RFC3415

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Network Working Group B. Wijnen Request for Comments: 3415 Lucent Technologies STD: 62 R. Presuhn Obsoletes: 2575 BMC Software, Inc. Category: Standards Track K. McCloghrie

                                                 Cisco Systems, Inc.
                                                       December 2002
         View-based Access Control Model (VACM) for the
           Simple Network Management Protocol (SNMP)

Status of this Memo

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2002). All Rights Reserved.

Abstract

This document describes the View-based Access Control Model (VACM) for use in the Simple Network Management Protocol (SNMP) architecture. It defines the Elements of Procedure for controlling access to management information. This document also includes a Management Information Base (MIB) for remotely managing the configuration parameters for the View-based Access Control Model. This document obsoletes RFC 2575.

Introduction

The Architecture for describing Internet Management Frameworks RFC3411 describes that an SNMP engine is composed of:

  1) a Dispatcher
  2) a Message Processing Subsystem,
  3) a Security Subsystem, and
  4) an Access Control Subsystem.

Applications make use of the services of these subsystems.

It is important to understand the SNMP architecture and its terminology to understand where the View-based Access Control Model described in this document fits into the architecture and interacts with other subsystems within the architecture. The reader is expected to have read and understood the description and terminology of the SNMP architecture, as defined in RFC3411.

The Access Control Subsystem of an SNMP engine has the responsibility for checking whether a specific type of access (read, write, notify) to a particular object (instance) is allowed.

It is the purpose of this document to define a specific model of the Access Control Subsystem, designated the View-based Access Control Model. Note that this is not necessarily the only Access Control Model.

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 BCP 14, RFC 2119.

Access Control

Access Control occurs (either implicitly or explicitly) in an SNMP entity when processing SNMP retrieval or modification request messages from an SNMP entity. For example a Command Responder application applies Access Control when processing requests that it received from a Command Generator application. These requests contain Read Class and Write Class PDUs as defined in RFC3411.

Access Control also occurs in an SNMP entity when an SNMP notification message is generated (by a Notification Originator application). These notification messages contain Notification Class PDUs as defined in RFC3411.

The View-based Access Control Model defines a set of services that an application (such as a Command Responder or a Notification Originator application) can use for checking access rights. It is the responsibility of the application to make the proper service calls for access checking.

Local Configuration Datastore

To implement the model described in this document, an SNMP entity needs to retain information about access rights and policies. This information is part of the SNMP engine's Local Configuration Datastore (LCD). See RFC3411 for the definition of LCD.

In order to allow an SNMP entity's LCD to be remotely configured, portions of the LCD need to be accessible as managed objects. A MIB module, the View-based Access Control Model Configuration MIB, which defines these managed object types is included in this document.

Elements of the Model

This section contains definitions to realize the access control service provided by the View-based Access Control Model.

Groups

A group is a set of zero or more <securityModel, securityName> tuples on whose behalf SNMP management objects can be accessed. A group defines the access rights afforded to all securityNames which belong to that group. The combination of a securityModel and a securityName maps to at most one group. A group is identified by a groupName.

The Access Control module assumes that the securityName has already been authenticated as needed and provides no further authentication of its own.

The View-based Access Control Model uses the securityModel and the securityName as inputs to the Access Control module when called to check for access rights. It determines the groupName as a function of securityModel and securityName.

securityLevel

Different access rights for members of a group can be defined for different levels of security, i.e., noAuthNoPriv, authNoPriv, and authPriv. The securityLevel identifies the level of security that will be assumed when checking for access rights. See the SNMP Architecture document RFC3411 for a definition of securityLevel.

The View-based Access Control Model requires that the securityLevel is passed as input to the Access Control module when called to check for access rights.

Contexts

An SNMP context is a collection of management information accessible by an SNMP entity. An item of management information may exist in more than one context. An SNMP entity potentially has access to many contexts. Details about the naming of management information can be found in the SNMP Architecture document RFC3411.

The View-based Access Control Model defines a vacmContextTable that lists the locally available contexts by contextName.

MIB Views and View Families

For security reasons, it is often valuable to be able to restrict the access rights of some groups to only a subset of the management information in the management domain. To provide this capability, access to a context is via a "MIB view" which details a specific set of managed object types (and optionally, the specific instances of object types) within that context. For example, for a given context, there will typically always be one MIB view which provides access to all management information in that context, and often there will be other MIB views each of which contains some subset of the information. So, the access allowed for a group can be restricted in the desired manner by specifying its rights in terms of the particular (subset) MIB view it can access within each appropriate context.

Since managed object types (and their instances) are identified via the tree-like naming structure of ISO's OBJECT IDENTIFIERs [ISO- ASN.1, RFC2578], it is convenient to define a MIB view as the combination of a set of "view subtrees", where each view subtree is a subtree within the managed object naming tree. Thus, a simple MIB view (e.g., all managed objects within the Internet Network Management Framework) can be defined as a single view subtree, while more complicated MIB views (e.g., all information relevant to a particular network interface) can be represented by the union of multiple view subtrees.

While any set of managed objects can be described by the union of some number of view subtrees, situations can arise that would require a very large number of view subtrees. This could happen, for example, when specifying all columns in one conceptual row of a MIB table because they would appear in separate subtrees, one per column, each with a very similar format. Because the formats are similar, the required set of subtrees can easily be aggregated into one structure. This structure is named a family of view subtrees after the set of subtrees that it conceptually represents. A family of view subtrees can either be included or excluded from a MIB view.

View Subtree

A view subtree is the set of all MIB object instances which have a common ASN.1 OBJECT IDENTIFIER prefix to their names. A view subtree is identified by the OBJECT IDENTIFIER value which is the longest OBJECT IDENTIFIER prefix common to all (potential) MIB object instances in that subtree.

ViewTreeFamily

A family of view subtrees is a pairing of an OBJECT IDENTIFIER value (called the family name) together with a bit string value (called the family mask). The family mask indicates which sub-identifiers of the associated family name are significant to the family's definition.

For each possible managed object instance, that instance belongs to a particular ViewTreeFamily if both of the following conditions are true:

- the OBJECT IDENTIFIER name of the managed object instance contains

  at least as many sub-identifiers as does the family name, and

- each sub-identifier in the OBJECT IDENTIFIER name of the managed

  object instance matches the corresponding sub-identifier of the
  family name whenever the corresponding bit of the associated
  family mask is non-zero.

When the configured value of the family mask is all ones, the view subtree family is identical to the single view subtree identified by the family name.

