OUT wholeMsg -- complete generated message OUT wholeMsg -- complete generated message
OUT wholeMsgLength -- length of the generated message OUT wholeMsgLength -- length of the generated message
) )
4.5.2. Process Incoming Message 4.5.2. Process Incoming Message
The Security Subsystem provides the following primitive to process The Security Subsystem provides the following primitive to process an
an incoming message: incoming message:
statusInformation = -- errorIndication or success statusInformation = -- errorIndication or success
-- error counter OID/value if error -- error counter OID/value if error
processIncomingMsg( processIncomingMsg(
IN messageProcessingModel -- typically, SNMP version IN messageProcessingModel -- typically, SNMP version
IN maxMessageSize -- of the sending SNMP entity IN maxMessageSize -- of the sending SNMP entity
IN securityParameters -- for the received message IN securityParameters -- for the received message
IN securityModel -- for the received message IN securityModel -- for the received message
IN securityLevel -- Level of Security IN securityLevel -- Level of Security
IN wholeMsg -- as received on the wire IN wholeMsg -- as received on the wire
IN wholeMsgLength -- length as received on the wire IN wholeMsgLength -- length as received on the wire
OUT securityEngineID -- identification of the principal OUT securityEngineID -- identification of the principal
OUT securityName -- identification of the principal OUT securityName -- identification of the principal
OUT scopedPDU, -- message (plaintext) payload OUT scopedPDU, -- message (plaintext) payload
OUT maxSizeResponseScopedPDU -- maximum size of the Response PDU OUT maxSizeResponseScopedPDU -- maximum size of the Response PDU
OUT securityStateReference -- reference to security state OUT securityStateReference -- reference to security state
) -- information, needed for response ) -- information, needed for response
4.5.3. Generate a Response Message 4.5.3. Generate a Response Message
The Security Subsystem provides the following primitive to generate The Security Subsystem provides the following primitive to generate a
a Response message: Response message:
statusInformation = statusInformation =
generateResponseMsg( generateResponseMsg(
IN messageProcessingModel -- typically, SNMP version IN messageProcessingModel -- typically, SNMP version
IN globalData -- message header, admin data IN globalData -- message header, admin data
IN maxMessageSize -- of the sending SNMP entity IN maxMessageSize -- of the sending SNMP entity
IN securityModel -- for the outgoing message IN securityModel -- for the outgoing message
IN securityEngineID -- authoritative SNMP entity IN securityEngineID -- authoritative SNMP entity
IN securityName -- on behalf of this principal IN securityName -- on behalf of this principal
IN securityLevel -- for the outgoing message IN securityLevel -- for the outgoing message
IN scopedPDU -- message (plaintext) payload IN scopedPDU -- message (plaintext) payload
IN securityStateReference -- reference to security state IN securityStateReference -- reference to security state
-- information from original request -- information from original request
OUT securityParameters -- filled in by Security Module OUT securityParameters -- filled in by Security Module
OUT wholeMsg -- complete generated message OUT wholeMsg -- complete generated message
OUT wholeMsgLength -- length of the generated message OUT wholeMsgLength -- length of the generated message
) )
4.6. User Based Security Model Internal Primitives 4.6. Common Primitives
4.6.1. User-based Security Model Primitives for Authentication
The User-based Security Model provides the following internal
primitives to pass data back and forth between the Security Model
itself and the authentication service:
statusInformation =
authenticateOutgoingMsg(
IN authKey -- secret key for authentication
IN wholeMsg -- unauthenticated complete message
OUT authenticatedWholeMsg -- complete authenticated message
)
statusInformation =
authenticateIncomingMsg(
IN authKey -- secret key for authentication
IN authParameters -- as received on the wire
IN wholeMsg -- as received on the wire
OUT authenticatedWholeMsg -- complete authenticated message
)
4.6.2. User-based Security Model Primitives for Privacy These primitive(s) are provided by multiple Subsystems.
The User-based Security Model provides the following internal 4.6.1. Release State Reference Information
primitives to pass data back and forth between the Security Model
itself and the privacy service:
statusInformation = All Subsystems which pass stateReference information also provide a
encryptData( primitive to release the memory that holds the referenced state
IN encryptKey -- secret key for encryption information:
IN dataToEncrypt -- data to encrypt (scopedPDU)
OUT encryptedData -- encrypted data (encryptedPDU)
OUT privParameters -- filled in by service provider
)
statusInformation = stateRelease(
decryptData( IN stateReference -- handle of reference to be released
IN decryptKey -- secret key for decrypting
IN privParameters -- as received on the wire
IN encryptedData -- encrypted data (encryptedPDU)
OUT decryptedData -- decrypted data (scopedPDU)
) )
4.7. Scenario Diagrams 4.7. Scenario Diagrams
4.7.1. Command Generator or Notification Originator Application 4.7.1. Command Generator or Notification Originator
This diagram shows how a Command Generator or Notification Originator This diagram shows how a Command Generator or Notification Originator
application requests that a PDU be sent, and how the response is application requests that a PDU be sent, and how the response is
returned (asynchronously) to that application. returned (asynchronously) to that application.
Command Dispatcher Message Security Command Dispatcher Message Security
Generator | Processing Model Generator | Processing Model
| | Model | | | Model |
| | | |
| sendPdu | | | | sendPdu | | |
|------------------->| | | |------------------->| | |
| | prepareOutgoingMessage | | | | prepareOutgoingMessage | |
: |------------------------->| | : |----------------------->| |
: | | generateRequestMsg | : | | generateRequestMsg |
: | |-------------------->| : | |-------------------->|
: | | | : | | |
: | |<--------------------| : | |<--------------------|
: | | | : | | |
: |<-------------------------| | : |<-----------------------| |
: | | | : | | |
: |------------------+ | | : |------------------+ | |
: | Send SNMP | | | : | Send SNMP | | |
: | Request Message | | | : | Request Message | | |
: | to Network | | | : | to Network | | |
: | v | | : | v | |
: : : : : : : : : :
: : : : : : : : : :
: : : : : : : : : :
: | | | | : | | | |
: | | | |
: | Receive SNMP | | | : | Receive SNMP | | |
: | Response Message | | | : | Response Message | | |
: | from Network | | | : | from Network | | |
: |<-----------------+ | | : |<-----------------+ | |
: | | | : | | |
: | prepareDataElements | | : | prepareDataElements | |
: |------------------------->| | : |----------------------->| |
: | | processIncomingMsg | : | | processIncomingMsg |
: | |-------------------->| : | |-------------------->|
: | | | : | | |
: | |<--------------------| : | |<--------------------|
: | | | : | | |
: |<-------------------------| | : |<-----------------------| |
| processResponsePdu | | | | processResponsePdu | | |
|<-------------------| | | |<-------------------| | |
| | | | | | | |
4.7.2. Scenario Diagram for a Command Responder Application 4.7.2. Scenario Diagram for a Command Responder Application
This diagram shows how a Command Responder or Notification Receiver This diagram shows how a Command Responder or Notification Receiver
application registers for handling a pduType, how a PDU is dispatched application registers for handling a pduType, how a PDU is dispatched
to the application after a SNMP message is received, and how the to the application after a SNMP message is received, and how the
Response is (asynchronously) send back to the network. Response is (asynchronously) send back to the network.
skipping to change at page 41, line 25 skipping to change at page 1, line 1432
| | | | | | | |
| registerContextEngineID | | | | registerContextEngineID | | |
|------------------------>| | | |------------------------>| | |
|<------------------------| | | | |<------------------------| | | |
| | Receive SNMP | | | | | Receive SNMP | | |
: | Message | | | : | Message | | |
: | from Network | | | : | from Network | | |
: |<-------------+ | | : |<-------------+ | |
: | | | : | | |
: | prepareDataElements | | : | prepareDataElements | |
: |-------------------->| | : |------------------->| |
: | | processIncomingMsg | : | | processIncomingMsg |
: | |-------------------->| : | |------------------->|
: | | | : | | |
: | |<--------------------| : | |<-------------------|
: | | | : | | |
: |<--------------------| | : |<-------------------| |
| processPdu | | | | processPdu | | |
|<------------------------| | | |<------------------------| | |
| | | | | | | |
: : : : : : : :
: : : : : : : :
| returnResponsePdu | | | | returnResponsePdu | | |
|------------------------>| | | |------------------------>| | |
: | prepareResponseMsg | | : | prepareResponseMsg | |
: |-------------------->| | : |------------------->| |
: | | generateResponseMsg | : | | generateResponseMsg |
: | |-------------------->| : | |------------------->|
: | | | : | | |
: | |<--------------------| : | |<-------------------|
: | | | : | | |
: |<--------------------| | : |<-------------------| |
: | | | : | | |
: |--------------+ | | : |--------------+ | |
: | Send SNMP | | | : | Send SNMP | | |
: | Message | | | : | Message | | |
: | to Network | | | : | to Network | | |
: | v | | : | v | |
5. Definition of Managed Objects for SNMP Management Frameworks 5. Managed Object Definitions for SNMP Management Frameworks
SNMP-FRAMEWORK-MIB DEFINITIONS ::= BEGIN SNMP-FRAMEWORK-MIB DEFINITIONS ::= BEGIN
IMPORTS IMPORTS
MODULE-IDENTITY, OBJECT-TYPE, MODULE-IDENTITY, OBJECT-TYPE,
OBJECT-IDENTITY, OBJECT-IDENTITY,
snmpModules, Unsigned32, Integer32 FROM SNMPv2-SMI snmpModules FROM SNMPv2-SMI
TEXTUAL-CONVENTION FROM SNMPv2-TC TEXTUAL-CONVENTION FROM SNMPv2-TC
MODULE-COMPLIANCE, OBJECT-GROUP FROM SNMPv2-CONF; MODULE-COMPLIANCE, OBJECT-GROUP FROM SNMPv2-CONF;
snmpFrameworkMIB MODULE-IDENTITY snmpFrameworkMIB MODULE-IDENTITY
LAST-UPDATED "9707260000Z" -- 26 July 1997, midnight LAST-UPDATED "9709300000Z" -- 30 September 1997
ORGANIZATION "SNMPv3 Working Group" ORGANIZATION "SNMPv3 Working Group"
CONTACT-INFO "WG-email: snmpv3@tis.com CONTACT-INFO "WG-email: snmpv3@tis.com
Subscribe: majordomo@tis.com Subscribe: majordomo@tis.com
In message body: subscribe snmpv3 In message body: subscribe snmpv3
Chair: Russ Mundy Chair: Russ Mundy
Trusted Information Systems Trusted Information Systems
postal: 3060 Washington Rd postal: 3060 Washington Rd
Glenwood MD 21738 Glenwood MD 21738
USA USA
email: mundy@tis.com email: mundy@tis.com
phone: +1-301-854-6889 phone: +1 301-854-6889
Co-editor Dave Harrington Co-editor Dave Harrington
Cabletron Systems, Inc Cabletron Systems, Inc.
postal: Post Office Box 5005 postal: Post Office Box 5005
MailStop: Durham MailStop: Durham
35 Industrial Way 35 Industrial Way
Rochester NH 03867-5005 Rochester, NH 03867-5005
USA USA
email: dbh@cabletron.com email: dbh@cabletron.com
phone: +1-603-337-7357 phone: +1 603-337-7357
Co-editor Randy Presuhn
BMC Software, Inc.
postal: 1190 Saratoga Avenue
Suite 130
San Jose, CA 95129
USA
email: rpresuhn@bmc.com
phone: +1 408-556-0720
Co-editor: Bert Wijnen Co-editor: Bert Wijnen
IBM T.J. Watson Research IBM T.J. Watson Research
postal: Schagen 33 postal: Schagen 33
3461 GL Linschoten 3461 GL Linschoten
Netherlands Netherlands
email: wijnen@vnet.ibm.com email: wijnen@vnet.ibm.com
phone: +31-348-432-794 phone: +31 348-432-794
" "
DESCRIPTION "The SNMP Management Architecture MIB" DESCRIPTION "The SNMP Management Architecture MIB"
::= { snmpModules 7 } -- DBH: check if this number is indeed OK ::= { snmpModules 7 } -- DBH: check if this number is indeed OK
-- Textual Conventions used in the SNMP Management Architecture *** -- Textual Conventions used in the SNMP Management Architecture ***
SnmpEngineID ::= TEXTUAL-CONVENTION SnmpEngineID ::= TEXTUAL-CONVENTION
STATUS current STATUS current
DESCRIPTION "An SNMP engine's administratively-unique identifier. DESCRIPTION "An SNMP engine's administratively-unique identifier.
