RFC 2275
View-based Access Control Model (VACM) for the Simple Network Management Protocol (SNMP)
View-based Access Control Model (VACM) for SNMP ✨
Part 1 of 7 💖
Okay bestie, RFC 2275 is the View-based Access Control Model (VACM) for the Simple Network Management Protocol (SNMP) 🎀. It was written by B. Wijnen (IBM T. J. Watson Research), R. Presuhn (BMC Software, Inc.), and K. McCloghrie (Cisco Systems, Inc.). It's on the Standards Track and it's dated January 1998. It obsoletes RFC 2265, and the header doesn't list any RFCs it updates 🦋. The authors are literally legends.
Status of This Memo 📜
This document is a standards track protocol spec for the Internet community, and it's asking for discussion and suggestions for improvements 🌸. If you want to know where this protocol stands in standardization, check the current edition of "Internet Official Protocol Standards" (STD 1). Distribution of this memo is unlimited 💅.
Copyright Notice ©️
Copyright (C) The Internet Society (1998). All Rights Reserved. 🫶
IANA Note 🔢
Okay so there was a clerical mix-up when the snmpModules numbers got assigned in this memo 😭. This RFC fixes that and gives the correct number assignment for the protocol. It obsoletes RFC 2265 🙈.
Abstract ✨
This doc describes the View-based Access Control Model for use in the SNMP architecture [RFC2271] 🦋. It spells out the Elements of Procedure for controlling access to management information. It also includes a MIB for remotely managing the configuration parameters of the View-based Access Control Model 💜.
Table of Contents 🗂️
1. Introduction 2
1.2. Access Control 3
1.3. Local Configuration Datastore 3
2. Elements of the Model 3
2.1. Groups 3
2.2. securityLevel 4
2.3. Contexts 4
2.4. MIB Views and View Families 4
2.4.1. View Subtree 5
2.4.2. ViewTreeFamily 5
2.5. Access Policy 6
3. Elements of Procedure 6
3.1. Overview of isAccessAllowed Process 8
3.2. Processing the isAccessAllowed Service Request 9
4. Definitions 10
5. Intellectual Property 26
6. Acknowledgements 27
7. Security Considerations 28
7.1. Recommended Practices 28
7.2. Defining Groups 29
7.3. Conformance 29
8. References 29
9. Editors' Addresses 30
A.1. Installation Parameters 31
B. Full Copyright Statement 361. Introduction 🌈
So the Architecture for Internet Management Frameworks [RFC2271] says an SNMP engine is made up of four things 👑:
1) a Dispatcher
2) a Message Processing Subsystem,
3) a Security Subsystem, and
4) an Access Control Subsystem.Applications use the services of these subsystems 🧚.
It's really important to get the SNMP architecture and its terminology down, so you can see where VACM fits in and how it talks to the other subsystems 💅. The reader is expected to already know the SNMP architecture terms from [RFC2271] 📚.
The Access Control Subsystem of an SNMP engine is in charge of checking whether a specific type of access (read, write, notify) to a particular object (instance) is allowed 🔥.
This document defines one specific model of the Access Control Subsystem, called the View-based Access Control Model. It's not the only Access Control Model out there, though 🦋.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119] 🫶.
1.2. Access Control 🔐
Access Control happens, either implicitly or explicitly, in an SNMP entity whenever it processes SNMP retrieval or modification request messages from an SNMP entity 💖. For example, a Command Responder application applies Access Control to requests it gets from a Command Generator application. These requests include GetRequest, GetNextRequest, GetBulkRequest, and SetRequest operations ✨.
Access Control also happens in an SNMP entity when it generates an SNMP notification message (via a Notification Originator application). These notification messages include InformRequest and SNMPv2-Trap operations 🔔.
The View-based Access Control Model defines a set of services that an application (like a Command Responder or a Notification Originator) can call to check access rights. The application itself is responsible for making the right service calls for access checking 👑.
