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Asked: 2026-06-03T04:54:19+00:00

Forgive my ignorance if this is a trivial question. I am writing some code

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Forgive my ignorance if this is a trivial question. I am writing some code to support communication over SNMPv3; our application only supports SNMPv2c currently.

The response object when communicating using SNMPv3 is blank unless I match community strings. I was under the impression that community strings were an “SNMPv2/1 thing” and that “the new way” was to use a username/authentical protocol/privacy protocol.

Wikipedia states that:

Although SNMPv3 makes no changes to the protocol aside from the addition of cryptographic security, it looks much different due to new textual conventions, concepts, and terminology.[1]

This statement leads me to believe that I do, in fact, need to supply community strings, too.

I just wanted to confirm this because it is difficult for me to tell whether I am getting data back because I fulfilled the SNMPv2 requirement or because I successfully fulfilled all the SNMPv3 requirements.

I’m using Dart’s SNMP library to communicate with the other device and I have specified that my request should user SNMP version three — but perhaps it falls back to SNMPv2 behind-the-scenes when given valid SNMP communities?

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1 Answer

  1. Editorial Team

    No, you don’t. The internal packet structure changes to a number of new concepts, like the above quote tries to indicate. The protocol side that the above is stating is the same has to do with PDU operations, etc. IE, technically there are 3 versions of SNMP:

    version 1:  community string based authentication with SMNPv1 PDUs
version 2c: community string based authentication with SNMPv2 PDUs
            (the SNMPv2 PDUs add GETBULK, INFORM, and REPORT PDUs)
version 3:  modular security with SNMPv2 PDUs

    IE, version 3 didn’t touch how the actual operations work (it’s still using the PDU types from version 2), but merely adds other header-stuff around them (like better and more modular security; in fact we now have 3 different security types to pick from at this point: USM, SSH, and (D)TLS).

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