When the configured value of the family mask is shorter than required to perform the above test, its value is implicitly extended with ones. Consequently, a view subtree family having a family mask of zero length always corresponds to a single view subtree.

Access Policy

The View-based Access Control Model determines the access rights of a group, representing zero or more securityNames which have the same access rights. For a particular context, identified by contextName, to which a group, identified by groupName, has access using a particular securityModel and securityLevel, that group's access rights are given by a read-view, a write-view and a notify-view.

The read-view represents the set of object instances authorized for the group when reading objects. Reading objects occurs when processing a retrieval operation (when handling Read Class PDUs).

The write-view represents the set of object instances authorized for the group when writing objects. Writing objects occurs when processing a write operation (when handling Write Class PDUs).

The notify-view represents the set of object instances authorized for the group when sending objects in a notification, such as when sending a notification (when sending Notification Class PDUs).

Elements of Procedure

This section describes the procedures followed by an Access Control module that implements the View-based Access Control Model when checking access rights as requested by an application (for example a Command Responder or a Notification Originator application). The abstract service primitive is:

  statusInformation =          -- success or errorIndication
      isAccessAllowed(
          securityModel        -- Security Model in use
          securityName         -- principal who wants access
          securityLevel        -- Level of Security
          viewType             -- read, write, or notify view
          contextName          -- context containing variableName
          variableName         -- OID for the managed object
          )

The abstract data elements are:

  statusInformation - one of the following:
     accessAllowed  - a MIB view was found and access is granted.
     notInView      - a MIB view was found but access is denied.
                      The variableName is not in the configured
                      MIB view for the specified viewType (e.g., in
                      the relevant entry in the vacmAccessTable).
     noSuchView     - no MIB view found because no view has been
                      configured for specified viewType (e.g., in
                      the relevant entry in the vacmAccessTable).
     noSuchContext  - no MIB view found because of no entry in the
                      vacmContextTable for specified contextName.
     noGroupName    - no MIB view found because no entry has been
                      configured in the vacmSecurityToGroupTable
                      for the specified combination of
                      securityModel and securityName.
     noAccessEntry  - no MIB view found because no entry has been
                      configured in the vacmAccessTable for the
                      specified combination of contextName,
                      groupName (from vacmSecurityToGroupTable),
                      securityModel and securityLevel.
     otherError     - failure, an undefined error occurred.
  securityModel - Security Model under which access is requested.
  securityName  - the principal on whose behalf access is requested.
  securityLevel - Level of Security under which access is requested.
  viewType      - view to be checked (read, write or notify).
  contextName   - context in which access is requested.
  variableName  - object instance to which access is requested.

Overview of isAccessAllowed Process

The following picture shows how the decision for access control is made by the View-based Access Control Model.

 +--------------------------------------------------------------------+
 |                                                                    |
 |      +-> securityModel -+                                          |
 |      |   (a)            |                                          |
 | who -+                  +-> groupName ----+                        |
 | (1)  |                  |   (x)           |                        |
 |      +-> securityName --+                 |                        |
 |          (b)                              |                        |
 |                                           |                        |
 | where -> contextName ---------------------+                        |
 | (2)      (e)                              |                        |
 |                                           |                        |
 |                                           |                        |
 |      +-> securityModel -------------------+                        |
 |      |   (a)                              |                        |
 | how -+                                    +-> viewName -+          |
 | (3)  |                                    |   (y)       |          |
 |      +-> securityLevel -------------------+             |          |
 |          (c)                              |             +-> yes/no |
 |                                           |             | decision |
 | why ---> viewType (read/write/notify) ----+             | (z)      |
 | (4)      (d)                                            |          |
 |                                                         |          |
 | what --> object-type ------+                            |          |
 | (5)      (m)               |                            |          |
 |                            +-> variableName (OID) ------+          |
 |                            |   (f)                                 |
 | which -> object-instance --+                                       |
 | (6)      (n)                                                       |
 |                                                                    |
 +--------------------------------------------------------------------+

How the decision for isAccessAllowed is made.

1) Inputs to the isAccessAllowed service are:

  (a)       securityModel    -- Security Model in use
  (b)       securityName     -- principal who wants to access
  (c)       securityLevel    -- Level of Security
  (d)       viewType         -- read, write, or notify view
  (e)       contextName      -- context containing variableName
  (f)       variableName     -- OID for the managed object
                             -- this is made up of:
                                - object-type (m)
                                - object-instance (n)

2) The partial "who" (1), represented by the securityModel (a) and

  the securityName (b), are used as the indices (a,b) into the
  vacmSecurityToGroupTable to find a single entry that produces a
  group, represented by groupName (x).

3) The "where" (2), represented by the contextName (e), the "who",

  represented by the groupName (x) from the previous step, and the
  "how" (3), represented by securityModel (a) and securityLevel (c),
  are used as indices (e,x,a,c) into the vacmAccessTable to find a
  single entry that contains three MIB views.

4) The "why" (4), represented by the viewType (d), is used to select

  the proper MIB view, represented by a viewName (y), from the
  vacmAccessEntry selected in the previous step.  This viewName (y)
  is an index into the vacmViewTreeFamilyTable and selects the set
  of entries that define the variableNames which are included in or
  excluded from the MIB view identified by the viewName (y).

5) The "what" (5) type of management data and "which" (6) particular

  instance, represented by the variableName (f), is then checked to
  be in the MIB view or not, e.g., the yes/no decision (z).

Processing the isAccessAllowed Service Request

This section describes the procedure followed by an Access Control module that implements the View-based Access Control Model whenever it receives an isAccessAllowed request.

1) The vacmContextTable is consulted for information about the SNMP

  context identified by the contextName.  If information about this
  SNMP context is absent from the table, then an errorIndication
  (noSuchContext) is returned to the calling module.

2) The vacmSecurityToGroupTable is consulted for mapping the

  securityModel and securityName to a groupName.  If the information
  about this combination is absent from the table, then an
  errorIndication (noGroupName) is returned to the calling module.

3) The vacmAccessTable is consulted for information about the

  groupName, contextName, securityModel and securityLevel.  If
  information about this combination is absent from the table, then
  an errorIndication (noAccessEntry) is returned to the calling
  module.

4) a) If the viewType is "read", then the read view is used for

     checking access rights.
  b) If the viewType is "write", then the write view is used for
     checking access rights.
  c) If the viewType is "notify", then the notify view is used for
     checking access rights.
  If the view to be used is the empty view (zero length viewName)
  then an errorIndication (noSuchView) is returned to the calling
  module.

