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# Agent-Side MIB Implementations

    import sys
    from pysnmp.entity import engine, config
    from pysnmp.entity.rfc3413 import cmdrsp, context
    from pysnmp.carrier.asyncio.dgram import udp
    from pysnmp.proto.api import v2c

    # Create SNMP engine
    snmpEngine = engine.SnmpEngine()

    # Transport setup

    # UDP over IPv4
    config.add_transport(
        snmpEngine, udp.DOMAIN_NAME, udp.UdpTransport().open_server_mode(("127.0.0.1", 161))
    )

    # SNMPv2c setup

    # SecurityName <-> CommunityName mapping.
    config.add_v1_system(snmpEngine, "my-area", "public")

    # Allow read MIB access for this user / securityModels at VACM
    config.add_vacm_user(snmpEngine, 2, "my-area", "noAuthNoPriv", (1, 3, 6, 5))

    # Create an SNMP context
    snmpContext = context.SnmpContext(snmpEngine)

    # --- create custom Managed Object Instance ---

    mibBuilder = snmpContext.get_mib_instrum().get_mib_builder()

    MibScalar, MibScalarInstance = mibBuilder.import_symbols(
        "SNMPv2-SMI", "MibScalar", "MibScalarInstance"
    )

    class MyStaticMibScalarInstance(MibScalarInstance):
        # noinspection PyUnusedLocal,PyUnusedLocal
        def getValue(self, name, **context):
            return self.getSyntax().clone(
                f"Python {sys.version} running on a {sys.platform} platform"
            )

    mibBuilder.export_symbols(
        "__MY_MIB",
        MibScalar((1, 3, 6, 5, 1), v2c.OctetString()),
        MyStaticMibScalarInstance((1, 3, 6, 5, 1), (0,), v2c.OctetString()),
    )

    # --- end of Managed Object Instance initialization ----

    # Register SNMP Applications at the SNMP engine for particular SNMP context
    cmdrsp.GetCommandResponder(snmpEngine, snmpContext)
    cmdrsp.NextCommandResponder(snmpEngine, snmpContext)
    cmdrsp.BulkCommandResponder(snmpEngine, snmpContext)

    # Register an imaginary never-ending job to keep I/O dispatcher running forever
    snmpEngine.transport_dispatcher.job_started(1)

    # Run I/O dispatcher which would receive queries and send responses
    try:
        snmpEngine.open_dispatcher()
    except:
        snmpEngine.close_dispatcher()
        raise

`Download` script.

## Implementing conceptual table

Listen and respond to SNMP GET/SET/GETNEXT/GETBULK queries with the following options:

- SNMPv2c

- with SNMP community “public”

- define a simple SNMP Table within a newly created EXAMPLE-MIB

- pre-populate SNMP Table with a single row of values

- allow read access only to the subtree where example SNMP Table resides

- over IPv4/UDP, listening at 127.0.0.1:161

The following Net-SNMP commands will populate and walk a table:

$ snmpset -v2c -c public 127.0.0.1 1.3.6.6.1.5.2.97.98.99 s “my value”
$ snmpset -v2c -c public 127.0.0.1 1.3.6.6.1.5.4.97.98.99 i 4
$ snmpwalk -v2c -c public 127.0.0.1 1.3.6

…while the following command will destroy the same row

$ snmpset -v2c -c public 127.0.0.1 1.3.6.6.1.5.4.97.98.99 i 6
$ snmpwalk -v2c -c public 127.0.0.1 1.3.6

    from pysnmp.entity import engine, config
    from pysnmp.entity.rfc3413 import cmdrsp, context
    from pysnmp.carrier.asyncio.dgram import udp
    from pysnmp.proto.api import v2c

    # Create SNMP engine
    snmpEngine = engine.SnmpEngine()

    # Transport setup

    # UDP over IPv4
    config.add_transport(
        snmpEngine, udp.DOMAIN_NAME, udp.UdpTransport().open_server_mode(("127.0.0.1", 161))
    )

    # SNMPv2c setup

    # SecurityName <-> CommunityName mapping.
    config.add_v1_system(snmpEngine, "my-area", "public")

    # Allow read MIB access for this user / securityModels at VACM
    config.add_vacm_user(
        snmpEngine, 2, "my-area", "noAuthNoPriv", (1, 3, 6, 6), (1, 3, 6, 6)
    )

