Agent side#
Implementing MIB objects#
This script explains how SNMP Agent application could model real-world data as Managed Objects defined in MIB.
from pysnmp.smi import builder
# MIB Builder is normally pre-created by SNMP engine
mibBuilder = builder.MibBuilder()
#
# This may be done in a stand-alone file and then loaded up
# by SNMP Agent
#
# A base class for a custom Managed Object
(MibScalarInstance,) = mibBuilder.importSymbols("SNMPv2-SMI", "MibScalarInstance")
# Managed object specification
(sysLocation,) = mibBuilder.importSymbols("SNMPv2-MIB", "sysLocation")
# Custom Managed Object
class MySysLocationInstance(MibScalarInstance):
# noinspection PyUnusedLocal
def readGet(self, name, *args):
# Just return a custom value
return name, self.syntax.clone("The Leaky Cauldron")
sysLocationInstance = MySysLocationInstance(sysLocation.name, (0,), sysLocation.syntax)
# Register Managed Object with a MIB tree
mibBuilder.exportSymbols(
# '__' prefixed MIB modules take precedence on indexing
"__MY-LOCATION-MIB",
sysLocationInstance=sysLocationInstance,
)
if __name__ == "__main__":
#
# This is what is done internally by Agent.
#
from pysnmp.smi import instrum, exval
mibInstrum = instrum.MibInstrumController(mibBuilder)
print("Remote manager read access to MIB instrumentation (table walk)")
oid, val = (), None
while 1:
oid, val = mibInstrum.readNextVars(((oid, val),))[0]
if exval.endOfMib.isSameTypeWith(val):
break
print(oid, val.prettyPrint())
Download
script.
Agent operations on MIB#
This script explains how SNMP Agent application manipulates its MIB possibly triggered by SNMP Manager’s commands.
# SNMP agent backend e.g. Agent access to Managed Objects
from pysnmp.smi import builder, instrum, exval
print("Loading MIB modules..."),
mibBuilder = builder.MibBuilder().loadModules(
"SNMPv2-MIB", "SNMP-FRAMEWORK-MIB", "SNMP-COMMUNITY-MIB"
)
print("done")
print("Building MIB tree..."),
mibInstrum = instrum.MibInstrumController(mibBuilder)
print("done")
print("Building table entry index from human-friendly representation..."),
(snmpCommunityEntry,) = mibBuilder.importSymbols(
"SNMP-COMMUNITY-MIB", "snmpCommunityEntry"
)
instanceId = snmpCommunityEntry.getInstIdFromIndices("my-router")
print("done")
print("Create/update SNMP-COMMUNITY-MIB::snmpCommunityEntry table row: ")
varBinds = mibInstrum.writeVars(
(
(snmpCommunityEntry.name + (2,) + instanceId, "mycomm"),
(snmpCommunityEntry.name + (3,) + instanceId, "mynmsname"),
(snmpCommunityEntry.name + (7,) + instanceId, "volatile"),
)
)
for oid, val in varBinds:
print(
"{} = {}".format(
".".join([str(x) for x in oid]),
not val.isValue and "N/A" or val.prettyPrint(),
)
)
print("done")
print("Read whole MIB (table walk)")
oid, val = (), None
while True:
oid, val = mibInstrum.readNextVars(((oid, val),))[0]
if exval.endOfMib.isSameTypeWith(val):
break
print(
"{} = {}".format(
".".join([str(x) for x in oid]),
not val.isValue and "N/A" or val.prettyPrint(),
)
)
print("done")
print("Unloading MIB modules..."),
mibBuilder.unloadModules()
print("done")
Download
script.
See also: library reference.