5) a) If there is no view configured for the specified viewType, then

     an errorIndication (noSuchView) is returned to the calling
     module.
  b) If the specified variableName (object instance) is not in the
     MIB view (see DESCRIPTION clause for vacmViewTreeFamilyTable in
     section 4), then an errorIndication (notInView) is returned to
     the calling module.
     Otherwise,
  c) The specified variableName is in the MIB view.  A
     statusInformation of success (accessAllowed) is returned to the
     calling module.

Definitions

SNMP-VIEW-BASED-ACM-MIB DEFINITIONS ::= BEGIN

IMPORTS

MODULE-COMPLIANCE, OBJECT-GROUP       FROM SNMPv2-CONF
MODULE-IDENTITY, OBJECT-TYPE,
snmpModules                           FROM SNMPv2-SMI
TestAndIncr,
RowStatus, StorageType                FROM SNMPv2-TC
SnmpAdminString,
SnmpSecurityLevel,
SnmpSecurityModel                     FROM SNMP-FRAMEWORK-MIB;

snmpVacmMIB MODULE-IDENTITY

LAST-UPDATED "200210160000Z"          -- 16 Oct 2002, midnight
ORGANIZATION "SNMPv3 Working Group"
CONTACT-INFO "WG-email:   [email protected]
              Subscribe:  [email protected]
                          In message body:  subscribe snmpv3
              Co-Chair:   Russ Mundy
                          Network Associates Laboratories
              postal:     15204 Omega Drive, Suite 300
                          Rockville, MD 20850-4601
                          USA
              email:      [email protected]
              phone:      +1 301-947-7107
              Co-Chair:   David Harrington
                          Enterasys Networks
              Postal:     35 Industrial Way
                          P. O. Box 5004
                          Rochester, New Hampshire 03866-5005
                          USA
              EMail:      [email protected]
              Phone:      +1 603-337-2614
              Co-editor:  Bert Wijnen
                          Lucent Technologies
              postal:     Schagen 33
                          3461 GL Linschoten
                          Netherlands
              email:      [email protected]
              phone:      +31-348-480-685
              Co-editor:  Randy Presuhn
                          BMC Software, Inc.
              postal:     2141 North First Street
                          San Jose, CA 95131
                          USA
              email:      [email protected]
              phone:      +1 408-546-1006
              Co-editor:  Keith McCloghrie
                          Cisco Systems, Inc.
              postal:     170 West Tasman Drive
                          San Jose, CA  95134-1706
                          USA
              email:      [email protected]
              phone:      +1-408-526-5260
             "
DESCRIPTION  "The management information definitions for the
              View-based Access Control Model for SNMP.
              Copyright (C) The Internet Society (2002). This
              version of this MIB module is part of RFC 3415;
              see the RFC itself for full legal notices.
             "

-- Revision history

REVISION     "200210160000Z"          -- 16 Oct 2002, midnight
DESCRIPTION  "Clarifications, published as RFC3415"
REVISION     "199901200000Z"          -- 20 Jan 1999, midnight
DESCRIPTION  "Clarifications, published as RFC2575"
REVISION     "199711200000Z"          -- 20 Nov 1997, midnight
DESCRIPTION  "Initial version, published as RFC2275"
::= { snmpModules 16 }

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

vacmMIBObjects OBJECT IDENTIFIER ::= { snmpVacmMIB 1 } vacmMIBConformance OBJECT IDENTIFIER ::= { snmpVacmMIB 2 }

-- Information about Local Contexts **********************************

vacmContextTable OBJECT-TYPE

SYNTAX       SEQUENCE OF VacmContextEntry
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "The table of locally available contexts.
             This table provides information to SNMP Command
             Generator applications so that they can properly
             configure the vacmAccessTable to control access to
             all contexts at the SNMP entity.
             This table may change dynamically if the SNMP entity
             allows that contexts are added/deleted dynamically
             (for instance when its configuration changes).  Such
             changes would happen only if the management
             instrumentation at that SNMP entity recognizes more
             (or fewer) contexts.
             The presence of entries in this table and of entries
             in the vacmAccessTable are independent.  That is, a
             context identified by an entry in this table is not
             necessarily referenced by any entries in the
             vacmAccessTable; and the context(s) referenced by an
             entry in the vacmAccessTable does not necessarily
             currently exist and thus need not be identified by an
             entry in this table.
             This table must be made accessible via the default
             context so that Command Responder applications have
             a standard way of retrieving the information.
             This table is read-only.  It cannot be configured via
             SNMP.
            "
::= { vacmMIBObjects 1 }

vacmContextEntry OBJECT-TYPE

SYNTAX       VacmContextEntry
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "Information about a particular context."
INDEX       {
              vacmContextName
            }
::= { vacmContextTable 1 }

VacmContextEntry ::= SEQUENCE

{
    vacmContextName SnmpAdminString
}

vacmContextName OBJECT-TYPE

SYNTAX       SnmpAdminString (SIZE(0..32))
MAX-ACCESS   read-only
STATUS       current
DESCRIPTION "A human readable name identifying a particular
             context at a particular SNMP entity.
             The empty contextName (zero length) represents the
             default context.
            "
::= { vacmContextEntry 1 }

-- Information about Groups ******************************************

vacmSecurityToGroupTable OBJECT-TYPE

SYNTAX       SEQUENCE OF VacmSecurityToGroupEntry
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "This table maps a combination of securityModel and
             securityName into a groupName which is used to define
             an access control policy for a group of principals.
            "
::= { vacmMIBObjects 2 }

vacmSecurityToGroupEntry OBJECT-TYPE

SYNTAX       VacmSecurityToGroupEntry
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "An entry in this table maps the combination of a
             securityModel and securityName into a groupName.
            "
INDEX       {
              vacmSecurityModel,
              vacmSecurityName
            }
::= { vacmSecurityToGroupTable 1 }

