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RFC 3411

 
 
 

An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks

Part 3 of 3, p. 40 to 64
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5.  Managed Object Definitions for SNMP Management Frameworks

SNMP-FRAMEWORK-MIB DEFINITIONS ::= BEGIN

IMPORTS
    MODULE-IDENTITY, OBJECT-TYPE,
    OBJECT-IDENTITY,
    snmpModules                           FROM SNMPv2-SMI
    TEXTUAL-CONVENTION                    FROM SNMPv2-TC
    MODULE-COMPLIANCE, OBJECT-GROUP       FROM SNMPv2-CONF;

snmpFrameworkMIB MODULE-IDENTITY
    LAST-UPDATED "200210140000Z"
    ORGANIZATION "SNMPv3 Working Group"
    CONTACT-INFO "WG-EMail:   snmpv3@lists.tislabs.com
                  Subscribe:  snmpv3-request@lists.tislabs.com

                  Co-Chair:   Russ Mundy
                              Network Associates Laboratories
                  postal:     15204 Omega Drive, Suite 300
                              Rockville, MD 20850-4601
                              USA
                  EMail:      mundy@tislabs.com
                  phone:      +1 301-947-7107

                  Co-Chair &
                  Co-editor:  David Harrington
                              Enterasys Networks
                  postal:     35 Industrial Way
                              P. O. Box 5005
                              Rochester, New Hampshire 03866-5005
                              USA
                  EMail:      dbh@enterasys.com
                  phone:      +1 603-337-2614

                  Co-editor:  Randy Presuhn
                              BMC Software, Inc.
                  postal:     2141 North First Street
                              San Jose, California 95131
                              USA
                  EMail:      randy_presuhn@bmc.com
                  phone:      +1 408-546-1006

                  Co-editor:  Bert Wijnen
                              Lucent Technologies
                  postal:     Schagen 33
                              3461 GL Linschoten
                              Netherlands

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                  EMail:      bwijnen@lucent.com
                  phone:      +31 348-680-485
                    "
       DESCRIPTION  "The SNMP Management Architecture MIB

                     Copyright (C) The Internet Society (2002). This
                     version of this MIB module is part of RFC 3411;
                     see the RFC itself for full legal notices.
                    "

       REVISION     "200210140000Z"         -- 14 October 2002
       DESCRIPTION  "Changes in this revision:
                     - Updated various administrative information.
                     - Corrected some typos.
                     - Corrected typo in description of SnmpEngineID
                       that led to range overlap for 127.
                     - Changed '255a' to '255t' in definition of
                       SnmpAdminString to align with current SMI.
                     - Reworded 'reserved' for value zero in
                       DESCRIPTION of SnmpSecurityModel.
                     - The algorithm for allocating security models
                       should give 256 per enterprise block, rather
                       than 255.
                     - The example engine ID of 'abcd' is not
                       legal. Replaced with '800002b804616263'H based
                       on example enterprise 696, string 'abc'.
                     - Added clarification that engineID should
                       persist across re-initializations.
                     This revision published as RFC 3411.
                    "
       REVISION     "199901190000Z"         -- 19 January 1999
       DESCRIPTION  "Updated editors' addresses, fixed typos.
                     Published as RFC 2571.
                    "
       REVISION     "199711200000Z"         -- 20 November 1997
       DESCRIPTION  "The initial version, published in RFC 2271.
                    "
       ::= { snmpModules 10 }

   -- Textual Conventions used in the SNMP Management Architecture ***

SnmpEngineID ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION "An SNMP engine's administratively-unique identifier.
                 Objects of this type are for identification, not for
                 addressing, even though it is possible that an
                 address may have been used in the generation of
                 a specific value.

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                 The value for this object may not be all zeros or
                 all 'ff'H or the empty (zero length) string.

                 The initial value for this object may be configured
                 via an operator console entry or via an algorithmic
                 function.  In the latter case, the following
                 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
                    rest of the data is composed.

                    0 - as defined by enterprise using former methods
                        that existed before SNMPv3. See item 2 below.

                    1 - as defined by this architecture, see item 3
                        below.

                    Note that this allows existing uses of the
                    engineID (also known as AgentID [RFC1910]) to
                    co-exist with any new uses.

                 2) The snmpEngineID has a length of 12 octets.

                    The first four octets are set to the binary
                    equivalent of the agent's SNMP management
                    private enterprise number as assigned by the
                    Internet Assigned Numbers Authority (IANA).
                    For example, if Acme Networks has been assigned
                    { enterprises 696 }, the first four octets would
                    be assigned '000002b8'H.