1.3. Local Configuration Datastore 🗄️
To implement this model, an SNMP entity needs to keep information about access rights and policies 💜. That info is part of the SNMP engine's Local Configuration Datastore (LCD). See [RFC2271] for the LCD definition 📖.
To let someone remotely configure an SNMP entity's LCD, the parts of the LCD that matter need to be accessible as managed objects. This document includes a MIB module, the View-based Access Control Model Configuration MIB, that defines these managed object types 🍓.
2. Elements of the Model 🧩
This section has the definitions that make up the access control service provided by the View-based Access Control Model 🎀.
2.1. Groups 👯
A group is a set of zero or more <securityModel, securityName> tuples that SNMP management objects can be accessed on behalf of 💅. A group sets the access rights for all the securityNames in that group. Each combination of a securityModel and a securityName maps to at most one group. Groups are identified by a groupName 🌸.
The Access Control module assumes the securityName has already been authenticated (as needed) and doesn't do any further authentication of its own 🔒.
When the View-based Access Control Model is asked to check access rights, it uses the securityModel and the securityName as inputs to the Access Control module. From those two, it works out the groupName 🦋.
2.2. securityLevel 🛡️
Members of a group can have different access rights for different security levels: noAuthNoPriv, authNoPriv, and authPriv ✨. The securityLevel is the level of security that gets assumed when checking access rights. For the definition of securityLevel, see the SNMP Architecture document [RFC2271] 📖.
The View-based Access Control Model requires that the securityLevel is passed in as input to the Access Control module when it's called to check access rights 💜.
2.3. Contexts 🗂️
An SNMP context is a collection of management information that an SNMP entity can access 🌈. One piece of management information can exist in more than one context, and an SNMP entity can have access to lots of contexts 🧚. For details on how management information gets named, check the SNMP Architecture document [RFC2271] 💖.
The View-based Access Control Model defines a vacmContextTable that lists the locally available contexts by contextName 📋.
2.4. MIB Views and View Families 🪟
Security reasons make it super useful to limit some groups' access rights to just a subset of the management information in the management domain 🔐. To do this, access to a context goes through a "MIB view", which details a specific set of managed object types (and optionally, the specific instances of those object types) within that context 🦋.
For any given context there's usually one MIB view that gives access to all the management information in it, and often there are other MIB views, each holding some subset of that info 💅. So you can restrict a group's access by spelling out its rights in terms of the particular (subset) MIB view it's allowed to use in each appropriate context ✨.
Managed object types (and their instances) are identified through the tree-like naming structure of ISO's OBJECT IDENTIFIERs [ISO-ASN.1, RFC1902]. That makes it handy to define a MIB view as a combination of a set of "view subtrees", where each view subtree is a subtree within the managed object naming tree 🌳. A simple MIB view (like all managed objects within the Internet Network Management Framework) can be a single view subtree, while more complicated MIB views (like all the info relevant to a particular network interface) can be the union of multiple view subtrees 🎀.
Any set of managed objects can be described as the union of some number of view subtrees, but sometimes you'd need a huge number of them 😭. For example, that happens when you spell out all the columns in one conceptual row of a MIB table, since they'd each end up in a separate subtree, one per column, all with a very similar format 🙈. Because the formats match, those subtrees can be bundled into one structure. That structure is called a family of view subtrees, named after the set of subtrees it conceptually represents 💜. A family of view subtrees can either be included in or excluded from a MIB view 👑.
2.4.1. View Subtree 🌿
A view subtree is the set of all MIB object instances whose names share a common ASN.1 OBJECT IDENTIFIER prefix 💖. A view subtree is identified by the OBJECT IDENTIFIER value that's the longest OBJECT IDENTIFIER prefix common to all the (potential) MIB object instances in that subtree 🦋.
