[SNMP4J] TCP Socket in SYN_RECV when sending V3 traps [RESOLVED]

[Neeraj Vaidya]

Hi Frank
My issue is resolved. Thanks for your guidance.
All I had to do was to not use any engine Id at all and thus allow engine id discovery.
On the net snmp trap Collector side I had to create a separate user for sending informs, which did not have any specific engine Id in the createUser directive.

Regards,
Neeraj

> On 19 Jun 2017, at 12:37, Neeraj Vaidya <neeraj.vaidya at yahoo.co.in> wrote:
> 
> Thanks Frank. So how do I get the authoritativeEngineId at runtime ?
> 
> The remote snmptrap collector has provided me with a user id of myuser and engine id of 0102030405. This is via an email correspondence which I had with the administrators of the remote system.
> 
> When I use the SnmpRequest tool bundled as part of snmp4j, which engineId parameters do I need to set  when sending an INFORM ?
> -l , -e , -E ?
> 
> I tried setting just the -e flag with 0102030405 on the command line of this tool and still at the receiving end i.e. in the logs of the net-snmp trap collector I see a message of "no match on engineID (80 00 88 .....)"
> Basically, the snmptrapd collector is not using 0102030405 for USM engine ID matching purposes. 
> 
> If I were to send just a coldStart trap with the SnmpRequest tool bundled in snmp4j distribution, what command line do I need to use ?
> My engine ID which I can successfully specify as the authoritativeEngineId via -e flag is 0102030405, when using the snmptrap utility.
> I was of the opinion that the same -e flag can be used in SnmpRequest utility as well.
> 
> Regards,
> Neeraj
> 
> --------------------------------------------
> On Mon, 19/6/17, Frank Fock <fock at agentpp.com> wrote:
> 
> Subject: Re: [SNMP4J] TCP Socket in SYN_RECV when sending V3 traps
> To: "Neeraj Vaidya" <neeraj.vaidya at yahoo.co.in>
> Cc: snmp4j at agentpp.org
> Date: Monday, 19 June, 2017, 8:31 AM
> 
> Hi Neeraj,
> 
> Please make sure, that you have understand the
> engine ID and context 
> engine ID terms and
> usages.
> It seems that you mix up things.
> Your example below cannot work for 
> INFORM
> PDUs, because
> you need to specify the
> authoritative engine ID as context engine ID 
> then. This is the
> INFORM
> *receivers* engine ID.
> Instead, you use the
> senders engine ID. The receiver should drop/ignore 
> such an INFORM message with
> unknownPduHandles counter increased.
> 
> Best regards,
> Frank
> 
> Am
> 16.06.2017 um 22:41 schrieb Neeraj Vaidya:
>> Hi Frank,
>> Coming back
> to this conversation as I have been away from this task due
> to other project commitments.
>> In the
> example below, I have also noticed that if I change the PDU
> type to INFORM, the receiving snmptrap collector (which is
> net-snmp snmptrapd) fails to match the engine id. It picks
> up something totally different from what I am setting
> below.
>> Is there some other place where
> I need to set the engineId ?
>> 
>> Regards,
>> Neeraj
>> 
>> Sent from my
> iPhone
>> 
>> On 24 May
> 2017, at 16:44, Frank Fock <fock at agentpp.com>
> wrote:
>> 
>>>> 
> ------------------------------------------------ Code Start
> ------------------------------------------------
>>>> 
>>>>    
>             Address address =
> GenericAddress.parse("tcp:rhelhost1/1163");
>>>> 
>>>>    
>      try {
>>>>             
> TransportMapping transportMapping = new
> DefaultTcpTransportMapping();
>>>>  
>            transportMapping.listen();
>>>>                      
>>>>              Snmp snmp = new
> Snmp(transportMapping);
>>>> 
>>>>              USM usm = new
> USM(SecurityProtocols.getInstance(),
>>>>                        
>                                new
> OctetString(MPv3.createLocalEngineID()), 0);
>>>>              
>>>>             
> SecurityModels.getInstance().addSecurityModel(usm);
>>>> 
>>>>    
>          //snmp.listen(); ----> Do I need to use this
> invocation ??
>>>> 
>>>>              byte[] b = (new
> BigInteger("0102030405",16)).toByteArray();
>>>> 
>>>>    
>          snmp.getUSM().addUser(new
> OctetString("snmp4j"),
>>>>                      new
> UsmUser(new OctetString("snmp4j"), AuthMD5.ID, new
> OctetString("snmp4j"), PrivDES.ID, new
> OctetString("snmp4j")));
>>>>              
>>>>              UserTarget
> target = new UserTarget();
>>>>    
>              
>>>>        
>      target.setAddress(address);
>>>>             
> target.setRetries(1);
>>>>      
>        target.setTimeout(5000);
>>>>             
> target.setVersion(SnmpConstants.version3);
>>>>             
> target.setSecurityLevel(SecurityLevel.AUTH_NOPRIV);
>>>>             
> target.setSecurityName(new
> OctetString("snmp4j"));
>>>>              
>>>>              // create the
> PDU
>>>>              ScopedPDU
> pdu = new ScopedPDU();
>>>>      
>        long sysUpTime =
> Instant.now().getEpochSecond();
>>>>              //pdu.add(new
> VariableBinding(SnmpConstants.sysUpTime),new OctetString(new
> Date().toString()));
>>>>        
>      pdu.setType(ScopedPDU.TRAP);
>>>>              pdu.add(new
> VariableBinding(SnmpConstants.sysUpTime, new
> TimeTicks(sysUpTime)));
>>>>      
>        pdu.add(new
> VariableBinding(SnmpConstants.snmpTrapOID,
> SnmpConstants.linkUp));
>>>>      
>        pdu.setContextEngineID(new
> OctetString().fromByteArray(b));
>>>>             
> snmp.setLocalEngine(b, 0, 0);
>>>>  
>            // send the PDU
>>>>              
>>>>              ResponseEvent
> response = null;
>>>> 
>>>>              response =
> snmp.send(pdu, target);
>>>> 
>>>>             
> Thread.sleep(10); // This Sleep somehow allows the entire
> TCP 3-way handshake to occur without terminating the
> program
>>>> 
>>>>              snmp.close();
>>>> 
>>>>    
>      } catch (IOException e) {
>>>>             
> e.printStackTrace();
>>>>        
>  } catch (InterruptedException e) {
>>>>             
> e.printStackTrace();
>>>>        
>  }
>>>> 
> ------------------------------------------------ Code End 
> -----------------------------------------------
> 
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