                    The remaining eight octets are determined via
                    one or more enterprise-specific methods. Such
                    methods must be designed so as to maximize the
                    possibility that the value of this object will
                    be unique in the agent's administrative domain.
                    For example, it may be the IP address of the SNMP
                    entity, or the MAC address of one of the
                    interfaces, with each address suitably padded
                    with random octets.  If multiple methods are
                    defined, then it is recommended that the first
                    octet indicate the method being used and the
                    remaining octets be a function of the method.

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                 3) The length of the octet string varies.

                    The first four octets are set to the binary
                    equivalent of the agent's SNMP management
                    private enterprise number as assigned by the
                    Internet Assigned Numbers Authority (IANA).
                    For example, if Acme Networks has been assigned
                    { enterprises 696 }, the first four octets would
                    be assigned '000002b8'H.

                    The very first bit is set to 1. For example, the
                    above value for Acme Networks now changes to be
                    '800002b8'H.

                    The fifth octet indicates how the rest (6th and
                    following octets) are formatted. The values for
                    the fifth octet are:

                      0     - reserved, unused.

                      1     - IPv4 address (4 octets)
                              lowest non-special IP address

                      2     - IPv6 address (16 octets)
                              lowest non-special IP address

                      3     - MAC address (6 octets)
                              lowest IEEE MAC address, canonical
                              order

                      4     - Text, administratively assigned
                              Maximum remaining length 27

                      5     - Octets, administratively assigned
                              Maximum remaining length 27

                      6-127 - reserved, unused

                    128-255 - as defined by the enterprise
                              Maximum remaining length 27
                "
    SYNTAX       OCTET STRING (SIZE(5..32))

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SnmpSecurityModel ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION "An identifier that uniquely identifies a
                 Security Model of the Security Subsystem within
                 this SNMP Management Architecture.

                 The values for securityModel are allocated as
                 follows:

                 - The zero value does not identify any particular
                   security model.

                 - Values between 1 and 255, inclusive, are reserved
                   for standards-track Security Models and are
                   managed by the Internet Assigned Numbers Authority
                   (IANA).
                 - Values greater than 255 are allocated to
                   enterprise-specific Security Models.  An
                   enterprise-specific securityModel value is defined
                   to be:

                   enterpriseID * 256 + security model within
                   enterprise

                   For example, the fourth Security Model defined by
                   the enterprise whose enterpriseID is 1 would be
                   259.

                 This scheme for allocation of securityModel
                 values allows for a maximum of 255 standards-
                 based Security Models, and for a maximum of
                 256 Security Models per enterprise.

                 It is believed that the assignment of new
                 securityModel values will be rare in practice
                 because the larger the number of simultaneously
                 utilized Security Models, the larger the
                 chance that interoperability will suffer.
                 Consequently, it is believed that such a range
                 will be sufficient.  In the unlikely event that
                 the standards committee finds this number to be
                 insufficient over time, an enterprise number
                 can be allocated to obtain an additional 256
                 possible values.

                 Note that the most significant bit must be zero;
                 hence, there are 23 bits allocated for various
                 organizations to design and define non-standard

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                 securityModels.  This limits the ability to
                 define new proprietary implementations of Security
                 Models to the first 8,388,608 enterprises.

                 It is worthwhile to note that, in its encoded
                 form, the securityModel value will normally
                 require only a single byte since, in practice,
                 the leftmost bits will be zero for most messages
                 and sign extension is suppressed by the encoding
                 rules.

                 As of this writing, there are several values
                 of securityModel defined for use with SNMP or
                 reserved for use with supporting MIB objects.
                 They are as follows:

                     0  reserved for 'any'
                     1  reserved for SNMPv1
                     2  reserved for SNMPv2c
                     3  User-Based Security Model (USM)
                "
    SYNTAX       INTEGER(0 .. 2147483647)


SnmpMessageProcessingModel ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION "An identifier that uniquely identifies a Message
                 Processing Model of the Message Processing
                 Subsystem within this SNMP Management Architecture.

                 The values for messageProcessingModel are
                 allocated as follows:

                 - Values between 0 and 255, inclusive, are
                   reserved for standards-track Message Processing
                   Models and are managed by the Internet Assigned
                   Numbers Authority (IANA).

                 - Values greater than 255 are allocated to
                   enterprise-specific Message Processing Models.
                   An enterprise messageProcessingModel value is
                   defined to be:

                   enterpriseID * 256 +
                        messageProcessingModel within enterprise

                   For example, the fourth Message Processing Model
                   defined by the enterprise whose enterpriseID

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                   is 1 would be 259.

                 This scheme for allocating messageProcessingModel
                 values allows for a maximum of 255 standards-
                 based Message Processing Models, and for a
                 maximum of 256 Message Processing Models per
                 enterprise.