VacmSecurityToGroupEntry ::= SEQUENCE

{
    vacmSecurityModel               SnmpSecurityModel,
    vacmSecurityName                SnmpAdminString,
    vacmGroupName                   SnmpAdminString,
    vacmSecurityToGroupStorageType  StorageType,
    vacmSecurityToGroupStatus       RowStatus
}

vacmSecurityModel OBJECT-TYPE

SYNTAX       SnmpSecurityModel(1..2147483647)
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "The Security Model, by which the vacmSecurityName
             referenced by this entry is provided.
             Note, this object may not take the 'any' (0) value.
            "
::= { vacmSecurityToGroupEntry 1 }

vacmSecurityName OBJECT-TYPE

SYNTAX       SnmpAdminString (SIZE(1..32))
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "The securityName for the principal, represented in a
             Security Model independent format, which is mapped by
             this entry to a groupName.
            "
::= { vacmSecurityToGroupEntry 2 }

vacmGroupName OBJECT-TYPE

SYNTAX       SnmpAdminString (SIZE(1..32))
MAX-ACCESS   read-create
STATUS       current
DESCRIPTION "The name of the group to which this entry (e.g., the
             combination of securityModel and securityName)
             belongs.
             This groupName is used as index into the
             vacmAccessTable to select an access control policy.
             However, a value in this table does not imply that an
             instance with the value exists in table vacmAccesTable.
            "
::= { vacmSecurityToGroupEntry 3 }

vacmSecurityToGroupStorageType OBJECT-TYPE

SYNTAX       StorageType
MAX-ACCESS   read-create
STATUS       current
DESCRIPTION "The storage type for this conceptual row.
             Conceptual rows having the value 'permanent' need not
             allow write-access to any columnar objects in the row.
            "
DEFVAL      { nonVolatile }
::= { vacmSecurityToGroupEntry 4 }

vacmSecurityToGroupStatus OBJECT-TYPE

SYNTAX       RowStatus
MAX-ACCESS   read-create
STATUS       current
DESCRIPTION "The status of this conceptual row.
             Until instances of all corresponding columns are
             appropriately configured, the value of the
             corresponding instance of the vacmSecurityToGroupStatus
             column is 'notReady'.
             In particular, a newly created row cannot be made
             active until a value has been set for vacmGroupName.
             The  RowStatus TC RFC2579 requires that this
             DESCRIPTION clause states under which circumstances
             other objects in this row can be modified:
             The value of this object has no effect on whether
             other objects in this conceptual row can be modified.
            "
::= { vacmSecurityToGroupEntry 5 }

-- Information about Access Rights ***********************************

vacmAccessTable OBJECT-TYPE

SYNTAX       SEQUENCE OF VacmAccessEntry
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "The table of access rights for groups.
             Each entry is indexed by a groupName, a contextPrefix,
             a securityModel and a securityLevel.  To determine
             whether access is allowed, one entry from this table
             needs to be selected and the proper viewName from that
             entry must be used for access control checking.
             To select the proper entry, follow these steps:
             1) the set of possible matches is formed by the
                intersection of the following sets of entries:
                  the set of entries with identical vacmGroupName
                  the union of these two sets:
                   - the set with identical vacmAccessContextPrefix
                   - the set of entries with vacmAccessContextMatch
                     value of 'prefix' and matching
                     vacmAccessContextPrefix
                  intersected with the union of these two sets:
                   - the set of entries with identical
                     vacmSecurityModel
                   - the set of entries with vacmSecurityModel
                     value of 'any'
                  intersected with the set of entries with
                  vacmAccessSecurityLevel value less than or equal
                  to the requested securityLevel
             2) if this set has only one member, we're done
                otherwise, it comes down to deciding how to weight
                the preferences between ContextPrefixes,
                SecurityModels, and SecurityLevels as follows:
                a) if the subset of entries with securityModel
                   matching the securityModel in the message is
                   not empty, then discard the rest.
                b) if the subset of entries with
                   vacmAccessContextPrefix matching the contextName
                   in the message is not empty,
                   then discard the rest
                c) discard all entries with ContextPrefixes shorter
                   than the longest one remaining in the set
                d) select the entry with the highest securityLevel
             Please note that for securityLevel noAuthNoPriv, all
             groups are really equivalent since the assumption that
             the securityName has been authenticated does not hold.
            "
::= { vacmMIBObjects 4 }

vacmAccessEntry OBJECT-TYPE

SYNTAX       VacmAccessEntry
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "An access right configured in the Local Configuration
             Datastore (LCD) authorizing access to an SNMP context.
             Entries in this table can use an instance value for
             object vacmGroupName even if no entry in table
             vacmAccessSecurityToGroupTable has a corresponding
             value for object vacmGroupName.
            "
INDEX       { vacmGroupName,
              vacmAccessContextPrefix,
              vacmAccessSecurityModel,
              vacmAccessSecurityLevel
            }
::= { vacmAccessTable 1 }

VacmAccessEntry ::= SEQUENCE

{
    vacmAccessContextPrefix    SnmpAdminString,
    vacmAccessSecurityModel    SnmpSecurityModel,
    vacmAccessSecurityLevel    SnmpSecurityLevel,
    vacmAccessContextMatch     INTEGER,
    vacmAccessReadViewName     SnmpAdminString,
    vacmAccessWriteViewName    SnmpAdminString,
    vacmAccessNotifyViewName   SnmpAdminString,
    vacmAccessStorageType      StorageType,
    vacmAccessStatus           RowStatus
}

vacmAccessContextPrefix OBJECT-TYPE

SYNTAX       SnmpAdminString (SIZE(0..32))
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "In order to gain the access rights allowed by this
             conceptual row, a contextName must match exactly
             (if the value of vacmAccessContextMatch is 'exact')
             or partially (if the value of vacmAccessContextMatch
             is 'prefix') to the value of the instance of this
             object.
            "
::= { vacmAccessEntry 1 }

vacmAccessSecurityModel OBJECT-TYPE

SYNTAX       SnmpSecurityModel
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "In order to gain the access rights allowed by this
             conceptual row, this securityModel must be in use.
            "
::= { vacmAccessEntry 2 }

vacmAccessSecurityLevel OBJECT-TYPE

SYNTAX       SnmpSecurityLevel
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "The minimum level of security required in order to
             gain the access rights allowed by this conceptual
             row.  A securityLevel of noAuthNoPriv is less than
             authNoPriv which in turn is less than authPriv.
             If multiple entries are equally indexed except for
             this vacmAccessSecurityLevel index, then the entry
             which has the highest value for
             vacmAccessSecurityLevel is selected.
            "
::= { vacmAccessEntry 3 }

