RFC 3413

Simple Network Management Protocol (SNMP) Applications

📅 published December 2002, from ietf

Simple Network Management Protocol (SNMP) Applications 🦋

okay bestie, first the receipts 📜

RFC number: 3413 (part of STD 62 💅)
Title: Simple Network Management Protocol (SNMP) Applications
Authors: D. Levi (Nortel Networks), P. Meyer (Secure Computing Corporation), and B. Stewart (listed as Retired 🫶)
Category: Standards Track
Date: December 2002
Obsoletes: RFC 2573 😭
Network Working Group: this one lives in that group

Status of this Memo 📌

this doc is a standards track protocol spec for the internet community, and it's literally asking everyone to chat about it and suggest fixes ✨ for the current standardization state, check the "Internet Official Protocol Standards" (STD 1). distribution of this memo is unlimited, so share away 🌸

Abstract 🍓

so this doc describes five types of SNMP applications that use an SNMP engine (as described in STD 62, RFC 3411). they are Command Generators, Command Responders, Notification Originators, Notification Receivers, and Proxy Forwarders. it's giving full squad energy 👑

it also defines MIB modules for specifying targets of management operations, for notification filtering, and for proxy forwarding. and yes, this doc obsoletes RFC 2573 💀

Table of Contents 🧚

   1       Overview ...............................................    2
   1.1     Command Generator Applications .........................    3
   1.2     Command Responder Applications .........................    3
   1.3     Notification Originator Applications ...................    3
   1.4     Notification Receiver Applications .....................    3
   1.5     Proxy Forwarder Applications ...........................    4
   2       Management Targets .....................................    5
   3       Elements Of Procedure ..................................    6
   3.1     Command Generator Applications .........................    6
   3.2     Command Responder Applications .........................    9
   3.3     Notification Originator Applications ...................   14
   3.4     Notification Receiver Applications .....................   17
   3.5     Proxy Forwarder Applications ...........................   19
   3.5.1   Request Forwarding .....................................   21
   3.5.1.1 Processing an Incoming Request .........................   21
   3.5.1.2 Processing an Incoming Response ........................   24
   3.5.1.3 Processing an Incoming Internal-Class PDU ..............   25
   3.5.2   Notification Forwarding ................................   26
   4       The Structure of the MIB Modules .......................   29
   4.1     The Management Target MIB Module .......................   29
   4.1.1   Tag Lists .....................,........................   29
   4.1.2   Definitions ..................,.........................   30
   4.2     The Notification MIB Module ............................   44
   4.2.1   Definitions ............................................   44
   4.3     The Proxy MIB Module ...................................   56
   4.3.1   Definitions ............................................   57
   5       Identification of Management Targets in
           Notification Originators ...............................   63
   6       Notification Filtering .................................   64
   7       Management Target Translation in
           Proxy Forwarder Applications ...........................   65
   7.1     Management Target Translation for
           Request Forwarding .....................................   65
   7.2     Management Target Translation for
           Notification Forwarding ................................   66
   8       Intellectual Property ..................................   67
   9       Acknowledgments ........................................   67
   10      Security Considerations ................................   69
   11      References .............................................   69
   A.      Trap Configuration Example .............................   71
           Editors' Addresses .....................................   73
           Full Copyright Statement ...............................   74

1. Overview ✨

okay so this section lays out the five types of SNMP apps 💖

Apps that start SNMP Read-Class and/or Write-Class requests are called 'command generators.' 🔥
Apps that respond to SNMP Read-Class and/or Write-Class requests are called 'command responders.' 💅
Apps that generate SNMP Notification-Class PDUs are called 'notification originators.' 🦋
Apps that receive SNMP Notification-Class PDUs are called 'notification receivers.' 🫶
Apps that forward SNMP messages are called 'proxy forwarders.' 🌈

ngl, there are no restrictions on which app types can hang out with a particular SNMP engine. like, one engine can be friends with both a command generator and a command responder at the same time 👑

the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this doc are to be read the way [RFC2119] describes. 📖

1.1. Command Generator Applications 🎀

a command generator app starts SNMP Read-Class and/or Write-Class requests, and it handles the responses to the requests it made itself 🌸

1.2. Command Responder Applications 🧚

a command responder app gets SNMP Read-Class and/or Write-Class requests that are meant for the local system. how does it know? the contextEngineID in the request matches the one of the local engine it came in through ✨ then it does the right protocol operation (using access control) and sends a response back to whoever asked 💅

1.3. Notification Originator Applications 🍓

a notification originator app is basically watching a system for certain events or conditions, and then it makes Notification-Class messages based on what it sees 👀 it needs a way to figure out where to send messages, and which SNMP version and security parameters to use. good news: this doc provides a mechanism and MIB module for exactly that 🫶

also, Notification-Class PDUs from a notification originator can be either Confirmed-Class or Unconfirmed-Class PDU types. both are valid, no drama 💜

1.4. Notification Receiver Applications 💜

a notification receiver app listens for notification messages, and it makes response messages whenever it gets a message with a Confirmed-Class PDU in it 🔥

1.5. Proxy Forwarder Applications 🌈

a proxy forwarder app forwards SNMP messages. quick heads up: implementing a proxy forwarder app is optional 🙈 so sections 3.5, 4.3, and 7 can be skipped if your implementation doesn't have one. no pressure 🫶

okay now the word "proxy" has been used SO loosely over the years it's honestly chaotic. it's had a bunch of different meanings, including (among others):

forwarding SNMP requests to other SNMP entities without caring what managed object types are being accessed. for example, forwarding an SNMP request from one transport domain to another, or translating requests from one version into another version 🔁
translating SNMP requests into operations of some non-SNMP management protocol 🌸
supporting aggregated managed objects, where the value of one managed object instance depends on the values of multiple other (remote) items of management information 🧩

every one of these can be a good time. aggregation, for example, can seriously cut down the bandwidth needed for big management jobs 💖

but cramming all of those into one word is just asking for confusion 😭

so this doc gives "proxy" a much tighter meaning 🎀 here, "proxy" means a proxy forwarder app that forwards SNMP messages without caring what managed objects are inside them. this is closest to the first meaning above. also, in the SNMP architecture [RFC3411], a proxy forwarder is actually an application, and it doesn't need to be tied to what people usually call an SNMP agent 🧚

so the difference between a traditional SNMP agent and a proxy forwarder app is pretty simple:

a proxy forwarder app forwards SNMP messages to other SNMP engines based on the context, no matter which specific managed object types are being accessed. then it sends the response to those forwarded messages back to the SNMP engine that the original message came from 🦋
on the other hand, the command responder app that's part of what people usually call an SNMP agent processes SNMP requests based on the (names of the) individual managed object types and instances being accessed. that makes it not a proxy forwarder app, from this doc's point of view 💅

so when a proxy forwarder app forwards a request or notification for a particular contextEngineID / contextName pair, two things are true. first, the info on how to forward it is tied to that context. second, the proxy forwarder doesn't need a detailed MIB view definition at all, since it forwards requests no matter what managed object types they touch ✨

a command responder app, though, does need the detailed MIB view definition. and even if it needs to send requests to other entities (via SNMP or otherwise), that depends on the individual managed object instances being accessed, not just on the context 🌈

and last thing for this part, bestie: a proxy forwarder app is designed to act as an intermediary between the two ends of a transaction 🫶 specifically, when it forwards Confirmed Notification-Class messages, it passes along the response once it comes back from the target the message was forwarded to. it does NOT make a response right away when the Notification-Class message arrives 🙌

2. Management Targets 🎯

Okay so some apps (notification generators and proxy forwarders especially) need a way to figure out where to send their messages and how to send them. This doc gives you a mechanism and a MIB module for exactly that 🗺️. The info that describes where and how to send a message is called a Management Target, and it has two kinds of info:

Destination information, consisting of a transport domain and a transport address. This is also termed a transport endpoint.
SNMP parameters, consisting of message processing model, security model, security level, and security name information.

The SNMP-TARGET-MIB module described later in this document has one table for each of these types of info 📋. There can be a many-to-many relationship between them in the MIB, which is giving mix and match energy 💜. You might have multiple transport endpoints sharing one set of SNMP parameters, or one transport endpoint hooked up to several sets of SNMP parameters.

3. Elements Of Procedure 💅

These sections spell out the procedures each type of app follows when it's generating messages to send or processing messages it received 📨. The apps talk to the Dispatcher through the abstract service interfaces defined in [RFC3411], so this is the part where we see how the conversation actually goes ✨.

3.1. Command Generator Applications 🚀

A command generator starts an SNMP request by calling the Dispatcher with this abstract service interface:

      statusInformation =              -- sendPduHandle if success
                                       -- errorIndication if failure
        sendPdu(
        IN   transportDomain           -- transport domain to be used
        IN   transportAddress          -- destination network address
        IN   messageProcessingModel    -- typically, SNMP version
        IN   securityModel             -- Security Model to use
        IN   securityName              -- on behalf of this principal
        IN   securityLevel             -- Level of Security requested
        IN   contextEngineID           -- data from/at this entity
        IN   contextName               -- data from/in this context
        IN   pduVersion                -- the version of the PDU
        IN   PDU                       -- SNMP Protocol Data Unit
        IN   expectResponse            -- TRUE or FALSE
             )

Here's the breakdown 🔍:

The transportDomain is the one for the destination of the message.
The transportAddress is the one for the destination of the message.
The messageProcessingModel tells the Dispatcher which Message Processing Model the app wants to use.
The securityModel is the security model the app wants to use.
The securityName is the security model independent name for the principal the app wants the message generated on behalf of.
The securityLevel is the security level the app is asking for.
The contextEngineID specifies the location of the management information being requested. Note that unless the request is being sent to a proxy, this value will usually be equal to the snmpEngineID value of the engine the request is going to 🫶.
The contextName specifies the local context name for the management information being requested.
The pduVersion indicates the version of the PDU to be sent.
The PDU is a value the command generator constructs, containing the management operation it wants to perform.
The expectResponse argument indicates that a response is expected.

The result of the sendPdu interface tells you whether the PDU was successfully sent 📬. If it was, the returned value will be a sendPduHandle. The command generator should store that sendPduHandle so it can match a response back to the original request. This is the whole "remember your receipt" moment 🧾.

The Dispatcher is responsible for delivering the response to a particular request to the correct command generator application 🎯. The abstract service interface used for that is:

      processResponsePdu(              -- process Response PDU
        IN   messageProcessingModel    -- typically, SNMP version
        IN   securityModel             -- Security Model in use
        IN   securityName              -- on behalf of this principal
        IN   securityLevel             -- Level of Security
        IN   contextEngineID           -- data from/at this SNMP entity
        IN   contextName               -- data from/in this context
        IN   pduVersion                -- the version of the PDU
        IN   PDU                       -- SNMP Protocol Data Unit
        IN   statusInformation         -- success or errorIndication
        IN   sendPduHandle             -- handle from sendPdu
             )

And here's what each of those means 💖:

The messageProcessingModel is the value from the received response.
The securityModel is the value from the received response.
The securityName is the value from the received response.
The securityLevel is the value from the received response.
The contextEngineID is the value from the received response.
The contextName is the value from the received response.
The pduVersion indicates the version of the PDU in the received response.
The PDU is the value from the received response.
The statusInformation indicates success or failure in receiving the response.
The sendPduHandle is the value returned by the sendPdu call that generated the original request this is a response to.

Now the procedure when a command generator receives a message 🧠✨:

If the received values of messageProcessingModel, securityModel, securityName, contextEngineID, contextName, and pduVersion are not all equal to the values used in the original request, the response is discarded 🗑️. Bye, imposter response 💀.
The operation type, request-id, error-status, error-index, and variable-bindings are extracted from the PDU and saved. If the request-id is not equal to the value used in the original request, the response is discarded 🙅‍♀️.
At this point, it's up to the application to decide what to do next 👑. The specific action is implementation dependent. If the statusInformation indicates that the request failed, an appropriate action might be to try transmitting the request again, or to notify the person operating the application that a failure happened 🚨.

3.2. Command Responder Applications ✨

okay so, before a command responder application can process messages, it must first link up with an SNMP engine 🔗 The abstract service interface for this is:

   statusInformation =       -- success or errorIndication
    registerContextEngineID(
    IN   contextEngineID     -- take responsibility for this one
    IN   pduType             -- the pduType(s) to be registered
         )

Where:

The statusInformation tells you whether the registration worked or flopped 💅
The contextEngineID is equal to the snmpEngineID of the SNMP engine that the command responder is registering with.
The pduType indicates a Read-Class and/or Write-Class PDU.