    # Create an SNMP context
    snmpContext = context.SnmpContext(snmpEngine)

    # --- define custom SNMP Table within a newly defined EXAMPLE-MIB ---

    mibBuilder = snmpContext.get_mib_instrum().get_mib_builder()

    (MibTable, MibTableRow, MibTableColumn, MibScalarInstance) = mibBuilder.import_symbols(
        "SNMPv2-SMI", "MibTable", "MibTableRow", "MibTableColumn", "MibScalarInstance"
    )

    (RowStatus,) = mibBuilder.import_symbols("SNMPv2-TC", "RowStatus")

    mibBuilder.export_symbols(
        "__EXAMPLE-MIB",
        # table object
        exampleTable=MibTable((1, 3, 6, 6, 1)).setMaxAccess("read-create"),
        # table row object, also carries references to table indices
        exampleTableEntry=MibTableRow((1, 3, 6, 6, 1, 5))
        .setMaxAccess("read-create")
        .setIndexNames((0, "__EXAMPLE-MIB", "exampleTableColumn1")),
        # table column: string index
        exampleTableColumn1=MibTableColumn(
            (1, 3, 6, 6, 1, 5, 1), v2c.OctetString()
        ).setMaxAccess("read-create"),
        # table column: string value
        exampleTableColumn2=MibTableColumn(
            (1, 3, 6, 6, 1, 5, 2), v2c.OctetString()
        ).setMaxAccess("read-create"),
        # table column: integer value with default
        exampleTableColumn3=MibTableColumn(
            (1, 3, 6, 6, 1, 5, 3), v2c.Integer32(123)
        ).setMaxAccess("read-create"),
        # table column: row status
        exampleTableStatus=MibTableColumn(
            (1, 3, 6, 6, 1, 5, 4), RowStatus("notExists")
        ).setMaxAccess("read-create"),
    )

    # --- end of custom SNMP table definition, empty table now exists ---

    # --- populate custom SNMP table with one row ---

    (
        exampleTableEntry,
        exampleTableColumn2,
        exampleTableColumn3,
        exampleTableStatus,
    ) = mibBuilder.import_symbols(
        "__EXAMPLE-MIB",
        "exampleTableEntry",
        "exampleTableColumn2",
        "exampleTableColumn3",
        "exampleTableStatus",
    )
    rowInstanceId = exampleTableEntry.getInstIdFromIndices("example record one")
    mibInstrumentation = snmpContext.get_mib_instrum()
    mibInstrumentation.write_variables(
        (exampleTableColumn2.name + rowInstanceId, "my string value"),
        (exampleTableColumn3.name + rowInstanceId, 123456),
        (exampleTableStatus.name + rowInstanceId, "createAndGo"),
    )

    # --- end of SNMP table population ---

    # Register SNMP Applications at the SNMP engine for particular SNMP context
    cmdrsp.GetCommandResponder(snmpEngine, snmpContext)
    cmdrsp.SetCommandResponder(snmpEngine, snmpContext)
    cmdrsp.NextCommandResponder(snmpEngine, snmpContext)
    cmdrsp.BulkCommandResponder(snmpEngine, snmpContext)

    # Register an imaginary never-ending job to keep I/O dispatcher running forever
    snmpEngine.transport_dispatcher.job_started(1)

    # Run I/O dispatcher which would receive queries and send responses
    try:
        snmpEngine.open_dispatcher()
    except:
        snmpEngine.close_dispatcher()
        raise

`Download` script.