                 It is believed that the assignment of new
                 messageProcessingModel values will be rare
                 in practice because the larger the number of
                 simultaneously utilized Message Processing Models,
                 the larger the chance that interoperability
                 will suffer. It is believed that such a range
                 will be sufficient.  In the unlikely event that
                 the standards committee finds this number to be
                 insufficient over time, an enterprise number
                 can be allocated to obtain an additional 256
                 possible values.

                 Note that the most significant bit must be zero;
                 hence, there are 23 bits allocated for various
                 organizations to design and define non-standard
                 messageProcessingModels.  This limits the ability
                 to define new proprietary implementations of
                 Message Processing Models to the first 8,388,608
                 enterprises.

                 It is worthwhile to note that, in its encoded
                 form, the messageProcessingModel value will
                 normally require only a single byte since, in
                 practice, the leftmost bits will be zero for
                 most messages and sign extension is suppressed
                 by the encoding rules.

                 As of this writing, there are several values of
                 messageProcessingModel defined for use with SNMP.
                 They are as follows:

                     0  reserved for SNMPv1
                     1  reserved for SNMPv2c
                     2  reserved for SNMPv2u and SNMPv2*
                     3  reserved for SNMPv3
                "
    SYNTAX       INTEGER(0 .. 2147483647)

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SnmpSecurityLevel ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION "A Level of Security at which SNMP messages can be
                 sent or with which operations are being processed;
                 in particular, one of:

                   noAuthNoPriv - without authentication and
                                  without privacy,
                   authNoPriv   - with authentication but
                                  without privacy,
                   authPriv     - with authentication and
                                  with privacy.

                 These three values are ordered such that
                 noAuthNoPriv is less than authNoPriv and
                 authNoPriv is less than authPriv.
                "
    SYNTAX       INTEGER { noAuthNoPriv(1),
                           authNoPriv(2),
                           authPriv(3)
                         }

SnmpAdminString ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "255t"
    STATUS       current
    DESCRIPTION "An octet string containing administrative
                 information, preferably in human-readable form.

                 To facilitate internationalization, this
                 information is represented using the ISO/IEC
                 IS 10646-1 character set, encoded as an octet
                 string using the UTF-8 transformation format
                 described in [RFC2279].

                 Since additional code points are added by
                 amendments to the 10646 standard from time
                 to time, implementations must be prepared to
                 encounter any code point from 0x00000000 to
                 0x7fffffff.  Byte sequences that do not
                 correspond to the valid UTF-8 encoding of a
                 code point or are outside this range are
                 prohibited.

                 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.

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                 The use of leading or trailing white space should
                 be avoided.

                 For code points not directly supported by user
                 interface hardware or software, an alternative
                 means of entry and display, such as hexadecimal,
                 may be provided.

                 For information encoded in 7-bit US-ASCII,
                 the UTF-8 encoding is identical to the
                 US-ASCII encoding.

                 UTF-8 may require multiple bytes to represent a
                 single character / code point; thus the length
                 of this object in octets may be different from
                 the number of characters encoded.  Similarly,
                 size constraints refer to the number of encoded
                 octets, not the number of characters represented
                 by an encoding.

                 Note that when this TC is used for an object that
                 is used or envisioned to be used as an index, then
                 a SIZE restriction MUST be specified so that the
                 number of sub-identifiers for any object instance
                 does not exceed the limit of 128, as defined by
                 [RFC3416].

                 Note that the size of an SnmpAdminString object is
                 measured in octets, not characters.
                "
    SYNTAX       OCTET STRING (SIZE (0..255))


-- Administrative assignments ***************************************

snmpFrameworkAdmin
    OBJECT IDENTIFIER ::= { snmpFrameworkMIB 1 }
snmpFrameworkMIBObjects
    OBJECT IDENTIFIER ::= { snmpFrameworkMIB 2 }
snmpFrameworkMIBConformance
    OBJECT IDENTIFIER ::= { snmpFrameworkMIB 3 }

-- the snmpEngine Group ********************************************

snmpEngine OBJECT IDENTIFIER ::= { snmpFrameworkMIBObjects 1 }

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snmpEngineID     OBJECT-TYPE
    SYNTAX       SnmpEngineID
    MAX-ACCESS   read-only
    STATUS       current
    DESCRIPTION "An SNMP engine's administratively-unique identifier.

