# 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

- using Asyncio framework for network transport

- 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

Requires Python 3.4 and later!

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

    # Get the event loop for this thread
    loop = asyncio.get_event_loop()

    # 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.addTransport(
        snmpEngine,
        udp.domainName + (1,),
        udp.UdpTransport().openServerMode(("127.0.0.1", 162)),
    )

    # UDP over IPv4, second listening interface/port
    config.addTransport(
        snmpEngine,
        udp.domainName + (2,),
        udp.UdpTransport().openServerMode(("127.0.0.1", 2162)),
    )

    # SNMPv1/2c setup

    # SecurityName <-> CommunityName mapping
    config.addV1System(snmpEngine, "my-area", "public")

    # Callback function for receiving notifications
    # noinspection PyUnusedLocal
    def cbFun(snmpEngine, stateReference, contextEngineId, contextName, varBinds, cbCtx):
        transportDomain, transportAddress = snmpEngine.msgAndPduDsp.getTransportInfo(
            stateReference
        )
        print(
            "Notification from {}, SNMP Engine {}, Context {}".format(
                transportAddress, 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)

    # Run asyncio main loop
    loop.run_forever()

`Download` script.

See also: library reference.