Heads up, if another command responder application is already registered with an SNMP engine, any further attempts to register with the same contextEngineID and pduType will be denied 🙅‍♀️ Technically this means separate command responder applications could each register for the different pdu types. But ngl, that's undesirable in practice, and only a single command responder application should be registered with an SNMP engine at any given time 🫶

A command responder application can unlink from an SNMP engine using this abstract service interface:

   unregisterContextEngineID(
     IN   contextEngineID     -- give up responsibility for this one
     IN   pduType             -- the pduType(s) to be unregistered
          )

Where:

The contextEngineID is equal to the snmpEngineID of the SNMP engine that the command responder is cancelling the registration with.
The pduType indicates a Read-Class and/or Write-Class PDU.

Once the command responder is registered, it just sits there and waits for SNMP messages to roll in 👀 The abstract service interface used for receiving them is:

processPdu(                     -- process Request/Notification PDU
  IN   messageProcessingModel   -- typically, SNMP version
  IN   securityModel            -- Security Model in use
  IN   securityName             -- on behalf of this principal
  IN   securityLevel            -- Level of Security
  IN   contextEngineID          -- data from/at this SNMP entity
  IN   contextName              -- data from/in this context
  IN   pduVersion               -- the version of the PDU
  IN   PDU                      -- SNMP Protocol Data Unit
  IN   maxSizeResponseScopedPDU -- maximum size of the Response PDU
  IN   stateReference           -- reference to state information
       )                        -- needed when sending a response

Where:

The messageProcessingModel indicates which Message Processing Model received and processed the message.
The securityModel is the value from the received message.
The securityName is the value from the received message.
The securityLevel is the value from the received message.
The contextEngineID is the value from the received message.
The contextName is the value from the received message.
The pduVersion indicates the version of the PDU in the received message.
The PDU is the value from the received message.
The maxSizeResponseScopedPDU is the maximum allowable size of a ScopedPDU containing a Response PDU (based on the maximum message size that the originator of the message can accept) 📏
The stateReference is a value which references cached information about each received request message. This value must be returned to the Dispatcher in order to generate a response 🎀

Okay, here's the procedure when a message comes in, step by step 🧚

(1) The operation type is determined from the ASN.1 tag value associated with the PDU parameter. The operation type should always be one of the types previously registered by the application.

(2) The request-id is extracted from the PDU and saved.

(3) Any PDU type specific parameters are extracted from the PDU and saved (for example, if the PDU type is an SNMPv2 GetBulk PDU, the non-repeaters and max-repetitions values are extracted).

(4) The variable-bindings are extracted from the PDU and saved.

(5) The management operation represented by the PDU type is performed with respect to the relevant MIB view within the context named by the contextName (for an SNMPv2 PDU type, the operation is performed according to the procedures set forth in [RFC1905]). The relevant MIB view is determined by the securityLevel, securityModel, contextName, securityName, and the class of the PDU type. To determine whether a particular object instance is within the relevant MIB view, the following abstract service interface is called:

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

Where:

The securityModel is the value from the received message.
The securityName is the value from the received message.
The securityLevel is the value from the received message.
The viewType indicates whether the PDU type is a Read-Class or Write-Class operation.
The contextName is the value from the received message.
The variableName is the object instance of the variable for which access rights are to be checked.

Normally, the result of the management operation will be a new PDU value, and processing will continue in step (6) below. However, at any time during the processing of the management operation, things can go sideways 😬 so watch for these:

If the isAccessAllowed ASI returns a noSuchView, noAccessEntry, or noGroupName error, processing of the management operation is halted, a PDU value is constructed using the values from the originally received PDU, but replacing the error-status with an authorizationError code, and error-index value of 0, and control is passed to step (6) below.
If the isAccessAllowed ASI returns an otherError, processing of the management operation is halted, a different PDU value is constructed using the values from the originally received PDU, but replacing the error-status with a genError code and the error-index with the index of the failed variable binding, and control is passed to step (6) below.
If the isAccessAllowed ASI returns a noSuchContext error, processing of the management operation is halted, no result PDU is generated, the snmpUnknownContexts counter is incremented, and control is passed to step (6) below for generation of a report message.
If the context named by the contextName parameter is unavailable, processing of the management operation is halted, no result PDU is generated, the snmpUnavailableContexts counter is incremented, and control is passed to step (6) below for generation of a report message.

(6) The Dispatcher is called to generate a response or report message. The abstract service interface is:

returnResponsePdu(
  IN   messageProcessingModel   -- typically, SNMP version
  IN   securityModel            -- Security Model in use
  IN   securityName             -- on behalf of this principal
  IN   securityLevel            -- same as on incoming request
  IN   contextEngineID          -- data from/at this SNMP entity
  IN   contextName              -- data from/in this context
  IN   pduVersion               -- the version of the PDU
  IN   PDU                      -- SNMP Protocol Data Unit
  IN   maxSizeResponseScopedPDU -- maximum size of the Response PDU
  IN   stateReference           -- reference to state information
                                -- as presented with the request
  IN   statusInformation        -- success or errorIndication
       )                        -- error counter OID/value if error

Where:

The messageProcessingModel is the value from the processPdu call.
The securityModel is the value from the processPdu call.
The securityName is the value from the processPdu call.
The securityLevel is the value from the processPdu call.
The contextEngineID is the value from the processPdu call.
The contextName is the value from the processPdu call.
The pduVersion indicates the version of the PDU to be returned. If no result PDU was generated, the pduVersion is an undefined value.
The PDU is the result generated in step (5) above. If no result PDU was generated, the PDU is an undefined value.
The maxSizeResponseScopedPDU is a local value indicating the maximum size of a ScopedPDU that the application can accept.
The stateReference is the value from the processPdu call.
The statusInformation either contains an indication that no error occurred and that a response should be generated, or contains an indication that an error occurred along with the OID and counter value of the appropriate error counter object.

Note that a command responder application should always call the returnResponsePdu abstract service interface, even in the event of an error such as a resource allocation error 🚨 In the event of such an error, the PDU value passed to returnResponsePdu should contain appropriate values for errorStatus and errorIndex.

Now, the snmpUnknownContexts and snmpUnavailableContexts counters are easy to mix up, so let's break it down 🤓 The snmpUnknownContexts counter goes up when a request comes in for a context that is unknown to the SNMP entity. The snmpUnavailableContexts counter goes up when a request comes in for a context that is known to the SNMP entity, but is currently unavailable. Figuring out when a context is unavailable is implementation specific, and some implementations may never run into this situation, so they may never increment the snmpUnavailableContexts counter 💜

3.3. Notification Originator Applications ✨

okay so notification originator apps are the ones that send out SNMP messages carrying Notification-Class PDUs (like SNMPv2-Trap PDUs or Inform PDUs) 📣. there's no rule saying which specific Notification-Class PDU types an implementation has to be able to make 🤷‍♀️ so you do you, bestie.

these apps need a way to figure out which management targets get the notifications, and how they do that is totally up to the implementation 🗺️. BUT if an implementation makes the configuration of management targets SNMP manageable, it MUST use the SNMP-TARGET-MIB module described in this document. no cap, that one's a must 🫶

when a notification originator wants to make a notification, it must first figure out the context where the info for that notification lives. that means the contextEngineID and contextName 🌸. then it has to pick the set of management targets it's sending to. for each target it also decides what specific PDU type the notification should contain, and if it's going to contain a Confirmed-Class PDU, it needs the number of retries and the retransmission algorithm 🔁.

how the originator figures all this out is implementation dependent 💅. once the app has the info, this procedure runs for each management target:

(1) first up, any appropriate filtering mechanisms get applied to decide whether the notification should go to this management target. if the filters say it should not be sent, processing moves on to the next management target 🙅‍♀️. Otherwise,

(2) the right set of variable-bindings gets pulled from the local MIB instrumentation inside the relevant MIB view 👀. that view is determined by the securityLevel, securityModel, contextName, and securityName of the management target. to check whether a particular object instance is inside the relevant MIB view, the isAccessAllowed abstract service interface gets used, same way as in the preceding section, except the viewType indicates a Notification-Class operation. if the statusInformation that comes back from isAccessAllowed doesn't say accessAllowed, the notification is not sent to the management target 😭

(3) the NOTIFICATION-TYPE OBJECT IDENTIFIER of the notification gets checked (this is the value of the variable binding whose name is snmpTrapOID.0, aka the second variable binding) using isAccessAllowed, with the same parameters from the step before. if the statusInformation doesn't come back as accessAllowed, the notification is not sent to the management target 🚫

(4) a PDU gets built using a locally unique request-id value, a PDU type that the implementation decides on, an error-status and error-index value of 0, and the variable-bindings we grabbed back in step (2) ✨

(5) if the notification contains an Unconfirmed-Class PDU, the Dispatcher gets called with this abstract service interface:

   statusInformation =              -- sendPduHandle if success
                                    -- errorIndication if failure
     sendPdu(
     IN   transportDomain           -- transport domain to be used
     IN   transportAddress          -- destination network address
     IN   messageProcessingModel    -- typically, SNMP version
     IN   securityModel             -- Security Model to use
     IN   securityName              -- on behalf of this principal
     IN   securityLevel             -- Level of Security requested
     IN   contextEngineID           -- data from/at this entity
     IN   contextName               -- data from/in this context
     IN   pduVersion                -- the version of the PDU
     IN   PDU                       -- SNMP Protocol Data Unit
     IN   expectResponse            -- TRUE or FALSE
          )

where:

The transportDomain is that of the management target.
The transportAddress is that of the management target.
The messageProcessingModel is that of the management target.
The securityModel is that of the management target.
The securityName is that of the management target.
The securityLevel is that of the management target.
The contextEngineID is the value originally determined for the notification.
The contextName is the value originally determined for the notification.
The pduVersion is the version of the PDU to be sent.
The PDU is the value constructed in step (4) above.
The expectResponse argument indicates that no response is expected.

Otherwise,

(6) if the notification contains a Confirmed-Class PDU, then:

a) the Dispatcher gets called using the sendPdu abstract service interface like in step (5) above, except the expectResponse argument indicates that a response is expected 📨

b) the app caches info about the management target 🗃️

c) if a response comes back within an appropriate time interval from the transport endpoint of the management target, the notification is considered acknowledged and the cached info gets deleted 🥳 Otherwise,

d) if a response doesn't come back within an appropriate time period, or if a report indication is received, the info about the management target gets pulled from the cache and steps a) through d) are repeated. steps a) through d) get repeated as many times as the previously determined retry count. if that retry count gets exceeded, the acknowledgement of the notification is considered to have failed, and processing of the notification for this management target is halted 💀 note that some report indications might be considered a failure. those report indications should be interpreted to mean the acknowledgement of the notification has failed, and steps a) through d) need not be repeated.

responses to Confirmed-Class PDU notifications will come back via the processResponsePdu abstract service interface 📬

to summarize, the steps a notification originator follows when deciding where to send a notification are:

Determine the targets to which the notification should be sent.
Apply any required filtering to the list of targets.
Determine which targets are authorized to receive the notification.

3.4. Notification Receiver Applications 🦋

notification receiver apps get SNMP Notification messages from the Dispatcher 📥. before any messages can be received, the notification receiver has to register with the Dispatcher using the registerContextEngineID abstract service interface. the parameters are:

The contextEngineID is an undefined 'wildcard' value. Notifications are delivered to a registered notification receiver regardless of the contextEngineID contained in the notification message.
The pduType indicates the type of notifications that the application wants to receive (for example, SNMPv2-Trap PDUs or Inform PDUs).

once the notification receiver is registered with the Dispatcher, messages come in through the processPdu abstract service interface 🎀. the parameters are:

The messageProcessingModel indicates which Message Processing Model received and processed the message.
The securityModel is the value from the received message.
The securityName is the value from the received message.
The securityLevel is the value from the received message.
The contextEngineID is the value from the received message.
The contextName is the value from the received message.
The pduVersion indicates the version of the PDU in the received message.
The PDU is the value from the received message.
The maxSizeResponseScopedPDU is the maximum allowable size of a ScopedPDU containing a Response PDU (based on the maximum message size that the originator of the message can accept).
If the message contains an Unconfirmed-Class PDU, the stateReference is undefined and unused. Otherwise, the stateReference is a value which references cached information about the notification. This value must be returned to the Dispatcher in order to generate a response.

when an Unconfirmed-Class PDU gets delivered to a notification receiver app, it first pulls out the SNMP operation type, request-id, error-status, error-index, and variable-bindings from the PDU. after that, processing depends on the particular implementation 🤍

when a Confirmed-Class PDU comes in, the notification receiver app follows this procedure:

(1) the PDU type, request-id, error-status, error-index, and variable-bindings get extracted from the PDU 🔍

(2) a Response-Class PDU gets built using the extracted request-id and variable-bindings, with error-status and error-index both set to 0 🧁

(3) the Dispatcher gets called to generate a response message using the returnResponsePdu abstract service interface. the parameters are:

The messageProcessingModel is the value from the processPdu call.
The securityModel is the value from the processPdu call.
The securityName is the value from the processPdu call.
The securityLevel is the value from the processPdu call.
The contextEngineID is the value from the processPdu call.
The contextName is the value from the processPdu call.
The pduVersion indicates the version of the PDU to be returned.
The PDU is the result generated in step (2) above.
The maxSizeResponseScopedPDU is a local value indicating the maximum size of a ScopedPDU that the application can accept.
The stateReference is the value from the processPdu call.
The statusInformation indicates that no error occurred and that a response should be generated.