2.4.2. ViewTreeFamily 🦋
okay so a family of view subtrees is basically a pair: an OBJECT IDENTIFIER value (that's the family name) plus a bit string (that's the family mask). the mask tells you which sub-identifiers of the family name actually matter for defining the family. it's giving precision 💅
an instance belongs to a particular ViewTreeFamily only if BOTH of these are true:
- the OBJECT IDENTIFIER name of the managed object instance has at least as many sub-identifiers as the family name does, and
- each sub-identifier in the instance's OBJECT IDENTIFIER name matches the corresponding sub-identifier of the family name whenever the matching bit in the family mask is non-zero.
when the family mask is all ones, the family is identical to the single view subtree named by the family name. iconic, no notes 🎀
if the configured family mask is too short for that test, it gets implicitly extended with ones. so a family mask of zero length always works out to a single view subtree ✨
2.5. Access Policy 🔥
the View-based Access Control Model decides what a group can do. a group is zero or more securityNames that all share the same access rights. for a given context (identified by contextName) that a group (identified by groupName) can reach, using a particular securityModel and securityLevel, those rights come down to three views: a read-view, a write-view and a notify-view. main character energy for sure 👑
the read-view is the set of object instances the group is allowed to read. reading happens when you process a retrieval operation, like a GetRequest, GetNextRequest or GetBulkRequest 📖
the write-view is the set of object instances the group is allowed to write. writing happens when you process a write operation, like a Set 🖊️
the notify-view is the set of object instances the group is allowed to send in a notification. this covers sending a notification, like an Inform or an SNMPv2-Trap 🔔
3. Elements of Procedure 🎀
this section is the step-by-step for how an Access Control module (the View-based Access Control Model one) checks access rights whenever an application asks, like a Command Responder or a Notification Originator. the abstract service primitive looks like this:
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.3.1. Overview of isAccessAllowed Process 🧩
here's the picture of how the View-based Access Control Model makes its access decision:
+--------------------------------------------------------------------+
| |
| +-> 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) |
| |
+--------------------------------------------------------------------+here's how the isAccessAllowed decision gets made, step by step 🔍
- the inputs to isAccessAllowed are:
- (a)
securityModel(the Security Model in use) - (b)
securityName(the principal who wants access) - (c)
securityLevel(the Level of Security) - (d)
viewType(read, write, or notify view) - (e)
contextName(the context containing variableName) - (f)
variableName(the OID for the managed object), made up of:- object-type (m)
- object-instance (n)
- (a)
- the partial "who" (1), which is the securityModel (a) and securityName (b), gets used as the indices (a,b) into the vacmSecurityToGroupTable. that finds one single entry that produces a group, called groupName (x).
- the "where" (2), which is the contextName (e), plus the "who" from the last step (the groupName (x)), plus the "how" (3), which is the securityModel (a) and securityLevel (c), all get used as the indices (e,x,a,c) into the vacmAccessTable. that finds one single entry holding three MIB views.
- the "why" (4), which is the viewType (d), picks the right MIB view from the vacmAccessEntry we just found. that MIB view is called viewName (y). it's an index into the vacmViewTreeFamilyTable and selects the entries that define which variableNames are included in or excluded from that MIB view 🎯
- finally, the "what" (5) type of data and the "which" (6) particular instance, which is the variableName (f), gets checked to see if it's in the MIB view or not. that gives the yes/no decision (z) 💖
3.2. Processing the isAccessAllowed Service Request 🚦
this section covers what the Access Control module does every time it gets an isAccessAllowed request:
- first, the vacmContextTable gets checked for info about the SNMP context identified by contextName. if that info isn't in the table, an errorIndication (
noSuchContext) goes back to the calling module 🙅 - next, the vacmSecurityToGroupTable gets checked to map the securityModel and securityName to a groupName. if that combination isn't in the table, an errorIndication (
noGroupName) goes back to the calling module. - then the vacmAccessTable gets checked for info about the groupName, contextName, securityModel and securityLevel. if that combination isn't there, an errorIndication (
noAccessEntry) goes back to the calling module. - now it picks the view based on the viewType:
- a) if the viewType is "read", the read view is used for checking access rights.
- b) if the viewType is "write", the write view is used for checking access rights.
- c) if the viewType is "notify", the notify view is used for checking access rights.
if the view to be used is the empty view (zero length viewName), an errorIndication (noSuchView) goes back to the calling module.
