[SNMP4J] Difficulty with SNMP v3 Set

[Frank Fock]

Hello Peter,

There could be two different reasons for your observation:

1. The agent uses different access rights for SET and GET PDUs
which the user you are using does not equally have on the device.
2. The engine time synchronization fails for some reason.

For the second case, using the latest SNMP4J version could
help if the device (or the sender) has a very weak internal clock.

The engine time can only be put in the sending request, if
there was already some communication with the agent.
If you create a new Snmp instance for each request then
this happens all the time. Thus, you should reuse a single
Snmp instance for all the communication.

Best regards,
Frank


Am 04.09.2013 19:46, schrieb McCarthy, Peter CIV NAWCTSD, 4.6.2.3:
> Hello all,
>
> I'm having difficulty with sending SNMP v3 sets to a secured (MD5/DES
> such as it is) power strip.  Code (largely taken from the get example in
> the documentation) is at the bottom:
>
> If I uncomment the GET STUFF section and comment out the SET STUFF
> section, everything works and all the correct data is returned.
>
> If I uncomment the SET STUFF section and comment out the GET STUFF
> section, no errors are returned.  However, the setting is not
> placed on the device (verified through the device's web interface).
>
> When I used Wireshark, I noticed on when a set message is sent, neither
> the authoritative time nor boot count is placed in the outgoing set
> request.
>
> Message flow, per Wireshark, looks like
>
>       (1) Outbound, generic set or get message
>       (2) Inbound,  1.3.6.1.6.3.15.1.1.4 (unknown engine)
>       (3) Outbound, some encrypted PDU
>       (4) Inbound,  response PDU
>
> Occasionally (rarely), there is another pair of messages between (2) and
> (3), namely:
>
>       (2a) Outbound, some encrypted PDU
>       (2b) Inbound, 1.3.6.1.6.3.15.1.1.2 (not in time window)
>
> If the "not in time window" appears, message (3) above will have
> authoritative time and boot count populated.
>
> Am I doing something wrong here?
>
> Thanks,
>
> Peter...
>
>          Address targetAddress =
> GenericAddress.parse("udp:192.168.1.107/161");
>          TransportMapping transport = new DefaultUdpTransportMapping();
>          Snmp snmp = new Snmp(transport);
>          MPv3 mpv3 =
>                  (MPv3)
> snmp.getMessageProcessingModel(MessageProcessingModel.MPv3);
>          USM usm = new USM(SecurityProtocols.getInstance(),
>                  new OctetString(mpv3.createLocalEngineID()), 0);
>          System.err.println("Enabled? " +
> usm.isEngineDiscoveryEnabled());
>          SecurityModels.getInstance().addSecurityModel(usm);
>          transport.listen();
>
>          // add user to the USM
>          snmp.getUSM().addUser(new OctetString("usernamehere"),
>                  new UsmUser(new OctetString("usernamehere"),
>                  AuthMD5.ID,
>                  new OctetString("passwordhere"),
>                  PrivDES.ID,
>                  new OctetString("passwordhere")));
>          // create the target
>          UserTarget target = new UserTarget();
>          target.setAddress(targetAddress);
>          target.setRetries(1);
>          target.setTimeout(5000);
>          target.setVersion(SnmpConstants.version3);
>          target.setSecurityLevel(SecurityLevel.AUTH_PRIV);
>          target.setSecurityName(new OctetString("usernamehere "));
>          
>
>          // GET STUFF
> //        PDU pdu = new ScopedPDU();
> //        pdu.add(new VariableBinding(new
> OID("1.3.6.1.4.1.318.1.1.12.1.2.0")));
> //        pdu.add(new VariableBinding(new
> OID("1.3.6.1.4.1.318.1.1.12.1.3.0")));
> //        pdu.add(new VariableBinding(new
> OID("1.3.6.1.4.1.318.1.1.12.1.5.0")));
> //        pdu.add(new VariableBinding(new
> OID("1.3.6.1.4.1.318.1.1.12.1.1.0")));
> //        pdu.add(new VariableBinding(new
> OID("1.3.6.1.4.1.318.1.1.12.3.3.1.1.4.2")));
> //        pdu.add(new VariableBinding(new
> OID("1.3.6.1.4.1.318.1.1.12.3.3.1.1.4.3")));
> //        pdu.add(new VariableBinding(new
> OID("1.3.6.1.4.1.318.1.1.12.3.4.1.1.4.2")));
> //        pdu.setType(PDU.GET);
>          
> 	  // SET STUFF
>          PDU pdu = new ScopedPDU();
>          OID o1 = new OID("1.3.6.1.4.1.318.1.1.12.3.4.1.1.4.2");
>          Integer32 i32 = new Integer32(32);
>          pdu.add(new VariableBinding(o1, i32));
>          pdu.setType(PDU.SET);
>          
>          // send the PDU
>          ResponseEvent response = snmp.send(pdu, target);
>          // extract the response PDU (could be null if timed out)
>          PDU responsePDU = response.getResponse();
>          System.err.println("Error status: " +
> responsePDU.getErrorStatus());
>          if(responsePDU != null) {
>              for (VariableBinding b : responsePDU.getVariableBindings())
> {
>                  System.err.println(b.toString());
>                  
>              }
>          }
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