                 This information SHOULD be stored in non-volatile
                 storage so that it remains constant across
                 re-initializations of the SNMP engine.
                "
    ::= { snmpEngine 1 }

snmpEngineBoots  OBJECT-TYPE
    SYNTAX       INTEGER (1..2147483647)
    MAX-ACCESS   read-only
    STATUS       current
    DESCRIPTION "The number of times that the SNMP engine has
                 (re-)initialized itself since snmpEngineID
                 was last configured.
                "
    ::= { snmpEngine 2 }

snmpEngineTime   OBJECT-TYPE
    SYNTAX       INTEGER (0..2147483647)
    UNITS        "seconds"
    MAX-ACCESS   read-only
    STATUS       current
    DESCRIPTION "The number of seconds since the value of
                 the snmpEngineBoots object last changed.
                 When incrementing this object's value would
                 cause it to exceed its maximum,
                 snmpEngineBoots is incremented as if a
                 re-initialization had occurred, and this
                 object's value consequently reverts to zero.
                "
    ::= { 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 }

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-- Registration Points for Authentication and Privacy Protocols **

snmpAuthProtocols OBJECT-IDENTITY
    STATUS        current
    DESCRIPTION  "Registration point for standards-track
                  authentication protocols used in SNMP Management
                  Frameworks.
                 "
    ::= { snmpFrameworkAdmin 1 }

snmpPrivProtocols OBJECT-IDENTITY
    STATUS        current
    DESCRIPTION  "Registration point for standards-track privacy
                  protocols used in SNMP Management Frameworks.
                 "
    ::= { snmpFrameworkAdmin 2 }

-- Conformance information ******************************************

snmpFrameworkMIBCompliances
               OBJECT IDENTIFIER ::= {snmpFrameworkMIBConformance 1}
snmpFrameworkMIBGroups
               OBJECT IDENTIFIER ::= {snmpFrameworkMIBConformance 2}

-- compliance statements

snmpFrameworkMIBCompliance MODULE-COMPLIANCE
    STATUS       current
    DESCRIPTION "The compliance statement for SNMP engines which
                 implement the SNMP Management Framework MIB.
                "
    MODULE    -- this module
        MANDATORY-GROUPS { snmpEngineGroup }

    ::= { snmpFrameworkMIBCompliances 1 }

-- units of conformance

snmpEngineGroup OBJECT-GROUP
    OBJECTS {
              snmpEngineID,
              snmpEngineBoots,
              snmpEngineTime,
              snmpEngineMaxMessageSize
            }
    STATUS       current
    DESCRIPTION "A collection of objects for identifying and
                 determining the configuration and current timeliness

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                 values of an SNMP engine.
                "
    ::= { snmpFrameworkMIBGroups 1 }

END

6.  IANA Considerations

   This document defines three number spaces administered by IANA, one
   for security models, another for message processing models, and a
   third for SnmpEngineID formats.

6.1.  Security Models

   The SnmpSecurityModel TEXTUAL-CONVENTION values managed by IANA are
   in the range from 0 to 255 inclusive, and are reserved for
   standards-track Security Models.  If this range should in the future
   prove insufficient, an enterprise number can be allocated to obtain
   an additional 256 possible values.

   As of this writing, there are several values of securityModel defined
   for use with SNMP or reserved for use with supporting MIB objects.
   They are as follows:

                           0  reserved for 'any'
                           1  reserved for SNMPv1
                           2  reserved for SNMPv2c
                           3  User-Based Security Model (USM)

6.2.  Message Processing Models

   The SnmpMessageProcessingModel TEXTUAL-CONVENTION values managed by
   IANA are in the range 0 to 255, inclusive.  Each value uniquely
   identifies a standards-track Message Processing Model of the Message
   Processing Subsystem within the SNMP Management Architecture.

   Should this range prove insufficient in the future, an enterprise
   number may be obtained for the standards committee to get an
   additional 256 possible values.

   As of this writing, there are several values of
   messageProcessingModel defined for use with SNMP.  They are as
   follows:

                           0  reserved for SNMPv1
                           1  reserved for SNMPv2c
                           2  reserved for SNMPv2u and SNMPv2*
                           3  reserved for SNMPv3

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6.3.  SnmpEngineID Formats

   The SnmpEngineID TEXTUAL-CONVENTION's fifth octet contains a format
   identifier.  The values managed by IANA are in the range 6 to 127,
   inclusive.  Each value uniquely identifies a standards-track
   SnmpEngineID format.

7.  Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   intellectual property or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; neither does it represent that it
   has made any effort to identify any such rights.  Information on the
   IETF's procedures with respect to rights in standards-track and
   standards-related documentation can be found in RFC 2028.  Copies of
   claims of rights made available for publication and any assurances of
   licenses to be made available, or the result of an attempt made to
   obtain a general license or permission for the use of such
   proprietary rights by implementors or users of this specification can
   be obtained from the IETF Secretariat.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights which may cover technology that may be required to practice
   this standard.  Please address the information to the IETF Executive
   Director.