The value for this object may not be all zeros or The value for this object may not be all zeros or
all 'ff'H or the empty (zero length) string. all 'ff'H or the empty (zero length) string.
The initial value for this object may be configured The initial value for this object may be configured
via an operator console entry or via an algorithmic via an operator console entry or via an algorithmic
function. In the latter case, the following function. In the latter case, the following
example algorithm is recommended. example algorithm is recommended.
In cases where there are multiple engines on the
same system, the use of this algorithm is NOT
appropriate, as it would result in all of those
engines ending up with the same ID value.
1) The very first bit is used to indicate how the 1) The very first bit is used to indicate how the
rest of the data is composed. rest of the data is composed.
0 - as defined by enterprise using former methods 0 - as defined by enterprise using former methods
that existed before SNMPv3. See item 2 below. that existed before SNMPv3. See item 2 below.
1 - as defined by this architecture, see item 3 1 - as defined by this architecture, see item 3
below. below.
Note that this allows existing uses of the Note that this allows existing uses of the
engineID (also known as AgentID [RFC1910]) to engineID (also known as AgentID [RFC1910]) to
co-exist with any new uses. co-exist with any new uses.
2) The snmpEngineID has a length of 12 octets. 2) The snmpEngineID has a length of 12 octets.
The first four octets are set to the binary The first four octets are set to the binary
equivalent of the agent's SNMP network management equivalent of the agent's SNMP management
private enterprise number as assigned by the private enterprise number as assigned by the
Internet Assigned Numbers Authority (IANA). Internet Assigned Numbers Authority (IANA).
For example, if Acme Networks has been assigned For example, if Acme Networks has been assigned
{ enterprises 696 }, the first four octets would { enterprises 696 }, the first four octets would
be assigned '000002b8'H. be assigned '000002b8'H.
The remaining eight octets are determined via The remaining eight octets are determined via
one or more enterprise specific methods. Such one or more enterprise-specific methods. Such
methods must be designed so as to maximize the methods must be designed so as to maximize the
possibility that the value of this object will possibility that the value of this object will
be unique in the agent's administrative domain. be unique in the agent's administrative domain.
For example, it may be the IP address of the SNMP For example, it may be the IP address of the SNMP
entity, or the MAC address of one of the entity, or the MAC address of one of the
interfaces, with each address suitably padded interfaces, with each address suitably padded
with random octets. If multiple methods are with random octets. If multiple methods are
defined, then it is recommended that the first defined, then it is recommended that the first
octet indicate the method being used and the octet indicate the method being used and the
remaining octets be a function of the method. remaining octets be a function of the method.
3) The length of the octet strings varies. 3) The length of the octet strings varies.
The first four octets are set to the binary The first four octets are set to the binary
equivalent of the agent's SNMP network management equivalent of the agent's SNMP management
private enterprise number as assigned by the private enterprise number as assigned by the
Internet Assigned Numbers Authority (IANA). Internet Assigned Numbers Authority (IANA).
For example, if Acme Networks has been assigned For example, if Acme Networks has been assigned
{ enterprises 696 }, the first four octets would { enterprises 696 }, the first four octets would
be assigned '000002b8'H. be assigned '000002b8'H.
The very first bit is set to 1. For example, the The very first bit is set to 1. For example, the
above value for Acme Networks now changes to be above value for Acme Networks now changes to be
'800002b8'H. '800002b8'H.
skipping to change at page 44, line 26 skipping to change at page 1, line 1599
0 - reserved, unused. 0 - reserved, unused.
1 - IPv4 address (4 octets) 1 - IPv4 address (4 octets)
lowest non-special IP address lowest non-special IP address
2 - IPv6 address (16 octets) 2 - IPv6 address (16 octets)
lowest non-special IP address lowest non-special IP address
3 - MAC address (6 octets) 3 - MAC address (6 octets)
lowest IEEE MAC address, canonical order lowest IEEE MAC address, canonical
order
4 - Text, administratively assigned 4 - Text, administratively assigned
Maximum remaining length 27 Maximum remaining length 27
5 - Octets, administratively assigned 5 - Octets, administratively assigned
Maximum remaining length 27 Maximum remaining length 27
6-127 - reserved, unused 6-127 - reserved, unused
127-255 - as defined by the enterprise 127-255 - as defined by the enterprise
Maximum remaining length 27 Maximum remaining length 27
" "
SYNTAX OCTET STRING (SIZE(1..32)) SYNTAX OCTET STRING (SIZE(1..32))
skipping to change at page 44, line 43 skipping to change at page 1, line 1616
6-127 - reserved, unused 6-127 - reserved, unused
127-255 - as defined by the enterprise 127-255 - as defined by the enterprise
Maximum remaining length 27 Maximum remaining length 27
" "
SYNTAX OCTET STRING (SIZE(1..32)) SYNTAX OCTET STRING (SIZE(1..32))
SnmpSecurityModel ::= TEXTUAL-CONVENTION SnmpSecurityModel ::= TEXTUAL-CONVENTION
STATUS current STATUS current
DESCRIPTION "An identifier that uniquely identifies a securityModel DESCRIPTION "An identifier that uniquely identifies a
of the Security Subsystem within the SNMP securityModel of the Security Subsystem within the
Management Architecture. SNMP Management Architecture.
The values for securityModel are allocated as follows: The values for securityModel are allocated as
follows:
- The zero value is reserved. - The zero value is reserved.
- Values between 1 and 255, inclusive, are reserved - Values between 1 and 255, inclusive, are reserved
for standards-track Security Models and are managed for standards-track Security Models and are
by the Internet Assigned Numbers Authority (IANA). managed by the Internet Assigned Numbers Authority
- Values greater than 255 are allocated to enterprise (IANA).
specific Security Models. An enterprise specific - Values greater than 255 are allocated to
securityModel value is defined to be: enterprise-specific Security Models. An
enterprise-specific securityModel value is defined
to be:
enterpriseID * 256 + security model within enterprise enterpriseID * 256 + security model within
enterprise
For example, the fourth Security Model defined by For example, the fourth Security Model defined by
the enterprise whose enterpriseID is 1 would be 260. the enterprise whose enterpriseID is 1 would be
260.
The eight bits allow a maximum of 255 (256-1 reserved) The eight bits allow a maximum of 255 (256-1
standards based Security Models. Similarly, they reserved) standards based Security Models.
allow a maximum of 255 Security Models per enterprise. Similarly, they allow a maximum of 255 Security
Models per enterprise.
It is believed that the assignment of new It is believed that the assignment of new
securityModel values will be rare in practice securityModel values will be rare in practice
because the larger the number of simultaneously because the larger the number of simultaneously
utilized Security Models, the larger the chance that utilized Security Models, the larger the
interoperability will suffer. Consequently, it is chance that interoperability will suffer.
believed that such a range will be sufficient. Consequently, it is believed that such a range
In the unlikely event that the standards committee will be sufficient. In the unlikely event that
finds this number to be insufficient over time, an the standards committee finds this number to be
enterprise number can be allocated to obtain an insufficient over time, an enterprise number
additional 255 possible values. can be allocated to obtain an additional 255
possible values.
Note that the most significant bit must be zero; Note that the most significant bit must be zero;
hence, there are 23 bits allocated for various hence, there are 23 bits allocated for various
organizations to design and define non-standard organizations to design and define non-standard
securityModels. This limits the ability to define securityModels. This limits the ability to
new proprietary implementations of Security Models define new proprietary implementations of Security
to the first 8,388,608 enterprises. Models to the first 8,388,608 enterprises.
It is worthwhile to note that, in its encoded form, It is worthwhile to note that, in its encoded
the securityModel value will normally require only a form, the securityModel value will normally
single byte since, in practice, the leftmost bits will require only a single byte since, in practice,
be zero for most messages and sign extension is the leftmost bits will be zero for most messages
suppressed by the encoding rules. and sign extension is suppressed by the encoding
rules.
As of this writing, there are several values of As of this writing, there are several values
securityModel defined for use with SNMP or reserved of securityModel defined for use with SNMP or
for use with supporting MIB objects. They are as reserved for use with supporting MIB objects.
follows: They are as follows:
0 reserved for 'none' 0 reserved for 'any'
1 reserved for SNMPv1 1 reserved for SNMPv1
2 reserved for SNMPv2c 2 reserved for SNMPv2c
3 User-Base Security Model (USM) 3 User-Based Security Model (USM)
255 reserved for 'any'
" "
SYNTAX INTEGER(0..2147483647) SYNTAX INTEGER(0..2147483647)
SnmpMessageProcessingModel ::= TEXTUAL-CONVENTION SnmpMessageProcessingModel ::= TEXTUAL-CONVENTION
STATUS current STATUS current
DESCRIPTION "An identifier that uniquely identifies a Message DESCRIPTION "An identifier that uniquely identifies a Message
Processing Model of the Message Processing Subsystem Processing Model of the Message Processing
within a SNMP Management Architecture. Subsystem within a SNMP Management Architecture.
The values for messageProcessingModel are allocated The values for messageProcessingModel are
as follows: allocated as follows:
- Values between 0 and 255, inclusive, are reserved - Values between 0 and 255, inclusive, are
for standards-track Message Processing Models and reserved for standards-track Message Processing
are managed by the Internet Assigned Numbers Models and are managed by the Internet Assigned
Authority (IANA). Numbers Authority (IANA).
