# Transport tweaks

## Serving multiple network interfaces

Receive SNMP TRAP/INFORM messages with the following options:

- SNMPv1/SNMPv2c

- with SNMP community “public”

- over IPv4/UDP, listening at 127.0.0.1:162 over IPv4/UDP, listening at 127.0.0.1:2162

- print received data on stdout

Either of the following Net-SNMP commands will send notifications to this receiver:

$ snmptrap -v2c -c public 127.0.0.1:162 123 1.3.6.1.6.3.1.1.5.1 1.3.6.1.2.1.1.5.0 s test
$ snmpinform -v2c -c public 127.0.0.1:2162 123 1.3.6.1.6.3.1.1.5.1

    from pysnmp.entity import engine, config
    from pysnmp.carrier.asyncio.dgram import udp
    from pysnmp.entity.rfc3413 import ntfrcv

    # Create SNMP engine with autogenernated engineID and pre-bound
    # to socket transport dispatcher
    snmpEngine = engine.SnmpEngine()

    # Transport setup

    # UDP over IPv4, first listening interface/port
    config.add_transport(
        snmpEngine,
        udp.DOMAIN_NAME + (1,),
        udp.UdpTransport().open_server_mode(("127.0.0.1", 162)),
    )

    # UDP over IPv4, second listening interface/port
    config.add_transport(
        snmpEngine,
        udp.DOMAIN_NAME + (2,),
        udp.UdpTransport().open_server_mode(("127.0.0.1", 2162)),
    )

    # SNMPv1/2c setup

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

    # Callback function for receiving notifications
    # noinspection PyUnusedLocal,PyUnusedLocal,PyUnusedLocal
    def cbFun(snmpEngine, stateReference, contextEngineId, contextName, varBinds, cbCtx):
        print(
            'Notification from ContextEngineId "{}", ContextName "{}"'.format(
                contextEngineId.prettyPrint(), contextName.prettyPrint()
            )
        )
        for name, val in varBinds:
            print(f"{name.prettyPrint()} = {val.prettyPrint()}")

    # Register SNMP Application at the SNMP engine
    ntfrcv.NotificationReceiver(snmpEngine, cbFun)

    snmpEngine.transport_dispatcher.job_started(1)  # this job would never finish

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

`Download` script.

See also: library reference.

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