## Serve non-default MIB tree

Listen and respond to SNMP GET/SET/GETNEXT/GETBULK queries with the following options:

- SNMPv3

- with USM username usr-md5-none

- using alternative set of Managed Objects addressed by contextEngineId: 8000000001020304, contextName: my-context

- allow access to SNMPv2-MIB objects (1.3.6.1.2.1)

- over IPv4/UDP, listening at 127.0.0.1:161

Either of the following Net-SNMP commands will walk this Agent:

$ snmpwalk -v3 -u usr-md5-none -l authNoPriv -A authkey1 -E 8000000001020304 -n my-context 127.0.0.1 .1.3.6
$ snmpwalk -v3 -u usr-md5-none -l authNoPriv -A authkey1 -E 8000000001020304 127.0.0.1 .1.3.6

    from pysnmp.entity import engine, config
    from pysnmp.entity.rfc3413 import cmdrsp, context
    from pysnmp.carrier.asyncio.dgram import udp
    from pysnmp.smi import instrum, builder
    from pysnmp.proto.api import v2c

    # Create SNMP engine
    snmpEngine = engine.SnmpEngine()

    # Transport setup

    # UDP over IPv4
    config.add_transport(
        snmpEngine, udp.DOMAIN_NAME, udp.UdpTransport().open_server_mode(("127.0.0.1", 161))
    )

    # SNMPv3/USM setup

    # user: usr-md5-none, auth: MD5, priv NONE
    config.add_v3_user(snmpEngine, "usr-md5-none", config.USM_AUTH_HMAC96_MD5, "authkey1")

    # Allow full MIB access for each user at VACM
    config.add_vacm_user(
        snmpEngine, 3, "usr-md5-none", "authNoPriv", (1, 3, 6, 1, 2, 1), (1, 3, 6, 1, 2, 1)
    )

    # Create an SNMP context with ContextEngineId = 8000000001020304
    snmpContext = context.SnmpContext(
        snmpEngine, contextEngineId=v2c.OctetString(hexValue="8000000001020304")
    )

    # Create an [empty] set of Managed Objects (MibBuilder), pass it to
    # Management Instrumentation Controller and register at SNMP Context
    # under ContextName 'my-context'
    snmpContext.register_context_name(
        v2c.OctetString("my-context"),  # Context Name
        instrum.MibInstrumController(builder.MibBuilder()),  # Managed Objects
    )

    # Register SNMP Applications at the SNMP engine for particular SNMP context
    cmdrsp.GetCommandResponder(snmpEngine, snmpContext)
    cmdrsp.SetCommandResponder(snmpEngine, snmpContext)
    cmdrsp.NextCommandResponder(snmpEngine, snmpContext)
    cmdrsp.BulkCommandResponder(snmpEngine, snmpContext)

    # Register an imaginary never-ending job to keep I/O dispatcher running forever
    snmpEngine.transport_dispatcher.job_started(1)

    # Run I/O dispatcher which would receive queries and send responses
    try:
        snmpEngine.open_dispatcher()
    except:
        snmpEngine.close_dispatcher()
        raise

`Download` script.

## Multiple MIB trees under distinct context names

Listen and respond to SNMP GET/SET/GETNEXT/GETBULK queries with the following options:

- SNMPv3

- with USM username usr-md5-none

- using two independent (empty) sets of Managed Objects addressed by SNMP context name context-a and context-b

- allow access to SNMPv2-MIB objects (1.3.6.1.2.1)

- over IPv4/UDP, listening at 127.0.0.1:161

Either of the following Net-SNMP commands will walk this Agent:

$ snmpwalk -v3 -u usr-md5-none -l authNoPriv -A authkey1 -n context-a 127.0.0.1 .1.3.6
$ snmpwalk -v3 -u usr-md5-none -l authNoPriv -A authkey1 -n context-b 127.0.0.1 .1.3.6

    from pysnmp.entity import engine, config
    from pysnmp.entity.rfc3413 import cmdrsp, context
    from pysnmp.carrier.asyncio.dgram import udp
    from pysnmp.smi import instrum, builder
    from pysnmp.proto.api import v2c

    # Create SNMP engine
    snmpEngine = engine.SnmpEngine()

    # Transport setup

    # UDP over IPv4
    config.add_transport(
        snmpEngine, udp.domainName, udp.UdpTransport().open_server_mode(("127.0.0.1", 161))
    )

    # SNMPv3/USM setup

    # user: usr-md5-none, auth: MD5, priv NONE
    config.add_v3_user(snmpEngine, "usr-md5-none", config.USM_AUTH_HMAC96_MD5, "authkey1")

    # Allow full MIB access for each user at VACM
    config.add_vacm_user(
        snmpEngine, 3, "usr-md5-none", "authNoPriv", (1, 3, 6, 1, 2, 1), (1, 3, 6, 1, 2, 1)
    )