- Values greater than 255 are allocated to enterprise - Values greater than 255 are allocated to
specific Message Processing Models. An enterprise enterprise-specific Message Processing Models.
messageProcessingModel value is defined to be: An enterprise messageProcessingModel value is
defined to be:
enterpriseID * 256 + enterpriseID * 256 +
messageProcessingModel within enterprise messageProcessingModel within enterprise
For example, the fourth Message Processing Model For example, the fourth Message Processing Model
defined by the enterprise whose enterpriseID is 1 defined by the enterprise whose enterpriseID
would be 260. is 1 would be 260.
The eight bits allow a maximum of 256 standards based The eight bits allow a maximum of 256 standards
Message Processing Models. Similarly, they allow a based Message Processing Models. Similarly, they
maximum 256 Message Processing Models per enterprise. allow a maximum 256 Message Processing Models
per enterprise.
It is believed that the assignment of new It is believed that the assignment of new
messageProcessingModel values will be rare in practice messageProcessingModel values will be rare
because the larger the number of simultaneously in practice because the larger the number of
utilized Message Processing Models, the larger the simultaneously utilized Message Processing Models,
chance that interoperability will suffer. It is the larger the chance that interoperability
believed that such a range will be sufficient. will suffer. It is believed that such a range
In the unlikely event that the standards committee will be sufficient. In the unlikely event that
finds this number to be insufficient over time, an the standards committee finds this number to be
enterprise number can be allocated to obtain an insufficient over time, an enterprise number
additional 256 possible values. can be allocated to obtain an additional 256
possible values.
Note that the most significant bit must be zero; Note that the most significant bit must be zero;
hence, there are 23 bits allocated for various hence, there are 23 bits allocated for various
organizations to design and define non-standard organizations to design and define non-standard
messageProcessingModels. This limits the ability messageProcessingModels. This limits the ability
to define new proprietary implementations of Message to define new proprietary implementations of
Processing Models to the first 8,388,608 enterprises. Message Processing Models to the first 8,388,608
enterprises.
It is worthwhile to note that, in its encoded form, It is worthwhile to note that, in its encoded
the securityModel value will normally require only a form, the securityModel value will normally
single byte since, in practice, the leftmost bits will require only a single byte since, in practice,
be zero for most messages and sign extension is the leftmost bits will be zero for most messages
suppressed by the encoding rules. and sign extension is suppressed by the encoding
rules.
As of this writing, there are several values of As of this writing, there are several values of
messageProcessingModel defined for use with SNMP. messageProcessingModel defined for use with SNMP.
They are as follows: They are as follows:
0 reserved for SNMPv1 0 reserved for SNMPv1
1 reserved for SNMPv2c 1 reserved for SNMPv2c
2 reserved for SNMPv2u 2 reserved for SNMPv2u and SNMPv2*
3 reserved for SNMPv3 3 reserved for SNMPv3
" "
SYNTAX INTEGER(0..2147483647) SYNTAX INTEGER(0..2147483647)
SnmpSecurityLevel ::= TEXTUAL-CONVENTION SnmpSecurityLevel ::= TEXTUAL-CONVENTION
STATUS current STATUS current
DESCRIPTION "A Level of Security at which SNMP messages can be DESCRIPTION "A Level of Security at which SNMP messages can be
sent or with which operations are being processed; sent or with which operations are being processed;
in particular, one of: in particular, one of:
noAuthNoPriv - without authentication and noAuthNoPriv - without authentication and
without privacy, without privacy,
authNoPriv - with authentication but authNoPriv - with authentication but
without privacy, without privacy,
authPriv - with authentication and authPriv - with authentication and
with privacy. with privacy.
These three values are ordered such that noAuthNoPriv These three values are ordered such that
is less than authNoPriv and authNoPriv is less than noAuthNoPriv is less than authNoPriv and
authPriv. authNoPriv is less than authPriv.
" "
SYNTAX INTEGER { noAuthNoPriv(1), SYNTAX INTEGER { noAuthNoPriv(1),
authNoPriv(2), authNoPriv(2),
authPriv(3) authPriv(3)
} }
SnmpAdminString ::= TEXTUAL-CONVENTION SnmpAdminString ::= TEXTUAL-CONVENTION
DISPLAY-HINT "255a" DISPLAY-HINT "255a"
STATUS current STATUS current
DESCRIPTION "An octet string containing administrative information, DESCRIPTION "An octet string containing administrative
preferably in human-readable form. information, preferably in human-readable form.
To facilitate internationalization, this information To facilitate internationalization, this
is represented using the ISO/IEC IS 10646-1 character information is represented using the ISO/IEC
set, encoded as an octet string using the UTF-8 IS 10646-1 character set, encoded as an octet
character encoding scheme described in RFC 2044. string using the UTF-8 transformation format
described in [RFC2044].
Since additional code points are added by amendments Since additional code points are added by
to the 10646 standard from time to time, amendments to the 10646 standard from time
implementations must be prepared to encounter any code to time, implementations must be prepared to
point from 0x00000000 to 0x7fffffff. encounter any code point from 0x00000000 to
0x7fffffff.
The use of control codes should be avoided. The use of control codes should be avoided.
When it is necessary to represent a newline,
the control code sequence CR LF should be used.
The use of leading or trailing white space should
be avoided.
For code points not directly supported by user For code points not directly supported by user
interface hardware or software, an alternative means interface hardware or software, an alternative
of entry and display, such as hexadecimal, may be means of entry and display, such as hexadecimal,
provided. may be provided.
For information encoded in 7-bit US-ASCII, the UTF-8 For information encoded in 7-bit US-ASCII,
representation is identical to the US-ASCII encoding. the UTF-8 encoding is identical to the
US-ASCII encoding.
Note that when this TC is used for an object that Note that when this TC is used for an object that
is used or envisioned to be used as an index, then a is used or envisioned to be used as an index, then
SIZE restriction must be specified so that the number a SIZE restriction must be specified so that the
sub-identifiers for any object instance do not exceed number sub-identifiers for any object instance
the limit of 128, as defined by [RFC1905]. do not exceed the limit of 128, as defined by
[RFC1905].
" "
SYNTAX OCTET STRING (SIZE (0..255)) SYNTAX OCTET STRING (SIZE (0..255))
-- Administrative assignments ***************************************
snmpFrameworkAdmin OBJECT IDENTIFIER ::= { snmpFrameworkMIB 1 } snmpFrameworkAdmin
snmpFrameworkMIBObjects OBJECT IDENTIFIER ::= { snmpFrameworkMIB 2 } OBJECT IDENTIFIER ::= { snmpFrameworkMIB 1 }
snmpFrameworkMIBConformance OBJECT IDENTIFIER ::= { snmpFrameworkMIB 3 } snmpFrameworkMIBObjects
OBJECT IDENTIFIER ::= { snmpFrameworkMIB 2 }
snmpFrameworkMIBConformance
OBJECT IDENTIFIER ::= { snmpFrameworkMIB 3 }
-- the snmpEngine Group ********************************************
snmpEngine OBJECT IDENTIFIER ::= { snmpFrameworkMIBObjects 1 } snmpEngine OBJECT IDENTIFIER ::= { snmpFrameworkMIBObjects 1 }
snmpEngineID OBJECT-TYPE snmpEngineID OBJECT-TYPE
SYNTAX SnmpEngineID SYNTAX SnmpEngineID
MAX-ACCESS read-only MAX-ACCESS read-only
STATUS current STATUS current
DESCRIPTION "An SNMP engine's administratively-unique identifier. DESCRIPTION "An SNMP engine's administratively-unique identifier.
" "
::= { snmpEngine 1 } ::= { snmpEngine 1 }
snmpEngineBoots OBJECT-TYPE snmpEngineBoots OBJECT-TYPE
SYNTAX Unsigned32 -- (1..4294967295) SYNTAX INTEGER (1..2147483647)
MAX-ACCESS read-only MAX-ACCESS read-only
STATUS current STATUS current
DESCRIPTION "The number of times that the SNMP engine has DESCRIPTION "The number of times that the SNMP engine has
(re-)initialized itself since its initial (re-)initialized itself since its initial
configuration. configuration.
" "
::= { snmpEngine 2 } ::= { snmpEngine 2 }
snmpEngineTime OBJECT-TYPE snmpEngineTime OBJECT-TYPE
SYNTAX Integer32 (0..2147483647) SYNTAX INTEGER (0..2147483647)
MAX-ACCESS read-only MAX-ACCESS read-only
STATUS current STATUS current
DESCRIPTION "The number of seconds since the SNMP engine last DESCRIPTION "The number of seconds since the SNMP engine last
incremented the snmpEngineBoots object. incremented the snmpEngineBoots object.
" "
::= { snmpEngine 3 } ::= { snmpEngine 3 }
snmpEngineMaxMessageSize OBJECT-TYPE
SYNTAX INTEGER (484..2147483647)
MAX-ACCESS read-only
STATUS current
DESCRIPTION "The maximum length in octets of an SNMP message
which this SNMP engine can send or receive and
process, determined as the minimum of the maximum
message size values supported among all of the
transports available to and supported by the engine.
"
::= { snmpEngine 4 }
-- Registration Points for Authentication and Privacy Protocols ** -- Registration Points for Authentication and Privacy Protocols **
snmpAuthProtocols OBJECT-IDENTITY snmpAuthProtocols OBJECT-IDENTITY
STATUS current STATUS current
DESCRIPTION "Registration point for standards-track authentication DESCRIPTION "Registration point for standards-track
protocols used in SNMP Management Frameworks. authentication protocols used in SNMP Management
Frameworks.
" "
::= { snmpFrameworkAdmin 1 } ::= { snmpFrameworkAdmin 1 }
snmpPrivProtocols OBJECT-IDENTITY snmpPrivProtocols OBJECT-IDENTITY
STATUS current STATUS current
DESCRIPTION "Registration point for standards-track privacy DESCRIPTION "Registration point for standards-track privacy
protocols used in SNMP Management Frameworks. protocols used in SNMP Management Frameworks.
" "
::= { snmpFrameworkAdmin 2 } ::= { snmpFrameworkAdmin 2 }
-- Conformance information ******************************************
snmpFrameworkMIBCompliances snmpFrameworkMIBCompliances
OBJECT IDENTIFIER ::= { snmpFrameworkMIBConformance 1 } OBJECT IDENTIFIER ::= { snmpFrameworkMIBConformance 1 }
snmpFrameworkMIBGroups snmpFrameworkMIBGroups
OBJECT IDENTIFIER ::= { snmpFrameworkMIBConformance 2 } OBJECT IDENTIFIER ::= { snmpFrameworkMIBConformance 2 }
-- compliance statements -- compliance statements
snmpFrameworkMIBCompliance MODULE-COMPLIANCE snmpFrameworkMIBCompliance MODULE-COMPLIANCE
STATUS current STATUS current
skipping to change at page 49, line 46 skipping to change at page 1, line 1911
MANDATORY-GROUPS { snmpEngineGroup } MANDATORY-GROUPS { snmpEngineGroup }
::= { snmpFrameworkMIBCompliances 1 } ::= { snmpFrameworkMIBCompliances 1 }
-- units of conformance -- units of conformance
snmpEngineGroup OBJECT-GROUP snmpEngineGroup OBJECT-GROUP
OBJECTS { OBJECTS {
snmpEngineID, snmpEngineID,
snmpEngineBoots, snmpEngineBoots,
snmpEngineTime snmpEngineTime,
snmpEngineMaxMessageSize
} }
STATUS current STATUS current
DESCRIPTION "A collection of objects for identifying and DESCRIPTION "A collection of objects for identifying and
determining the configuration and current timeliness determining the configuration and current timeliness
values of an SNMP engine. values of an SNMP engine.
