Transport tweaks

TRAP over multiple transports

The following script sends two SNMP TRAP notification using the following options:

• with SNMPv1
• with community name ‘public’
• over IPv4/UDP and IPv6/UDP
• send TRAP notification
• to a Manager at demo.snmplabs.com:162 and [::1]
• with TRAP ID ‘coldStart’ specified as an OID
• include managed objects information:
• with default Uptime value
• with default Agent Address with ‘127.0.0.1’
• overriding Enterprise OID with 1.3.6.1.4.1.20408.4.1.1.2

The following Net-SNMP commands will produce similar SNMP notification:

$ snmptrap -v1 -c public udp:demo.snmplabs.com 1.3.6.1.4.1.20408.4.1.1.2 127.0.0.1 1 0 12345

$ snmptrap -v1 -c public udp6:[::1] 1.3.6.1.4.1.20408.4.1.1.2 127.0.0.1 1 0 12345

from pysnmp.carrier.asyncore.dispatch import AsyncoreDispatcher
from pysnmp.carrier.asyncore.dgram import udp, udp6
from pyasn1.codec.ber import encoder
from pysnmp.proto import api

# Protocol version to use
pMod = api.PROTOCOL_MODULES[api.SNMP_VERSION_1]
# pMod = api.protoModules[api.protoVersion2c]

# Build PDU
trapPDU = pMod.TrapPDU()
pMod.apiTrapPDU.setDefaults(trapPDU)

# Traps have quite different semantics across proto versions
if pMod == api.PROTOCOL_MODULES[api.SNMP_VERSION_1]:
    pMod.apiTrapPDU.setEnterprise(trapPDU, (1, 3, 6, 1, 1, 2, 3, 4, 1))
    pMod.apiTrapPDU.setGenericTrap(trapPDU, 'coldStart')

# Build message
trapMsg = pMod.Message()
pMod.apiMessage.setDefaults(trapMsg)
pMod.apiMessage.setCommunity(trapMsg, 'public')
pMod.apiMessage.setPDU(trapMsg, trapPDU)

transportDispatcher = AsyncoreDispatcher()

# UDP/IPv4
transportDispatcher.registerTransport(
    udp.DOMAIN_NAME, udp.UdpSocketTransport().openClientMode()
)

transportDispatcher.sendMessage(
    encoder.encode(trapMsg), udp.DOMAIN_NAME, ('demo.snmplabs.com', 162)
)

# UDP/IPv6
transportDispatcher.registerTransport(
    udp6.DOMAIN_NAME, udp6.Udp6SocketTransport().openClientMode()
)

transportDispatcher.sendMessage(
    encoder.encode(trapMsg), udp6.DOMAIN_NAME, ('::1', 162)
)

# Dispatcher will finish as all scheduled messages are sent
transportDispatcher.runDispatcher()

transportDispatcher.closeDispatcher()

Download script.

INFORM over multiple transports

The following script sends SNMP INFORM notification using the following options:

• with SNMPv2c
• with community name ‘public’
• over IPv4/UDP and IPv6/UDP
• send INFORM notification
• to a Manager at demo.snmplabs.com:162 and [::1]:162
• with TRAP ID ‘coldStart’ specified as an OID

The following Net-SNMP command will produce similar SNMP notification:

$ snmpinform -v2c -c public udp:demo.snmplabs.com 0 1.3.6.1.6.3.1.1.5.1

$ snmpinform -v2c -c public udp6:[::1] 0 1.3.6.1.6.3.1.1.5.1

from time import time
from pysnmp.carrier.asyncore.dispatch import AsyncoreDispatcher
from pysnmp.carrier.asyncore.dgram import udp, udp6
from pyasn1.codec.ber import encoder, decoder
from pysnmp.proto.api import v2c as pMod

# Build PDU
reqPDU = pMod.InformRequestPDU()
pMod.apiTrapPDU.setDefaults(reqPDU)

# Build message
trapMsg = pMod.Message()
pMod.apiMessage.setDefaults(trapMsg)
pMod.apiMessage.setCommunity(trapMsg, 'public')
pMod.apiMessage.setPDU(trapMsg, reqPDU)

startedAt = time()


def cbTimerFun(timeNow):
    if timeNow - startedAt > 3:
        raise Exception("Request timed out")


def cbRecvFun(transportDispatcher, transportDomain, transportAddress,
              wholeMsg, reqPDU=reqPDU):

    while wholeMsg:
        rspMsg, wholeMsg = decoder.decode(wholeMsg, asn1Spec=pMod.Message())
        rspPDU = pMod.apiMessage.getPDU(rspMsg)

        # Match response to request
        if pMod.apiPDU.getRequestID(reqPDU) == pMod.apiPDU.getRequestID(rspPDU):

            # Check for SNMP errors reported
            errorStatus = pMod.apiPDU.getErrorStatus(rspPDU)
            if errorStatus:
                print(errorStatus.prettyPrint())

            else:
                print('INFORM message delivered, response var-binds follow')

                for oid, val in pMod.apiPDU.getVarBinds(rspPDU):
                    print('%s = %s' % (oid.prettyPrint(), val.prettyPrint()))

            transportDispatcher.jobFinished(1)

    return wholeMsg


transportDispatcher = AsyncoreDispatcher()

transportDispatcher.registerRecvCbFun(cbRecvFun)
transportDispatcher.registerTimerCbFun(cbTimerFun)

# UDP/IPv4
transportDispatcher.registerTransport(
    udp.DOMAIN_NAME, udp.UdpSocketTransport().openClientMode()
)
transportDispatcher.sendMessage(
    encoder.encode(trapMsg), udp.DOMAIN_NAME, ('demo.snmplabs.com', 162)
)
transportDispatcher.jobStarted(1)

# UDP/IPv6
# transportDispatcher.registerTransport(
#    udp6.domainName, udp6.Udp6SocketTransport().openClientMode()
# )
# transportDispatcher.sendMessage(
#    encoder.encode(trapMsg), udp6.domainName, ('::1', 162)
# )
# transportDispatcher.jobStarted(1)

# Dispatcher will finish as all scheduled messages are sent
transportDispatcher.runDispatcher()

transportDispatcher.closeDispatcher()

Download script.

See also: library reference.