(4) after this, processing depends on the particular implementation 💖

3.5. Proxy Forwarder Applications ✨

okay so a proxy forwarder application is the one that forwards SNMP messages along 💌 bestie. There are four basic types of messages it might need to forward, grouped by the class of PDU type inside each message:

Those containing Read-Class or Write-Class PDU types (for example, Get, GetNext, GetBulk, and Set PDU types). These are about requesting or modifying information that lives within a particular context.
Those containing Notification-Class PDU types (for example, SNMPv2-Trap and Inform PDU types). These are about notifications concerning information within a particular context.
Those containing a Response-Class PDU type. Forwarding Response-Class PDUs always happens because a response came back to a previously forwarded message 🔁
Those containing Internal-Class PDU types (for example, a Report PDU). Forwarding these always happens because an Internal-Class PDU came back in response to a previously forwarded message 🫶

For the first type, the proxy forwarder's job is to deliver a request for management information to an SNMP engine that is "closer" or "downstream in the path" to the SNMP engine that actually has access to that information. Then it delivers the response with the information back to the SNMP engine the request came from. The context information in a request is what tells you which SNMP engine has access to the requested information, and that decides where and how the request gets forwarded 🧚

For the second type, the proxy forwarder figures out which SNMP engines should receive notifications about management information from a particular location. The context information in a notification message says which location the information in the notification applies to, and that's what determines which SNMP engines should get the notification 🎀

For the third type, the proxy forwarder works out which previously forwarded request or notification (if any) the response matches, and then forwards that response back to the initiator of the request or notification 💅

For the fourth type, the proxy forwarder works out which previously forwarded request or notification (if any) the Internal-Class PDU matches, and then forwards the Internal-Class PDU back to the initiator of the request or notification 🌸

When forwarding messages, a proxy forwarder application has to translate incoming management target information into outgoing management target information. How that translation happens is implementation specific 🤷‍♀️ In lots of cases it'll be driven by a preconfigured translation table. If a proxy forwarder application makes the contents of this table SNMP manageable, it MUST use the SNMP-PROXY-MIB module defined in this document 🔥

3.5.1. Request Forwarding 🌈

There are two phases for request forwarding. First, the incoming request gets passed through the proxy application. Then, the resulting response gets passed back. These two phases are described in the next two sections 💖

3.5.1.1. Processing an Incoming Request

A proxy forwarder application that wants to forward request messages has to register with the Dispatcher first, using the registerContextEngineID abstract service interface. It must register each contextEngineID it wants to forward messages for, and it must register for each pduType too. Heads up: if the proxy's configuration changes, the particular contextEngineID values it's forwarding for might change too. The proxy forwarder should call the registerContextEngineID and unregisterContextEngineID abstract service interfaces as needed so they match its current configuration ✨

A proxy forwarder application should never try to register a value of contextEngineID that equals the snmpEngineID of the SNMP engine the proxy forwarder is associated with 🙈 nope, not that one.

Once the proxy forwarder has registered for the right contextEngineID values, it can start processing messages. Here's the procedure it follows:

(1) A message comes in through the processPdu abstract service interface. The incoming management target information from the processPdu interface gets translated into outgoing management target information. Note that this translation may vary for different values of contextEngineID and/or contextName. The translation should result in a single management target 🧩

(2) If appropriate outgoing management target information can't be found, the proxy forwarder increments the snmpProxyDrops counter [RFC1907], and then calls the Dispatcher using the returnResponsePdu abstract service interface. The parameters are:

The messageProcessingModel is the value from the processPdu call.
The securityModel is the value from the processPdu call.
The securityName is the value from the processPdu call.
The securityLevel is the value from the processPdu call.
The contextEngineID is the value from the processPdu call.
The contextName is the value from the processPdu call.
The pduVersion is the value from the processPdu call.
The PDU is an undefined value.
The maxSizeResponseScopedPDU is a local value indicating the maximum size of a ScopedPDU that the application can accept.
The stateReference is the value from the processPdu call.
The statusInformation indicates that an error occurred and includes the OID and value of the snmpProxyDrops object.

Processing of the message stops right there. Otherwise,

(3) A new PDU gets constructed. A unique value of request-id should be used in the new PDU (this value is what lets a later response message get matched back up with this request 🔗). The rest of the new PDU is identical to the received PDU, unless the incoming SNMP version and the outgoing SNMP version support different PDU versions. In that case the proxy forwarder may need to translate the PDU. (A method for doing that translation is described in [RFC2576].)

(4) The proxy forwarder calls the Dispatcher to generate the forwarded message, using the sendPdu abstract service interface. The parameters are:

The transportDomain is that of the outgoing management target.
The transportAddress is that of the outgoing management target.
The messageProcessingModel is that of the outgoing management target.
The securityModel is that of the outgoing management target.
The securityName is that of the outgoing management target.
The securityLevel is that of the outgoing management target.
The contextEngineID is the value from the processPdu call.
The contextName is the value from the processPdu call.
The pduVersion is the version of the PDU to be sent.
The PDU is the value constructed in step (3) above.
The expectResponse argument indicates that a response is expected. If the sendPdu call is unsuccessful, the proxy forwarder performs the steps described in (2) above. Otherwise:

(5) The proxy forwarder caches the following information so it can match an incoming response to the forwarded request 🗂️

The sendPduHandle returned from the call to sendPdu,
The request-id from the received PDU.
The contextEngineID,
The contextName,
The stateReference,
The incoming management target information,
The outgoing management information,
Any other information needed to match an incoming response to the forwarded request.

If this information can't be cached (maybe because of a lack of resources), the proxy forwarder performs the steps described in (2) above. Otherwise:

(6) Processing of the request stops until a response to the forwarded request is received, or until an appropriate time interval has expired. If that time interval expires before a response has been received, the cached information about this request is removed 🧹

3.5.1.2. Processing an Incoming Response

A proxy forwarder follows this procedure when an incoming response is received 💫

(1) The incoming response is received using the processResponsePdu interface. The proxy forwarder uses the received parameters to locate an entry in its cache of pending forwarded requests. It does this by matching the received parameters against the cached values of sendPduHandle, contextEngineID, contextName, outgoing management target information, and the request-id contained in the received PDU (the proxy forwarder must extract the request-id for this purpose). If an appropriate cache entry can't be found, processing of the response is halted. Otherwise:

(2) The cache information is extracted, and removed from the cache.

(3) A new Response-Class PDU is constructed, using the request-id value from the original forwarded request (as extracted from the cache). All other values are identical to those in the received Response-Class PDU, unless the incoming SNMP version and the outgoing SNMP version support different PDU versions. In that case the proxy forwarder may need to translate the PDU. (A method for doing that translation is described in [RFC2576].)

(4) The proxy forwarder calls the Dispatcher using the returnResponsePdu abstract service interface. The parameters are:

The messageProcessingModel indicates the Message Processing Model by which the original incoming message was processed.
The securityModel is that of the original incoming management target extracted from the cache.
The securityName is that of the original incoming management target extracted from the cache.
The securityLevel is that of the original incoming management target extracted from the cache.
The contextEngineID is the value extracted from the cache.
The contextName is the value extracted from the cache.
The pduVersion indicates the version of the PDU to be returned.
The PDU is the (possibly translated) Response PDU.
The maxSizeResponseScopedPDU is a local value indicating the maximum size of a ScopedPDU that the application can accept.
The stateReference is the value extracted from the cache.
The statusInformation indicates that no error occurred and that a Response PDU message should be generated.

3.5.1.3. Processing an Incoming Internal-Class PDU 🎀

okay so a proxy forwarder follows this procedure whenever an incoming Internal-Class PDU shows up ✨

(1) bestie, the incoming Internal-Class PDU gets received using the processResponsePdu interface. the proxy forwarder uses the received parameters to hunt down an entry in its cache of pending forwarded requests 🔍. it does this by matching the received parameters with the cached values of sendPduHandle. if no appropriate cache entry can be found, processing of the Internal-Class PDU is halted. otherwise:

(2) the cache information gets extracted, and then removed from the cache 🧹

(3) if the original incoming management target information indicates an SNMP version which does not support Report PDUs, processing of the Internal-Class PDU is halted 🙈

(4) the proxy forwarder calls the Dispatcher using the returnResponsePdu abstract service interface. the parameters are:

The messageProcessingModel indicates the Message Processing Model by which the original incoming message was processed.
The securityModel is that of the original incoming management target extracted from the cache.
The securityName is that of the original incoming management target extracted from the cache.
The securityLevel is that of the original incoming management target extracted from the cache.
The contextEngineID is the value extracted from the cache.
The contextName is the value extracted from the cache.
The pduVersion indicates the version of the PDU to be returned.
The PDU is unused.
The maxSizeResponseScopedPDU is a local value indicating the maximum size of a ScopedPDU that the application can accept.
The stateReference is the value extracted from the cache.
The statusInformation contains values specific to the Internal-Class PDU type (for example, for a Report PDU, the statusInformation contains the contextEngineID, contextName, counter OID, and counter value received in the incoming Report PDU) ✨

3.5.2. Notification Forwarding 🦋

so a proxy forwarder receives notifications in the same way a notification receiver application does, using the processPdu abstract service interface 💅 here's the procedure that runs when a notification comes in:

(1) the incoming management target information received from the processPdu interface gets translated into outgoing management target information. ngl this translation can vary for different values of contextEngineID and/or contextName, so keep that in mind 👀 the translation may also result in multiple management targets.

(2) if appropriate outgoing management target information cannot be found and the notification was an Unconfirmed-Class PDU, processing of the notification is halted. if appropriate outgoing management target information cannot be found and the notification was a Confirmed-Class PDU, the proxy forwarder increments the snmpProxyDrops object, and calls the Dispatcher using the returnResponsePdu abstract service interface. the parameters are:

The messageProcessingModel is the value from the processPdu call.
The securityModel is the value from the processPdu call.
The securityName is the value from the processPdu call.
The securityLevel is the value from the processPdu call.
The contextEngineID is the value from the processPdu call.
The contextName is the value from the processPdu call.
The pduVersion is the value from the processPdu call.
The PDU is an undefined and unused value.
The maxSizeResponseScopedPDU is a local value indicating the maximum size of a ScopedPDU that the application can accept.
The stateReference is the value from the processPdu call.
The statusInformation indicates that an error occurred and that a Report message should be generated.

Processing of the message stops at this point. Otherwise,

(3) the proxy forwarder generates a notification using the procedures described in the preceding section on Notification Originators, with the following exceptions:

The contextEngineID and contextName values from the original received notification are used.
The outgoing management targets previously determined are used.
No filtering mechanisms are applied.
The variable-bindings from the original received notification are used, rather than retrieving variable-bindings from local MIB instrumentation. In particular, no access-control is applied to these variable-bindings, nor to the value of the variable-binding containing snmpTrapOID.0.
If the original notification contains a Confirmed-Class PDU, then any outgoing management targets for which the outgoing SNMP version does not support any PDU types that are both Notification-Class and Confirmed-Class PDUs will not be used when generating the forwarded notifications.
If, for any of the outgoing management targets, the incoming SNMP version and the outgoing SNMP version support different PDU versions, the proxy forwarder may need to perform a translation on the PDU. (A method for performing such a translation is described in [RFC2576].)

(4) if the original received notification contains an Unconfirmed-Class PDU, processing of the notification is now completed. otherwise, the original received notification must contain a Confirmed-Class PDU, and processing continues 🫶

(5) if the forwarded notifications included any Confirmed-Class PDUs, processing continues when the procedures described in the section for Notification Originators determine that either:

None of the generated notifications containing Confirmed-Class PDUs have been successfully acknowledged within the longest of the time intervals, in which case processing of the original notification is halted, or,
At least one of the generated notifications containing Confirmed-Class PDUs is successfully acknowledged, in which case a response to the original received notification containing an Confirmed-Class PDU is generated as described in the following steps.