" "
::= { snmpFrameworkMIBGroups 1 } ::= { snmpFrameworkMIBGroups 1 }
END END
6. Security Considerations 6. Security Considerations
This document describes how an implementation can include a Security This document describes how an implementation can include a Security
Model to protect network management messages and an Access Control Model to protect management messages and an Access Control Model to
Model to control access to management information. control access to management information.
The level of security provided is determined by the specific Security The level of security provided is determined by the specific Security
Model implementation(s) and the specific Access Control Model Model implementation(s) and the specific Access Control Model
implementation(s) used. implementation(s) used.
Applications have access to data which is not secured. Applications Applications have access to data which is not secured. Applications
should take reasonable steps to protect the data from disclosure. should take reasonable steps to protect the data from disclosure.
It is the responsibility of the purchaser of an implementation to It is the responsibility of the purchaser of an implementation to
ensure that: ensure that:
skipping to change at page 52, line 13 skipping to change at page 1, line 1959
inadvertent disclosure. inadvertent disclosure.
7. Editor's Addresses 7. Editor's Addresses
Co-editor: Bert Wijnen Co-editor: Bert Wijnen
IBM T.J. Watson Research IBM T.J. Watson Research
postal: Schagen 33 postal: Schagen 33
3461 GL Linschoten 3461 GL Linschoten
Netherlands Netherlands
email: wijnen@vnet.ibm.com email: wijnen@vnet.ibm.com
phone: +31-348-432-794 phone: +31 348-432-794
Co-editor Dave Harrington Co-editor Dave Harrington
Cabletron Systems, Inc Cabletron Systems, Inc
postal: Post Office Box 5005 postal: Post Office Box 5005
MailStop: Durham MailStop: Durham
35 Industrial Way 35 Industrial Way
Rochester NH 03867-5005 Rochester, NH 03867-5005
USA USA
email: dbh@cabletron.com email: dbh@cabletron.com
phone: +1-603-337-7357 phone: +1 603-337-7357
Co-editor Randy Presuhn
BMC Software, Inc.
postal: 1190 Saratoga Avenue
Suite 130
San Jose, CA 95129
USA
email: rpresuhn@bmc.com
phone: +1 408-556-0720
8. Acknowledgements 8. Acknowledgements
This document is the result of the efforts of the SNMPv3 Working Group. This document is the result of the efforts of the SNMPv3 Working
Some special thanks are in order to the following SNMPv3 WG members: Group. Some special thanks are in order to the following SNMPv3 WG
members:
Dave Battle (SNMP Research, Inc.) Dave Battle (SNMP Research, Inc.)
Uri Blumenthal (IBM T.J. Watson Research Center) Uri Blumenthal (IBM T.J. Watson Research Center)
Jeff Case (SNMP Research, Inc.) Jeff Case (SNMP Research, Inc.)
John Curran (BBN) John Curran (BBN)
T. Max Devlin (Hi-TECH Connections) T. Max Devlin (Hi-TECH Connections)
John Flick (Hewlett Packard) John Flick (Hewlett Packard)
David Harrington (Cabletron Systems Inc.) David Harrington (Cabletron Systems Inc.)
N.C. Hien (IBM T.J. Watson Research Center) N.C. Hien (IBM T.J. Watson Research Center)
Dave Levi (SNMP Research, Inc.) Dave Levi (SNMP Research, Inc.)
skipping to change at page 53, line 35 skipping to change at page 1, line 2011
Dave Perkins (DeskTalk) Dave Perkins (DeskTalk)
Peter Polkinghorne (Brunel University) Peter Polkinghorne (Brunel University)
Randy Presuhn (BMC Software, Inc.) Randy Presuhn (BMC Software, Inc.)
David Reid (SNMP Research, Inc.) David Reid (SNMP Research, Inc.)
Shawn Routhier (Epilogue) Shawn Routhier (Epilogue)
Juergen Schoenwaelder (TU Braunschweig) Juergen Schoenwaelder (TU Braunschweig)
Bob Stewart (Cisco Systems) Bob Stewart (Cisco Systems)
Bert Wijnen (IBM T.J. Watson Research Center) Bert Wijnen (IBM T.J. Watson Research Center)
The document is based on recommendations of the IETF Security and The document is based on recommendations of the IETF Security and
Administrative Framework Evolution for SNMP Advisory Team. Administrative Framework Evolution for SNMP Advisory Team. Members
Members of that Advisory Team were: of that Advisory Team were:
David Harrington (Cabletron Systems Inc.) David Harrington (Cabletron Systems Inc.)
Jeff Johnson (Cisco Systems) Jeff Johnson (Cisco Systems)
David Levi (SNMP Research Inc.) David Levi (SNMP Research Inc.)
John Linn (Openvision) John Linn (Openvision)
Russ Mundy (Trusted Information Systems) chair Russ Mundy (Trusted Information Systems) chair
Shawn Routhier (Epilogue) Shawn Routhier (Epilogue)
Glenn Waters (Nortel) Glenn Waters (Nortel)
Bert Wijnen (IBM T. J. Watson Research Center) Bert Wijnen (IBM T. J. Watson Research Center)
skipping to change at page 55, line 8 skipping to change at page 1, line 2041
Keith McCloghrie (Cisco Systems) Keith McCloghrie (Cisco Systems)
Brian O'Keefe (Hewlett Packard) Brian O'Keefe (Hewlett Packard)
Marshall T. Rose (Dover Beach Consulting) Marshall T. Rose (Dover Beach Consulting)
Jon Saperia (BGS Systems Inc.) Jon Saperia (BGS Systems Inc.)
Steve Waldbusser (International Network Services) Steve Waldbusser (International Network Services)
Glenn W. Waters (Bell-Northern Research Ltd.) Glenn W. Waters (Bell-Northern Research Ltd.)
9. References 9. References
[RFC1155] Rose, M., and K. McCloghrie, "Structure and Identification [RFC1155] Rose, M., and K. McCloghrie, "Structure and Identification
of Management Information for TCP/IP-based internets", STD 16, of Management Information for TCP/IP-based internets", STD 16, RFC
RFC 1155, May 1990. 1155, May 1990.
[RFC1157] Case, J., M. Fedor, M. Schoffstall, and J. Davin, [RFC1157] Case, J., M. Fedor, M. Schoffstall, and J. Davin, "The
"The Simple Network Management Protocol", STD 15, RFC 1157, Simple Network Management Protocol", STD 15, RFC 1157, University
University of Tennessee at Knoxville, Performance Systems s of Tennessee at Knoxville, Performance Systems s International,
International, Performance International, and the MIT Laboratory Performance International, and the MIT Laboratory for Computer
for Computer Science, May 1990. Science, May 1990.
[RFC1212] Rose, M., and K. McCloghrie, "Concise MIB Definitions", [RFC1212] Rose, M., and K. McCloghrie, "Concise MIB Definitions", STD
STD 16, RFC 1212, March 1991. 16, RFC 1212, March 1991.
[RFC1901] The SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., [RFC1901] The SNMPv2 Working Group, Case, J., McCloghrie, K., Rose,
and S., Waldbusser, "Introduction to Community-based SNMPv2", M., and S., Waldbusser, "Introduction to Community-based SNMPv2",
RFC 1901, January 1996. RFC 1901, January 1996.
[RFC1902] The SNMPv2 Working Group, Case, J., McCloghrie, K., [RFC1902] The SNMPv2 Working Group, Case, J., McCloghrie, K., Rose,
Rose, M., and S., Waldbusser, "Structure of Management M., and S., Waldbusser, "Structure of Management Information for
Information for Version 2 of the Simple Network Management Version 2 of the Simple Network Management Protocol (SNMPv2)",
Protocol (SNMPv2)", RFC 1902, January 1996. RFC 1902, January 1996.
[RFC1903] The SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., [RFC1903] The SNMPv2 Working Group, Case, J., McCloghrie, K., Rose,
and S. Waldbusser, "Textual Conventions for Version 2 of the Simple M., and S. Waldbusser, "Textual Conventions for Version 2 of the
Network Management Protocol (SNMPv2)", RFC 1903, January 1996. Simple Network Management Protocol (SNMPv2)", RFC 1903, January
1996.
[RFC1904] The SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., [RFC1904] The SNMPv2 Working Group, Case, J., McCloghrie, K., Rose,
and S., Waldbusser, "Conformance Statements for Version 2 of the M., and S., Waldbusser, "Conformance Statements for Version 2 of
Simple Network Management Protocol (SNMPv2)", RFC 1904, the Simple Network Management Protocol (SNMPv2)", RFC 1904,
January 1996. January 1996.
[RFC1905] The SNMPv2 Working Group, Case, J., McCloghrie, K., [RFC1905] The SNMPv2 Working Group, Case, J., McCloghrie, K., Rose,
Rose, M., and S., Waldbusser, "Protocol Operations for M., and S., Waldbusser, "Protocol Operations for Version 2 of the
Version 2 of the Simple Network Management Protocol (SNMPv2)", Simple Network Management Protocol (SNMPv2)", RFC 1905, January
RFC 1905, January 1996. 1996.
[RFC1906] The SNMPv2 Working Group, Case, J., McCloghrie, K., [RFC1906] The SNMPv2 Working Group, Case, J., McCloghrie, K., Rose,
Rose, M., and S. Waldbusser, "Transport Mappings for M., and S. Waldbusser, "Transport Mappings for Version 2 of the
Version 2 of the Simple Network Management Protocol (SNMPv2)", Simple Network Management Protocol (SNMPv2)", RFC 1906, January
RFC 1906, January 1996. 1996.
[RFC1907] The SNMPv2 Working Group, Case, J., McCloghrie, K., [RFC1907] The SNMPv2 Working Group, Case, J., McCloghrie, K., Rose,
Rose, M., and S. Waldbusser, "Management Information Base for M., and S. Waldbusser, "Management Information Base for Version 2
Version 2 of the Simple Network Management Protocol (SNMPv2)", of the Simple Network Management Protocol (SNMPv2)", RFC 1907
RFC 1907 January 1996. January 1996.
[RFC1908] The SNMPv2 Working Group, Case, J., McCloghrie, K., [RFC1908] The SNMPv2 Working Group, Case, J., McCloghrie, K., Rose,
Rose, M., and S. Waldbusser, "Coexistence between Version 1 M., and S. Waldbusser, "Coexistence between Version 1 and Version
and Version 2 of the SNMP-standard Network Management 2 of the SNMP-standard Network Management Framework", RFC 1908,
Framework", RFC 1908, January 1996. January 1996.
