[SNMP4J] java.lang.NullPointerException: Context engine ID must not be null
Frank Fock
fock at agentpp.com
Fri Aug 12 19:07:20 CEST 2016
Hi Philippe,
SNMP4J 2.5.0 does not need to be fixed, you simply have to provide the context engine ID (empty string for the default security engine ID) and the context name in the construction of the PDU factory.
Best regards
Frank
> Am 12.08.2016 um 15:15 schrieb FLORENT Philippe <Philippe.FLORENT at edenred.com>:
>
> Mixing terms ? ok.. sorry about that
>
> With some softwares, if I don’t use the leading dot, they return a different result
>
> If v 2.5 is not fixed, then as I said, it seems useless when accessing v3 snmp machines
>
> Anyway I am just new in snmp, sorry if I get confused
>
> Have a nice day
>
> -----Original Message-----
> From: Frank Fock [mailto:fock at agentpp.com]
> Sent: vendredi 12 août 2016 10:56
> To: FLORENT Philippe
> Cc: snmp4j at agentpp.org
> Subject: Re: [SNMP4J] java.lang.NullPointerException: Context engine ID must not be null
>
> The OID is not fine for a GET PDU request.
> Mixing terms (GET, WALK, GETNEXT, etc.) as you like does not help you and others.
> For me it makes giving support more difficult and time consuming, because I have to guess and write a lot of postings to clarify stuff that is most likely not related to the root cause.
>
> BTW, OIDs do *not* start with a dot ("."). This leading dot is *not* standard conform.
> It is a (IMHO bad) "feature" of NET-SNMP - nothing else.
>
>
>
>> Am 12.08.2016 um 08:51 schrieb FLORENT Philippe:
>> I do a GET on a perfectly fine oid
>> - works with snmpwalk (linux cli)
>> - works as GET in Mib Browser (might do a walk too when I click on the GET button)
>>
>> So I managed to get the data using snmp4j tables , there it works(at least with v 1.1)
>>
>> -----Original Message-----
>> From: Frank Fock [mailto:fock at agentpp.com]
>> Sent: jeudi 11 août 2016 14:42
>> To: FLORENT Philippe
>> Cc: snmp4j at agentpp.org
>> Subject: Re: [SNMP4J] java.lang.NullPointerException: Context engine ID must not be null
>>
>> Hi Philippe,
>> It's how I wrote. You are not specifying the instance sub-identifiers. A GETNEXT will *never* return a noSuchInstance error! (If the agent is SNMP standard conform) Best regards Frank
>>
>>> Am 11.08.2016 um 11:03 schrieb FLORENT Philippe <Philippe.FLORENT at edenred.com>:
>>>
>>> Please help, I am really struggling with this, that OID exists, no matter I use GT or GETNEXT, it return "no such instance"
>>>
>>> If I look the infos on that oid : .1.3.6.1.2.1.4.20.1.2
>>>
>>> Walk:
>>> -------
>>> IP-MIB::ipAdEntIfIndex.127.0.0.1 = INTEGER: 1
>>> IP-MIB::ipAdEntIfIndex.192.168.1.128 = INTEGER: 2
>>>
>>> snmptranslate -Td :
>>> -------------------------
>>> IP-MIB::ipAdEntIfIndex
>>> ipAdEntIfIndex OBJECT-TYPE
>>> -- FROM IP-MIB
>>> SYNTAX INTEGER (1..2147483647)
>>> MAX-ACCESS read-only
>>> STATUS deprecated
>>> DESCRIPTION "The index value which uniquely identifies the interface to
>>> which this entry is applicable. The interface identified by
>>> a particular value of this index is the same interface as
>>> identified by the same value of the IF-MIB's ifIndex."
>>> ::= { iso(1) org(3) dod(6) internet(1) mgmt(2) mib-2(1) ip(4)
>>> ipAddrTable(20) ipAddrEntry(1) 2 }
>>>
>>>
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: Frank Fock [mailto:fock at agentpp.com]
>>> Sent: jeudi 11 août 2016 10:26
>>> To: FLORENT Philippe
>>> Cc: snmp4j at agentpp.org
>>> Subject: Re: [SNMP4J] java.lang.NullPointerException: Context engine
>>> ID must not be null
>>>
>>> Hi,
>>> If walk (which is a GETNEXT in fact) and GET behave differently then most likely you are using the wrong OID (wrong instance identifier). Sometimes the agent is broken too.
>>> In your case, you should put the Snmp instance in listen mode to receive answers from the agent. See FAQ for details.
