How to lookup mib-table in pysnmp?

Question

When I use snmpwalk on a OID ( 1.3.6.1.4.1.2021.4), i get the following result as:

UCD-SNMP-MIB::memIndex.0 = INTEGER: 0

UCD-SNMP-MIB::memErrorName.0 = STRING: swap

UCD-SNMP-MIB::memMinimumSwap.0 = INTEGER: 16000 kB

But, when i use the pysnmp module to query the same OID, i get the results as:

(ObjectName(1.3.6.1.4.1.2021.4.1.0), Integer(0))

(ObjectName(1.3.6.1.4.1.2021.4.2.0), OctetString('swap'))

(ObjectName(1.3.6.1.4.1.2021.4.12.0), Integer(16000))

I have put the pysnmp_mibs in os.environ and the code i'm using is:

from pysnmp.entity.rfc3413.oneliner import cmdgen
from pysnmp.smi import builder, view, error

errorIndication, errorStatus, errorIndex, \
             varBindTable = cmdGen.nextCmd (
cmdgen.CommunityData('test-agent', 'public'),
cmdgen.UdpTransportTarget ( (localhost, 161) ),
('1.3.6.1.4.1.2021.4')
)

if errorIndication:
    log.warn(errorIndication)
    return
else:
    if errorStatus:
        log.warn( '%s at %s\n' % (
            errorStatus.prettyPrint (),
            errorIndex and varBindTable[-1][int (errorIndex) - 1] or '?'
            ))
        return
    else:
        for varBindTableRow in varBindTable:
            for oid, val in varBindTableRow:
                    (symName, modName), indices = cmdgen.mibvar.oidToMibName(
                        cmdGen.mibViewController, oid
                        )
                    val = cmdgen.mibvar.cloneFromMibValue(
                                  cmdGen.mibViewController, modName, symName, val
                          )
            print varBindTableRow

My question is why is snmpwalk and pysnmp results different, and what should i do to get the results same as snmpwalk using pysnmp module?

---

Edited:

i tried the code,but on querying 1.3.6.1.2.1.4.22.1 i get the following error

NoSuchObjectError: NoSuchObjectError({'str': 'No MIB info for    (1, 3, 6, 1, 4, 1, 2021, 4, 1, 0) (closest parent (1, 3, 6, 1, 4, 1))'})

I have loaded the IP-MIB module as:

mibBuilder = builder.MibBuilder() 
mibPath = mibBuilder.getMibSources()+(builder.DirMibSource(path_to_mib_dir),)
mibBuilder.setMibSources(*mibPath)
mibBuilder.loadModules('IP-MIB')
mibView = view.MibViewController(mibBuilder)

What i am confused is how do i use this mibView in

(symName,modName),indices=cmdgen.mibvar.oidToMibName(cmdGen.mibViewController, oid)
val=cmdgen.mibvar.cloneFromMibValue(cmdGen.mibViewController,modName, symName, val)

should the cmdGen.mibViewController be replaced with the mibView?

but it works on OID 1.3.6.1.2.1.1.3: and i get the result as expected as:

SNMPv2-MIB::sysUpTime.0 = 27

Answer 1

Try printing:

print '%s::%s.%s = %s' % (
                    modName, symName,
                    '.'.join(map(lambda v: v.prettyPrint(), indices),
                    val.prettyPrint()
                    )

instead of

print varBindTableRow

Also make sure you load appropriate MIB.

Answer 2

Sorry, but the results are the same !

If your problem is about 16000 versus 16000 KB, you must know that SNMP does not return the unit. SNMP V2 MIB allow just a place to give information about it, so SNMPWALK(as a client) is using it, not pysnmp.