[RFC1909] McCloghrie, K., Editor, "An Administrative Infrastructure [RFC1909] McCloghrie, K., Editor, "An Administrative Infrastructure
for SNMPv2", RFC1909, February 1996 for SNMPv2", RFC1909, February 1996.
[RFC1910] Waters, G., Editor, "User-based Security Model for SNMPv2", [RFC1910] Waters, G., Editor, "User-based Security Model for SNMPv2",
RFC1910, February 1996 RFC1910, February 1996.
[RFC2044] Yergeau, F., "UTF-8, a transformation format of Unicode and
ISO 10646", RFC 2044, October 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[SNMP-MPD] The SNMPv3 Working Group, Case, J., Harrington, D., [SNMP-MPD] The SNMPv3 Working Group, Case, J., Harrington, D.,
Wijnen, B., "Message Processing and Dispatching for the Simple Wijnen, B., "Message Processing and Dispatching for the Simple
Network Management Protocol (SNMP)", Network Management Protocol (SNMP)", draft-ietf-snmpv3-mpc-03.txt,
draft-ietf-snmpv3-mpc-03.txt, August 1997 August 1997.
[SNMP-USM] The SNMPv3 Working Group, Blumenthal, U., Wijnen, B., [SNMP-USM] The SNMPv3 Working Group, Blumenthal, U., Wijnen, B., "The
"The User-Based Security Model for Version 3 of the Simple User-Based Security Model for Version 3 of the Simple Network
Network Management Protocol (SNMPv3)", Management Protocol (SNMPv3)", draft-ietf-snmpv3-usm-01.txt,
draft-ietf-snmpv3-usm-01.txt, August 1997. August 1997.
[SNMP-ACM] The SNMPv3 Working Group, Wijnen, B., Presuhn, R., [SNMP-ACM] The SNMPv3 Working Group, Wijnen, B., Presuhn, R.,
McCloghrie, K., "View-based Access Control Model for the Simple McCloghrie, K., "View-based Access Control Model for the Simple
Network Management Protocol (SNMP)", Network Management Protocol (SNMP)", draft-ietf-snmpv3-acm-02.txt,
draft-ietf-snmpv3-acm-02.txt, August 1997. August 1997.
[SNMP-APPL] The SNMPv3 Working Group, Levi, D. B., Meyer, P., [SNMP-APPL] The SNMPv3 Working Group, Levi, D. B., Meyer, P.,
Stewart, B., "SNMPv3 Applications", Stewart, B., "SNMPv3 Applications",
<draft-ietf-snmpv3-appl-01.txt>, August 1997 <draft-ietf-snmpv3-appl-01.txt>, August 1997
APPENDIX A APPENDIX A
A. Guidelines for Model Designers A. Guidelines for Model Designers
This appendix describes guidelines for designers of models which are This appendix describes guidelines for designers of models which are
expected to fit into the architecture defined in this document. expected to fit into the architecture defined in this document.
SNMPv1 and SNMPv2c are two SNMP frameworks which use communities to SNMPv1 and SNMPv2c are two SNMP frameworks which use communities to
provide trivial authentication and access control. SNMPv1 and SNMPv2c provide trivial authentication and access control. SNMPv1 and SNMPv2c
Frameworks can coexist with Frameworks designed according to this Frameworks can coexist with Frameworks designed according to this
architecture, and modified versions of SNMPv1 and SNMPv2c Frameworks architecture, and modified versions of SNMPv1 and SNMPv2c Frameworks
could be designed to meet the requirements of this architecture, but could be designed to meet the requirements of this architecture, but
this document does not provide guidelines for that this document does not provide guidelines for that coexistence.
coexistence.
Within any subsystem model, there should be no reference to any Within any subsystem model, there should be no reference to any
specific model of another subsystem, or to data defined by a specific specific model of another subsystem, or to data defined by a specific
model of another subsystem. model of another subsystem.
Transfer of data between the subsystems is deliberately described as Transfer of data between the subsystems is deliberately described as
a fixed set of abstract data elements and primitive functions which a fixed set of abstract data elements and primitive functions which
can be overloaded to satisfy the needs of multiple model definitions. can be overloaded to satisfy the needs of multiple model definitions.
Documents which define models to be used within this architecture Documents which define models to be used within this architecture
SHOULD use the standard primitives between subsystems, possibly SHOULD use the standard primitives between subsystems, possibly
defining specific mechanisms for converting the abstract data elements defining specific mechanisms for converting the abstract data
into model-usable formats. This constraint exists to allow subsystem elements into model-usable formats. This constraint exists to allow
and model documents to be written recognizing common borders of the subsystem and model documents to be written recognizing common
subsystem and model. Vendors are not constrained to recognize these borders of the subsystem and model. Vendors are not constrained to
borders in their implementations. recognize these borders in their implementations.
The architecture defines certain standard services to be provided The architecture defines certain standard services to be provided
between subsystems, and the architecture defines abstract service between subsystems, and the architecture defines abstract service
interfaces to request these services. interfaces to request these services.
Each model definition for a subsystem SHOULD support the standard Each model definition for a subsystem SHOULD support the standard
service interfaces, but whether, or how, or how well, it performs service interfaces, but whether, or how, or how well, it performs the
the service is dependent on the model definition. service is dependent on the model definition.
A.1. Security Model Design Requirements A.1. Security Model Design Requirements
A.1.1. Threats A.1.1. Threats
A document describing a Security Model MUST describe how the model A document describing a Security Model MUST describe how the model
protects against the threats described under "Security Requirements protects against the threats described under "Security Requirements
of this Architecture", section 1.4. of this Architecture", section 1.4.
A.1.2. Security Processing A.1.2. Security Processing
skipping to change at page 58, line 4 skipping to change at page 1, line 2173
A.1.1. Threats A.1.1. Threats
A document describing a Security Model MUST describe how the model A document describing a Security Model MUST describe how the model
protects against the threats described under "Security Requirements protects against the threats described under "Security Requirements
of this Architecture", section 1.4. of this Architecture", section 1.4.
A.1.2. Security Processing A.1.2. Security Processing
Received messages MUST be validated by a Model of the Security Received messages MUST be validated by a Model of the Security
Subsystem. Validation includes authentication and privacy processing Subsystem. Validation includes authentication and privacy processing
if needed, but it is explicitly allowed to send messages which do not if needed, but it is explicitly allowed to send messages which do not
require authentication or privacy. require authentication or privacy.
A received message contains a specified Level of Security to be used A received message contains a specified securityLevel to be used
during processing. All messages requiring privacy MUST also require during processing. All messages requiring privacy MUST also require
authentication. authentication.
A Security Model specifies rules by which authentication and privacy A Security Model specifies rules by which authentication and privacy
are to be done. A model may define mechanisms to provide additional are to be done. A model may define mechanisms to provide additional
security features, but the model definition is constrained to using security features, but the model definition is constrained to using
(possibly a subset of) the abstract data elements defined in this (possibly a subset of) the abstract data elements defined in this
document for transferring data between subsystems. document for transferring data between subsystems.
Each Security Model may allow multiple security protocols to be used Each Security Model may allow multiple security protocols to be used
concurrently within an implementation of the model. Each Security concurrently within an implementation of the model. Each Security
Model defines how to determine which protocol to use, given the Model defines how to determine which protocol to use, given the
securityLevel and the security parameters relevant to the message. securityLevel and the security parameters relevant to the message.
Each Security Model, with its associated protocol(s) defines how the Each Security Model, with its associated protocol(s) defines how the
sending/receiving entities are identified, and how secrets are sending/receiving entities are identified, and how secrets are
configured. configured.
Authentication and Privacy protocols supported by Security Models are Authentication and Privacy protocols supported by Security Models are
uniquely identified using Object Identifiers. IETF standard protocols uniquely identified using Object Identifiers. IETF standard protocols
for authentication or privacy should have an identifier defined within for authentication or privacy should have an identifier defined
the snmpAuthProtocols or the snmpPrivProtocols subtrees. Enterprise within the snmpAuthProtocols or the snmpPrivProtocols subtrees.
specific protocol identifiers should be defined within the enterprise Enterprise specific protocol identifiers should be defined within the
subtree. enterprise subtree.
For privacy, the Security Model defines what portion of the message For privacy, the Security Model defines what portion of the message
is encrypted. is encrypted.
The persistent data used for security should be SNMP-manageable, but The persistent data used for security should be SNMP-manageable, but
the Security Model defines whether an instantiation of the MIB is a the Security Model defines whether an instantiation of the MIB is a
conformance requirement. conformance requirement.
Security Models are replaceable within the Security Subsystem. Security Models are replaceable within the Security Subsystem.
Multiple Security Model implementations may exist concurrently within Multiple Security Model implementations may exist concurrently within
skipping to change at page 59, line 4 skipping to change at page 1, line 2224
A Message Processing Model requests that a Security Model: A Message Processing Model requests that a Security Model:
- verifies that the message has not been altered, - verifies that the message has not been altered,
- authenticates the identification of the principal for whom the - authenticates the identification of the principal for whom the
message was generated. message was generated.
- decrypts the message if it was encrypted. - decrypts the message if it was encrypted.
Additional requirements may be defined by the model, and additional Additional requirements may be defined by the model, and additional
services may be provided by the model, but the model is constrained services may be provided by the model, but the model is constrained
to use the following primitives for transferring data between to use the following primitives for transferring data between
subsystems. Implementations are not so constrained. subsystems. Implementations are not so constrained.
A Message Processing Model uses the processMsg primitive as A Message Processing Model uses the processMsg primitive as described
described in section 4.5. in section 4.5.
A.1.4. Security MIBs A.1.4. Security MIBs
Each Security Model defines the MIB module(s) required for security Each Security Model defines the MIB module(s) required for security
processing, including any MIB module(s) required for the security processing, including any MIB module(s) required for the security
protocol(s) supported. The MIB module(s) SHOULD be defined protocol(s) supported. The MIB module(s) SHOULD be defined
concurrently with the procedures which use the MIB module(s). The concurrently with the procedures which use the MIB module(s). The
MIB module(s) are subject to normal access control rules. MIB module(s) are subject to normal access control rules.
The mapping between the model dependent security ID and the The mapping between the model-dependent security ID and the
securityName MUST be able to be determined using SNMP, if the model securityName MUST be able to be determined using SNMP, if the model-
dependent MIB is instantiated and if access control policy allows dependent MIB is instantiated and if access control policy allows
access. access.
A.1.5. Cached Security Data A.1.5. Cached Security Data
For each message received, the Security Model caches the state For each message received, the Security Model caches the state
information such that a Response message can be generated using the information such that a Response message can be generated using the
same security information, even if the Local Configuration Datastore same security information, even if the Local Configuration Datastore
is altered between the time of the incoming request and the outgoing is altered between the time of the incoming request and the outgoing
response. response.