(6) a Response-Class PDU is constructed, using the values of request-id and variable-bindings from the original received Notification-Class PDU, and error-status and error-index values of 0 🌸

(7) the Dispatcher is called using the returnResponsePdu abstract service interface. the parameters are:

The messageProcessingModel is the value from the processPdu call.
The securityModel is the value from the processPdu call.
The securityName is the value from the processPdu call.
The securityLevel is the value from the processPdu call.
The contextEngineID is the value from the processPdu call.
The contextName is the value from the processPdu call.
The pduVersion indicates the version of the PDU constructed in step (6) above.
The PDU is the value constructed in step (6) above.
The maxSizeResponseScopedPDU is a local value indicating the maximum size of a ScopedPDU that the application can accept.
The stateReference is the value from the processPdu call.
The statusInformation indicates that no error occurred and that a Response-Class PDU message should be generated.

4. The Structure of the MIB Modules 🧩

there are three separate MIB modules described in this document: the management target MIB, the notification MIB, and the proxy MIB. the following sections describe the structure of these three MIB modules 💜

the use of these MIBs by particular types of applications is described later in this document:

The use of the management target MIB and the notification MIB in notification originator applications is described in section 5.
The use of the notification MIB for filtering notifications in notification originator applications is described in section 6.
The use of the management target MIB and the proxy MIB in proxy forwarding applications is described in section 7.

4.1. The Management Target MIB Module 🎯

the SNMP-TARGET-MIB module contains objects for defining management targets. it consists of two tables and conformance/compliance statements 📋

the first table, the snmpTargetAddrTable, contains information about transport domains and addresses. it also contains an object, snmpTargetAddrTagList, which provides a mechanism for grouping entries.

the second table, the snmpTargetParamsTable, contains information about SNMP version and security information to be used when sending messages to particular transport domains and addresses.

the Management Target MIB is intended to provide a general-purpose mechanism for specifying transport address, and for specifying parameters of SNMP messages generated by an SNMP entity. it is used within this document for generation of notifications and for proxy forwarding. however, it may be used for other purposes. if another document makes use of this MIB, that document is responsible for specifying how it is used. for example, [RFC2576] uses this MIB for source address validation of SNMPv1 messages 🦋

4.1.1. Tag Lists 🏷️

the snmpTargetAddrTagList object is used for grouping entries in the snmpTargetAddrTable. the value of this object contains a list of tag values which are used to select target addresses to be used for a particular operation.

a tag value, which may also be used in MIB objects other than snmpTargetAddrTagList, is an arbitrary string of octets, but may not contain a delimiter character. delimiter characters are defined to be one of the following characters:

An ASCII space character (0x20).
An ASCII TAB character (0x09).
An ASCII carriage return (CR) character (0x0D).
An ASCII line feed (LF) character (0x0A).

in addition, a tag value within a tag list may not have a zero length. generally, a particular MIB object may contain either:

a zero-length octet string representing an empty list, or
a single tag value, in which case the value of the MIB object may not contain a delimiter character, or
a list of tag values, separated by single delimiter characters.

for a list of tag values, these constraints imply certain restrictions on the value of a MIB object:

There cannot be a leading or trailing delimiter character.
There cannot be multiple adjacent delimiter characters.

4.1.2. Definitions ✨

okay bestie, this is the actual MIB module 💖 the whole thing is in one code block so nothing gets lost 🫶

   SNMP-TARGET-MIB DEFINITIONS ::= BEGIN

   IMPORTS
       MODULE-IDENTITY,
       OBJECT-TYPE,
       snmpModules,
       Counter32,
       Integer32
           FROM SNMPv2-SMI

       TEXTUAL-CONVENTION,
       TDomain,
       TAddress,
       TimeInterval,
       RowStatus,
       StorageType,
       TestAndIncr
           FROM SNMPv2-TC

       SnmpSecurityModel,
       SnmpMessageProcessingModel,
       SnmpSecurityLevel,
       SnmpAdminString
           FROM SNMP-FRAMEWORK-MIB

       MODULE-COMPLIANCE,
       OBJECT-GROUP
           FROM SNMPv2-CONF;

   snmpTargetMIB MODULE-IDENTITY
       LAST-UPDATED "200210140000Z"
       ORGANIZATION "IETF SNMPv3 Working Group"
       CONTACT-INFO
           "WG-email:   snmpv3@lists.tislabs.com
            Subscribe:  majordomo@lists.tislabs.com
                        In message body:  subscribe snmpv3

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

            Co-Chair:   David Harrington
                        Enterasys Networks
            Postal:     35 Industrial Way
                        P. O. Box 5004
                        Rochester, New Hampshire 03866-5005
                        USA
            EMail:      dbh@enterasys.com
            Phone:      +1 603-337-2614

            Co-editor:  David B. Levi
                        Nortel Networks
            Postal:     3505 Kesterwood Drive
                        Knoxville, Tennessee 37918
            EMail:      dlevi@nortelnetworks.com
            Phone:      +1 865 686 0432

            Co-editor:  Paul Meyer
                        Secure Computing Corporation
            Postal:     2675 Long Lake Road

                        Roseville, Minnesota 55113
            EMail:      paul_meyer@securecomputing.com
            Phone:      +1 651 628 1592

            Co-editor:  Bob Stewart
                        Retired"
       DESCRIPTION
           "This MIB module defines MIB objects which provide
            mechanisms to remotely configure the parameters used
            by an SNMP entity for the generation of SNMP messages.

            Copyright (C) The Internet Society (2002). This
            version of this MIB module is part of RFC 3413;
            see the RFC itself for full legal notices.
           "
       REVISION    "200210140000Z"             -- 14 October 2002
       DESCRIPTION "Fixed DISPLAY-HINTS for UTF-8 strings, fixed hex
                    value of LF characters, clarified meaning of zero
                    length tag values, improved tag list examples.
                    Published as RFC 3413."
       REVISION    "199808040000Z"             -- 4 August 1998
       DESCRIPTION "Clarifications, published as
                    RFC 2573."
       REVISION    "199707140000Z"             -- 14 July 1997
       DESCRIPTION "The initial revision, published as RFC2273."
       ::= { snmpModules 12 }

   snmpTargetObjects       OBJECT IDENTIFIER ::= { snmpTargetMIB 1 }
   snmpTargetConformance   OBJECT IDENTIFIER ::= { snmpTargetMIB 3 }

   SnmpTagValue ::= TEXTUAL-CONVENTION
       DISPLAY-HINT "255t"
       STATUS       current
       DESCRIPTION
           "An octet string containing a tag value.
            Tag values are preferably in human-readable form.

            To facilitate internationalization, this information
            is represented using the ISO/IEC IS 10646-1 character
            set, encoded as an octet string using the UTF-8
            character encoding scheme described in RFC 2279.

            Since additional code points are added by amendments
            to the 10646 standard from time to time,
            implementations must be prepared to encounter any code
            point from 0x00000000 to 0x7fffffff.

            The use of control codes should be avoided, and certain
            control codes are not allowed as described below.

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

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

            Note that when this TC is used for an object that
            is used or envisioned to be used as an index, then a
            SIZE restriction must be specified so that the number
            of sub-identifiers for any object instance does not
            exceed the limit of 128, as defined by [RFC1905].

            An object of this type contains a single tag value
            which is used to select a set of entries in a table.

            A tag value is an arbitrary string of octets, but
            may not contain a delimiter character.  Delimiter
            characters are defined to be one of the following:

                -  An ASCII space character (0x20).

                -  An ASCII TAB character (0x09).

                -  An ASCII carriage return (CR) character (0x0D).

                -  An ASCII line feed (LF) character (0x0A).

            Delimiter characters are used to separate tag values
            in a tag list.  An object of this type may only
            contain a single tag value, and so delimiter
            characters are not allowed in a value of this type.

            Note that a tag value of 0 length means that no tag is
            defined.  In other words, a tag value of 0 length would
            never match anything in a tag list, and would never
            select any table entries.

            Some examples of valid tag values are:

                - 'acme'

                - 'router'

                - 'host'

            The use of a tag value to select table entries is
            application and MIB specific."
       SYNTAX       OCTET STRING (SIZE (0..255))

   SnmpTagList ::= TEXTUAL-CONVENTION
       DISPLAY-HINT "255t"
       STATUS       current
       DESCRIPTION
           "An octet string containing a list of tag values.
            Tag values are preferably in human-readable form.

            To facilitate internationalization, this information
            is represented using the ISO/IEC IS 10646-1 character
            set, encoded as an octet string using the UTF-8
            character encoding scheme described in RFC 2279.

            Since additional code points are added by amendments
            to the 10646 standard from time to time,
            implementations must be prepared to encounter any code
            point from 0x00000000 to 0x7fffffff.

            The use of control codes should be avoided, except as
            described below.

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

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

            An object of this type contains a list of tag values
            which are used to select a set of entries in a table.

            A tag value is an arbitrary string of octets, but
            may not contain a delimiter character.  Delimiter
            characters are defined to be one of the following:

                -  An ASCII space character (0x20).

                -  An ASCII TAB character (0x09).

                -  An ASCII carriage return (CR) character (0x0D).

                -  An ASCII line feed (LF) character (0x0A).

            Delimiter characters are used to separate tag values
            in a tag list.  Only a single delimiter character may
            occur between two tag values.  A tag value may not
            have a zero length.  These constraints imply certain
            restrictions on the contents of this object:

                - There cannot be a leading or trailing delimiter
                  character.

                - There cannot be multiple adjacent delimiter
                  characters.

            Some examples of valid tag lists are:

                - ''                        -- an empty list

                - 'acme'                    -- list of one tag

                - 'host router bridge'      -- list of several tags

            Note that although a tag value may not have a length of
            zero, an empty string is still valid.  This indicates
            an empty list (i.e. there are no tag values in the list).

            The use of the tag list to select table entries is
            application and MIB specific.  Typically, an application
            will provide one or more tag values, and any entry
            which contains some combination of these tag values
            will be selected."
       SYNTAX       OCTET STRING (SIZE (0..255))

   --
   --
   -- The snmpTargetObjects group
   --
   --

   snmpTargetSpinLock OBJECT-TYPE
       SYNTAX      TestAndIncr
       MAX-ACCESS  read-write
       STATUS      current
       DESCRIPTION
           "This object is used to facilitate modification of table
            entries in the SNMP-TARGET-MIB module by multiple
            managers.  In particular, it is useful when modifying
            the value of the snmpTargetAddrTagList object.

            The procedure for modifying the snmpTargetAddrTagList
            object is as follows:

                1.  Retrieve the value of snmpTargetSpinLock and
                    of snmpTargetAddrTagList.

2.  Generate a new value for snmpTargetAddrTagList.

                3.  Set the value of snmpTargetSpinLock to the
                    retrieved value, and the value of
                    snmpTargetAddrTagList to the new value.  If
                    the set fails for the snmpTargetSpinLock
                    object, go back to step 1."
       ::= { snmpTargetObjects 1 }

   snmpTargetAddrTable OBJECT-TYPE
       SYNTAX      SEQUENCE OF SnmpTargetAddrEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "A table of transport addresses to be used in the generation
            of SNMP messages."
       ::= { snmpTargetObjects 2 }

   snmpTargetAddrEntry OBJECT-TYPE
       SYNTAX      SnmpTargetAddrEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "A transport address to be used in the generation
            of SNMP operations.

            Entries in the snmpTargetAddrTable are created and
            deleted using the snmpTargetAddrRowStatus object."
       INDEX { IMPLIED snmpTargetAddrName }
       ::= { snmpTargetAddrTable 1 }

   SnmpTargetAddrEntry ::= SEQUENCE {
       snmpTargetAddrName         SnmpAdminString,
       snmpTargetAddrTDomain      TDomain,
       snmpTargetAddrTAddress     TAddress,
       snmpTargetAddrTimeout      TimeInterval,
       snmpTargetAddrRetryCount   Integer32,
       snmpTargetAddrTagList      SnmpTagList,
       snmpTargetAddrParams       SnmpAdminString,
       snmpTargetAddrStorageType  StorageType,
       snmpTargetAddrRowStatus    RowStatus
   }

   snmpTargetAddrName OBJECT-TYPE
       SYNTAX      SnmpAdminString (SIZE(1..32))
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "The locally arbitrary, but unique identifier associated
            with this snmpTargetAddrEntry."
       ::= { snmpTargetAddrEntry 1 }

Okay so the MIB definitions keep going, and the vibe is very table-and-row-status energy 💅🎀 Here's the next chunk of the snmpTarget objects, conformance info, and the basic group.

   snmpTargetAddrTDomain OBJECT-TYPE
       SYNTAX      TDomain
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "This object indicates the transport type of the address
            contained in the snmpTargetAddrTAddress object."
       ::= { snmpTargetAddrEntry 2 }

   snmpTargetAddrTAddress OBJECT-TYPE
       SYNTAX      TAddress
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "This object contains a transport address.  The format of
            this address depends on the value of the
            snmpTargetAddrTDomain object."
       ::= { snmpTargetAddrEntry 3 }

   snmpTargetAddrTimeout OBJECT-TYPE
       SYNTAX      TimeInterval
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "This object should reflect the expected maximum round
            trip time for communicating with the transport address
            defined by this row.  When a message is sent to this
            address, and a response (if one is expected) is not
            received within this time period, an implementation
            may assume that the response will not be delivered.