- last step, the actual check:
- a) if there's no view configured for the specified viewType, an errorIndication (
noSuchView) goes back to the calling module. - b) if the specified variableName (object instance) isn't in the MIB view (see the DESCRIPTION clause for vacmViewTreeFamilyTable in section 4), an errorIndication (
notInView) goes back to the calling module.
- a) if there's no view configured for the specified viewType, an errorIndication (
otherwise,
- c) the specified variableName is in the MIB view, so a statusInformation of success (
accessAllowed) goes back to the calling module ✅
4. Definitions 📜
here comes the MIB module itself, starting with its header:
SNMP-VIEW-BASED-ACM-MIB DEFINITIONS ::= BEGINOkay so this is where the actual MIB module gets going, bestie 🎀 The imports pull in all the building blocks we need from other MIBs, and then the module identity gives it its name and contacts ✨
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 "9711200000Z" -- 20 Nov 1997, midnight
ORGANIZATION "SNMPv3 Working Group"
CONTACT-INFO "WG-email: snmpv3@tis.com
Subscribe: majordomo@tis.com
In message body: subscribe snmpv3
Chair: Russ Mundy
Trusted Information Systems
postal: 3060 Washington Rd
Glenwood MD 21738
USA
email: mundy@tis.com
phone: +1-301-854-6889
Co-editor: Bert Wijnen
IBM T.J. Watson Research
postal: Schagen 33
3461 GL Linschoten
Netherlands
email: wijnen@vnet.ibm.com
phone: +31-348-432-794
Co-editor: Randy Presuhn
BMC Software, Inc
postal: 1190 Saratoga Avenue, Suite 130
San Jose, CA 95129-3433
USA
email: rpresuhn@bmc.com
phone: +1-408-556-0720
Co-editor: Keith McCloghrie
Cisco Systems, Inc.
postal: 170 West Tasman Drive
San Jose, CA 95134-1706
USA
email: kzm@cisco.com
phone: +1-408-526-5260
"
DESCRIPTION "The management information definitions for the
View-based Access Control Model for SNMP.
"
::= { snmpModules 16 }Next up is the admin assignments and the context stuff 🦋 The vacmContextTable is basically the list of contexts that exist locally at the SNMP entity, and it's read-only, so nobody gets to mess with it over SNMP 💅
-- 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 }Now the groups bit 👑 This is where a securityModel plus securityName gets mapped into a groupName, and that groupName is what you use to pick an access policy. It's giving principal-to-group matchmaking 💜
-- 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.
The securityName for a principal represented in a
Security Model independent format.
"
::= { 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.
"
::= { 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.
The RowStatus TC [RFC1903] 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 }Last bit for this part is the access rights 🌈 The vacmAccessTable is the big one. It has that whole multi-step selection process for picking the right entry, so read the DESCRIPTION carefully, it's a lot of set intersections but it's so worth it 🧚
-- 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 contextPrefix, a groupName
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 identical
securityModels is not empty, discard the rest.
b) if the subset of entries with identical
vacmAccessContextPrefix is not empty,
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.
"
INDEX { vacmGroupName,
vacmAccessContextPrefix,
vacmAccessSecurityModel,
vacmAccessSecurityLevel
}
::= { vacmAccessTable 1 }Okay bestie, picking up right where the access rows left off 💖 Here's the rest of the access table's columns, all exactly as they are:
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 wins.
"
::= { 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.
See also the example in the DESCRIPTION clause of
the vacmAccessTable above.
"
::= { 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 [RFC1903] 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 }Now we're moving on to the MIB views section 🦋 Think of it like the "which stuff can you see" menu, and it's giving very precise vibes.
