Synchronous SNMP (v3arch)¶

This chapter illustrates various uses of the synchronous high-level programming interface to some of Standard SNMP Applications, as defined in RFC3413.

Note

The following examples involve creating Python iterator, the next() call is used to invoke iterator just once.

In most examples approximate analogues of well known Net-SNMP snmp* tools command line options are shown. That may help those readers who, by chance are familiar with Net-SNMP tools, better understanding what the example code does.

Here’s a quick example on a simple SNMP GET by high-level API:

with SNMPv1, community ‘public’

over IPv4/UDP

to an Agent at demo.snmplabs.com:161

for two instances of SNMPv2-MIB::sysDescr.0 MIB object,

from pysnmp.hlapi import *

iterator = getCmd(
    SnmpEngine(),
    CommunityData('public', mpModel=0),
    UdpTransportTarget(('demo.snmplabs.com', 161)),
    ContextData(),
    ObjectType(ObjectIdentity('SNMPv2-MIB', 'sysDescr', 0))
)

errorIndication, errorStatus, errorIndex, varBinds = next(iterator)

if errorIndication:
    print(errorIndication)

elif errorStatus:
    print('%s at %s' % (errorStatus.prettyPrint(),
                        errorIndex and varBinds[int(errorIndex) - 1][0] or '?'))

else:
    for varBind in varBinds:
        print(' = '.join([x.prettyPrint() for x in varBind]))

To make use of SNMPv3 and USM, the following code performs a series of SNMP GETNEXT operations effectively fetching a table of SNMP variables from SNMP Agent:

with SNMPv3, user ‘usr-md5-none’, MD5 authentication, no privacy
over IPv4/UDP
to an Agent at demo.snmplabs.com:161
for all OIDs in IF-MIB

from pysnmp.hlapi import *

iterator = nextCmd(
    SnmpEngine(),
    UsmUserData('usr-md5-none', 'authkey1'),
    UdpTransportTarget(('demo.snmplabs.com', 161)),
    ContextData(),
    ObjectType(ObjectIdentity('IF-MIB'))
)

for errorIndication, errorStatus, errorIndex, varBinds in iterator:

    if errorIndication:
        print(errorIndication)
        break

    elif errorStatus:
        print('%s at %s' % (errorStatus.prettyPrint(),
                            errorIndex and varBinds[int(errorIndex) - 1][0] or '?'))
        break

    else:
        for varBind in varBinds:
            print(' = '.join([x.prettyPrint() for x in varBind]))

More examples on Command Generator API usage follow.

Sending SNMP TRAP’s and INFORM’s is as easy with PySNMP library. The following code sends SNMP TRAP:

SNMPv1
with community name ‘public’
over IPv4/UDP
send TRAP notification
with Generic Trap #1 (warmStart) and Specific Trap 0
with default Uptime
with default Agent Address
with Enterprise OID 1.3.6.1.4.1.20408.4.1.1.2
include managed object information ‘1.3.6.1.2.1.1.1.0’ = ‘my system’

from pysnmp.hlapi import *

iterator = sendNotification(
    SnmpEngine(),
    CommunityData('public', mpModel=0),
    UdpTransportTarget(('demo.snmplabs.com', 162)),
    ContextData(),
    'trap',
    NotificationType(
        ObjectIdentity('1.3.6.1.6.3.1.1.5.2')
    ).addVarBinds(
        ('1.3.6.1.6.3.1.1.4.3.0', '1.3.6.1.4.1.20408.4.1.1.2'),
        ('1.3.6.1.2.1.1.1.0', OctetString('my system'))
    ).loadMibs(
        'SNMPv2-MIB'
    )
)

errorIndication, errorStatus, errorIndex, varBinds = next(iterator)

if errorIndication:
    print(errorIndication)

More examples on Notification Originator API usage follow.

More sophisticated or less popular SNMP operations can still be performed with PySNMP through its Native API to Standard SNMP Applications.

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Synchronous SNMP (v3arch)¶