            Note that the time interval that an application waits
            for a response may actually be derived from the value
            of this object.  The method for deriving the actual time
            interval is implementation dependent.  One such method
            is to derive the expected round trip time based on a
            particular retransmission algorithm and on the number
            of timeouts which have occurred.  The type of message may
            also be considered when deriving expected round trip
            times for retransmissions.  For example, if a message is
            being sent with a securityLevel that indicates both
            authentication and privacy, the derived value may be
            increased to compensate for extra processing time spent
            during authentication and encryption processing."
       DEFVAL { 1500 }
       ::= { snmpTargetAddrEntry 4 }

   snmpTargetAddrRetryCount OBJECT-TYPE
       SYNTAX      Integer32 (0..255)
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "This object specifies a default number of retries to be
            attempted when a response is not received for a generated
            message.  An application may provide its own retry count,
            in which case the value of this object is ignored."
       DEFVAL { 3 }
       ::= { snmpTargetAddrEntry 5 }

   snmpTargetAddrTagList OBJECT-TYPE
       SYNTAX      SnmpTagList
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "This object contains a list of tag values which are
            used to select target addresses for a particular
            operation."
       DEFVAL { "" }
       ::= { snmpTargetAddrEntry 6 }

   snmpTargetAddrParams OBJECT-TYPE
       SYNTAX      SnmpAdminString (SIZE(1..32))
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "The value of this object identifies an entry in the
            snmpTargetParamsTable.  The identified entry
            contains SNMP parameters to be used when generating
            messages to be sent to this transport address."
       ::= { snmpTargetAddrEntry 7 }

   snmpTargetAddrStorageType 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 }
       ::= { snmpTargetAddrEntry 8 }

   snmpTargetAddrRowStatus OBJECT-TYPE
       SYNTAX      RowStatus
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "The status of this conceptual row.

            To create a row in this table, a manager must
            set this object to either createAndGo(4) or
            createAndWait(5).

            Until instances of all corresponding columns are
            appropriately configured, the value of the
            corresponding instance of the snmpTargetAddrRowStatus
            column is 'notReady'.

            In particular, a newly created row cannot be made
            active until the corresponding instances of
            snmpTargetAddrTDomain, snmpTargetAddrTAddress, and
            snmpTargetAddrParams have all been set.

            The following objects may not be modified while the
            value of this object is active(1):
                - snmpTargetAddrTDomain
                - snmpTargetAddrTAddress
            An attempt to set these objects while the value of
            snmpTargetAddrRowStatus is active(1) will result in
            an inconsistentValue error."
       ::= { snmpTargetAddrEntry 9 }

   snmpTargetParamsTable OBJECT-TYPE
       SYNTAX      SEQUENCE OF SnmpTargetParamsEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "A table of SNMP target information to be used
            in the generation of SNMP messages."
       ::= { snmpTargetObjects 3 }

   snmpTargetParamsEntry OBJECT-TYPE
       SYNTAX      SnmpTargetParamsEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "A set of SNMP target information.

            Entries in the snmpTargetParamsTable are created and
            deleted using the snmpTargetParamsRowStatus object."
       INDEX { IMPLIED snmpTargetParamsName }
       ::= { snmpTargetParamsTable 1 }

   SnmpTargetParamsEntry ::= SEQUENCE {
       snmpTargetParamsName           SnmpAdminString,
       snmpTargetParamsMPModel        SnmpMessageProcessingModel,
       snmpTargetParamsSecurityModel  SnmpSecurityModel,
       snmpTargetParamsSecurityName   SnmpAdminString,
       snmpTargetParamsSecurityLevel  SnmpSecurityLevel,
       snmpTargetParamsStorageType    StorageType,
       snmpTargetParamsRowStatus      RowStatus
   }

   snmpTargetParamsName OBJECT-TYPE
       SYNTAX      SnmpAdminString (SIZE(1..32))
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "The locally arbitrary, but unique identifier associated
            with this snmpTargetParamsEntry."
       ::= { snmpTargetParamsEntry 1 }

   snmpTargetParamsMPModel OBJECT-TYPE
       SYNTAX      SnmpMessageProcessingModel
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "The Message Processing Model to be used when generating
            SNMP messages using this entry."
       ::= { snmpTargetParamsEntry 2 }

   snmpTargetParamsSecurityModel OBJECT-TYPE
       SYNTAX      SnmpSecurityModel (1..2147483647)
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "The Security Model to be used when generating SNMP
             messages using this entry.  An implementation may
             choose to return an inconsistentValue error if an
             attempt is made to set this variable to a value
             for a security model which the implementation does
             not support."
       ::= { snmpTargetParamsEntry 3 }

   snmpTargetParamsSecurityName OBJECT-TYPE
       SYNTAX      SnmpAdminString
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "The securityName which identifies the Principal on
            whose behalf SNMP messages will be generated using
            this entry."
       ::= { snmpTargetParamsEntry 4 }

   snmpTargetParamsSecurityLevel OBJECT-TYPE
       SYNTAX      SnmpSecurityLevel
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "The Level of Security to be used when generating
            SNMP messages using this entry."
       ::= { snmpTargetParamsEntry 5 }

   snmpTargetParamsStorageType 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 }
       ::= { snmpTargetParamsEntry 6 }

   snmpTargetParamsRowStatus OBJECT-TYPE
       SYNTAX      RowStatus
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "The status of this conceptual row.

            To create a row in this table, a manager must
            set this object to either createAndGo(4) or
            createAndWait(5).

            Until instances of all corresponding columns are
            appropriately configured, the value of the
            corresponding instance of the snmpTargetParamsRowStatus
            column is 'notReady'.

            In particular, a newly created row cannot be made
            active until the corresponding
            snmpTargetParamsMPModel,
            snmpTargetParamsSecurityModel,
            snmpTargetParamsSecurityName,
            and snmpTargetParamsSecurityLevel have all been set.

            The following objects may not be modified while the
            value of this object is active(1):
                - snmpTargetParamsMPModel
                - snmpTargetParamsSecurityModel
                - snmpTargetParamsSecurityName
                - snmpTargetParamsSecurityLevel
            An attempt to set these objects while the value of
            snmpTargetParamsRowStatus is active(1) will result in
            an inconsistentValue error."
       ::= { snmpTargetParamsEntry 7 }

   snmpUnavailableContexts OBJECT-TYPE
       SYNTAX       Counter32
       MAX-ACCESS   read-only
       STATUS       current
       DESCRIPTION
           "The total number of packets received by the SNMP
            engine which were dropped because the context
            contained in the message was unavailable."
       ::= { snmpTargetObjects 4 }

   snmpUnknownContexts OBJECT-TYPE
       SYNTAX       Counter32
       MAX-ACCESS   read-only
       STATUS       current
       DESCRIPTION
           "The total number of packets received by the SNMP
            engine which were dropped because the context
            contained in the message was unknown."
       ::= { snmpTargetObjects 5 }

   --
   --
   -- Conformance information
   --
   --

   snmpTargetCompliances OBJECT IDENTIFIER ::=
                                           { snmpTargetConformance 1 }
   snmpTargetGroups      OBJECT IDENTIFIER ::=
                                           { snmpTargetConformance 2 }

   --
   --
   -- Compliance statements
   --
   --

   snmpTargetCommandResponderCompliance MODULE-COMPLIANCE
       STATUS      current
       DESCRIPTION
           "The compliance statement for SNMP entities which include
            a command responder application."
       MODULE -- This Module
           MANDATORY-GROUPS { snmpTargetCommandResponderGroup }
       ::= { snmpTargetCompliances 1 }

   snmpTargetBasicGroup OBJECT-GROUP
       OBJECTS {
           snmpTargetSpinLock,
           snmpTargetAddrTDomain,
           snmpTargetAddrTAddress,
           snmpTargetAddrTagList,
           snmpTargetAddrParams,
           snmpTargetAddrStorageType,
           snmpTargetAddrRowStatus,
           snmpTargetParamsMPModel,
           snmpTargetParamsSecurityModel,
           snmpTargetParamsSecurityName,
           snmpTargetParamsSecurityLevel,
           snmpTargetParamsStorageType,
           snmpTargetParamsRowStatus
       }
       STATUS      current
       DESCRIPTION
           "A collection of objects providing basic remote
            configuration of management targets."
       ::= { snmpTargetGroups 1 }

snmpTargetResponseGroup OBJECT-GROUP OBJECTS { snmpTargetAddrTimeout, snmpTargetAddrRetryCount } STATUS current DESCRIPTION "A collection of objects providing remote configuration of management targets for applications which generate SNMP messages for which a response message would be expected." ::= { snmpTargetGroups 2 }

snmpTargetCommandResponderGroup OBJECT-GROUP

OBJECTS { snmpUnavailableContexts, snmpUnknownContexts } STATUS current DESCRIPTION "A collection of objects required for command responder applications, used for counting error conditions." ::= { snmpTargetGroups 3 }

END

4.2. The Notification MIB Module ✨

okay so the SNMP-NOTIFICATION-MIB module is basically the remote control for how an SNMP entity sets up its notifications 🔔 it holds objects for configuring the parameters an entity uses when it generates notifications, and it's got three tables plus the conformance and compliance statements 💅

the first one is the snmpNotifyTable 🎀 its entries pick which entries in the snmpTargetAddrTable should be used for generating notifications, AND what type of notifications should go out. main character energy 👑

the second table, the snmpNotifyFilterProfileTable, sparsely augments the snmpTargetParamsTable with an object that links a set of filters to a particular management target 🦋

the third table, the snmpNotifyFilterTable, defines the filters themselves. these are used to limit how many notifications get generated through particular management targets 🌸 iykyk, it keeps things from getting spammy 🙈

4.2.1. Definitions 💜

ok here's the whole MIB module exactly as written, because implementers rely on every single character 🫶

   SNMP-NOTIFICATION-MIB DEFINITIONS ::= BEGIN

   IMPORTS
       MODULE-IDENTITY,
       OBJECT-TYPE,
       snmpModules
           FROM SNMPv2-SMI

       RowStatus,
       StorageType
           FROM SNMPv2-TC

       SnmpAdminString
           FROM SNMP-FRAMEWORK-MIB

       SnmpTagValue,
       snmpTargetParamsName
           FROM SNMP-TARGET-MIB

       MODULE-COMPLIANCE,
       OBJECT-GROUP
           FROM SNMPv2-CONF;

   snmpNotificationMIB MODULE-IDENTITY
       LAST-UPDATED "200210140000Z"
       ORGANIZATION "IETF SNMPv3 Working Group"
       CONTACT-INFO
           "WG-email:   snmpv3@lists.tislabs.com
            Subscribe:  majordomo@lists.tislabs.com
                        In message body:  subscribe snmpv3

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

            Co-Chair:   David Harrington
                        Enterasys Networks
            Postal:     35 Industrial Way
                        P. O. Box 5004
                        Rochester, New Hampshire 03866-5005
                        USA
            EMail:      dbh@enterasys.com
            Phone:      +1 603-337-2614

            Co-editor:  David B. Levi
                        Nortel Networks
            Postal:     3505 Kesterwood Drive
                        Knoxville, Tennessee 37918
            EMail:      dlevi@nortelnetworks.com
            Phone:      +1 865 686 0432

            Co-editor:  Paul Meyer
                        Secure Computing Corporation
            Postal:     2675 Long Lake Road
                        Roseville, Minnesota 55113
            EMail:      paul_meyer@securecomputing.com
            Phone:      +1 651 628 1592

            Co-editor:  Bob Stewart
                        Retired"

       DESCRIPTION
           "This MIB module defines MIB objects which provide
            mechanisms to remotely configure the parameters
            used by an SNMP entity for the generation of
            notifications.

            Copyright (C) The Internet Society (2002). This
            version of this MIB module is part of RFC 3413;
            see the RFC itself for full legal notices.
           "
       REVISION    "200210140000Z"             -- 14 October 2002
       DESCRIPTION "Clarifications, published as
                    RFC 3413."
       REVISION    "199808040000Z"             -- 4 August 1998
       DESCRIPTION "Clarifications, published as
                    RFC 2573."
       REVISION    "199707140000Z"             -- 14 July 1997
       DESCRIPTION "The initial revision, published as RFC2273."
       ::= { snmpModules 13 }

   snmpNotifyObjects       OBJECT IDENTIFIER ::=
                                             { snmpNotificationMIB 1 }
   snmpNotifyConformance   OBJECT IDENTIFIER ::=
                                             { snmpNotificationMIB 3 }

   --
   --
   -- The snmpNotifyObjects group
   --
   --

   snmpNotifyTable OBJECT-TYPE
       SYNTAX      SEQUENCE OF SnmpNotifyEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "This table is used to select management targets which should
            receive notifications, as well as the type of notification
            which should be sent to each selected management target."
       ::= { snmpNotifyObjects 1 }

   snmpNotifyEntry OBJECT-TYPE
       SYNTAX      SnmpNotifyEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "An entry in this table selects a set of management targets
            which should receive notifications, as well as the type of
            notification which should be sent to each selected
            management target.