8.  Acknowledgements

   This document is the result of the efforts of the SNMPv3 Working
   Group.  Some special thanks are in order to the following SNMPv3 WG
   members:

      Harald Tveit Alvestrand (Maxware)
      Dave Battle (SNMP Research, Inc.)
      Alan Beard (Disney Worldwide Services)
      Paul Berrevoets (SWI Systemware/Halcyon Inc.)
      Martin Bjorklund (Ericsson)
      Uri Blumenthal (IBM T.J. Watson Research Center)
      Jeff Case (SNMP Research, Inc.)
      John Curran (BBN)
      Mike Daniele (Compaq Computer Corporation)
      T. Max Devlin (Eltrax Systems)
      John Flick (Hewlett Packard)
      Rob Frye (MCI)
      Wes Hardaker (U.C.Davis, Information Technology - D.C.A.S.)

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      David Harrington (Cabletron Systems Inc.)
      Lauren Heintz (BMC Software, Inc.)
      N.C. Hien (IBM T.J. Watson Research Center)
      Michael Kirkham (InterWorking Labs, Inc.)
      Dave Levi (SNMP Research, Inc.)
      Louis A Mamakos (UUNET Technologies Inc.)
      Joe Marzot (Nortel Networks)
      Paul Meyer (Secure Computing Corporation)
      Keith McCloghrie (Cisco Systems)
      Bob Moore (IBM)
      Russ Mundy (TIS Labs at Network Associates)
      Bob Natale (ACE*COMM Corporation)
      Mike O'Dell (UUNET Technologies Inc.)
      Dave Perkins (DeskTalk)
      Peter Polkinghorne (Brunel University)
      Randy Presuhn (BMC Software, Inc.)
      David Reeder (TIS Labs at Network Associates)
      David Reid (SNMP Research, Inc.)
      Aleksey Romanov (Quality Quorum)
      Shawn Routhier (Epilogue)
      Juergen Schoenwaelder (TU Braunschweig)
      Bob Stewart (Cisco Systems)
      Mike Thatcher (Independent Consultant)
      Bert Wijnen (IBM T.J. Watson Research Center)

   The document is based on recommendations of the IETF Security and
   Administrative Framework Evolution for SNMP Advisory Team.  Members
   of that Advisory Team were:

      David Harrington (Cabletron Systems Inc.)
      Jeff Johnson (Cisco Systems)
      David Levi (SNMP Research Inc.)
      John Linn (Openvision)
      Russ Mundy (Trusted Information Systems) chair
      Shawn Routhier (Epilogue)
      Glenn Waters (Nortel)
      Bert Wijnen (IBM T. J. Watson Research Center)

   As recommended by the Advisory Team and the SNMPv3 Working Group
   Charter, the design incorporates as much as practical from previous
   RFCs and drafts. As a result, special thanks are due to the authors
   of previous designs known as SNMPv2u and SNMPv2*:

      Jeff Case (SNMP Research, Inc.)
      David Harrington (Cabletron Systems Inc.)
      David Levi (SNMP Research, Inc.)
      Keith McCloghrie (Cisco Systems)
      Brian O'Keefe (Hewlett Packard)

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      Marshall T. Rose (Dover Beach Consulting)
      Jon Saperia (BGS Systems Inc.)
      Steve Waldbusser (International Network Services)
      Glenn W. Waters (Bell-Northern Research Ltd.)

9.  Security Considerations

   This document describes how an implementation can include a Security
   Model to protect management messages and an Access Control Model to
   control access to management information.

   The level of security provided is determined by the specific Security
   Model implementation(s) and the specific Access Control Model
   implementation(s) used.

   Applications have access to data which is not secured.  Applications
   SHOULD take reasonable steps to protect the data from disclosure.

   It is the responsibility of the purchaser of an implementation to
   ensure that:

      1) an implementation complies with the rules defined by this
         architecture,

      2) the Security and Access Control Models utilized satisfy the
         security and access control needs of the organization,

      3) the implementations of the Models and Applications comply with
         the model and application specifications,

      4) and the implementation protects configuration secrets from
         inadvertent disclosure.

   This document also contains a MIB definition module.  None of the
   objects defined is writable, and the information they represent is
   not deemed to be particularly sensitive.  However, if they are deemed
   sensitive in a particular environment, access to them should be
   restricted through the use of appropriately configured Security and
   Access Control models.

10.  References

10.1.  Normative References

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

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   [RFC2279]   Yergeau, F., "UTF-8, a transformation format of ISO
               10646", RFC 2279, January 1998.

   [RFC2578]   McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
               Rose, M. and S. Waldbusser, "Structure of Management
               Information Version 2 (SMIv2)", STD 58, RFC 2578, April
               1999.

