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|
"""
IPv6-to-IPv4 conversion
+++++++++++++++++++++++
Act as a local SNMPv1/v2c Agent listening on a UDP/IPv6 transport, relay
messages to distant SNMPv1/2c Agent over UDP/IPv4 transport:
* with local SNMPv2c community 'public'
* local Agent listening at [::1]:161
* remote SNMPv2c community 'public'
* remote Agent listening at 195.218.195.228:161
This script can be queried with the following Net-SNMP command:
| $ snmpget -v2c -c public udp6:[::1]:161 sysDescr.0
due to proxy, it is equivalent to
| $ snmpget -v2c -c public 195.218.195.228:161 sysDescr.0
Warning: for production operation you would need to modify this script
so that it will re-map possible duplicate request-ID values, coming in
initial request PDUs from different Managers, into unique values to
avoid sending duplicate request-IDs to Agents.
"""#
from pysnmp.carrier.asyncore.dgram import udp, udp6
from pysnmp.entity import engine, config
from pysnmp.entity.rfc3413 import cmdrsp, cmdgen, context
from pysnmp.proto.api import v2c
from pysnmp import error
# Create SNMP engine with autogenernated engineID and pre-bound
# to socket transport dispatcher
snmpEngine = engine.SnmpEngine()
#
# Transport setup
#
# Agent section
# UDP over IPv6
config.addTransport(
snmpEngine,
udp6.domainName,
udp6.Udp6Transport().openServerMode(('::1', 161))
)
# Manager section
# UDP over IPv4
config.addTransport(
snmpEngine,
udp.domainName,
udp.UdpTransport().openClientMode()
)
#
# SNMPv1/2c setup (Agent role)
#
# SecurityName <-> CommunityName mapping
config.addV1System(snmpEngine, '1-my-area', 'public')
#
# SNMPv1/v2c setup (Manager role)
#
# Here we configure securityName lexicographically lesser than '1-my-area'
# to let it match first in snmpCommunityTable on response processing.
#
config.addV1System(snmpEngine, '0-distant-area', 'public',
transportTag='remote')
#
# Transport target used by Manager
#
config.addTargetParams(
snmpEngine, 'distant-agent-auth', '0-distant-area', 'noAuthNoPriv', 1
)
config.addTargetAddr(
snmpEngine, 'distant-agent',
udp.domainName, ('195.218.195.228', 161),
'distant-agent-auth', retryCount=0, tagList='remote'
)
# Default SNMP context
config.addContext(snmpEngine, '')
class CommandResponder(cmdrsp.CommandResponderBase):
cmdGenMap = {
v2c.GetRequestPDU.tagSet: cmdgen.GetCommandGenerator(),
v2c.SetRequestPDU.tagSet: cmdgen.SetCommandGenerator(),
v2c.GetNextRequestPDU.tagSet: cmdgen.NextCommandGeneratorSingleRun(),
v2c.GetBulkRequestPDU.tagSet: cmdgen.BulkCommandGeneratorSingleRun()
}
pduTypes = cmdGenMap.keys() # This app will handle these PDUs
# SNMP request relay
def handleMgmtOperation(self, snmpEngine, stateReference, contextName,
PDU, acInfo):
cbCtx = stateReference, PDU
contextEngineId = None # address authoritative SNMP Engine
try:
self.cmdGenMap[PDU.tagSet].sendPdu(
snmpEngine, 'distant-agent',
contextEngineId, contextName,
PDU,
self.handleResponsePdu, cbCtx
)
except error.PySnmpError:
self.handleResponsePdu(
stateReference, 'error', None, cbCtx
)
# SNMP response relay
def handleResponsePdu(self, snmpEngine, sendRequestHandle,
errorIndication, PDU, cbCtx):
stateReference, reqPDU = cbCtx
if errorIndication:
PDU = v2c.apiPDU.getResponse(reqPDU)
PDU.setErrorStatus(PDU, 5)
self.sendPdu(
snmpEngine, stateReference, PDU
)
self.releaseStateInformation(stateReference)
CommandResponder(snmpEngine, context.SnmpContext(snmpEngine))
snmpEngine.transportDispatcher.jobStarted(1) # this job would never finish
# Run I/O dispatcher which would receive queries and send responses
try:
snmpEngine.transportDispatcher.runDispatcher()
except:
snmpEngine.transportDispatcher.closeDispatcher()
raise
|
