[SNMP4J] Problem receiving traps I generate

[Frank Fock]

Hi Eric,

It works as it was designed ;-). I guess, you
are sending a SNMPv1 TRAP-PDU with SNMPv2c
which is a protocol violation.
Just send a NOTIFICATION PDU instead and
everything would be fine.

(Alternatively, you may send the V1TRAP
with SNMPv1)

Best regards,
Frank

On 18.03.2011 16:54, Eric Thiebaut wrote:
> Hi,
>
> I am sending a trap and trying to subscribe to it, but I'm facing some problems.
> I'm compiling against the released source package of of 1.11.2 (in order to debug).
>
> Sending the trap is pretty straight forward:
>          PDUv1 pdu = new PDUv1();
>          pdu.setType(PDU.V1TRAP);
>          ...
>          this.snmp.send(pdu, target);
>
> I can check with wireshark and my packet looks fine.
>
> Now I'm subscribing for events (actually in the same process):
>                  TransportMapping transport =
>                      new DefaultUdpTransportMapping(new UdpAddress("0.0.0.0/10160"));
>                  snmp = new Snmp(transport);
>                  snmp.addCommandResponder(this);
>                  transport.listen();
>
>
> All this is pretty straight forward.
> But when traps are received, the reception thread throws an exception in PDU.java
> as pduType.getValue() returns PDU.V1TRAP (as expected), which is not supported by the class PDU.
>
> The problem seems to come from MessageDispatcherImpl:
>        Integer32 version = new Integer32();
>        version.decodeBER(wholeMessage);
>        MessageProcessingModel mp = getMessageProcessingModel(version.getValue());
>
> version decodes to 1. The mp at position 1 is MPv2c, and not MPv1 (which is at position 0).
> So when MPv2c decodes the pdu, it creates a PDU object and not PDUv1 object, which does not support v1 traps.
>
> Is this expected? At the moment I cannot receive my traps because of this.
> Am I doing something wrong?
>
> Thanks
>
> Eric
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