   [RFC2579]   McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
               Rose, M. and S. Waldbusser, "Textual Conventions for
               SMIv2", STD 58, RFC 2579, April 1999.

   [RFC2580]   McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
               Rose, M. and S. Waldbusser, "Conformance Statements for
               SMIv2", STD 58, RFC 2580, April 1999.

   [RFC3412]   Case, J., Harrington, D., Presuhn, R. and B. Wijnen,
               "Message Processing and Dispatching for the Simple
               Network Management Protocol (SNMP)", STD 62, RFC 3412,
               December 2002.

   [RFC3413]   Levi, D., Meyer, P. and B. Stewart, "Simple Network
               Management Protocol (SNMP) Applications", STD 62, RFC
               3413, December 2002.

   [RFC3414]   Blumenthal, U. and B. Wijnen, "User-Based Security Model
               (USM) for Version 3 of the Simple Network Management
               Protocol (SNMPv3)", STD 62, RFC 3414, December 2002.

   [RFC3415]   Wijnen, B., Presuhn, R. and K. McCloghrie, "View-based
               Access Control Model (VACM) for the Simple Network
               Management Protocol (SNMP)", STD 62, RFC 3415, December
               2002.

   [RFC3416]   Presuhn, R., Case, J., McCloghrie, K., Rose, M. and S.
               Waldbusser, "Protocol Operations for the Simple Network
               Management Protocol (SNMP)", STD 62, RFC 3416, December
               2002.

   [RFC3417]   Presuhn, R., Case, J., McCloghrie, K., Rose, M. and S.
               Waldbusser, "Transport Mappings for the Simple Network
               Management Protocol (SNMP)", STD 62, RFC 3417, December
               2002.

   [RFC3418]   Presuhn, R., Case, J., McCloghrie, K., Rose, M. and S.
               Waldbusser, "Management Information Base (MIB) for the
               Simple Network Management Protocol (SNMP)", STD 62, RFC
               3418, December 2002.

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10.2.  Informative References

   [RFC1155]   Rose, M. and K. McCloghrie, "Structure and Identification
               of Management Information for TCP/IP-based internets",
               STD 16, RFC 1155, May 1990.

   [RFC1157]   Case, J., Fedor, M., Schoffstall, M. and J. Davin, "The
               Simple Network Management Protocol", STD 15, RFC 1157,
               May 1990.

   [RFC1212]   Rose, M. and K. McCloghrie, "Concise MIB Definitions",
               STD 16, RFC 1212, March 1991.

   [RFC1901]   Case, J., McCloghrie, K., Rose, M. and S. Waldbusser,
               "Introduction to Community-based SNMPv2", RFC 1901,
               January 1996.

   [RFC1909]   McCloghrie, K., Editor, "An Administrative Infrastructure
               for SNMPv2", RFC 1909, February 1996.

   [RFC1910]   Waters, G., Editor, "User-based Security Model for
               SNMPv2", RFC 1910, February 1996.

   [RFC2028]   Hovey, R. and S. Bradner, "The Organizations Involved in
               the IETF Standards Process", BCP 11, RFC 2028, October
               1996.

   [RFC2576]   Frye, R., Levi, D., Routhier, S. and B. Wijnen,
               "Coexistence between Version 1, Version 2, and Version 3
               of the Internet-Standard Network Management Framework",
               RFC 2576, March 2000.

   [RFC2863]   McCloghrie, K. and F. Kastenholz, "The Interfaces Group
               MIB", RFC 2863, June 2000.

   [RFC3410]   Case, J., Mundy, R., Partain, D. and B. Stewart,
               "Introduction and Applicability Statements for Internet-
               Standard Management Framework", RFC 3410, December 2002.

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Appendix A

A.  Guidelines for Model Designers

   This appendix describes guidelines for designers of models which are
   expected to fit into the architecture defined in this document.

   SNMPv1 and SNMPv2c are two SNMP frameworks which use communities to
   provide trivial authentication and access control.  SNMPv1 and
   SNMPv2c Frameworks can coexist with Frameworks designed according to
   this architecture, and modified versions of SNMPv1 and SNMPv2c
   Frameworks could be designed to meet the requirements of this
   architecture, but this document does not provide guidelines for that
   coexistence.

   Within any subsystem model, there should be no reference to any
   specific model of another subsystem, or to data defined by a specific
   model of another subsystem.

   Transfer of data between the subsystems is deliberately described as
   a fixed set of abstract data elements and primitive functions which
   can be overloaded to satisfy the needs of multiple model definitions.

   Documents which define models to be used within this architecture
   SHOULD use the standard primitives between subsystems, possibly
   defining specific mechanisms for converting the abstract data
   elements into model-usable formats.  This constraint exists to allow
   subsystem and model documents to be written recognizing common
   borders of the subsystem and model.  Vendors are not constrained to
   recognize these borders in their implementations.

