# Transport tweaks

## Serving multiple network interfaces

Receive SNMP TRAP/INFORM messages with the following options:

- SNMPv1/SNMPv2c

- with SNMP community “public”

- listen on two local network interfaces:

    - IPv4/UDP, listening at 127.0.0.1:162

    - IPv4/UDP, listening at 127.0.0.1:2162

- using Twisted 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

    from twisted.internet import reactor
    from pysnmp.entity import engine, config
    from pysnmp.carrier.twisted.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.addTransport(
        snmpEngine,
        udp.domainName + (1,),
        udp.UdpTwistedTransport().openServerMode(('127.0.0.1', 162))
    )

    # UDP over IPv4, second listening interface/port
    config.addTransport(
        snmpEngine,
        udp.domainName + (2,),
        udp.UdpTwistedTransport().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,PyUnusedLocal,PyUnusedLocal
    def cbFun(snmpEngine, stateReference, contextEngineId, contextName,
              varBinds, cbCtx):
        print('Notification from ContextEngineId "%s", Context "%s"' % (contextEngineId.prettyPrint(),
                                                                        contextName.prettyPrint()))
        for name, val in varBinds:
            print('%s = %s' % (name.prettyPrint(), val.prettyPrint()))

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

    # Run Twisted main loop
    reactor.run()

`Download` script.

See also: library reference.