    # Create an SNMP context with default ContextEngineId (same as SNMP engine ID)
    snmpContext = context.SnmpContext(snmpEngine)

    # Create multiple independent trees of MIB managed objects (empty so far)
    mibTreeA = instrum.MibInstrumController(builder.MibBuilder())
    mibTreeB = instrum.MibInstrumController(builder.MibBuilder())

    # Register MIB trees at distinct SNMP Context names
    snmpContext.register_context_name(v2c.OctetString("context-a"), mibTreeA)
    snmpContext.register_context_name(v2c.OctetString("context-b"), mibTreeB)

    # Register SNMP Applications at the SNMP engine for particular SNMP context
    cmdrsp.GetCommandResponder(snmpEngine, snmpContext)
    cmdrsp.SetCommandResponder(snmpEngine, snmpContext)
    cmdrsp.NextCommandResponder(snmpEngine, snmpContext)
    cmdrsp.BulkCommandResponder(snmpEngine, snmpContext)

    # Register an imaginary never-ending job to keep I/O dispatcher running forever
    snmpEngine.transport_dispatcher.job_started(1)

    # Run I/O dispatcher which would receive queries and send responses
    try:
        snmpEngine.open_dispatcher()

    except:
        snmpEngine.close_dispatcher()
        raise

`Download` script.

## Custom MIB Controller

Listen and respond to SNMP GET/SET/GETNEXT/GETBULK queries with the following options:

- SNMPv3

- with USM username usr-none-none

- using alternative set of Managed Objects addressed by contextName: my-context

- allow access to SNMPv2-MIB objects (1.3.6.1.2.1)

- over IPv4/UDP, listening at 127.0.0.1:161

The following Net-SNMP command will send GET request to this Agent:

$ snmpget -v3 -u usr-none-none -l noAuthNoPriv -n my-context -Ir 127.0.0.1 sysDescr.0

    from pysnmp.entity import engine, config
    from pysnmp.entity.rfc3413 import cmdrsp, context
    from pysnmp.carrier.asyncio.dgram import udp
    from pysnmp.smi import instrum
    from pysnmp.proto.api import v2c

    # Create SNMP engine
    snmpEngine = engine.SnmpEngine()

    # Transport setup

    # UDP over IPv4
    config.add_transport(
        snmpEngine, udp.DOMAIN_NAME, udp.UdpTransport().open_server_mode(("127.0.0.1", 161))
    )

    # SNMPv3/USM setup

    # user: usr-none-none, auth: NONE, priv NONE
    config.add_v3_user(snmpEngine, "usr-none-none")

    # Allow full MIB access for each user at VACM
    config.add_vacm_user(
        snmpEngine,
        3,
        "usr-none-none",
        "noAuthNoPriv",
        (1, 3, 6, 1, 2, 1),
        (1, 3, 6, 1, 2, 1),
    )

    # Create an SNMP context
    snmpContext = context.SnmpContext(snmpEngine)

    # Very basic Management Instrumentation Controller without
    # any Managed Objects attached. It supports only GET's and
    # always echos request var-binds in response.
    class EchoMibInstrumController(instrum.AbstractMibInstrumController):
        def read_variables(self, *varBinds, **context):
            return [
                (ov[0], v2c.OctetString("You queried OID %s" % ov[0])) for ov in varBinds
            ]

    # Create a custom Management Instrumentation Controller and register at
    # SNMP Context under ContextName 'my-context'
    snmpContext.register_context_name(
        v2c.OctetString("my-context"),  # Context Name
        EchoMibInstrumController(),  # Management Instrumentation
    )

    # Register GET&SET Applications at the SNMP engine for a custom SNMP context
    cmdrsp.GetCommandResponder(snmpEngine, snmpContext)
    cmdrsp.SetCommandResponder(snmpEngine, snmpContext)

    # Register an imaginary never-ending job to keep I/O dispatcher running forever
    snmpEngine.transport_dispatcher.job_started(1)

    # Run I/O dispatcher which would receive queries and send responses
    try:
        snmpEngine.open_dispatcher()
    except:
        snmpEngine.close_dispatcher()
        raise

`Download` script.

See also: library reference.