            Entries in the snmpNotifyTable are created and
            deleted using the snmpNotifyRowStatus object."
       INDEX { IMPLIED snmpNotifyName }
       ::= { snmpNotifyTable 1 }

   SnmpNotifyEntry ::= SEQUENCE {
       snmpNotifyName         SnmpAdminString,
       snmpNotifyTag          SnmpTagValue,
       snmpNotifyType         INTEGER,
       snmpNotifyStorageType  StorageType,
       snmpNotifyRowStatus    RowStatus
   }

   snmpNotifyName OBJECT-TYPE
       SYNTAX      SnmpAdminString (SIZE(1..32))
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "The locally arbitrary, but unique identifier associated
            with this snmpNotifyEntry."
       ::= { snmpNotifyEntry 1 }

   snmpNotifyTag OBJECT-TYPE
       SYNTAX      SnmpTagValue
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "This object contains a single tag value which is used
            to select entries in the snmpTargetAddrTable.  Any entry
            in the snmpTargetAddrTable which contains a tag value
            which is equal to the value of an instance of this
            object is selected.  If this object contains a value
            of zero length, no entries are selected."
       DEFVAL { "" }
       ::= { snmpNotifyEntry 2 }

   snmpNotifyType OBJECT-TYPE
       SYNTAX      INTEGER {
                       trap(1),
                       inform(2)
                   }
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "This object determines the type of notification to

            be generated for entries in the snmpTargetAddrTable
            selected by the corresponding instance of
            snmpNotifyTag.  This value is only used when
            generating notifications, and is ignored when
            using the snmpTargetAddrTable for other purposes.

            If the value of this object is trap(1), then any
            messages generated for selected rows will contain
            Unconfirmed-Class PDUs.

            If the value of this object is inform(2), then any
            messages generated for selected rows will contain
            Confirmed-Class PDUs.

            Note that if an SNMP entity only supports
            generation of Unconfirmed-Class PDUs (and not
            Confirmed-Class PDUs), then this object may be
            read-only."
       DEFVAL { trap }
       ::= { snmpNotifyEntry 3 }

   snmpNotifyStorageType 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 }
       ::= { snmpNotifyEntry 4 }

   snmpNotifyRowStatus OBJECT-TYPE
       SYNTAX      RowStatus
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "The status of this conceptual row.

            To create a row in this table, a manager must
            set this object to either createAndGo(4) or
            createAndWait(5)."
       ::= { snmpNotifyEntry 5 }

   snmpNotifyFilterProfileTable OBJECT-TYPE
       SYNTAX      SEQUENCE OF SnmpNotifyFilterProfileEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "This table is used to associate a notification filter
            profile with a particular set of target parameters."
       ::= { snmpNotifyObjects 2 }

   snmpNotifyFilterProfileEntry OBJECT-TYPE
       SYNTAX      SnmpNotifyFilterProfileEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "An entry in this table indicates the name of the filter
            profile to be used when generating notifications using
            the corresponding entry in the snmpTargetParamsTable.

            Entries in the snmpNotifyFilterProfileTable are created
            and deleted using the snmpNotifyFilterProfileRowStatus
            object."
       INDEX { IMPLIED snmpTargetParamsName }
       ::= { snmpNotifyFilterProfileTable 1 }

   SnmpNotifyFilterProfileEntry ::= SEQUENCE {
       snmpNotifyFilterProfileName         SnmpAdminString,
       snmpNotifyFilterProfileStorType     StorageType,
       snmpNotifyFilterProfileRowStatus    RowStatus
   }

   snmpNotifyFilterProfileName OBJECT-TYPE
       SYNTAX      SnmpAdminString (SIZE(1..32))
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "The name of the filter profile to be used when generating
            notifications using the corresponding entry in the
            snmpTargetAddrTable."
       ::= { snmpNotifyFilterProfileEntry 1 }

   snmpNotifyFilterProfileStorType 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 }
       ::= { snmpNotifyFilterProfileEntry 2 }

   snmpNotifyFilterProfileRowStatus OBJECT-TYPE

       SYNTAX      RowStatus
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "The status of this conceptual row.

            To create a row in this table, a manager must
            set this object to either createAndGo(4) or
            createAndWait(5).

            Until instances of all corresponding columns are
            appropriately configured, the value of the
            corresponding instance of the
            snmpNotifyFilterProfileRowStatus column is 'notReady'.

            In particular, a newly created row cannot be made
            active until the corresponding instance of
            snmpNotifyFilterProfileName has been set."
       ::= { snmpNotifyFilterProfileEntry 3 }

   snmpNotifyFilterTable OBJECT-TYPE
       SYNTAX      SEQUENCE OF SnmpNotifyFilterEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "The table of filter profiles.  Filter profiles are used
            to determine whether particular management targets should
            receive particular notifications.

            When a notification is generated, it must be compared
            with the filters associated with each management target
            which is configured to receive notifications, in order to
            determine whether it may be sent to each such management
            target.

            A more complete discussion of notification filtering
            can be found in section 6. of [SNMP-APPL]."
       ::= { snmpNotifyObjects 3 }

   snmpNotifyFilterEntry OBJECT-TYPE
       SYNTAX      SnmpNotifyFilterEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "An element of a filter profile.

            Entries in the snmpNotifyFilterTable are created and
            deleted using the snmpNotifyFilterRowStatus object."

       INDEX {         snmpNotifyFilterProfileName,
               IMPLIED snmpNotifyFilterSubtree }
       ::= { snmpNotifyFilterTable 1 }

   SnmpNotifyFilterEntry ::= SEQUENCE {
       snmpNotifyFilterSubtree           OBJECT IDENTIFIER,
       snmpNotifyFilterMask              OCTET STRING,
       snmpNotifyFilterType              INTEGER,
       snmpNotifyFilterStorageType       StorageType,
       snmpNotifyFilterRowStatus         RowStatus
   }

   snmpNotifyFilterSubtree OBJECT-TYPE
       SYNTAX      OBJECT IDENTIFIER
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "The MIB subtree which, when combined with the corresponding
            instance of snmpNotifyFilterMask, defines a family of
            subtrees which are included in or excluded from the
            filter profile."
       ::= { snmpNotifyFilterEntry 1 }

   snmpNotifyFilterMask 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 snmpNotifyFilterSubtree, defines a family of
            subtrees which are included in or excluded from the
            filter profile.

            Each bit of this bit mask corresponds to a
            sub-identifier of snmpNotifyFilterSubtree, 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 matches this
            family of filter 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 filter subtrees if, for
            each sub-identifier of the value of
            snmpNotifyFilterSubtree, either:

              the i-th bit of snmpNotifyFilterMask is 0, or

              the i-th sub-identifier of X is equal to the i-th
              sub-identifier of the value of
              snmpNotifyFilterSubtree.

            If the value of this bit mask is M bits long and
            there are more than M sub-identifiers in the
            corresponding instance of snmpNotifyFilterSubtree,
            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 filter subtrees is the one
            subtree uniquely identified by the corresponding
            instance of snmpNotifyFilterSubtree."
       DEFVAL { ''H }
       ::= { snmpNotifyFilterEntry 2 }

   snmpNotifyFilterType OBJECT-TYPE
       SYNTAX      INTEGER {
                       included(1),
                       excluded(2)
                   }
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "This object indicates whether the family of filter subtrees
            defined by this entry are included in or excluded from a
            filter.  A more detailed discussion of the use of this
            object can be found in section 6. of [SNMP-APPL]."
       DEFVAL { included }
       ::= { snmpNotifyFilterEntry 3 }

   snmpNotifyFilterStorageType 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 }
       ::= { snmpNotifyFilterEntry 4 }

   snmpNotifyFilterRowStatus OBJECT-TYPE
       SYNTAX      RowStatus
       MAX-ACCESS  read-create
       STATUS      current
       DESCRIPTION
           "The status of this conceptual row.

            To create a row in this table, a manager must
            set this object to either createAndGo(4) or
            createAndWait(5)."
       ::= { snmpNotifyFilterEntry 5 }

   --
   --
   -- Conformance information
   --
   --

   snmpNotifyCompliances OBJECT IDENTIFIER ::=
                                           { snmpNotifyConformance 1 }
   snmpNotifyGroups      OBJECT IDENTIFIER ::=
                                           { snmpNotifyConformance 2 }

   --
   --
   -- Compliance statements
   --
   --

   snmpNotifyBasicCompliance MODULE-COMPLIANCE
       STATUS      current
       DESCRIPTION
           "The compliance statement for minimal SNMP entities which
            implement only SNMP Unconfirmed-Class notifications and
            read-create operations on only the snmpTargetAddrTable."
       MODULE SNMP-TARGET-MIB
           MANDATORY-GROUPS { snmpTargetBasicGroup }

           OBJECT snmpTargetParamsMPModel
           MIN-ACCESS    read-only
           DESCRIPTION
               "Create/delete/modify access is not required."

           OBJECT snmpTargetParamsSecurityModel
           MIN-ACCESS    read-only
           DESCRIPTION
               "Create/delete/modify access is not required."

           OBJECT snmpTargetParamsSecurityName
           MIN-ACCESS    read-only
           DESCRIPTION
               "Create/delete/modify access is not required."

           OBJECT snmpTargetParamsSecurityLevel
           MIN-ACCESS    read-only
           DESCRIPTION
               "Create/delete/modify access is not required."

           OBJECT snmpTargetParamsStorageType
           SYNTAX INTEGER {
               readOnly(5)
           }
           MIN-ACCESS    read-only
           DESCRIPTION
               "Create/delete/modify access is not required.
                Support of the values other(1), volatile(2),
                nonVolatile(3), and permanent(4) is not required."

           OBJECT snmpTargetParamsRowStatus
           SYNTAX INTEGER {
               active(1)
           }
           MIN-ACCESS    read-only
           DESCRIPTION
               "Create/delete/modify access to the
                snmpTargetParamsTable is not required.
                Support of the values notInService(2), notReady(3),
                createAndGo(4), createAndWait(5), and destroy(6) is
                not required."

       MODULE -- This Module
           MANDATORY-GROUPS { snmpNotifyGroup }

           OBJECT snmpNotifyTag
           MIN-ACCESS    read-only
           DESCRIPTION
               "Create/delete/modify access is not required."

           OBJECT snmpNotifyType
           SYNTAX INTEGER {
               trap(1)
           }
           MIN-ACCESS    read-only
           DESCRIPTION
               "Create/delete/modify access is not required.
                Support of the value notify(2) is not required."

           OBJECT snmpNotifyStorageType
           SYNTAX INTEGER {
               readOnly(5)
           }
           MIN-ACCESS    read-only
           DESCRIPTION
               "Create/delete/modify access is not required.
                Support of the values other(1), volatile(2),
                nonVolatile(3), and permanent(4) is not required."

           OBJECT snmpNotifyRowStatus
           SYNTAX INTEGER {
               active(1)
           }
           MIN-ACCESS    read-only
           DESCRIPTION
               "Create/delete/modify access to the
                snmpNotifyTable is not required.
                Support of the values notInService(2), notReady(3),
                createAndGo(4), createAndWait(5), and destroy(6) is
                not required."