A Message Processing Model has the responsibility for explicitly A Message Processing Model has the responsibility for explicitly
releasing the cached data if such data is no longer needed. To enable releasing the cached data if such data is no longer needed. To enable
this, an abstract securityStateReference data element is passed from this, an abstract securityStateReference data element is passed from
the Security Model to the Message Processing Model. the Security Model to the Message Processing Model.
The cached security data may be implicitly released via the generation The cached security data may be implicitly released via the
of a response, or explicitly released by using the stateRelease generation of a response, or explicitly released by using the
primitive, as described in section 4.1. stateRelease primitive, as described in section 4.1.
A.2. Message Processing Model Design Requirements A.2. Message Processing Model Design Requirements
An SNMP engine contains a Message Processing Subsystem which may An SNMP engine contains a Message Processing Subsystem which may
contain multiple Message Processing Models. contain multiple Message Processing Models.
The Message Processing Model MUST always (conceptually) pass the The Message Processing Model MUST always (conceptually) pass the
complete PDU, i.e. it never forwards less than the complete list of complete PDU, i.e., it never forwards less than the complete list of
varBinds. varBinds.
A.2.1. Receiving an SNMP Message from the Network A.2.1. Receiving an SNMP Message from the Network
Upon receipt of a message from the network, the Dispatcher in the Upon receipt of a message from the network, the Dispatcher in the
SNMP engine determines the version of the SNMP message and interacts SNMP engine determines the version of the SNMP message and interacts
with the corresponding Message Processing Model to determine the with the corresponding Message Processing Model to determine the
abstract data elements. abstract data elements.
A Message Processing Model specifies the SNMP Message format it A Message Processing Model specifies the SNMP Message format it
supports and describes how to determine the values of the abstract supports and describes how to determine the values of the abstract
data elements (like msgID, msgMaxSize, msgFlags, msgSecurityParameters, data elements (like msgID, msgMaxSize, msgFlags,
securityModel, securityLevel etc). A Message Processing Model interacts msgSecurityParameters, securityModel, securityLevel etc). A Message
with a Security Model to provide security processing for the message Processing Model interacts with a Security Model to provide security
using the processMsg primitive, as described in section 4.5. processing for the message using the processMsg primitive, as
described in section 4.5.
A.2.2. Sending an SNMP Message to the Network A.2.2. Sending an SNMP Message to the Network
The Dispatcher in the SNMP engine interacts with a Message Processing The Dispatcher in the SNMP engine interacts with a Message Processing
Model to prepare an outgoing message. For that it uses the following Model to prepare an outgoing message. For that it uses the following
primitives: primitives:
- for requests and notifications: - for requests and notifications: prepareOutgoingMessage, as
prepareOutgoingMessage, as described in section 4.4 described in section 4.4
- for response messages: - for response messages: prepareResponseMessage, as described in
prepareResponseMessage, as described in section 4.4 section 4.4
A Message Processing Model, when preparing an Outgoing SNMP Message, A Message Processing Model, when preparing an Outgoing SNMP Message,
interacts with a Security Model to secure the message. For that it uses interacts with a Security Model to secure the message. For that it
the following primitives: uses the following primitives:
- for requests and notifications: - for requests and notifications: generateRequestMsg, as
generateRequestMsg, as described in section 4.5. described in section 4.5.
- for response messages: - for response messages: generateResponseMsg as described in
generateResponseMsg as described in section 4.5. section 4.5.
Once the SNMP message is prepared by a Message Processing Model, the Once the SNMP message is prepared by a Message Processing Model,
Dispatcher sends the message to the desired address using the appropriate the Dispatcher sends the message to the desired address using the
transport. appropriate transport.
A.3. Application Design Requirements A.3. Application Design Requirements
Within an application, there may be an explicit binding to a specific Within an application, there may be an explicit binding to a specific
SNMP message version, i.e. a specific Message Processing Model, and to SNMP message version, i.e., a specific Message Processing Model, and
a specific Access Control Model, but there should be no reference to to a specific Access Control Model, but there should be no reference
any data defined by a specific Message Processing Model or Access to any data defined by a specific Message Processing Model or Access
Control Model. Control Model.
Within an application, there should be no reference to any specific Within an application, there should be no reference to any specific
Security Model, or any data defined by a specific Security Model. Security Model, or any data defined by a specific Security Model.
An application determines whether explicit or implicit access control An application determines whether explicit or implicit access control
should be applied to the operation, and, if access control is needed, should be applied to the operation, and, if access control is needed,
which Access Control Model should be used. which Access Control Model should be used.
An application has the responsibility to define any MIB module(s) used An application has the responsibility to define any MIB module(s)
to provide application-specific services. used to provide application-specific services.
Applications interact with the SNMP engine to initiate messages, Applications interact with the SNMP engine to initiate messages,
receive responses, receive asynchronous messages, and send responses. receive responses, receive asynchronous messages, and send responses.
A.3.1. Applications that Initiate Messages A.3.1. Applications that Initiate Messages
Applications may request that the SNMP engine send messages containing Applications may request that the SNMP engine send messages
SNMP commands or notifications using the sendPdu primitive as described containing SNMP commands or notifications using the sendPdu primitive
in section 4.2. as described in section 4.2.
If it is desired that a message be sent to multiple targets, it is the If it is desired that a message be sent to multiple targets, it is
responsibility of the application to provide the iteration. the responsibility of the application to provide the iteration.
The SNMP engine assumes necessary access control has been applied to The SNMP engine assumes necessary access control has been applied to
the PDU, and provides no access control services. the PDU, and provides no access control services.
The SNMP engine looks at the "expectResponse" parameter, and if a The SNMP engine looks at the "expectResponse" parameter, and if a
response is expected, then the appropriate information is cached such response is expected, then the appropriate information is cached such
that a later response can be associated to this message, and can then that a later response can be associated to this message, and can then
be returned to the application. A sendPduHandle is returned to the be returned to the application. A sendPduHandle is returned to the
application so it can later correspond the response with this message application so it can later correspond the response with this message
as well. as well.
skipping to change at page 62, line 6 skipping to change at page 1, line 2363
associated application using the processResponsePdu primitive, as associated application using the processResponsePdu primitive, as
described in section 4.2. described in section 4.2.
A.3.3. Applications that Receive Asynchronous Messages A.3.3. Applications that Receive Asynchronous Messages
When an SNMP engine receives a message that is not the response to a When an SNMP engine receives a message that is not the response to a
request from this SNMP engine, it must determine to which application request from this SNMP engine, it must determine to which application
the message should be given. the message should be given.
An Application that wishes to receive asynchronous messages registers An Application that wishes to receive asynchronous messages registers
itself with the engine using the primitive registerContextEngineID itself with the engine using the primitive registerContextEngineID as
as described in section 4.2. described in section 4.2.
An Application that wishes to stop receiving asynchronous messages An Application that wishes to stop receiving asynchronous messages
should unregister itself with the SNMP engine using the primitive should unregister itself with the SNMP engine using the primitive
unregisterContextEngineID as described in section 4.2. unregisterContextEngineID as described in section 4.2.
Only one registration per combination of PDU type and contextEngineID Only one registration per combination of PDU type and contextEngineID
is permitted at the same time. Duplicate registrations are ignored. is permitted at the same time. Duplicate registrations are ignored.
An errorIndication will be returned to the application that attempts An errorIndication will be returned to the application that attempts
to duplicate a registration. to duplicate a registration.
All asynchronously received messages containing a registered All asynchronously received messages containing a registered
combination of PDU type and contextEngineID are sent to the combination of PDU type and contextEngineID are sent to the
application which registered to support that combination. application which registered to support that combination.
The engine forwards the PDU to the registered application, using the The engine forwards the PDU to the registered application, using the
processPdu primitive, as described in section 4.2. processPdu primitive, as described in section 4.2.
A.3.4. Applications that Send Responses A.3.4. Applications that Send Responses
Request operations require responses. An application sends Request operations require responses. An application sends a
a response via the returnResponsePdu primitive, as described in response via the returnResponsePdu primitive, as described in section
section 4.2. 4.2.
The contextEngineID, contextName, securityModel, securityName, The contextEngineID, contextName, securityModel, securityName,
securityLevel, and stateReference parameters are from the initial securityLevel, and stateReference parameters are from the initial
processPdu primitive. The PDU and statusInformation are the results processPdu primitive. The PDU and statusInformation are the results
of processing. of processing.
A.4. Access Control Model Design Requirements A.4. Access Control Model Design Requirements
An Access Control Model determines whether the specified securityName An Access Control Model determines whether the specified securityName
is allowed to perform the requested operation on a specified managed is allowed to perform the requested operation on a specified managed
object. The Access Control Model specifies the rules by which access object. The Access Control Model specifies the rules by which access
control is determined. control is determined.
The persistent data used for access control should be manageable using The persistent data used for access control should be manageable
SNMP, but the Access Control Model defines whether an instantiation of using SNMP, but the Access Control Model defines whether an
the MIB is a conformance requirement. instantiation of the MIB is a conformance requirement.
The Access Control Model must provide the primitive isAccessAllowed The Access Control Model must provide the primitive isAccessAllowed.
B. Issues
The change log will be deleted for last call; the issues list will be
deleted when it is time to publish as an RFC.
B.1. Showstoppers
B.2. Open Issues
- we need a mechanism for a manager to be able to discover what
securityModels are supported by a particular implementation
B.3. Resolved Issues
. contextEngineID in reportPDU = snmpEngineID of report generator
. returnResponsePdu - are all parameters needed? overrides allowed?
all parameters kept for future flexibility
overrides not supported by SNMPv3
. use of IN/OUT indicators in primitives accepted
. NT/Unix-like access control - can be defined as future model
. user-friendly names? yes, but with limits
. SnmpAdminString as index? yes, but restrict sizes
. need both MMS and maxSizeResponseScopedPDU? yes.
. synchronous vs. asynchronous primitives? synchronous preferred
. should we change MIB naming? no, it is acceptable
. is it ok that USM is bound to SNMPv3? while undesirable, it is
acceptable. A cleaner model may be defined in the future.
. should securityModel "any" be supported? for ACM use, not SNMPv3
. what defines SNMPv3? a document will be published after Munich
. Is an application-level handle needed for request/response matching?
yes. create sendPduHandle
. Is wild card contextEngineID/pduType registration needed? No. This is
an internal interface, and wild carding can be supported by an
implementation, but is not required in the standard.
. Should indices be integers or SnmpAdminStrings? SnmpAdminStrings
is the consensus.
. Should protocols be identified as OIDs or Integers? OIDs
. terminology:
securityLevel rather than LoS
msgXXXX to identify message fields in SNMPv3
. OID or Integer for auth/priv protocol identifiers
Consensus: use OID
. Is Glossary needed to describe primitive parameters, or is the
expanded template adequate for this purpose?
Consensus: Terms are basically all defined in section 3.
. state_reference releases
Consensus: documents checked; we think it is OK now
. new SnmpEngineID format rules to be discussed yet.
