[SNMP4J] SNMP4J V3 Traps with specified Engine ID

[Frank Fock]

Hi Imene,

Your understanding of SNMPv3 trap sending is not correct.
SNMPv3 notifications (traps) are sent from a command responder 
entity and are therefore authoritative. That means, the sender
(which is the command responder entity) uses its own security
engine ID within the notification PDU. 

The receiver (= command generator) then uses the security engine
ID provided in the notification PDU to authentication/decrypt the
notification. 

Therefore your setup should work already, except that you have not
set the context name of the ScopedPDU object yet.

Best regards
Frank

> On 06 Jan 2015, at 21:26, Boussour, Imene (6076618) <imene.boussour at bell.ca> wrote:
> 
> Hello List,
> 
> I am trying to send SNMP V3 Traps to a remote server (using a Trap monitor software on windows) from my Java application, I use SNMP4j stack API.
> My questions is around the engine ID, on the Trap receiver application we need to create an SNMP V3 account with, username, auth protocol... but also a Context Name.
> On the SNMP4j side, there is multiple areas where we can define of set the engineID:
> 1 - USM usm = new USM(SecurityProtocols.getInstance().addDefaultProtocols(), new OctetString(MPv3.createLocalEngineID()), 0);
> 2- snmp.getUSM().addUser(mSecurityName, OctetString.fromHexString("80:00:13:70:c0:a8:01:0d"), new UsmUser(mSecurityName, mAuthProtocol, , mPrivProtocol, mPrivPassphrase));
> 3- UsmUser(mSecurityName, mAuthProtocol, , mPrivProtocol, mPrivPassphrase), OctetString.fromHexString("80:00:13:70:c0:a8:01:0d"));
> 4- pdu.setContextEngineID(OctetString.fromHexString("80:00:13:70:c0:a8:01:0d"));
> 
> For context Name , I only found this:
> pdu.setContextName(new OctetString("contextName"));
> 
> 
> The SNMP4J createlocalEngineId method creates a random number, Can this work?
> My understanding of SNMP trap V3, is that the Engine ID should match on the sender and receiver. So, when we specify a custom engine ID on SNMP4J, which one should we use?
> 
> And here is the Code I am using to send Traps:
> 
>                     // ltargetAddress represents the host and port we plan to communicate with
>                     // in the format: host/port
>                     Address ltargetAddress = GenericAddress.parse (mTransportType + ":" + mRemoteAddress + "/" + mRemotePort);
> 
>                     TransportMapping<?> transport;
>                     if (ltargetAddress instanceof UdpAddress) {
>                           transport = new DefaultUdpTransportMapping();
>                     } else {
>                           transport = new DefaultTcpTransportMapping();
>                     }
> 
>                     //Create SNMP Session
>                     Snmp snmp = new Snmp(transport);
> 
>                     USM usm = new USM(SecurityProtocols.getInstance()
>                                  .addDefaultProtocols(), new OctetString(
>                                  MPv3.createLocalEngineID()), 0);
> 
>                     SecurityProtocols.getInstance().addPrivacyProtocol(new PrivAES192());
> 
>                     SecurityModels.getInstance().addSecurityModel(usm);
> 
>                     //transport.listen();
> 
>                     //Setting the security protocols
>                     snmp.getUSM().addUser(
>                                  mSecurityName,
>                                  new UsmUser(mSecurityName, mAuthProtocol,
>                                                mAuthPassphrase, mPrivProtocol,
>                                                mPrivPassphrase));
> 
> 
>                     // Create Target
>                     UserTarget target = new UserTarget();
>                     target.setAddress(ltargetAddress);
>                     target.setRetries(1);
>                     target.setTimeout(11500);
>                     target.setVersion(SnmpConstants.version3);
>                     target.setSecurityLevel(SecurityLevel.AUTH_PRIV);
>                     target.setSecurityName(mSecurityName);
> 
>                     // Create PDU for V3
>                     ScopedPDU pdu = new ScopedPDU();
>                     pdu.setType(ScopedPDU.TRAP);
> 
>                     // Adding OIDs
>                     pdu.add(new VariableBinding(SnmpConstants.sysUpTime,
>                    new OctetString(new Date().toString())));
> 
>                     pdu.add(new VariableBinding(SnmpConstants.snmpTrapOID,
>                                                       SnmpConstants.linkDown));
> 
>                     pdu.add(new VariableBinding(new OID(mOID), new OctetString(pMessage)));
> 
>                     pdu.add(new VariableBinding(SnmpConstants.snmpTrapAddress,
> 
>                     new IpAddress(mRemoteAddress)));
> 
>                     //Send the PDU
>                     snmp.listen();
>                     snmp.send(pdu, target);
>                     snmp.close();
> 
> Thanks,
> Imene
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