       ::= { snmpNotifyCompliances 1 }

   snmpNotifyBasicFiltersCompliance MODULE-COMPLIANCE
       STATUS      current
       DESCRIPTION
           "The compliance statement for SNMP entities which implement
            SNMP Unconfirmed-Class notifications with filtering, and
            read-create operations on all related tables."
       MODULE SNMP-TARGET-MIB
           MANDATORY-GROUPS { snmpTargetBasicGroup }
       MODULE -- This Module
           MANDATORY-GROUPS { snmpNotifyGroup,
                              snmpNotifyFilterGroup }
       ::= { snmpNotifyCompliances 2 }

   snmpNotifyFullCompliance MODULE-COMPLIANCE
       STATUS      current
       DESCRIPTION
           "The compliance statement for SNMP entities which either
            implement only SNMP Confirmed-Class notifications, or both
            SNMP Unconfirmed-Class and Confirmed-Class notifications,
            plus filtering and read-create operations on all related
            tables."
       MODULE SNMP-TARGET-MIB
           MANDATORY-GROUPS { snmpTargetBasicGroup,
                              snmpTargetResponseGroup }
       MODULE -- This Module
           MANDATORY-GROUPS { snmpNotifyGroup,
                              snmpNotifyFilterGroup }
       ::= { snmpNotifyCompliances 3 }

   snmpNotifyGroup OBJECT-GROUP
       OBJECTS {
           snmpNotifyTag,
           snmpNotifyType,
           snmpNotifyStorageType,
           snmpNotifyRowStatus
       }
       STATUS      current
       DESCRIPTION
           "A collection of objects for selecting which management
            targets are used for generating notifications, and the
            type of notification to be generated for each selected
            management target."
       ::= { snmpNotifyGroups 1 }

   snmpNotifyFilterGroup OBJECT-GROUP
       OBJECTS {
           snmpNotifyFilterProfileName,
           snmpNotifyFilterProfileStorType,
           snmpNotifyFilterProfileRowStatus,
           snmpNotifyFilterMask,
           snmpNotifyFilterType,
           snmpNotifyFilterStorageType,
           snmpNotifyFilterRowStatus
       }
       STATUS      current
       DESCRIPTION
           "A collection of objects providing remote configuration
            of notification filters."
       ::= { snmpNotifyGroups 2 }

   END

4.3. The Proxy MIB Module ✨

okay so the SNMP-PROXY-MIB module is all about remote control 🎀 It defines the MIB objects that let you configure, from a distance, the parameters an SNMP entity uses for proxy forwarding operations. 💅

It only has one table, and that table is called snmpProxyTable 🦋 Its whole job is to define translations between management targets, which get used when messages are forwarded. literally the matchmaker of the management world 💖

4.3.1. Definitions 💖

okay so this is the actual MIB module, the blueprint for the proxy table, and it's giving a whole lot of structure 🎀 every object, index, and conformance group is listed out below, exactly as written.

SNMP-PROXY-MIB DEFINITIONS ::= BEGIN

IMPORTS
    MODULE-IDENTITY,
    OBJECT-TYPE,
    snmpModules
        FROM SNMPv2-SMI

    RowStatus,
    StorageType
        FROM SNMPv2-TC

    SnmpEngineID,
    SnmpAdminString
        FROM SNMP-FRAMEWORK-MIB

    SnmpTagValue
        FROM SNMP-TARGET-MIB

    MODULE-COMPLIANCE,
    OBJECT-GROUP
        FROM SNMPv2-CONF;

snmpProxyMIB MODULE-IDENTITY
    LAST-UPDATED "200210140000Z"
    ORGANIZATION "IETF SNMPv3 Working Group"
    CONTACT-INFO
        "WG-email:   snmpv3@lists.tislabs.com
         Subscribe:  majordomo@lists.tislabs.com
                     In message body:  subscribe snmpv3

         Co-Chair:   Russ Mundy
                     Network Associates Laboratories
         Postal:     15204 Omega Drive, Suite 300
                     Rockville, MD 20850-4601
                     USA
         EMail:      mundy@tislabs.com
         Phone:      +1 301-947-7107
         Co-Chair:   David Harrington
                     Enterasys Networks
         Postal:     35 Industrial Way
                     P. O. Box 5004
                     Rochester, New Hampshire 03866-5005
                     USA
         EMail:      dbh@enterasys.com
         Phone:      +1 603-337-2614

         Co-editor:  David B. Levi
                     Nortel Networks
         Postal:     3505 Kesterwood Drive
                     Knoxville, Tennessee 37918
         EMail:      dlevi@nortelnetworks.com
         Phone:      +1 865 686 0432

         Co-editor:  Paul Meyer
                     Secure Computing Corporation
         Postal:     2675 Long Lake Road
                     Roseville, Minnesota 55113
         EMail:      paul_meyer@securecomputing.com
         Phone:      +1 651 628 1592

         Co-editor:  Bob Stewart
                     Retired"
    DESCRIPTION
        "This MIB module defines MIB objects which provide
         mechanisms to remotely configure the parameters
         used by a proxy forwarding application.

         Copyright (C) The Internet Society (2002). This
         version of this MIB module is part of RFC 3413;
         see the RFC itself for full legal notices.
        "
    REVISION    "200210140000Z"             -- 14 October 2002
    DESCRIPTION "Clarifications, published as
                 RFC 3413."
    REVISION    "199808040000Z"             -- 4 August 1998
    DESCRIPTION "Clarifications, published as
                 RFC 2573."
    REVISION    "199707140000Z"             -- 14 July 1997
    DESCRIPTION "The initial revision, published as RFC2273."
    ::= { snmpModules 14 }

snmpProxyObjects        OBJECT IDENTIFIER ::= { snmpProxyMIB 1 }
snmpProxyConformance    OBJECT IDENTIFIER ::= { snmpProxyMIB 3 }

--
--
-- The snmpProxyObjects group
--
--

snmpProxyTable OBJECT-TYPE
    SYNTAX      SEQUENCE OF SnmpProxyEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
        "The table of translation parameters used by proxy forwarder
         applications for forwarding SNMP messages."
    ::= { snmpProxyObjects 2 }

snmpProxyEntry OBJECT-TYPE
    SYNTAX      SnmpProxyEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
        "A set of translation parameters used by a proxy forwarder
         application for forwarding SNMP messages.

         Entries in the snmpProxyTable are created and deleted
         using the snmpProxyRowStatus object."
    INDEX { IMPLIED snmpProxyName }
    ::= { snmpProxyTable 1 }

SnmpProxyEntry ::= SEQUENCE {
    snmpProxyName               SnmpAdminString,
    snmpProxyType               INTEGER,
    snmpProxyContextEngineID    SnmpEngineID,
    snmpProxyContextName        SnmpAdminString,
    snmpProxyTargetParamsIn     SnmpAdminString,
    snmpProxySingleTargetOut    SnmpAdminString,
    snmpProxyMultipleTargetOut  SnmpTagValue,
    snmpProxyStorageType        StorageType,
    snmpProxyRowStatus          RowStatus
}

snmpProxyName OBJECT-TYPE
    SYNTAX      SnmpAdminString (SIZE(1..32))
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
        "The locally arbitrary, but unique identifier associated
         with this snmpProxyEntry."
    ::= { snmpProxyEntry 1 }

snmpProxyType OBJECT-TYPE
    SYNTAX      INTEGER {
                    read(1),
                    write(2),
                    trap(3),
                    inform(4)
                }
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
        "The type of message that may be forwarded using
         the translation parameters defined by this entry."
    ::= { snmpProxyEntry 2 }

snmpProxyContextEngineID OBJECT-TYPE
    SYNTAX      SnmpEngineID
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
        "The contextEngineID contained in messages that
         may be forwarded using the translation parameters
         defined by this entry."
    ::= { snmpProxyEntry 3 }

snmpProxyContextName OBJECT-TYPE
    SYNTAX      SnmpAdminString
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
        "The contextName contained in messages that may be
         forwarded using the translation parameters defined
         by this entry.

         This object is optional, and if not supported, the
         contextName contained in a message is ignored when
         selecting an entry in the snmpProxyTable."
    ::= { snmpProxyEntry 4 }

snmpProxyTargetParamsIn OBJECT-TYPE
    SYNTAX      SnmpAdminString
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
        "This object selects an entry in the snmpTargetParamsTable.
         The selected entry is used to determine which row of the
         snmpProxyTable to use for forwarding received messages."
    ::= { snmpProxyEntry 5 }

snmpProxySingleTargetOut OBJECT-TYPE
    SYNTAX      SnmpAdminString
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
        "This object selects a management target defined in the
         snmpTargetAddrTable (in the SNMP-TARGET-MIB).  The
         selected target is defined by an entry in the
         snmpTargetAddrTable whose index value (snmpTargetAddrName)
         is equal to this object.

         This object is only used when selection of a single
         target is required (i.e. when forwarding an incoming
         read or write request)."
    ::= { snmpProxyEntry 6 }

snmpProxyMultipleTargetOut OBJECT-TYPE
    SYNTAX      SnmpTagValue
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
        "This object selects a set of management targets defined
         in the snmpTargetAddrTable (in the SNMP-TARGET-MIB).

         This object is only used when selection of multiple
         targets is required (i.e. when forwarding an incoming
         notification)."
    ::= { snmpProxyEntry 7 }

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

snmpProxyRowStatus OBJECT-TYPE
    SYNTAX      RowStatus
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
        "The status of this conceptual row.

         To create a row in this table, a manager must
         set this object to either createAndGo(4) or
         createAndWait(5).

         The following objects may not be modified while the
         value of this object is active(1):
             - snmpProxyType
             - snmpProxyContextEngineID
             - snmpProxyContextName
             - snmpProxyTargetParamsIn
             - snmpProxySingleTargetOut
             - snmpProxyMultipleTargetOut"
    ::= { snmpProxyEntry 9 }

--
--
-- Conformance information
--
--

snmpProxyCompliances OBJECT IDENTIFIER ::=
                                         { snmpProxyConformance 1 }
snmpProxyGroups      OBJECT IDENTIFIER ::=
                                         { snmpProxyConformance 2 }

--
--
-- Compliance statements
--
--

snmpProxyCompliance MODULE-COMPLIANCE
    STATUS      current
    DESCRIPTION
        "The compliance statement for SNMP entities which include
         a proxy forwarding application."
    MODULE SNMP-TARGET-MIB
        MANDATORY-GROUPS { snmpTargetBasicGroup,
                           snmpTargetResponseGroup }
    MODULE -- This Module
        MANDATORY-GROUPS { snmpProxyGroup }
    ::= { snmpProxyCompliances 1 }

snmpProxyGroup OBJECT-GROUP
    OBJECTS {
        snmpProxyType,
        snmpProxyContextEngineID,
        snmpProxyContextName,
        snmpProxyTargetParamsIn,
        snmpProxySingleTargetOut,
        snmpProxyMultipleTargetOut,
        snmpProxyStorageType,
        snmpProxyRowStatus
    }
    STATUS      current
    DESCRIPTION
        "A collection of objects providing remote configuration of
         management target translation parameters for use by
         proxy forwarder applications."
    ::= { snmpProxyGroups 3 }

END

5. Identification of Management Targets in Notification Originators ✨

okay so this section is all about how a notification originator app figures out who gets the notifications 📬 it's giving detective energy, honestly 🕵️‍♀️

A notification originator looks at every active entry in the snmpNotifyTable to find its management targets 🎯 each active entry picks out zero or more entries in the snmpTargetAddrTable. Whenever a notification gets generated, it gets sent to every target those selected snmpTargetAddrTable entries point to (subject to access control and notification filtering 🔒).

Any snmpTargetAddrTable entry whose snmpTargetAddrTagList object has a tag value that matches a value of snmpNotifyTag gets selected by the snmpNotifyTable entry that holds that snmpNotifyTag instance. Ngl this is so cute: one snmpTargetAddrEntry can be picked by multiple snmpNotifyTable entries, so the same target can get several notifications. For example, it lets both traps and informs go to the same target 💌

Each snmpTargetAddrEntry has a pointer to the snmpTargetParamsTable (snmpTargetAddrParams) 👉 that pointer picks out a set of SNMP parameters to use when generating notifications. If the selected entry in the snmpTargetParamsTable doesn't exist, that management target is not used to generate notifications. no entry, no vibes 🚫

Now the notification type decides the PDU class 🎀 The value of snmpNotifyType tells you which one to use. If it's trap(1), the notification should contain an Unconfirmed-Class PDU.

If it's inform(2), the notification should contain a Confirmed-Class PDU, and the timeout and number of retries for that notification are the values of snmpTargetAddrTimeout and snmpTargetAddrRetryCount 🔁

There's one exception, and it's a plot twist 🍿 when snmpTargetParamsMPModel points at an SNMP version that supports a different PDU version, the notification may be sent using a different PDU type. ([RFC2576] defines the PDU type when the outgoing SNMP version is SNMPv1 💅)

6. Notification Filtering 🫧

this section covers how a notification originator app uses this MIB module to filter which notifications actually get generated. filtering era, bestie 💖

A notification originator uses the snmpNotifyFilterTable to do the filtering 🧹 A notification filter profile can be attached to a particular entry in the snmpTargetParamsTable. The filter profile in use is the entry in the snmpNotifyFilterProfileTable whose index equals the index of that snmpTargetParamsTable entry. If there's no such entry in the snmpNotifyFilterProfileTable, no filtering happens for that management target 🌸

If there is one, its snmpNotifyFilterProfileName value gets compared with the matching part of the index of every active entry in the snmpNotifyFilterTable. All the entries where that comparison is an exact match are used to filter any notification generated with the associated snmpTargetParamsEntry. If no entries match, no filtering happens, and the notification may be sent to the management target ✨

If matching entries do exist, the notification may be sent only if its NOTIFICATION-TYPE OBJECT IDENTIFIER is specifically included 🎯 (that's the value of the variable binding named snmpTrapOID.0, which is the second variable binding), and none of the object instances in its variable-bindings are specifically excluded by the matching entries. both conditions have to hold, no exceptions 🙅‍♀️

Each set of snmpNotifyFilterTable entries gets split into two collections of filter subtrees: the included filter subtrees and the excluded filter subtrees. The snmpNotifyFilterType object tells you which collection each matching entry goes into 🗂️

To decide whether a notification name or object instance is excluded by the matching entries, compare its OBJECT IDENTIFIER with each matching entry:

For a notification name: if none of them match, the notification name is considered excluded, and the notification should not be sent to this management target.
For an object instance: if none of them match, the object instance is considered included, and the notification may be sent to this management target.
If one or more match: the notification name or object instance is included or excluded based on the snmpNotifyFilterType value of the entry whose snmpNotifyFilterSubtree has the most sub-identifiers 🏆
If multiple entries match and they all have the same number of sub-identifiers, the snmpNotifyFilterType value from the matching entry whose instance is lexicographically largest decides inclusion or exclusion.

