# 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.asyncore.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.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,PyUnusedLocal,PyUnusedLocal
    def cbFun(snmpEngine, stateReference, contextEngineId, contextName,
              varBinds, cbCtx):
        print('Notification from ContextEngineId "%s", ContextName "%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)

    snmpEngine.transportDispatcher.jobStarted(1)  # this job would never finish

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

`Download` script.

## Using multiple network transports

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 IPv6/UDP, listening at [::1]:162

- print received data on stdout

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

$ snmptrap -v1 -c public 127.0.0.1 1.3.6.1.4.1.20408.4.1.1.2 127.0.0.1 1 1 123 1.3.6.1.2.1.1.1.0 s test
$ snmptrap -v2c -c public udp6:[::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 127.0.0.1 123 1.3.6.1.6.3.1.1.5.1

    from pysnmp.entity import engine, config
    from pysnmp.carrier.asyncore.dgram import udp, udp6
    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
    config.addTransport(
        snmpEngine,
        udp.domainName,
        udp.UdpTransport().openServerMode(('127.0.0.1', 162))
    )

    # UDP over IPv6
    config.addTransport(
        snmpEngine,
        udp6.domainName,
        udp6.Udp6Transport().openServerMode(('::1', 162))
    )

    # 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", ContextName "%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)

    snmpEngine.transportDispatcher.jobStarted(1)  # this job would never finish

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

`Download` script.

## Receive notifications noting peer address

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

- use observer facility to pull lower-level request details from SNMP engine

- 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

    from pysnmp.entity import engine, config
    from pysnmp.carrier.asyncore.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.UdpTransport().openServerMode(('127.0.0.1', 162))
    )

    # SNMPv1/2c setup

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

    # Callback function for receiving notifications
    # noinspection PyUnusedLocal,PyUnusedLocal
    def cbFun(snmpEngine, stateReference, contextEngineId, contextName,
              varBinds, cbCtx):
        # Get an execution context...
        execContext = snmpEngine.observer.getExecutionContext(
            'rfc3412.receiveMessage:request'
        )

        # ... and use inner SNMP engine data to figure out peer address
        print('Notification from %s, ContextEngineId "%s", ContextName "%s"' % ('@'.join([str(x) for x in execContext['transportAddress']]),
                                                                                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)

    snmpEngine.transportDispatcher.jobStarted(1)  # this job would never finish

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

`Download` script.

See also: library reference.