vacmAccessContextMatch OBJECT-TYPE

SYNTAX       INTEGER
            { exact (1), -- exact match of prefix and contextName
              prefix (2) -- Only match to the prefix
            }
MAX-ACCESS   read-create
STATUS       current
DESCRIPTION "If the value of this object is exact(1), then all
             rows where the contextName exactly matches
             vacmAccessContextPrefix are selected.
             If the value of this object is prefix(2), then all
             rows where the contextName whose starting octets
             exactly match vacmAccessContextPrefix are selected.
             This allows for a simple form of wildcarding.
            "
DEFVAL      { exact }
::= { vacmAccessEntry 4 }

vacmAccessReadViewName OBJECT-TYPE

SYNTAX       SnmpAdminString (SIZE(0..32))
MAX-ACCESS   read-create
STATUS       current
DESCRIPTION "The value of an instance of this object identifies
             the MIB view of the SNMP context to which this
             conceptual row authorizes read access.
             The identified MIB view is that one for which the
             vacmViewTreeFamilyViewName has the same value as the
             instance of this object; if the value is the empty
             string or if there is no active MIB view having this
             value of vacmViewTreeFamilyViewName, then no access
             is granted.
            "
DEFVAL      { H }   -- the empty string
::= { vacmAccessEntry 5 }

vacmAccessWriteViewName OBJECT-TYPE

SYNTAX       SnmpAdminString (SIZE(0..32))
MAX-ACCESS   read-create
STATUS       current
DESCRIPTION "The value of an instance of this object identifies
             the MIB view of the SNMP context to which this
             conceptual row authorizes write access.
             The identified MIB view is that one for which the
             vacmViewTreeFamilyViewName has the same value as the
             instance of this object; if the value is the empty
             string or if there is no active MIB view having this
             value of vacmViewTreeFamilyViewName, then no access
             is granted.
            "
DEFVAL      { H }   -- the empty string
::= { vacmAccessEntry 6 }

vacmAccessNotifyViewName OBJECT-TYPE

SYNTAX       SnmpAdminString (SIZE(0..32))
MAX-ACCESS   read-create
STATUS       current
DESCRIPTION "The value of an instance of this object identifies
             the MIB view of the SNMP context to which this
             conceptual row authorizes access for notifications.
             The identified MIB view is that one for which the
             vacmViewTreeFamilyViewName has the same value as the
             instance of this object; if the value is the empty
             string or if there is no active MIB view having this
             value of vacmViewTreeFamilyViewName, then no access
             is granted.
            "
DEFVAL      { H }   -- the empty string
::= { vacmAccessEntry 7 }

vacmAccessStorageType OBJECT-TYPE

SYNTAX       StorageType
MAX-ACCESS   read-create
STATUS       current
DESCRIPTION "The storage type for this conceptual row.
             Conceptual rows having the value 'permanent' need not
             allow write-access to any columnar objects in the row.
            "
DEFVAL      { nonVolatile }
::= { vacmAccessEntry 8 }

vacmAccessStatus OBJECT-TYPE

SYNTAX       RowStatus
MAX-ACCESS   read-create
STATUS       current
DESCRIPTION "The status of this conceptual row.
             The  RowStatus TC RFC2579 requires that this
             DESCRIPTION clause states under which circumstances
             other objects in this row can be modified:
             The value of this object has no effect on whether
             other objects in this conceptual row can be modified.
            "
::= { vacmAccessEntry 9 }

-- Information about MIB views ***************************************

-- Support for instance-level granularity is optional. -- -- In some implementations, instance-level access control -- granularity may come at a high performance cost. Managers -- should avoid requesting such configurations unnecessarily.

vacmMIBViews OBJECT IDENTIFIER ::= { vacmMIBObjects 5 }

vacmViewSpinLock OBJECT-TYPE

SYNTAX       TestAndIncr
MAX-ACCESS   read-write
STATUS       current
DESCRIPTION "An advisory lock used to allow cooperating SNMP
             Command Generator applications to coordinate their
             use of the Set operation in creating or modifying
             views.
             When creating a new view or altering an existing
             view, it is important to understand the potential
             interactions with other uses of the view.  The
             vacmViewSpinLock should be retrieved.  The name of
             the view to be created should be determined to be
             unique by the SNMP Command Generator application by
             consulting the vacmViewTreeFamilyTable.  Finally,
             the named view may be created (Set), including the
             advisory lock.
             If another SNMP Command Generator application has
             altered the views in the meantime, then the spin
             lock's value will have changed, and so this creation
             will fail because it will specify the wrong value for
             the spin lock.
             Since this is an advisory lock, the use of this lock
             is not enforced.
            "
::= { vacmMIBViews 1 }

vacmViewTreeFamilyTable OBJECT-TYPE

SYNTAX       SEQUENCE OF VacmViewTreeFamilyEntry
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "Locally held information about families of subtrees
             within MIB views.
             Each MIB view is defined by two sets of view subtrees:
               - the included view subtrees, and
               - the excluded view subtrees.
             Every such view subtree, both the included and the
             excluded ones, is defined in this table.
             To determine if a particular object instance is in
             a particular MIB view, compare the object instance's
             OBJECT IDENTIFIER with each of the MIB view's active
             entries in this table.  If none match, then the
             object instance is not in the MIB view.  If one or
             more match, then the object instance is included in,
             or excluded from, the MIB view according to the
             value of vacmViewTreeFamilyType in the entry whose
             value of vacmViewTreeFamilySubtree has the most
             sub-identifiers.  If multiple entries match and have
             the same number of sub-identifiers (when wildcarding
             is specified with the value of vacmViewTreeFamilyMask),
             then the lexicographically greatest instance of
             vacmViewTreeFamilyType determines the inclusion or
             exclusion.
             An object instance's OBJECT IDENTIFIER X matches an
             active entry in this table when the number of
             sub-identifiers in X is at least as many as in the
             value of vacmViewTreeFamilySubtree for the entry,
             and each sub-identifier in the value of
             vacmViewTreeFamilySubtree matches its corresponding
             sub-identifier in X.  Two sub-identifiers match
             either if the corresponding bit of the value of
             vacmViewTreeFamilyMask for the entry is zero (the
             'wild card' value), or if they are equal.
             A 'family' of subtrees is the set of subtrees defined
             by a particular combination of values of
             vacmViewTreeFamilySubtree and vacmViewTreeFamilyMask.
             In the case where no 'wild card' is defined in the
             vacmViewTreeFamilyMask, the family of subtrees reduces
             to a single subtree.
             When creating or changing MIB views, an SNMP Command
             Generator application should utilize the
             vacmViewSpinLock to try to avoid collisions.  See
             DESCRIPTION clause of vacmViewSpinLock.
             When creating MIB views, it is strongly advised that
             first the 'excluded' vacmViewTreeFamilyEntries are
             created and then the 'included' entries.
             When deleting MIB views, it is strongly advised that
             first the 'included' vacmViewTreeFamilyEntries are
             deleted and then the 'excluded' entries.
             If a create for an entry for instance-level access
             control is received and the implementation does not
             support instance-level granularity, then an
             inconsistentName error must be returned.
            "
::= { vacmMIBViews 2 }

vacmViewTreeFamilyEntry OBJECT-TYPE

SYNTAX       VacmViewTreeFamilyEntry
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "Information on a particular family of view subtrees
             included in or excluded from a particular SNMP
             context's MIB view.
             Implementations must not restrict the number of
             families of view subtrees for a given MIB view,
             except as dictated by resource constraints on the
             overall number of entries in the
             vacmViewTreeFamilyTable.
             If no conceptual rows exist in this table for a given
             MIB view (viewName), that view may be thought of as
             consisting of the empty set of view subtrees.
            "
INDEX       { vacmViewTreeFamilyViewName,
              vacmViewTreeFamilySubtree
            }
::= { vacmViewTreeFamilyTable 1 }

VacmViewTreeFamilyEntry ::= SEQUENCE

{
    vacmViewTreeFamilyViewName     SnmpAdminString,
    vacmViewTreeFamilySubtree      OBJECT IDENTIFIER,
    vacmViewTreeFamilyMask         OCTET STRING,
    vacmViewTreeFamilyType         INTEGER,
    vacmViewTreeFamilyStorageType  StorageType,
    vacmViewTreeFamilyStatus       RowStatus
}

vacmViewTreeFamilyViewName OBJECT-TYPE

SYNTAX       SnmpAdminString (SIZE(1..32))
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "The human readable name for a family of view subtrees.
            "
::= { vacmViewTreeFamilyEntry 1 }

vacmViewTreeFamilySubtree OBJECT-TYPE

SYNTAX       OBJECT IDENTIFIER
MAX-ACCESS   not-accessible
STATUS       current
DESCRIPTION "The MIB subtree which when combined with the
             corresponding instance of vacmViewTreeFamilyMask
             defines a family of view subtrees.
            "
::= { vacmViewTreeFamilyEntry 2 }

vacmViewTreeFamilyMask OBJECT-TYPE

SYNTAX       OCTET STRING (SIZE (0..16))
MAX-ACCESS   read-create
STATUS       current
DESCRIPTION "The bit mask which, in combination with the
             corresponding instance of vacmViewTreeFamilySubtree,
             defines a family of view subtrees.
             Each bit of this bit mask corresponds to a
             sub-identifier of vacmViewTreeFamilySubtree, with the
             most significant bit of the i-th octet of this octet
             string value (extended if necessary, see below)
             corresponding to the (8*i - 7)-th sub-identifier, and
             the least significant bit of the i-th octet of this
             octet string corresponding to the (8*i)-th
             sub-identifier, where i is in the range 1 through 16.
             Each bit of this bit mask specifies whether or not
             the corresponding sub-identifiers must match when
             determining if an OBJECT IDENTIFIER is in this
             family of view subtrees; a '1' indicates that an
             exact match must occur; a '0' indicates 'wild card',
             i.e., any sub-identifier value matches.
             Thus, the OBJECT IDENTIFIER X of an object instance
             is contained in a family of view subtrees if, for
             each sub-identifier of the value of
             vacmViewTreeFamilySubtree, either:
               the i-th bit of vacmViewTreeFamilyMask is 0, or
               the i-th sub-identifier of X is equal to the i-th
               sub-identifier of the value of
               vacmViewTreeFamilySubtree.
             If the value of this bit mask is M bits long and
             there are more than M sub-identifiers in the
             corresponding instance of vacmViewTreeFamilySubtree,
             then the bit mask is extended with 1's to be the
             required length.
             Note that when the value of this object is the
             zero-length string, this extension rule results in
             a mask of all-1's being used (i.e., no 'wild card'),
             and the family of view subtrees is the one view
             subtree uniquely identified by the corresponding
             instance of vacmViewTreeFamilySubtree.
             Note that masks of length greater than zero length
             do not need to be supported.  In this case this
             object is made read-only.
            "
DEFVAL      { H }
::= { vacmViewTreeFamilyEntry 3 }

vacmViewTreeFamilyType OBJECT-TYPE

SYNTAX       INTEGER  { included(1), excluded(2) }
MAX-ACCESS   read-create
STATUS       current
DESCRIPTION "Indicates whether the corresponding instances of
             vacmViewTreeFamilySubtree and vacmViewTreeFamilyMask
             define a family of view subtrees which is included in
             or excluded from the MIB view.
            "
DEFVAL      { included }
::= { vacmViewTreeFamilyEntry 4 }

vacmViewTreeFamilyStorageType OBJECT-TYPE

SYNTAX       StorageType
MAX-ACCESS   read-create
STATUS       current
DESCRIPTION "The storage type for this conceptual row.
             Conceptual rows having the value 'permanent' need not
             allow write-access to any columnar objects in the row.
            "
DEFVAL      { nonVolatile }
::= { vacmViewTreeFamilyEntry 5 }

vacmViewTreeFamilyStatus OBJECT-TYPE

SYNTAX       RowStatus
MAX-ACCESS   read-create
STATUS       current
DESCRIPTION "The status of this conceptual row.
             The  RowStatus TC RFC2579 requires that this
             DESCRIPTION clause states under which circumstances
             other objects in this row can be modified:
             The value of this object has no effect on whether
             other objects in this conceptual row can be modified.
            "
::= { vacmViewTreeFamilyEntry 6 }

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

vacmMIBCompliances OBJECT IDENTIFIER ::= { vacmMIBConformance 1 } vacmMIBGroups OBJECT IDENTIFIER ::= { vacmMIBConformance 2 }

-- Compliance statements *********************************************

vacmMIBCompliance MODULE-COMPLIANCE

STATUS       current
DESCRIPTION "The compliance statement for SNMP engines which
             implement the SNMP View-based Access Control Model
             configuration MIB.
            "
MODULE -- this module
    MANDATORY-GROUPS { vacmBasicGroup }
    OBJECT        vacmAccessContextMatch
    MIN-ACCESS    read-only
    DESCRIPTION  "Write access is not required."
    OBJECT        vacmAccessReadViewName
    MIN-ACCESS    read-only
    DESCRIPTION  "Write access is not required."
    OBJECT        vacmAccessWriteViewName
    MIN-ACCESS    read-only
    DESCRIPTION  "Write access is not required."
    OBJECT        vacmAccessNotifyViewName
    MIN-ACCESS    read-only
    DESCRIPTION  "Write access is not required."
    OBJECT        vacmAccessStorageType
    MIN-ACCESS    read-only
    DESCRIPTION  "Write access is not required."
    OBJECT        vacmAccessStatus
    MIN-ACCESS    read-only
    DESCRIPTION  "Create/delete/modify access to the
                  vacmAccessTable is not required.
                 "
    OBJECT        vacmViewTreeFamilyMask
    WRITE-SYNTAX  OCTET STRING (SIZE (0))
    MIN-ACCESS    read-only
    DESCRIPTION  "Support for configuration via SNMP of subtree
                  families using wild-cards is not required.
                 "
    OBJECT        vacmViewTreeFamilyType
    MIN-ACCESS    read-only
    DESCRIPTION  "Write access is not required."
    OBJECT        vacmViewTreeFamilyStorageType
    MIN-ACCESS    read-only
    DESCRIPTION  "Write access is not required."
    OBJECT        vacmViewTreeFamilyStatus
    MIN-ACCESS    read-only
    DESCRIPTION  "Create/delete/modify access to the
                  vacmViewTreeFamilyTable is not required.
                 "
::= { vacmMIBCompliances 1 }

-- Units of conformance **********************************************

vacmBasicGroup OBJECT-GROUP

OBJECTS {
          vacmContextName,
          vacmGroupName,
          vacmSecurityToGroupStorageType,
          vacmSecurityToGroupStatus,
          vacmAccessContextMatch,
          vacmAccessReadViewName,
          vacmAccessWriteViewName,
          vacmAccessNotifyViewName,
          vacmAccessStorageType,
          vacmAccessStatus,
          vacmViewSpinLock,
          vacmViewTreeFamilyMask,
          vacmViewTreeFamilyType,
          vacmViewTreeFamilyStorageType,
          vacmViewTreeFamilyStatus
        }
STATUS       current
DESCRIPTION "A collection of objects providing for remote
             configuration of an SNMP engine which implements
             the SNMP View-based Access Control Model.
            "
::= { vacmMIBGroups 1 }

END

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 BCP-11. 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.

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

Security Considerations

Recommended Practices

This document is meant for use in the SNMP architecture. The View- based Access Control Model described in this document checks access rights to management information based on:

- contextName, representing a set of management information at the

  managed system where the Access Control module is running.

- groupName, representing a set of zero or more securityNames. The

  combination of a securityModel and a securityName is mapped into a
  group in the View-based Access Control Model.

- securityModel under which access is requested.

- securityLevel under which access is requested.

- operation performed on the management information.

- MIB views for read, write or notify access.

When the User-based Access Control module is called for checking access rights, it is assumed that the calling module has ensured the authentication and privacy aspects as specified by the securityLevel that is being passed.

When creating entries in or deleting entries from the vacmViewTreeFamilyTable it is important to do such in the sequence as recommended in the DESCRIPTION clause of the vacmViewTreeFamilyTable definition. Otherwise unwanted access may be granted while changing the entries in the table.

Defining Groups

The groupNames are used to give access to a group of zero or more securityNames. Within the View-Based Access Control Model, a groupName is considered to exist if that groupName is listed in the vacmSecurityToGroupTable.

By mapping the combination of a securityModel and securityName into a groupName, an SNMP Command Generator application can add/delete securityNames to/from a group, if proper access is allowed.

Further it is important to realize that the grouping of <securityModel, securityName> tuples in the vacmSecurityToGroupTable does not take securityLevel into account. It is therefore important that the security administrator uses the securityLevel index in the vacmAccessTable to separate noAuthNoPriv from authPriv and/or authNoPriv access.

Conformance

For an implementation of the View-based Access Control Model to be conformant, it MUST implement the SNMP-VIEW-BASED-ACM-MIB according to the vacmMIBCompliance. It also SHOULD implement the initial configuration, described in appendix A.

Access to the SNMP-VIEW-BASED-ACM-MIB

The objects in this MIB control the access to all MIB data that is accessible via the SNMP engine and they may be considered sensitive in many environments. It is important to closely control (both read and write) access to these to these MIB objects by using appropriately configured Access Control models (for example the View-based Access Control Model as specified in this document).

References

Normative References

RFC2119 Bradner, S., "Key words for use in RFCs to Indicate

           Requirement Levels", BCP 14, RFC 2119, March 1997.

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.

RFC3411 Harrington, D., Presuhn, R. and B. Wijnen, "An

           Architecture for describing Simple Network Management
           Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
           December 2002.

[SNMP3412] 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.

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.

Informative References

[ISO-ASN.1] Information processing systems - Open Systems

           Interconnection - Specification of Abstract Syntax
           Notation One (ASN.1), International Organization for
           Standardization.  International Standard 8824, (December,
           1987).

Appendix A - Installation

A.1. Installation Parameters

During installation, an authoritative SNMP engine which supports this View-based Access Control Model SHOULD be configured with several initial parameters. These include for the View-based Access Control Model:

1) A security configuration

  The choice of security configuration determines if initial
  configuration is implemented and if so how.  One of three possible
  choices is selected:
     -  initial-minimum-security-configuration
     -  initial-semi-security-configuration
     -  initial-no-access-configuration
  In the case of a initial-no-access-configuration, there is no
  initial configuration, and so the following steps are irrelevant.