Now the matching rule itself 🧩 An OBJECT IDENTIFIER X matches an entry in the snmpNotifyFilterTable when X has at least as many sub-identifiers as the entry's snmpNotifyFilterSubtree value, and every sub-identifier in snmpNotifyFilterSubtree matches its corresponding sub-identifier in X. Two sub-identifiers match if the corresponding bit of snmpNotifyFilterMask is zero (that's the 'wild card' value 🃏), or if the two sub-identifiers are equal.

7. Management Target Translation in Proxy Forwarder Applications 🔀

this section is about how a proxy forwarder app takes incoming management target info and turns it into outgoing management target info so it can forward messages. it's basically a glow-up for targets ✨ There are actually two mechanisms a proxy forwarder can use: one for forwarding request messages, and one for forwarding notification messages. two routes, same energy 💅

7.1. Management Target Translation for Request Forwarding

When forwarding request messages, the proxy forwarder picks a single entry in the snmpProxyTable. To pick it, it does these comparisons:

The snmpProxyType must be read(1) if the request is a Read-Class PDU. The snmpProxyType must be write(2) if the request is a Write-Class PDU.
The contextEngineID must equal the snmpProxyContextEngineID object.
If the snmpProxyContextName object is supported, it must equal the contextName.
The snmpProxyTargetParamsIn object identifies an entry in the snmpTargetParamsTable. The messageProcessingModel, security model, securityName, and securityLevel must match the values of snmpTargetParamsMPModel, snmpTargetParamsSecurityModel, snmpTargetParamsSecurityName, and snmpTargetParamsSecurityLevel of that identified entry.

There might be several snmpProxyTable entries where all of these comparisons succeed 👯 In that case, the proxy forwarder picks the entry whose snmpProxyName is lexicographically smallest out of the ones that passed.

The outgoing management target info is identified by the snmpProxySingleTargetOut object of the chosen entry 🎯 That object points to an entry in the snmpTargetAddrTable, and that entry has a reference to the snmpTargetParamsTable (snmpTargetAddrParams). If either the snmpTargetAddrTable entry or the snmpTargetParamsTable entry doesn't exist, this snmpProxyEntry doesn't give valid forwarding info, and the proxy forwarder should try to find another row 🔍

If there's no snmpProxyTable entry where all of the conditions above can be met, then there's no appropriate forwarding info, and the proxy forwarder should take appropriate action 🚨

Otherwise, the snmpTargetAddrTDomain, snmpTargetAddrTAddress, snmpTargetAddrTimeout, and snmpTargetRetryCount of the identified snmpTargetAddrEntry, along with the snmpTargetParamsMPModel, snmpTargetParamsSecurityModel, snmpTargetParamsSecurityName, and snmpTargetParamsSecurityLevel of the identified snmpTargetParamsEntry, are used as the destination management target 🥳

7.2. Management Target Translation for Notification Forwarding

When forwarding notification messages, the proxy forwarder picks multiple entries in the snmpProxyTable 🫂 To pick them, it does these comparisons:

The snmpProxyType must be trap(3) if the notification is an Unconfirmed-Class PDU. The snmpProxyType must be inform(4) if the request is a Confirmed-Class PDU.
The contextEngineID must equal the snmpProxyContextEngineID object.
If the snmpProxyContextName object is supported, it must equal the contextName.
The snmpProxyTargetParamsIn object identifies an entry in the snmpTargetParamsTable. The messageProcessingModel, security model, securityName, and securityLevel must match the values of snmpTargetParamsMPModel, snmpTargetParamsSecurityModel, snmpTargetParamsSecurityName, and snmpTargetParamsSecurityLevel of that identified entry in the snmpTargetParamsTable.

Every entry where these conditions are met gets selected 🌈 The snmpProxyMultipleTargetOut object of each of those entries is then used to select a set of entries in the snmpTargetAddrTable. Any snmpTargetAddrEntry whose snmpTargetAddrTagList object contains a tag value equal to the value of snmpProxyMultipleTargetOut, and whose snmpTargetAddrParams object references an existing entry in the snmpTargetParamsTable, gets selected as a destination for the forwarded notification 📣

8. Intellectual Property 📜

The IETF doesn't take a position on whether any intellectual property or other rights claimed to apply to the implementation or use of the technology in this document are valid or in scope, or on whether any license under those rights might or might not be available. It also doesn't say it has tried to find any such rights. Info on the IETF's procedures for rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication, any assurances of licenses to be made available, or the result of any attempt to get a general license or permission for implementors or users of this specification to use such proprietary rights 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 that may cover technology required to practice this standard 🔔 Please send that information to the IETF Executive Director 💌

9. Acknowledgments ✨

okay so this whole doc came out of the SNMPv3 Working Group, and they deserve every bit of praise 💖 special shoutouts to these 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 (Enterasys Networks)
Lauren Heintz (BMC Software, Inc.)
N.C. Hien (IBM T.J. Watson Research Center)
Michael Kirkham (InterWorking Labs, Inc.)
Dave Levi (Nortel Networks)
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 (Lucent Technologies)

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 (Enterasys Networks)
Jeff Johnson (Cisco Systems)
David Levi (Nortel Networks)
John Linn (Openvision)
Russ Mundy (Trusted Information Systems) chair
Shawn Routhier (Epilogue)
Glenn Waters (Nortel)
Bert Wijnen (Lucent Technologies)

As the Advisory Team and the SNMPv3 Working Group Charter recommended, the design takes as much as practical from previous RFCs and drafts 🌸 so big thanks go to the authors of the earlier designs known as SNMPv2u and SNMPv2*:

Jeff Case (SNMP Research, Inc.)
David Harrington (Enterasys Networks)
David Levi (Nortel Networks)
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.)

10. Security Considerations 🔐

this part is serious, bestie 😭 The SNMP applications described in this document typically have direct access to MIB instrumentation, so it is very important that these applications are strict about access control, exactly as this document describes 💀

There may also be some notification generator applications that don't touch MIB instrumentation through access control at all. Instead, they get MIB information some other way, like from a command line. The implementors and users of such applications must be responsible for not divulging MIB information that would normally be inaccessible due to access control 🙈

Finally, the MIBs described in this document contain potentially sensitive information, so a security administrator may want to limit access to these MIBs 🔒

11. References 📚

11.1 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.
[RFC3412] Case, J., Harrington, D., Presuhn, R. and B. Wijnen, "Message Processing and Dispatching for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3412, December 2002.
[RFC3415] Wijnen, B., Presuhn, R. and K. McCloghrie, "View-based Access Control Model (VACM) for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3415, December 2002.
[RFC3416] Presuhn, R., Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Protocol Operations for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3416, December 2002.
[RFC3418] Presuhn, R., Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Management Information Base (MIB) for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3418, December 2002.

11.2 Informative References

[RFC1157] Case, J., Fedor, M., Schoffstall, M. and J. Davin, "Simple Network Management Protocol", STD 15, RFC 1157, May 1990.
[RFC1213] McCloghrie, K. and M. Rose, Editors, "Management Information Base for Network Management of TCP/IP-based internets: MIB-II", STD 17, RFC 1213, March 1991.
[RFC2576] Frye, R.,Levi, D., Routhier, S. and B. Wijnen, "Coexistence between Version 1, Version 2, and Version 3 of the Internet-standard Network Management Framework", RFC 2576, February 1999.

Appendix A - Trap Configuration Example 🎀

this one's an example setup for a Notification Generator application that implements the snmpNotifyBasicCompliance level 🧚 the configuration tells the Notification Generator to send notifications to 3 separate managers: the first 2 use authentication with no privacy, and the third uses both authentication and privacy.

the config is made up of three rows in the snmpTargetAddrTable, two rows in the snmpTargetTable, and two rows in the snmpNotifyTable:

      * snmpTargetAddrName        = "addr1"
        snmpTargetAddrTDomain     = snmpUDPDomain
        snmpTargetAddrTAddress    = 128.1.2.3/162
        snmpTargetAddrTagList     = "group1"
        snmpTargetAddrParams      = "AuthNoPriv-joe"
        snmpTargetAddrStorageType = readOnly(5)
        snmpTargetAddrRowStatus   = active(1)

      * snmpTargetAddrName        = "addr2"
        snmpTargetAddrTDomain     = snmpUDPDomain
        snmpTargetAddrTAddress    = 128.2.4.6/162
        snmpTargetAddrTagList     = "group1"
        snmpTargetAddrParams      = "AuthNoPriv-joe"
        snmpTargetAddrStorageType = readOnly(5)
        snmpTargetAddrRowStatus   = active(1)

      * snmpTargetAddrName        = "addr3"
        snmpTargetAddrTDomain     = snmpUDPDomain
        snmpTargetAddrTAddress    = 128.1.5.9/162
        snmpTargetAddrTagList     = "group2"
        snmpTargetAddrParams      = "AuthPriv-bob"
        snmpTargetAddrStorageType = readOnly(5)
        snmpTargetAddrRowStatus   = active(1)

      * snmpTargetParamsName                   = "AuthNoPriv-joe"
        snmpTargetParamsMPModel                = 3
        snmpTargetParamsSecurityModel          = 3 (USM)
        snmpTargetParamsSecurityName           = "joe"
        snmpTargetParamsSecurityLevel          = authNoPriv(2)
        snmpTargetParamsStorageType            = readOnly(5)
        snmpTargetParamsRowStatus              = active(1)

      * snmpTargetParamsName                   = "AuthPriv-bob"
        snmpTargetParamsMPModel                = 3
        snmpTargetParamsSecurityModel          = 3 (USM)
        snmpTargetParamsSecurityName           = "bob"
        snmpTargetParamsSecurityLevel          = authPriv(3)
        snmpTargetParamsStorageType            = readOnly(5)
        snmpTargetParamsRowStatus              = active(1)

      * snmpNotifyName         = "group1"
        snmpNotifyTag          = "group1"
        snmpNotifyType         = trap(1)
        snmpNotifyStorageType  = readOnly(5)
        snmpNotifyRowStatus    = active(1)

      * snmpNotifyName         = "group2"
        snmpNotifyTag          = "group2"
        snmpNotifyType         = trap(1)
        snmpNotifyStorageType  = readOnly(5)
        snmpNotifyRowStatus    = active(1)

these entries set up two groups of management targets 💅 the first group has two management targets:

                                first target      second target
                                ------------      -------------
      messageProcessingModel   SNMPv3            SNMPv3
               securityModel   3 (USM)           3 (USM)
                securityName   "joe"             "joe"
               securityLevel   authNoPriv(2)     authNoPriv(2)
             transportDomain   snmpUDPDomain     snmpUDPDomain
            transportAddress   128.1.2.3/162     128.2.4.6/162

and the second group has a single management target:

      messageProcessingModel   SNMPv3
               securityLevel   authPriv(3)
               securityModel   3 (USM)
                securityName   "bob"
             transportDomain   snmpUDPDomain
            transportAddress   128.1.5.9/162

Editors' Addresses 💌

   David B. Levi
   Nortel Networks
   3505 Kesterwood Drive
   Knoxville, TN 37918
   U.S.A.

   Phone: +1 865 686 0432
   EMail: dlevi@nortelnetworks.com


   Paul Meyer
   Secure Computing Corporation
   2675 Long Lake Road
   Roseville, MN 55113
   U.S.A.

   Phone: +1 651 628 1592
   EMail: paul_meyer@securecomputing.com


   Bob Stewart
   Retired

Full Copyright Statement 💜

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📦 where this page comes from

ietf: rfc3413 2002-12
💖 girlified by claude-haiku-5-5 on 2026-10-17: a language model's rewrite of the original, under its terms