-- 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, 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 }That's the views table setup done! Next up is the view family entries 🌸✨
okay so the vacmViewTreeFamilyEntry is where the view magic actually happens 🦋 each row is one family of view subtrees, and the index is the viewName plus the subtree, so it's giving very organized energy ✨
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 [RFC1903] 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 }okay the mask column is the one that makes my brain do a little spin 🌀 each bit lines up with a sub-identifier, a 1 means it has to match exactly, and a 0 is a wild card that matches anything 🎀 if the mask is shorter than the subtree, it gets padded out with 1s, so nothing sneaks through as a wild card by accident 💅
the zero-length mask is the iconic case 👑 the padding rule turns it into all 1s, which means no wild cards at all, and the family is just that one exact subtree 🧚 and masks longer than zero don't have to be supported, in which case the object is read-only 🙈
ngl the conformance section is the boring-but-important part, so here it is in full 📚
-- 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 }
ENDokay so the compliance statement is basically the "minimum you gotta do" list 💖 the MODULE-COMPLIANCE for vacmMIBCompliance says the vacmBasicGroup is mandatory, and most of the access objects only need read-only support, so write access isn't required for those 🌸 the vacmViewTreeFamilyMask is the one with a little twist: it only has to take an empty OCTET STRING on write, meaning wild-card families over SNMP aren't required 🦋 and vacmBasicGroup is just the big bundle of every object in here, all under vacmMIBGroups 1 🍓
5. Intellectual Property ✨
okay real talk about IP stuff 💅 the IETF doesn't take a position on whether any intellectual property rights that might be claimed around this technology are valid or in scope 🫶 it also doesn't say whether licenses for those rights are available, and it doesn't claim it went looking for any of them 🌈 if you want to know how the IETF handles rights for standards-track and standards-related docs, check out BCP-11 📚 claims of rights that were filed for publication, and any assurances about licenses, or the results of trying to get a general license or permission for implementers or users, can all be requested from the IETF Secretariat 🧚
and if you know about any copyrights, patents, patent applications, or other proprietary rights that might cover tech needed to practice this standard, the IETF is literally inviting you to tell them 💜 send that info to the IETF Executive Director 👑 no cap, it's the responsible move 🙌
6. Acknowledgements ✨
Okay bestie, this RFC was a whole group project 🫶 It came from the SNMPv3 Working Group, and they deserve SO much credit. Huge thanks to these SNMPv3 WG members:
- Dave Battle (SNMP Research, Inc.)
- Uri Blumenthal (IBM T.J. Watson Research Center)
- Jeff Case (SNMP Research, Inc.)
- John Curran (BBN)
- T. Max Devlin (Hi-TECH Connections)
- John Flick (Hewlett Packard)
- David Harrington (Cabletron Systems Inc.)
- N.C. Hien (IBM T.J. Watson Research Center)
- Dave Levi (SNMP Research, Inc.)
- Louis A Mamakos (UUNET Technologies Inc.)
- Paul Meyer (Secure Computing Corporation)
- Keith McCloghrie (Cisco Systems)
- Russ Mundy (Trusted Information Systems, Inc.)
- Bob Natale (ACE*COMM Corporation)
- Mike O'Dell (UUNET Technologies Inc.)
- Dave Perkins (DeskTalk)
- Peter Polkinghorne (Brunel University)
- Randy Presuhn (BMC Software, Inc.)
- David Reid (SNMP Research, Inc.)
- Shawn Routhier (Epilogue)
- Juergen Schoenwaelder (TU Braunschweig)
- Bob Stewart (Cisco Systems)
- Bert Wijnen (IBM T.J. Watson Research Center)
The design is based on recommendations from the IETF Security and Administrative Framework Evolution for SNMP Advisory Team 🦋 The 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)
The Advisory Team and the SNMPv3 Working Group Charter both asked the design to pull in as much as practical from earlier RFCs and drafts 🌸 So special thanks go to the authors of the earlier 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.)
7. Security Considerations 🔥
Okay this section is the serious one, so let's get into it 💀
7.1. Recommended Practices
This document is meant to be used in the SNMP architecture ✨ The View-based Access Control Model described here checks access rights to management information based on:
- contextName, which represents a set of management information at the managed system where the Access Control module is running.