Consensus: Limit size to be 1..32
. needs changes to meet STDGUIDE guidelines
We think we're meeting them now
. we punted snmpEngineMaxMessageSize at 2nd interim because that
info travels in each SNMPv3 message. However, we may want to
re-introduce it so that SNMPv1/v2c managers can learn the value!!
Consensus: Nobody picked up on this, so it seems not needed.
. Do we need a mechanism to discover securityModels supported
Can be decided after Munich
. add a "Decision History" section (as an appendix?)
Can be decided after Munich
B.3.1. Issues discussed at second Interim Meeting:
. A "readable" introduction supplement may be done after Munich.
. Applications are responsible for retries, but implementations may
differ.
. TCs should not be defined just to describe primitive parameters.
If they cannot be described adequately in text, they can be defined
in a Glossary. Avoid describing implementation details.
. Is SnmpAdminString appropriate for all strings, such as
securityIdentifier and context and group? These had different
sizes and semantics. size and semantics may be defined in
syntax and description of OBJECT
. AdminString has size (0..255); revisit for UTF-8 discussions
. securityModel #s - 00 for IETF standards; from v2* documents
. protocol IDs - integer or OID? voted 13-0 for OID.
. uniqueness of securityName
. mapping between principal and securityName is outside scope of WG.
. principals may have more than one securityName in an entity
. mappings may exist between many types of MDID and a single
securityName
. mappings may exist between different (model, Name) and the same
securityName by varying the model or the Name.
. the securityName and a MDID may be identical. This can be defined
by the Security Model.
(user,"public") may map to securityName "public"
. [securityName, securityModel] yields zero or one MDName, with
exceptions for backwards compatibility. The exception is defined
by the model, and the problems are the province of the model to
resolve.
B.4. Change Log
Current version
- Changed MIB objects from Integer32 to INTEGER to match USM
fields.
- changed "network management" to simply "management"
- added caveat to EngineID selection algorithm
- Added language in register/deregister ASI to permit
implementation-specific wildcarding, as agreed in Munich.
- re-worded description of maxSizeResponseScopedPDU
- added RFC 2119 words and referece
- added reference for UTF-8
- removed "none" reserved value from SnmpSecurityModel textual
convention, changed "any" value from 255 to zero.
- modifications to SnmpAdminString agreed to in Munich meeting
- updated editor list
- converted to nroff, with some minor layout changes
[version 4.14]
. formatting
. pagination
[version 4.13]
. new acknowledgements
. updated references
. updated issues list
. ordered security, editors, acknowledgements, references sections
. checked line lengths
[version 4.12]
. cleanup
. added expectResponse to processIncomingMsg to address Levi-raised
concern
. acknowledgements
. MIB checked by SMICng
. post to snmpv3 mailing list
[version 4.11]
. Change Primitives between MP and SEC to try and address the issue
of architectural binding to message format.
. Added securityName and securityLevel to the returnResponsePdu
primitive so that architecturally it could be different for a
request and a response.
. Rename processMsg primitive to processIncomingMsg
[version 4.10]
. spell check
[version 4.9]
. editorial changes
. fix SnmpEngineID TC
. add a note to SnmpAdminString
. rename title of section 1.1
. expand description of Dispatcher a bit
[version 4.8]
. Added parameter pduVersion on primitives:
sendPdu
processPdu
returnResponsePdu
processResponsePdu
prepareDataElements
prepareOutgoingMessage
prepareResponseMessage
. Added parameter messageProcessingModel on the primitive:
processPdu
processResponsePdu
returnResponsePdu
. Removed messageProcessingModel parameter from primitives:
registerContextEngineID
unregisterContextEngineID
. Renamed SNMP Version Multiplexer to Dispatcher
. Renamed Version Multiplexer to Message Multiplexer
. Renamed Application Multiplexer to PDU Dispatcher
. Rearranged some parameters in various Primitives so the sequence
of parameters is now more consistent.
[version 4.7]
. editorial cleanup
. changed asterisk text
. modified snmpv3 framework description to eliminate dependencies
. reorder 4.2.x to reflect transaction order
. changed SnmpEngineID size to 1..32
[version 4.6]
. Changes to use synchronous primitives where possible
. Changes to describe SNMP Version Multiplexer
. Remove (empty) glossary
. Redraw documentation figure
. Redraw Operational Overview Figure
. Remove old section 4 (Architectural Elements of Procedure)
These moved to the MP document into the SNMP Version Multiplexer
section.
. Move Overview of all primitives from Appendix to Section 4.
. Simplify Appendix A to just described Model Designer Guidelines
and refer back to section 4 for specific primitives
. Remove Appendix B (An Evolutionary Architecture - Design Goals)
. added design decision regarding security
. Included latest Snmp SecurityModel TC (as it was actually posted
to the SNMPv3 mailing list).
[version 4.5]
. start with <draft-ietf-snmpv3-next-gen-arch-03.txt>
. change vendor to implementor
. change LoS to securityLevel
. remove mention of enterprise
. change Internet Management Framework to SNMP Management Framework
. modify usage of "frameworks" to improve internal consistency.
. change Message Processing Abstract Service Interface to
Application Multiplexor
. change description of SNMP engine
. moved "one-to-one association" for entity and engine to discussion
of engine.
. changed distributing to dispatching
. added asterisks to indicate v3* items are also not required.
. changed "community access control" to "other access control"
. added TC for SnmpMessageProcessingModel
. modified Security Considerations
. modified acknowledgements
[version 4.4]
. Fixed one error in the MIB (found with SMICng)
. Reformatted text for SnmpAdminString, no change in text.
. Changed text for SnmpEngineID.. this is still under discussion.
But this new text seems to be getting close to what we want.
. Added an issue w.r.t. snmpEngineMaxMessageSize
. adapt Primitive names and parameters to very latest (July 11) names
. removed blank lines before the .p page controls.
. publish as <draft-ietf-snmpv3-next-gen-arch-03.txt>
[version 4.3]
. some minor editing adjustments
[version 4.2]
. modify abstract so there is no requirement for one entity
to contain both a command generator and a notification receiver.
. modify Introduction list of entities which are meant to be
supported
. reorganized sections 1 through 4 for more consistency in contents.
. described section contents in Introduction:Target Audience
. move documentation descriptions to section 2
. rewrite section 4 to be more like a real elements of procedure.
. modified SnmpSecurityModel and SnmpEngineID definitions
. replaced MIB with Bert's replacement
. added Randy's TC for SnmpAdminString
. modified the example algorithm text for SnmpEngineID
. rewrote security considerations for brevity.
. modified "context" description
. moved "Threats" to Goals/Requirements
. eliminated snmpEngineMaxMessageSize object
. posted to snmpv3 (by DBH)
[version 4.1]
. Adopt "abstract" to new terminology
. Addressed all comments I (BW) made to DBH in an earlier email
. Changed Introduction section to new terminology
. changed wording for "implementation" to indicate it may contain
multiple models.
. Section 2. Started some wording on Goals and Design decisions
. Added the overview picture of a traditional agent and a
traditional manager. This is in section 2.
. Changed overview figure in section 3. to address the comments
by Dave Levi. It now lists the type of applications
. At various places ensure that text (easily) fits within 72
columns as required by RFC-editors Guidelines document.
. Section 2.3 (new section) has the documents set overview.
I verified the claims about standards. Not sure I worded the
SNMPv2 std correctly,. We'll hear it if we did it wrong.
. Section 2.4 (new section) gives overview of SNMP entities based
on modified Dave Levi figure. I (Bert) wonder however if it would
not be better to move it to after section 3.1.13
. Section 3. Added more figures... please let us know if you find
then useful and/or helpful. We could also move these back to
section 2 if such makes more sense.
. Added a picture in section 3.2.
It also shows some of access control, so not sure it really fits
here, although it does map principal to model-dependent security
ID to securityName
. Replace "<" with "is lower than" in section 3.4.3 which seems
better in a text document.
. Renamed section 4.1 to "SNMP engine processing" instead of
"The Message Processing Subsystem" because the transport
mappings, mpc multiplexor and such is done in ARCH document so
it is done "in general in the engine" and it passes a specific
message to a Message Processing Subsystem.
. "bulletized" some stuff in section 4.2 and 4.3.
Dave, this is just how I (Bert) like it better. Feel free to
undo it if you strongly disagree
. Section 4.3 changed "initiate a transaction" to "originate a
notification".
. Inserted title line for section 4.4 (I think it was missing)
I have named it "Information Model" in accordance with the change
I made (after Russ's comments) in the document figure to lump SMI,
TC and Conformance together.
. Inserted a title for section 4.5 named "Operational Model" to
get in sync with the the lumping together of ProtoOps and Transport
Mappings in document overview
. Renumber section 4.4.4 to 4,5,1 and added 4.5.2 to follow the
document overview figure. If we really want to follow it, then
maybe we should also reorder some of these sections. Like
Access Control seems specifically misplaced. So I decided to move
it before applications as section 4.3, so the 4.x above should
all be read as 4.x+1
. Removed size from SnmpEngineID TC... why did you limit it to
(0..2048). Did we not decide to leave it open?
. Should we not remove snmpEngineMaxMessageSize from the MIB.
That was agreed at 2nd interim. It travels in every message and so
seems to be useless. However, I think it could indeed still help
SNMPv1 or SNMPv2c managers.
. I kept your definitions of registration-points for auth and priv
protocols, but my recollection is that they would be completely
removed from ARCH and that it would all be done in SEC document.
. Modified Security Considerations. Was still talking about LPM.
. Appendix. I am still wondering if we need to use capitals for
things like "Security Model" "Subsystem" and such. This is only
an appendix... but we better be consistent, no? Anyway
I changed it so it is consistent (at least I tried).
. Appendix, renamed imf to snmpFramework
. Appendix, changed state_reference and state_release to
stateReference and stateRelease to be consistent with other names
for abstract data and primitives.
. A.2 changed MessageEngine to SNMP engine
. Fixed ASI primitives to be in sync with SEC document.
I also thought that our ARCH document-outline wanted to at least
have the primitives listed within the main body of the text, no?
. Adapted send_pdu to sendPdu primitive as reconciled by Randy
In fact I made sure all primitives are in-line with current
agreement on names and parameters.
. Rename title of A.2.4 and A.2.5 so it fits on 1 line in contents
. I did not look at appendix B. That is your (DBH) specialty is it
not ? ;-).
. Quick simple spell check done with "spell" on AIX
[version 4.0]
. move section 7 - Model Requirements to an appendix
. move Section 3 - Design Goals to an appendix
. modified Section 5 - Naming
. remove "possibly multiple"
. moved Section 5 to Section 3
. change orangelets to applications
. modify description of applications
. change scopedPDU-MMS and PDU-MMS to maxSizeResponseScopedPDU
. change Scoped-PDU and ScopedPDU to scopedPDU (no dash, lower case S)
. change imfxxx to snmpFrameworkxxx
. change security-entity to principal
. change securityIdentity to securityName
. change MIID to securityName
. eliminate all reference to groupName or group
. LoS ordering noAuthNoPriv < authNoPriv < authPriv
. Los TC naming - noAuthNoPriv(1), authNoPriv(2), authPriv(3)
. remove TCs not used in MIBs - securityIdentity TC etc
. changed Message Processing and Control to Message Processing
. changed future tense to present tense
. eliminate messageEngine
. added/updated primitives
. addressed issues raised on the mailing list
[version 3.1]
. change securityIdentity to MIID
. write text to explain the differences between security-identities,
model-dependent identifiers, and model-independent identifiers.
. write text to explain distinction within the LCD of the security
data, the access control data, and the orangelet data.
. identify issues
. publish as <draft-ietf-snmpv3-next-gen-arch-02.txt>
[version 3.0]
. add section on threats for message security
. add section on threats for access control
. change application to orangelet
. remove references to F-Ts
. change securityIdentity to security-identity
. change securityCookie to securityIdentity
. the format of securityIdentity is defined by the model
. add securityModel to passed parameters as needed
. eliminate group from passed parameters
. remove unused IMPORTS
. add glossary section with initial set of words to define
. differentiate the messageEngine from the contextEngine
. eliminate the term SNMPng
. rewrote 1.1. A Note on Terminology
. eliminated assumptions about SNMP processing always being
message related
. rewrote 4.x to reflect new thinking
. rewrote 5.x to reflect new thinking
. rewrote 6.x (the MIB) to reflect new thinking
. added MIB objects at this level (previously only TCs)
. rewrote 7.x
. sent to v3edit list
Table of Contents Table of Contents
0. Issues 2 1. Introduction ................................................... 2
0.1. Resolved Issues 2
0.1.1. Issues discussed at second Interim Meeting: 3
0.2. Change Log 4
1. Introduction 10
1.1. Overview 10
1.2. SNMP Management Systems 10
1.3. Goals of this Architecture 11
1.4. Security Requirements of this Architecture 12
1.5. Design Decisions 13
2. Documentation Overview 15
2.1. Document Roadmap 16
2.2. Applicability Statement 16
2.3. Coexistence and Transition 16
2.4. Transport Mappings 17
2.5. Message Processing 17
2.6. Security 17
2.7. Access Control 17
2.8. Protocol Operations 18
2.9. Applications 18
2.10. Structure of Management Information 18
2.11. Textual Conventions 18
2.12. Conformance Statements 18
2.13. Management Information Base Modules 19
2.13.1. SNMP Instrumentation MIBs 19
2.14. SNMP Framework Documents 19
2.15. Operational Overview 21
3. Elements of the Architecture 23
3.1. The Naming of Entities 23
3.1.1. SNMP entity 24
3.1.2. SNMP engine 24
3.1.3. snmpEngineID 24
3.1.4. Dispatcher 24
3.1.5. Message Processing Subsystem 25
3.1.6. Message Processing Model 25
3.1.7. Security Subsystem 26
3.1.8. Security Model 26
3.1.9. Security Protocol 26
3.1.10. Access Control Subsystem 27
3.1.11. Access Control Model 27
3.1.12. Applications 28
3.1.13. SNMP Agent 28
3.1.14. SNMP Manager 28
3.2. The Naming of Identities 29
3.2.1. Principal 29
3.2.2. securityName 29
3.2.3. Model dependent security ID 29
3.3. The Naming of Management Information 30
3.3.1. An SNMP Context 31
3.3.2. contextEngineID 31
3.3.3. contextName 31
3.3.4. scopedPDU 32 1.1. Overview ..................................................... 2
3.4. Other Constructs 32
3.4.1. maxSizeResponseScopedPDU 32 1.2. SNMP ......................................................... 2
3.4.2. Local Configuration Datastore 32
3.4.3. securityLevel 32 1.3. Goals of this Architecture ................................... 3
4. Abstract Service Interfaces. 33
4.1. Common Primitives 33 1.4. Security Requirements of this Architecture ................... 4
4.1.1. Release State Reference Information 33
4.2. Dispatcher Primitives 33 1.5. Design Decisions ............................................. 5
4.2.1. Generate Outgoing Request or Notification 33
4.2.2. Process Incoming Request or Notification PDU 34 2. Documentation Overview ......................................... 6
4.2.3. Generate Outgoing Response 34
4.2.4. Process Incoming Response PDU 34 2.1. Document Roadmap ............................................. 8
4.2.5. Registering Responsibility for Handling SNMP PDUs. 35
4.3. Message Processing Subsystem Primitives 35 2.2. Applicability Statement ...................................... 8
4.3.1. Prepare an Outgoing SNMP Request or Notification Message 35
4.3.2. Prepare an Outgoing SNMP Response Message 36 2.3. Coexistence and Transition ................................... 8
4.3.3. Prepare Data Elements from an Incoming SNMP Message 36
4.4. Access Control Subsystem Primitives 37 2.4. Transport Mappings ........................................... 8
4.5. Security Subsystem Primitives 37
4.5.1. Generate a Request or Notification Message 37 2.5. Message Processing ........................................... 9
4.5.2. Process Incoming Message 37
4.5.3. Generate a Response Message 38 2.6. Security ..................................................... 9
4.6. User Based Security Model Internal Primitives 38
4.6.1. User-based Security Model Primitives for Authentication 38 2.7. Access Control ............................................... 9
4.6.2. User-based Security Model Primitives for Privacy 39
4.7. Scenario Diagrams 40 2.8. Protocol Operations .......................................... 10
4.7.1. Command Generator or Notification Originator Application 40
4.7.2. Scenario Diagram for a Command Responder Application 41 2.9. Applications ................................................. 10
5. Definition of Managed Objects for SNMP Management Frameworks 42
6. Security Considerations 51 2.10. Structure of Management Information ......................... 10
7. Editor's Addresses 52
8. Acknowledgements 53 2.11. Textual Conventions ......................................... 10
9. References 55
A. Guidelines for Model Designers 57 2.12. Conformance Statements ...................................... 11
A.1. Security Model Design Requirements 57
A.1.1. Threats 57 2.13. Management Information Base Modules ......................... 11
A.1.2. Security Processing 57
A.1.3. Validate the security-stamp in a received message 58 2.13.1. SNMP Instrumentation MIBs ................................. 11
A.1.4. Security MIBs 59
A.1.5. Cached Security Data 59 2.14. SNMP Framework Documents .................................... 11
A.2. Message Processing Model Design Requirements 60
A.2.1. Receiving an SNMP Message from the Network 60 3. Elements of the Architecture ................................... 12
A.2.2. Sending an SNMP Message to the Network 60
A.3. Application Design Requirements 60 3.1. The Naming of Entities ....................................... 12
A.3.1. Applications that Initiate Messages 61
A.3.2. Applications that Receive Responses 61 3.1.1. SNMP entity ................................................ 13
A.3.3. Applications that Receive Asynchronous Messages 61
A.3.4. Applications that Send Responses 62 3.1.2. SNMP engine ................................................ 13
A.4. Access Control Model Design Requirements 62
3.1.3. snmpEngineID ............................................... 14
3.1.4. Dispatcher ................................................. 14
3.1.5. Message Processing Subsystem ............................... 15
3.1.6. Message Processing Model ................................... 15
3.1.7. Security Subsystem ......................................... 16
3.1.8. Security Model ............................................. 16
3.1.9. Security Protocol .......................................... 16
3.1.10. Access Control Subsystem .................................. 17
3.1.11. Access Control Model ...................................... 17
3.1.12. Applications .............................................. 17
3.1.13. SNMP Manager .............................................. 18
3.1.14. SNMP Agent ................................................ 19
3.2. The Naming of Identities ..................................... 20
3.2.1. Principal .................................................. 20
3.2.2. securityName ............................................... 20
3.2.3. Model-dependent security ID ................................ 21
3.3. The Naming of Management Information ......................... 22
3.3.1. An SNMP Context ............................................ 23
3.3.2. contextEngineID ............................................ 23
3.3.3. contextName ................................................ 24
3.3.4. scopedPDU .................................................. 24
3.4. Other Constructs ............................................. 24
3.4.1. maxSizeResponseScopedPDU ................................... 24
3.4.2. Local Configuration Datastore .............................. 24
3.4.3. securityLevel .............................................. 24
4. Abstract Service Interfaces. .................................. 25
4.1. Common Primitives ............................................ 25
4.1.1. Release State Reference Information ........................ 25
4.2. Dispatcher Primitives ........................................ 25
4.2.1. Generate Outgoing Request or Notification .................. 25
4.2.2. Process Incoming Request or Notification PDU ............... 26
4.2.3. Generate Outgoing Response ................................. 27
4.2.4. Process Incoming Response PDU .............................. 27
4.2.5. Registering Responsibility for Handling SNMP PDUs. ........ 27
4.3. Message Processing Subsystem Primitives ...................... 28
4.3.1. Prepare Outgoing SNMP Request or Notification Message ...... 28
4.3.2. Prepare an Outgoing SNMP Response Message .................. 29
4.3.3. Prepare Data Elements from an Incoming SNMP Message ........ 30
4.4. Access Control Subsystem Primitives .......................... 30
4.5. Security Subsystem Primitives ................................ 31
4.5.1. Generate a Request or Notification Message ................. 31
4.5.2. Process Incoming Message ................................... 31
4.5.3. Generate a Response Message ................................ 32
4.6. Common Primitives ............................................ 32
4.6.1. Release State Reference Information ........................ 32
4.7. Scenario Diagrams ............................................ 33
4.7.1. Command Generator or Notification Originator ............... 33
4.7.2. Scenario Diagram for a Command Responder Application ....... 34
5. Managed Object Definitions for SNMP Management Frameworks ...... 35
6. Security Considerations ........................................ 44
7. Editor's Addresses ............................................. 45
8. Acknowledgements ............................................... 45
9. References ..................................................... 47
A. Guidelines for Model Designers ................................. 49
A.1. Security Model Design Requirements ........................... 49
A.1.1. Threats .................................................... 49
A.1.2. Security Processing ........................................ 50
A.1.3. Validate the security-stamp in a received message .......... 50
A.1.4. Security MIBs .............................................. 51
A.1.5. Cached Security Data ....................................... 51
A.2. Message Processing Model Design Requirements ................. 51
A.2.1. Receiving an SNMP Message from the Network ................. 52
A.2.2. Sending an SNMP Message to the Network ..................... 52
A.3. Application Design Requirements .............................. 52
A.3.1. Applications that Initiate Messages ........................ 53
A.3.2. Applications that Receive Responses ........................ 53
A.3.3. Applications that Receive Asynchronous Messages ............ 53
A.3.4. Applications that Send Responses ........................... 54
A.4. Access Control Model Design Requirements ..................... 54
B. Issues ......................................................... 55
B.1. Showstoppers ................................................. 55
B.2. Open Issues .................................................. 55
B.3. Resolved Issues .............................................. 55
B.3.1. Issues discussed at second Interim Meeting: ................ 56
B.4. Change Log ................................................... 56
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