   The architecture defines certain standard services to be provided
   between subsystems, and the architecture defines abstract service
   interfaces to request these services.

   Each model definition for a subsystem SHOULD support the standard
   service interfaces, but whether, or how, or how well, it performs the
   service is dependent on the model definition.

A.1.  Security Model Design Requirements

A.1.1.  Threats

   A document describing a Security Model MUST describe how the model
   protects against the threats described under "Security Requirements
   of this Architecture", section 1.4.

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A.1.2.  Security Processing

   Received messages MUST be validated by a Model of the Security
   Subsystem.  Validation includes authentication and privacy processing
   if needed, but it is explicitly allowed to send messages which do not
   require authentication or privacy.

   A received message contains a specified securityLevel to be used
   during processing.  All messages requiring privacy MUST also require
   authentication.

   A Security Model specifies rules by which authentication and privacy
   are to be done.  A model may define mechanisms to provide additional
   security features, but the model definition is constrained to using
   (possibly a subset of) the abstract data elements defined in this
   document for transferring data between subsystems.

   Each Security Model may allow multiple security protocols to be used
   concurrently within an implementation of the model.  Each Security
   Model defines how to determine which protocol to use, given the
   securityLevel and the security parameters relevant to the message.
   Each Security Model, with its associated protocol(s) defines how the
   sending/receiving entities are identified, and how secrets are
   configured.

   Authentication and Privacy protocols supported by Security Models are
   uniquely identified using Object Identifiers.  IETF standard
   protocols for authentication or privacy should have an identifier
   defined within the snmpAuthProtocols or the snmpPrivProtocols
   subtrees.  Enterprise specific protocol identifiers should be defined
   within the enterprise subtree.

   For privacy, the Security Model defines what portion of the message
   is encrypted.

   The persistent data used for security should be SNMP-manageable, but
   the Security Model defines whether an instantiation of the MIB is a
   conformance requirement.

   Security Models are replaceable within the Security Subsystem.
   Multiple Security Model implementations may exist concurrently within
   an SNMP engine.  The number of Security Models defined by the SNMP
   community should remain small to promote interoperability.

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A.1.3.  Validate the security-stamp in a received message

   A Message Processing Model requests that a Security Model:

      -  verifies that the message has not been altered,

      -  authenticates the identification of the principal for whom the
         message was generated.

      -  decrypts the message if it was encrypted.

   Additional requirements may be defined by the model, and additional
   services may be provided by the model, but the model is constrained
   to use the following primitives for transferring data between
   subsystems.  Implementations are not so constrained.

   A Message Processing Model uses the processIncomingMsg primitive as
   described in section 4.4.2.

A.1.4.  Security MIBs

   Each Security Model defines the MIB module(s) required for security
   processing, including any MIB module(s) required for the security
   protocol(s) supported.  The MIB module(s) SHOULD be defined
   concurrently with the procedures which use the MIB module(s).  The
   MIB module(s) are subject to normal access control rules.

   The mapping between the model-dependent security ID and the
   securityName MUST be able to be determined using SNMP, if the model-
   dependent MIB is instantiated and if access control policy allows
   access.

A.1.5.  Cached Security Data

   For each message received, the Security Model caches the state
   information such that a Response message can be generated using the
   same security information, even if the Local Configuration Datastore
   is altered between the time of the incoming request and the outgoing
   response.

   A Message Processing Model has the responsibility for explicitly
   releasing the cached data if such data is no longer needed.  To
   enable this, an abstract securityStateReference data element is
   passed from the Security Model to the Message Processing Model.

   The cached security data may be implicitly released via the
   generation of a response, or explicitly released by using the
   stateRelease primitive, as described in section 4.5.1.

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A.2.  Message Processing Model Design Requirements

   An SNMP engine contains a Message Processing Subsystem which may
   contain multiple Message Processing Models.

   The Message Processing Model MUST always (conceptually) pass the
   complete PDU, i.e., it never forwards less than the complete list of
   varBinds.

A.2.1.  Receiving an SNMP Message from the Network

   Upon receipt of a message from the network, the Dispatcher in the
   SNMP engine determines the version of the SNMP message and interacts
   with the corresponding Message Processing Model to determine the
   abstract data elements.

   A Message Processing Model specifies the SNMP Message format it
   supports and describes how to determine the values of the abstract
   data elements (like msgID, msgMaxSize, msgFlags,
   msgSecurityParameters, securityModel, securityLevel etc).  A Message
   Processing Model interacts with a Security Model to provide security
   processing for the message using the processIncomingMsg primitive, as
   described in section 4.4.2.

