How to implement SNMP TRAP originator in v2c with pysnmp - snmp

Question

I am implementing a SNMP command responder using pysnmp which will respond to SNMP GET/GETNEXT/SET and also will originate SNMP TRAP messages based on events. I have already implemented GET/GETNEXT/SET based on this example but facing issues with TRAP. For TRAP I have followed this example which is for SNMP v1. I have converted it for v2c as instructed(changing line 31,32 and excluding 39-41). It worked, originated a TRAP message in v2c. But I want to originate a TRAP message with specific OID and octet string. Couldn't find any example of this. How can I do this?

Answer 1

Debian's package python-pysnmp4-doc v4.2.5-1 contains trap-v2c.py
#
# Notification Originator
#
# Send SNMP TRAP notification using the following options:
#
# * SNMPv2c
# * with community name 'public'
# * over IPv4/UDP
# * send TRAP notification
# * to a Manager at 127.0.0.1:162
# * with TRAP ID 'coldStart' specified as an OID
# * include managed objects information:
# 1.3.6.1.2.1.1.1.0 = 'Example Notificator'
# 1.3.6.1.2.1.1.5.0 = 'Notificator Example'
from pysnmp.entity import engine, config
from pysnmp.carrier.asynsock.dgram import udp
from pysnmp.entity.rfc3413 import ntforg, context
from pysnmp.proto.api import v2c
# Create SNMP engine instance
snmpEngine = engine.SnmpEngine()
# SecurityName <-> CommunityName mapping
config.addV1System(snmpEngine, 'my-area', 'public', transportTag='all-my-managers')
# Specify security settings per SecurityName (SNMPv2c -> 1)
config.addTargetParams(snmpEngine, 'my-creds', 'my-area', 'noAuthNoPriv', 1)
# Setup transport endpoint and bind it with security settings yielding
# a target name
config.addTransport(
snmpEngine,
udp.domainName,
udp.UdpSocketTransport().openClientMode()
)
config.addTargetAddr(
snmpEngine, 'my-nms',
udp.domainName, ('localhost', 162),
'my-creds',
tagList='all-my-managers'
)
# Specify what kind of notification should be sent (TRAP or INFORM),
# to what targets (chosen by tag) and what filter should apply to
# the set of targets (selected by tag)
config.addNotificationTarget(
snmpEngine, 'my-notification', 'my-filter', 'all-my-managers', 'trap'
)
# Allow NOTIFY access to Agent's MIB by this SNMP model (2), securityLevel
# and SecurityName
config.addContext(snmpEngine, '')
config.addVacmUser(snmpEngine, 2, 'my-area', 'noAuthNoPriv', (), (), (1,3,6))
# *** SNMP engine configuration is complete by this line ***
# Create default SNMP context where contextEngineId == SnmpEngineId
snmpContext = context.SnmpContext(snmpEngine)
# Create Notification Originator App instance.
ntfOrg = ntforg.NotificationOriginator(snmpContext)
# Error/confirmation receiver
def cbFun(sendRequestHandle, errorIndication, cbCtx):
print('Notification %s, status - %s' % (
sendRequestHandle, errorIndication and errorIndication or 'delivered'
)
)
# Build and submit notification message to dispatcher
ntfOrg.sendNotification(
snmpEngine,
# Notification targets
'my-notification',
# Trap OID (SNMPv2-MIB::coldStart)
(1,3,6,1,6,3,1,1,5,1),
# ( (oid, value), ... )
( ((1,3,6,1,2,1,1,1,0), v2c.OctetString('Example Notificator')),
((1,3,6,1,2,1,1,5,0), v2c.OctetString('Notificator Example')) ),
cbFun
)
print('Notification is scheduled to be sent')
# Run I/O dispatcher which would send pending message and process response
snmpEngine.transportDispatcher.runDispatcher()