Change or personalize OID

Question

Finally managed to have my RPI computer module to work with SNMP. I have a script running that gives me one of my parameters and if I use query using SNMP I get the info back.

pi@raspberrypi:~ $ snmpwalk -v2c -c public localhost NET-SNMP-EXTEND-MIB::nsExtendObjects | grep snmp_status
NET-SNMP-EXTEND-MIB::nsExtendCommand."snmp_status" = STRING: /home/pi/BDC/snmp_status.py
NET-SNMP-EXTEND-MIB::nsExtendArgs."snmp_status" = STRING:
NET-SNMP-EXTEND-MIB::nsExtendInput."snmp_status" = STRING:
NET-SNMP-EXTEND-MIB::nsExtendCacheTime."snmp_status" = INTEGER: 5
NET-SNMP-EXTEND-MIB::nsExtendExecType."snmp_status" = INTEGER: exec(1)
NET-SNMP-EXTEND-MIB::nsExtendRunType."snmp_status" = INTEGER: run-on-read(1)
NET-SNMP-EXTEND-MIB::nsExtendStorage."snmp_status" = INTEGER: permanent(4)
NET-SNMP-EXTEND-MIB::nsExtendStatus."snmp_status" = INTEGER: active(1)
NET-SNMP-EXTEND-MIB::nsExtendOutput1Line."snmp_status" = STRING: 0
NET-SNMP-EXTEND-MIB::nsExtendOutputFull."snmp_status" = STRING: 0
NET-SNMP-EXTEND-MIB::nsExtendOutNumLines."snmp_status" = INTEGER: 1
NET-SNMP-EXTEND-MIB::nsExtendResult."snmp_status" = INTEGER: 0
NET-SNMP-EXTEND-MIB::nsExtendOutLine."snmp_status".1 = STRING: 0

If my unit is in alarm replies with NET-SNMP-EXTEND-MIB::nsExtendOutLine."snmp_status".1 = STRING: 1 if not in alarm replies with NET-SNMP-EXTEND-MIB::nsExtendOutLine."snmp_status".1 = STRING: 0

This status is stored in a file and it's parsed to the SNMP using a python script.

Now... next question. The SNMP server gives me the following OID .1.3.6.1.4.1.8072.1.3.2.3.1.2.11.115.110.109.112.95.115.116.97.116.117.115

and for each parameter it gives me one very different IOD.

How can I change this for something more easy... like the ones we see on MIB files?

Answer 1

If you are doing it in the command line, use

snmptranslate -m NET-SNMP-EXTEND-MIB .1.3.6.1.4.1.8072.1.3.2.3.1.2.11.115.110.109.112.95.115.116.97.116.117.115

To do it purely programmatically (i.e. without parsing command line output), you will need a way to parse the MIB files. I think such tools probably exist in Python, but I've never used them myself.

More often, I hard-code constants for the OIDs that I'm interested in, and manually inspect the MIB to know how to decode the index for each object. The OID you gave is an instance of NET-SNMP-EXTEND-MIB::nsExtendOutputFull, which belongs to nsExtendOutput1Entry. Normally the *Entry types will have an INDEX field telling you which field is used as the index of that table. In this case, it has an AUGMENTS field instead, which points you to nsExtendConfigEntry. The INDEX fornsExtendConfigEntry is nsExtendToken, which has a type of DisplayString (basically an OCTET STRING that is limited to human-readable characters).

Here's an example of how I would do this in Python -- you'll need pip install snmp:

from snmp.types import OID, OctetString

nsExtendOutputFull = OID.parse(".1.3.6.1.4.1.8072.1.3.2.3.1.2")

oid = OID.parse(".1.3.6.1.4.1.8072.1.3.2.3.1.2.11.115.110.109.112.95.115.116.97.116.117.115")
nsExtendToken = oid.extractIndex(nsExtendOutputFull, OctetString)
print(f"Index = {nsExtendToken}")

Here's the output:

Index = OctetString(b'snmp_status')