A.2.2.  Sending an SNMP Message to the Network

   The Dispatcher in the SNMP engine interacts with a Message Processing
   Model to prepare an outgoing message.  For that it uses the following
   primitives:

      -  for requests and notifications: prepareOutgoingMessage, as
         described in section 4.2.1.

      -  for response messages: prepareResponseMessage, as described in
         section 4.2.2.

   A Message Processing Model, when preparing an Outgoing SNMP Message,
   interacts with a Security Model to secure the message.  For that it
   uses the following primitives:

      -  for requests and notifications: generateRequestMsg, as
         described in section 4.4.1.

      -  for response messages: generateResponseMsg as described in
         section 4.4.3.

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   Once the SNMP message is prepared by a Message Processing Model, the
   Dispatcher sends the message to the desired address using the
   appropriate transport.

A.3.  Application Design Requirements

   Within an application, there may be an explicit binding to a specific
   SNMP message version, i.e., a specific Message Processing Model, and
   to a specific Access Control Model, but there should be no reference
   to any data defined by a specific Message Processing Model or Access
   Control Model.

   Within an application, there should be no reference to any specific
   Security Model, or any data defined by a specific Security Model.

   An application determines whether explicit or implicit access control
   should be applied to the operation, and, if access control is needed,
   which Access Control Model should be used.

   An application has the responsibility to define any MIB module(s)
   used to provide application-specific services.

   Applications interact with the SNMP engine to initiate messages,
   receive responses, receive asynchronous messages, and send responses.

A.3.1.  Applications that Initiate Messages

   Applications may request that the SNMP engine send messages
   containing SNMP commands or notifications using the sendPdu primitive
   as described in section 4.1.1.

   If it is desired that a message be sent to multiple targets, it is
   the responsibility of the application to provide the iteration.

   The SNMP engine assumes necessary access control has been applied to
   the PDU, and provides no access control services.

   The SNMP engine looks at the "expectResponse" parameter, and if a
   response is expected, then the appropriate information is cached such
   that a later response can be associated to this message, and can then
   be returned to the application.  A sendPduHandle is returned to the
   application so it can later correspond the response with this message
   as well.

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A.3.2.  Applications that Receive Responses

   The SNMP engine matches the incoming response messages to outstanding
   messages sent by this SNMP engine, and forwards the response to the
   associated application using the processResponsePdu primitive, as
   described in section 4.1.4.

A.3.3.  Applications that Receive Asynchronous Messages

   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
   the message should be given.

   An Application that wishes to receive asynchronous messages registers
   itself with the engine using the primitive registerContextEngineID as
   described in section 4.1.5.

   An Application that wishes to stop receiving asynchronous messages
   should unregister itself with the SNMP engine using the primitive
   unregisterContextEngineID as described in section 4.1.5.

   Only one registration per combination of PDU type and contextEngineID
   is permitted at the same time.  Duplicate registrations are ignored.
   An errorIndication will be returned to the application that attempts
   to duplicate a registration.

   All asynchronously received messages containing a registered
   combination of PDU type and contextEngineID are sent to the
   application which registered to support that combination.

   The engine forwards the PDU to the registered application, using the
   processPdu primitive, as described in section 4.1.2.

A.3.4.  Applications that Send Responses

   Request operations require responses.  An application sends a
   response via the returnResponsePdu primitive, as described in section
   4.1.3.

   The contextEngineID, contextName, securityModel, securityName,
   securityLevel, and stateReference parameters are from the initial
   processPdu primitive.  The PDU and statusInformation are the results
   of processing.

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A.4.  Access Control Model Design Requirements

   An Access Control Model determines whether the specified securityName
   is allowed to perform the requested operation on a specified managed
   object.  The Access Control Model specifies the rules by which access
   control is determined.

   The persistent data used for access control should be manageable
   using SNMP, but the Access Control Model defines whether an
   instantiation of the MIB is a conformance requirement.

   The Access Control Model must provide the primitive isAccessAllowed.

Editors' Addresses

   Bert Wijnen
   Lucent Technologies
   Schagen 33
   3461 GL Linschoten
   Netherlands

   Phone: +31 348-680-485
   EMail: bwijnen@lucent.com


   David Harrington
   Enterasys Networks
   Post Office Box 5005
   35 Industrial Way
   Rochester, New Hampshire 03866-5005
   USA

   Phone: +1 603-337-2614
   EMail: dbh@enterasys.com


   Randy Presuhn
   BMC Software, Inc.
   2141 North First Street
   San Jose, California 95131
   USA

   Phone: +1 408-546-1006
   Fax: +1 408-965-0359
   EMail: randy_presuhn@bmc.com

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