- groupName, which represents 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 gets called to check access rights, it's assumed that the calling module already handled the authentication and privacy stuff that the securityLevel being passed in says it should 🔐
Also, when you're creating or deleting entries in the vacmViewFamiliyTreeTable, the order matters a LOT 😭 Do it in the sequence recommended in the DESCRIPTION clause of the vacmViewFamilityTable definition. If you don't, unwanted access may be granted while the table is being changed. Major danger zone 🚨
7.2. Defining Groups
The groupNames are how access gets handed out to a group of zero or more securityNames 🧚 Inside the View-Based Access Control Model, a groupName counts as existing only if it's listed in the vacmSecurityToGroupTable.
When you map a securityModel and securityName combo into a groupName, an SNMP Command Generator application can add or delete securityNames to and from a group, as long as the proper access is allowed 💅
Here's the lowkey tricky part: the grouping of <securityModel, securityName> tuples in the vacmSecurityToGroupTable does NOT take securityLevel into account 👀 So the security administrator really needs to use the securityLevel index in the vacmAccessTable to keep noAuthNoPriv apart from authPriv and/or authNoPriv access. Don't skip this, bestie 🙈
7.3. Conformance
To be conformant, an implementation of the View-based Access Control Model MUST implement the SNMP-VIEW-BASED-ACM-MIB 👑 It also SHOULD implement the initial configuration described in appendix A 🌈
8. References 📚
- [RFC1902] Case, J., McCloghrie, K., Rose, M. and S., Waldbusser, "Structure of Management Information for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1902, January 1996.
- [RFC1903] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Textual Conventions for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1903, January 1996.
- [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
- [RFC2271] Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture for describing SNMP Management Frameworks", RFC 2271, January 1998.
- [RFC2272] Case, J., Harrington, D., Presuhn, R., and B. Wijnen, "Message Processing and Dispatching for the Simple Network Management Protocol (SNMP)", RFC 2272, January 1998.
- [RFC2274] Blumenthal, U., and B. Wijnen, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)", RFC 2274, January 1998.
- [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).
9. Editors' Addresses 💌
Bert Wijnen
IBM T. J. Watson Research
Schagen 33
3461 GL Linschoten
Netherlands
EMail: wijnen@vnet.ibm.com
Phone: +31-348-432-794
Randy Presuhn
BMC Software, Inc
1190 Saratoga Avenue, Suite 130
San Jose, CA 95129-3433
USA
EMail: rpresuhn@bmc.com
Phone: +1-408-556-0720
Keith McCloghrie
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
USA
EMail: kzm@cisco.com
Phone: +1-408-526-5260APPENDIX A - Installation 🎀
A.1. Installation Parameters
Here's the setup part ✨ During installation, an authoritative SNMP engine that supports this View-based Access Control Model SHOULD be configured with several initial parameters. For the View-based Access Control Model, these include:
1) A security configuration
The security configuration choice decides whether an initial configuration gets implemented, and if so, how. You pick exactly one of three options:
- initial-minimum-security-configuration
- initial-semi-security-configuration
- initial-no-access-configuration
If you go with initial-no-access-configuration, there's no initial configuration at all, so the steps below don't apply 🙈
2) A default context
One entry in the vacmContextTable with a contextName of "" (the empty string), representing the default context. Heads up, this table gets created automatically if a default context exists 💖
no privacy support privacy support
------------------ ---------------
vacmContextName "" ""3) An initial group
One entry in the vacmSecurityToGroupTable to allow access to group "initial" 🧚
no privacy support privacy support
------------------ ---------------
vacmSecurityModel 3 (USM) 3 (USM)
vacmSecurityName "initial" "initial"
vacmGroupName "initial" "initial"
vacmSecurityToGroupStorageType anyValidStorageType anyValidStorageType
vacmSecurityToGroupStatus active active4) Initial access rights
Three entries in the vacmAccessTable, like so:
- 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"".
Those translate into the following entries in the vacmAccessTable 🦋 The columns marked with (index) are index-only objects, so they aren't really present in this table.