2) A default context

  One entry in the vacmContextTable with a contextName of "" (the
  empty string), representing the default context.  Note that this
  table gets created automatically if a default context exists.
     vacmContextName                  ""

3) An initial group

  One entry in the vacmSecurityToGroupTable to allow access to group
  "initial".
     vacmSecurityModel                3 (USM)
     vacmSecurityName                 "initial"
     vacmGroupName                    "initial"
     vacmSecurityToGroupStorageType   anyValidStorageType
     vacmSecurityToGroupStatus        active

4) Initial access rights

  Three entries in the vacmAccessTable as follows:
  -  read-notify access for securityModel USM, securityLevel
     "noAuthNoPriv" on behalf of securityNames that belong to the
     group "initial" to the <restricted> MIB view in the default
     context with contextName "".
  -  read-write-notify access for securityModel USM, securityLevel
     "authNoPriv" on behalf of securityNames that belong to the
     group "initial" to the <internet> MIB view in the default
     context with contextName "".
  -  if privacy is supported, read-write-notify access for
     securityModel USM, securityLevel "authPriv" on behalf of
     securityNames that belong to the group "initial" to the
     <internet> MIB view in the default context with contextName "".
  That translates into the following entries in the vacmAccessTable.
  -  One entry to be used for unauthenticated access (noAuthNoPriv):
     vacmGroupName                    "initial"
     vacmAccessContextPrefix          ""
     vacmAccessSecurityModel          3 (USM)
     vacmAccessSecurityLevel          noAuthNoPriv
     vacmAccessContextMatch           exact
     vacmAccessReadViewName           "restricted"
     vacmAccessWriteViewName          ""
     vacmAccessNotifyViewName         "restricted"
     vacmAccessStorageType            anyValidStorageType
     vacmAccessStatus                 active
  -  One entry to be used for authenticated access (authNoPriv) with
     optional privacy (authPriv):
     vacmGroupName                    "initial"
     vacmAccessContextPrefix          ""
     vacmAccessSecurityModel          3 (USM)
     vacmAccessSecurityLevel          authNoPriv
     vacmAccessContextMatch           exact
     vacmAccessReadViewName           "internet"
     vacmAccessWriteViewName          "internet"
     vacmAccessNotifyViewName         "internet"
     vacmAccessStorageType            anyValidStorageType
     vacmAccessStatus                 active

5) Two MIB views, of which the second one depends on the security

  configuration.
  -  One view, the <internet> view, for authenticated access:
     -  the <internet> MIB view is the following subtree:
           "internet"  (subtree 1.3.6.1)
  -  A second view, the <restricted> view, for unauthenticated
     access.  This view is configured according to the selected
     security configuration:
  -  For the initial-no-access-configuration there is no default
     initial configuration, so no MIB views are pre-scribed.
  -  For the initial-semi-secure-configuration:
        the <restricted> MIB view is the union of these subtrees:
        (a) "system"       (subtree 1.3.6.1.2.1.1)      RFC3918
        (b) "snmp"         (subtree 1.3.6.1.2.1.11)     RFC3918
        (c) "snmpEngine"   (subtree 1.3.6.1.6.3.10.2.1) RFC3411
        (d) "snmpMPDStats" (subtree 1.3.6.1.6.3.11.2.1) RFC3412
        (e) "usmStats"     (subtree 1.3.6.1.6.3.15.1.1) RFC3414
  -  For the initial-minimum-secure-configuration:
        the <restricted> MIB view is the following subtree.
            "internet"  (subtree 1.3.6.1)

This translates into the following "internet" entry in the vacmViewTreeFamilyTable:

                             minimum-secure      semi-secure
                             ----------------    ---------------

vacmViewTreeFamilyViewName "internet" "internet" vacmViewTreeFamilySubtree 1.3.6.1 1.3.6.1 vacmViewTreeFamilyMask "" "" vacmViewTreeFamilyType 1 (included) 1 (included) vacmViewTreeFamilyStorageType anyValidStorageType anyValidStorageType vacmViewTreeFamilyStatus active active

In addition it translates into the following "restricted" entries in the vacmViewTreeFamilyTable:

                             minimum-secure      semi-secure
                             ----------------    ---------------

vacmViewTreeFamilyViewName "restricted" "restricted" vacmViewTreeFamilySubtree 1.3.6.1 1.3.6.1.2.1.1 vacmViewTreeFamilyMask "" "" vacmViewTreeFamilyType 1 (included) 1 (included) vacmViewTreeFamilyStorageType anyValidStorageType anyValidStorageType vacmViewTreeFamilyStatus active active

vacmViewTreeFamilyViewName "restricted" vacmViewTreeFamilySubtree 1.3.6.1.2.1.11 vacmViewTreeFamilyMask "" vacmViewTreeFamilyType 1 (included) vacmViewTreeFamilyStorageType anyValidStorageType vacmViewTreeFamilyStatus active

vacmViewTreeFamilyViewName "restricted" vacmViewTreeFamilySubtree 1.3.6.1.6.3.10.2.1 vacmViewTreeFamilyMask "" vacmViewTreeFamilyType 1 (included) vacmViewTreeFamilyStorageType anyValidStorageType vacmViewTreeFamilyStatus active

vacmViewTreeFamilyViewName "restricted" vacmViewTreeFamilySubtree 1.3.6.1.6.3.11.2.1 vacmViewTreeFamilyMask "" vacmViewTreeFamilyType 1 (included) vacmViewTreeFamilyStorageType anyValidStorageType vacmViewTreeFamilyStatus active

vacmViewTreeFamilyViewName "restricted" vacmViewTreeFamilySubtree 1.3.6.1.6.3.15.1.1 vacmViewTreeFamilyMask "" vacmViewTreeFamilyType 1 (included) vacmViewTreeFamilyStorageType anyValidStorageType vacmViewTreeFamilyStatus active

B. Change Log

Changes made since RFC 2575:

  -  Removed reference from abstract as per RFC-Editor guidelines
  -  Updated references

Changes made since RFC 2275:

  -  Added text to vacmSecurityToGroupStatus DESCRIPTION clause to
     clarify under which conditions an entry in the
     vacmSecurityToGroupTable can be made active.
  -  Added REVISION clauses to MODULE-IDENTITY
  -  Clarified text in vacmAccessTable DESCRIPTION clause.
  -  Added a DEFVAL clause to vacmAccessContextMatch object.
  -  Added missing columns in Appendix A and re-arranged for
     clarity.
  -  Fixed oids in appendix A.
  -  Use the PDU Class terminology instead of RFC1905 PDU types.
  -  Added section 7.4 about access control to the MIB.
  -  Fixed references to new/revised documents
  -  Fix Editor contact information.
  -  fixed spelling errors
  -  removed one vacmAccesEntry from sample in appendix A.
  -  made some more clarifications.
  -  updated acknowledgement section.

Editors' Addresses

Bert Wijnen Lucent Technologies Schagen 33 3461 GL Linschoten Netherlands

Phone: +31-348-480-685 EMail: [email protected]

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

Phone: +1 408-546-1006 EMail: [email protected]

Keith McCloghrie Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706 USA

Phone: +1-408-526-5260 EMail: [email protected]

Full Copyright Statement

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Acknowledgement

Funding for the RFC Editor function is currently provided by the Internet Society.