I keep getting this error snmp report reqid=0 (Counter32 snmpUnknownPDUHandlers=2) from the snmp.log.

I’m getting it on the example examples.confd/snmpa/5-simple-v3.


  1. make all
  2. make start
  3. Trying to connect to snmp agent on port 4000, one of the users defined in the usm_init.xml
  4. Getting the error

From what I read about snmpUnknownPDUHandlers looks like there’s no application registered on this users connection.

How can I fix it?

Can you show the snmp request (step #3 in your posting) that you have sent that have resulted in your error?

Does the following snmp request cause any error on your system?

$ snmpwalk -v3 -u initial localhost:4000 enterprise

I get this error on the snmpwalk command:

enterprise: Unknown Object Identifier (Sub-id not found: (top) -> enterprise)

I don’t know how to handle it…

When I use snmp server from a remote I get the snmpUnknownPDUHandlers.
The request:

Server --> Agent

Server <-- Agent

Server --> Agent

Server <-- Agent

Does it help?
For some reasons it doesn’t show the pictures :confused:

Instead of enterprise, you can replace it with the actual numerical OID.

Here’s another example usage of snmpwalk for the 5-simple-v3 example:

$ snmpwalk -v3 -u initial localhost:4000
SNMPv2-SMI::enterprises.24961. = STRING: ""
SNMPv2-SMI::enterprises.24961. = STRING: ""

OK, it works,

I’ll just have to figure out why it doesn’t work from my other snmp agent.

I don’t get something;

Why when I do:

snmpwalk -v3 -u initial_authPriv

I successfully getting the output, and nobody asks me for any password.
Is it ok?


SNMP v3 requests can be sent unauthenticated and unencrypted (noAuthNoPriv). In fact, that is the default behavior of snmpwalk.

You can use the -l option of snmpwalk to specify the security level of your request:

-l LEVEL		set security level (noAuthNoPriv|authNoPriv|authPriv)

MaybeI don’t understand the snmp v3 protocol : ( ,
But it sounds strange to me, that:
a. In the example (5-simple-v3), in usm_init.xml there’s a declaration of a user, that should have authentication (MD5) and encryption (DES) - the user initial_authPriv
b. Someone can walk on the MIB tree with the user initial_authPriv without any authentication/encryption

I don’t understand :\

It looks like you are confused about the security model being used by SNMP v3. This forum is not meant for discussion of SNMP concepts. However, I will provide you with some reference material here. Read RFC 2574, User-based Security Model for SNMPv3, to understand the background information on the security model being defined. By reading section 1.1 on Threats, section 1.2 on Goals and Constraints, and section 1.3 on Security Services should give you a better idea of the purpose of the authentication and privacy mechanisms being defined.

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