>>> Best regards
>>> Frank
>>>
>>>> Am 11.08.2016 um 09:29 schrieb FLORENT Philippe <Philippe.FLORENT at edenred.com>:
>>>>
>>>> Hello everyone,
>>>>
>>>>
>>>> - Doing a get on some OID give me "unkown instance" although they work with snmpwalk on the command line and GET works with mib explorer
>>>>
>>>>
>>>>
>>>> - So I try to implement an snmp walk in snmp4j but I keep getting that error
>>>>
>>>> Here is the code
>>>>
>>>> I tried to use request.getContextEngineID(), but it is also null
>>>>
>>>> public class SnmpProber
>>>> {
>>>> private Snmp snmp;
>>>> private UserTarget target;
>>>>
>>>> private byte[] authEngineId0=null;
>>>>
>>>> public SnmpProber(String ipAddress,String port,String userName,String authPass,String privPass)
>>>> {
>>>> try
>>>> {
>>>> Address targetAddress = GenericAddress.parse("udp:"+ipAddress+"/"+port);
>>>> TransportMapping transport = new DefaultUdpTransportMapping();
>>>> snmp = new Snmp(transport);
>>>> USM usm = new USM(SecurityProtocols.getInstance(),new OctetString(MPv3.createLocalEngineID()), 0);
>>>> SecurityModels.getInstance().addSecurityModel(usm);
>>>> transport.listen();
>>>>
>>>> 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(userName));
>>>>
>>>> authEngineId0 =
>>>> snmp.discoverAuthoritativeEngineID(target.getAddress(), 5000);
>>>>
>>>> if(authEngineId0==null)
>>>> System.out.println("cannot connect");
>>>> else
>>>> {
>>>> // add user to the USM
>>>> UsmUser usmUser=new UsmUser(new OctetString(userName),
>>>> AuthSHA.ID,
>>>> new OctetString(authPass),
>>>> PrivAES128.ID,
>>>> new OctetString(privPass));
>>>>
>>>> snmp.getUSM().addUser(new OctetString("v3DefaultUser"),
>>>> new OctetString(authEngineId0),
>>>> usmUser);
>>>> }
>>>> } catch (IOException ex) {
>>>> Logger.getLogger(SnmpProber.class.getName()).log(Level.SEVERE, null, ex);
>>>> }
>>>> }
>>>>
>>>> public boolean isOk()
>>>> {
>>>> return authEngineId0!=null;
>>>> }
>>>>
>>>> class WalkCounts {
>>>> public int requests;
>>>> public int objects;
>>>> }
>>>>
>>>> public List<VariableBinding> walk(String oid)
>>>> {
>>>> final List<VariableBinding> result;
>>>> result = new LinkedList<VariableBinding>();
>>>> ScopedPDU request;
>>>> request = new ScopedPDU();
>>>> request.setType(PDU.GETNEXT);
>>>>
>>>> request.add(new VariableBinding(new OID(oid)));
>>>>
>>>> request.setNonRepeaters(0);
>>>>
>>>> OID rootOID = request.get(0).getOid();
>>>>
>>>> final WalkCounts counts = new WalkCounts();
>>>> final long startTime = System.currentTimeMillis();
>>>> TreeUtils treeUtils = new TreeUtils(snmp, new
>>>> DefaultPDUFactory());
>>>>
>>>> TreeListener treeListener = new TreeListener()
>>>> {
>>>> public boolean next(TreeEvent e) {
>>>> counts.requests++;
>>>>
>>>> if (e.getVariableBindings() != null) {
>>>> VariableBinding[] vbs = e.getVariableBindings();
>>>> counts.objects += vbs.length;
>>>> for (int i = 0; i < vbs.length; i++) {
>>>> if (result != null) {
>>>> result.add(vbs[i]);
>>>> }
>>>> System.out.println(vbs[i].toString());
>>>> }
>>>> }
>>>> return true;
>>>> }
>>>>
>>>> @Override
>>>> public void finished(TreeEvent e) {
>>>> if ((e.getVariableBindings() != null)
>>>> && (e.getVariableBindings().length > 0)) {
>>>> next(e);
>>>> }
>>>>
>>>> System.out.println("Total requests sent: "+ counts.requests);
>>>> System.out.println("Total objects received: "+ counts.objects);
>>>> System.out.println("Total walk time: "+ (System.currentTimeMillis() - startTime)+ " milliseconds");
>>>>
>>>> if (e.isError()) {
>>>> System.err.println("The following error occurred during walk:");
>>>> System.err.println(e.getErrorMessage());
>>>> }
>>>> synchronized (this) {
>>>> this.notify();
>>>> }
>>>> }
>>>>
>>>> @Override
>>>> public boolean isFinished() {
>>>> return true;
>>>> }
>>>> };
>>>>
>>>> synchronized (treeListener)
>>>> {
>>>> treeUtils.getSubtree(target, rootOID, null, treeListener); <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< exception here
>>>> try
>>>> {
>>>> treeListener.wait();
>>>> }
>>>> catch (InterruptedException ex)
>>>> {
>>>> System.out.println("Tree retrieval interrupted: "+ex);
>>>> Thread.currentThread().interrupt();
>>>> }
>>>> }
>>>>
>>>> return result;
>>>> }
>>>>
>>>> public void Release()
>>>> {
>>>> try {
>>>> snmp.close();
>>>> } catch (IOException ex) {
>>>> Logger.getLogger(SnmpProber.class.getName()).log(Level.SEVERE, null, ex);
>>>> }
>>>> }
>>>> }
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> SNMP4J mailing list
>>>> SNMP4J at agentpp.org
>>>> https://oosnmp.net/mailman/listinfo/snmp4j
>
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