- One entry for unauthenticated access (noAuthNoPriv):
no privacy support privacy support
------------------ ---------------
vacmAccessContextPrefix "" ""
vacmGroupName (index) "initial" "initial"
vacmSecurityModel (index) 3 (USM) 3 (USM)
vacmAccessSecurityLevel noAuthNoPriv noAuthNoPriv
vacmAccessReadViewName "restricted" "restricted"
vacmAccessWriteViewName "" ""
vacmAccessNotifyViewName "restricted" "restricted"
vacmAccessStorageType anyValidStorageType anyValidStorageType
vacmAccessStatus active active- One entry for authenticated access but without privacy (authNoPriv):
no privacy support privacy support
------------------ ---------------
vacmAccessContextPrefix "" ""
vacmGroupName (index) "initial" "initial"
vacmSecurityModel (index) 3 (USM) 3 (USM)
vacmAccessSecurityLevel authNoPriv authNoPriv
vacmAccessReadViewName "internet" "internet"
vacmAccessWriteViewName "internet" "internet"
vacmAccessNotifyViewName "internet" "internet"
vacmAccessStorageType anyValidStorageType anyValidStorageType
vacmAccessStatus active active- One entry for authenticated access with privacy (authPriv):
no privacy support privacy support
------------------ ---------------
vacmAccessContextPrefix ""
vacmGroupName (index) "initial"
vacmSecurityModel (index) 3 (USM)
vacmAccessSecurityLevel authPriv
vacmAccessReadViewName "internet"
vacmAccessWriteViewName "internet"
vacmAccessNotifyViewName "internet"
vacmAccessStorageType anyValidStorageType
vacmAccessStatus active- Two MIB views, and the second one depends on the security configuration. 🎀
- One view, the <internet> view, is for authenticated access. 🔐
- The <internet> MIB view is this subtree:
"internet" (subtree 1.3.6.1)
- The <internet> MIB view is this subtree:
- The second view, the <restricted> view, is for unauthenticated access. 👀 Its setup depends on which security configuration you picked:
- For the initial-no-access-configuration, there's 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: 🧚
- For the initial-minimum-secure-configuration, the <restricted> MIB view is this one subtree:
"internet" (subtree 1.3.6.1)
This becomes 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 activeIt also becomes these "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 1.3.6.1.6.3.7.2.1
vacmViewTreeFamilyMask ""
vacmViewTreeFamilyType 1 (included)
vacmViewTreeFamilyStorageType anyValidStorageType
vacmViewTreeFamilyStatus active
vacmViewTreeFamilyViewName "restricted"
vacmViewTreeFamilySubtree 1.3.6.1.6.3.8.2.1
vacmViewTreeFamilyMask ""
vacmViewTreeFamilyType 1 (included)
vacmViewTreeFamilyStorageType anyValidStorageType
vacmViewTreeFamilyStatus active
vacmViewTreeFamilyViewName "restricted"
vacmViewTreeFamilySubtree 1.3.6.1.6.3.9.2.1
vacmViewTreeFamilyMask ""
vacmViewTreeFamilyType 1 (included)
vacmViewTreeFamilyStorageType anyValidStorageType
vacmViewTreeFamilyStatus activeB. Full Copyright Statement 🌈
Copyright (C) The Internet Society (1998). All Rights Reserved. ©️
You can copy and share this document and translations of it. You can also write derivative works that comment on or explain it, or help people implement it, and publish and distribute those in whole or in part with no restrictions, as long as the copyright notice and this paragraph stay on every copy and derivative work. ✨
The document itself can't be modified in any way, like removing the copyright notice or the references to the Internet Society or other Internet organizations. The exceptions are when it's needed to develop Internet standards, in which case the copyright procedures in the Internet Standards process must be followed, or when it's being translated into languages other than English. 🫶
These limited permissions are perpetual and won't be revoked by the Internet Society or its successors or assigns. 💜
This document and the information in it are provided on an "AS IS" basis, and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 🦋
📦 where this page comes from
- ietf: rfc2275 1998-01
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms