Cant connect to SNMP4J by firing snmpget command

SNMP4J
1

My use case is:-

  1. I will have an snmpv3 agent running.
  2. The snmp manager will fire a snmpget command with proper creds and auth
  3. Application should accpt the get command and return appropriate value

I have tried a lotm but I can’t connect the agent using snmpget command. Please help what I am missing,

Agent is running. sudo nc -v -u -w 3 172.24.80.1 161 gives me following output

Connection to 127.0.0.1 161 port [udp/snmp] succeeded!

Here is my relevant piece of code:

SNMPV3UserInfo userInfo = new SNMPV3UserInfo();
		userInfo.setUsername("usr_1");
		userInfo.setAddress("100.94.135.193");
		userInfo.setAuthPswd("temp_password");
		userInfo.setPrivPswd("temp_password");

MPv3 mp = new MPv3();
        mp.setLocalEngineID(LOCAL_ENGINE_ID.getValue());

        ThreadPool threadPool = ThreadPool.create("SnmpGet", 10);
        MessageDispatcher dispatcher = new MultiThreadedMessageDispatcher(threadPool, new MessageDispatcherImpl());

        CommandResponder cr = new CommandResponder() {
            @Override
            public void processPdu(CommandResponderEvent commandResponderEvent) {
                System.out.println("..............1Anirban1...........");
            }
        };

        //byte[] egineId = MPv3.createLocalEngineID(new OctetString(hostIpAddress + UUID.randomUUID().toString()));

        Address address = new UdpAddress(InetAddress.getLocalHost(), 161);
        TransportMappings transportMappings = TransportMappings.getInstance();
        TransportMapping tm = transportMappings.createTransportMapping(address);

        this.userInfo = userInfo;
        snmp = new Snmp(dispatcher, tm);
        snmp.getMessageDispatcher().addMessageProcessingModel(mp);

        USM usm = new USM(SecurityProtocols.getInstance(), LOCAL_ENGINE_ID, 0);
        SecurityModels.getInstance().addSecurityModel(usm);
        snmp.getMessageDispatcher().addMessageProcessingModel(mp);
        snmp.getMessageDispatcher().addCommandResponder(cr);
        UsmUser user = new UsmUser(
                new OctetString(userInfo.getUsername()),
                getAuthProtocol(userInfo.getAythType()), new OctetString(userInfo.getAuthPswd()),
                getPrivProtocol(userInfo.getPrivType()), new OctetString(userInfo.getPrivPswd()));

        // Very important to add snmp as command responder which will finally process the PDU:
        snmp.getMessageDispatcher().addCommandResponder(snmp);
        snmp.getUSM().addUser(new OctetString(userInfo.getUsername()), user);
        snmp.listen();

Here is the snmpget command I am using:-

sudo snmpget -u usr_1 -l authPriv -a MD5 -x DES -A temp_password -X temp_password -L eo  127.0.0.1 1.3.6.1.4.1.27675.20.10.1.2.0
2

Your code does not implement a SNMP agent. You should use SNMP4J-AGENT for that.
I do not know what you expect to happen, but your code will not return any response PDU.

The command responder is added twice.

3

Thank you Frank.
Got a cue from your reply and implemented an agent. It works fine. I also used the SampleAgent that you have provided in the SNMP Agent Distro.

My Use case is:

  1. I have a number of xml files which has performance counters of my network. Each counter has an OID associated with it.
  2. The manager will fire a GET or a WALK with an OID.
  3. My agent would search in the XML files and return the value of it.

Now, my problem is I am not able to sent back a customized RESPONSE type PDU. Command responders are for processing incoming PDUs.

Can you please give me few advices?

4

Thanks. I have figured it out how to achieve this. I have extended MOScalar class and overridden the get and next methods.

Is that ok?

5

That is perfect if the "OID"s you refer to are as scalar OBJET-TYPEs. If they are conceptual tables, using the DefaultMOTable with one of the available TableModels would be better.

6

Thanks Frank, It works.
The only thing is that I dint want to include the column id to the table sub indexes. Is that Possible?

7

Yes, that should be the normal approach. Maybe you have to give us more details about

Column IDs are not part of INDEX clauses (never) because those represent to row IDs.

8

I am doing a walk with an oid say, “1.3.6.1.2.1.31.1.1.1.17”. My indexes are 10, 20, 30 40 … and so on. So, the output of snmp walk should be 1.3.6.1.2.1.31.1.1.1.17.10, 1.3.6.1.2.1.31.1.1.1.17.20, 1.3.6.1.2.1.31.1.1.1.17.30 and so on.

I have built a MOTable with the data. My column id is 1 and row id are 10, 20 , 30 40 etc… Whn I do snmp walk my my snmp walk out put values are 1.3.6.1.2.1.31.1.1.1.17.1.10,1.3.6.1.2.1.31.1.1.1.17.1.20 etc… I am getting an extra “1” which is the columnID.

In the code I found this following function

public OID getCellOID(OID index, int col) {
            OID retval = new OID(getOID());
            retval.append(getColumn(col).getColumnID());
            retval.append(index);
            return retval;
        }
I tried commenting "retval.append(getColumn(col).getColumnID());", snmpwalk doesnt walk.

My code is as follows.
MOTableIndex snmp4jDemoEntryIndex =
                    DefaultMOFactory.getInstance().createIndex(new MOTableSubIndex[] {
                                    DefaultMOFactory.getInstance().createSubIndex(oid,
                                            SMIConstants.SYNTAX_INTEGER, 1, 1)
                            },
                            true,
                            new MOTableIndexValidator() {
                                public boolean isValidIndex(OID index) {
                                    boolean isValidIndex = true;
                                    //--AgentGen BEGIN=snmp4jDemoEntry::isValidIndex
                                    //--AgentGen END
                                    return isValidIndex;
                                }
                            });

            MOMutableTableModel snmp4jDemoEntryModel =
                    DefaultMOFactory.getInstance().createTableModel(oid,
                            snmp4jDemoEntryIndex,
                            columns);

            MOTable<DefaultMOMutableRow2PC,
                    MOColumn,
                    MOMutableTableModel> snmp4jDemoEntry =
                    new MyMOtable(oid, snmp4jDemoEntryIndex, columns, snmp4jDemoEntryModel);

Where columns are:
new MOColumn[] {new MOMutableColumn(1,
                SMIConstants.SYNTAX_GAUGE32,
                DefaultMOFactory.getInstance().createAccess(MOAccessImpl.ACCESSIBLE_FOR_READ_CREATE),
                new Gauge32(1))};
9

The extra “1” table entry ID is required to comply with the SMMP standard! You can define a MIB specification where “1.3.6.1.2.1.31.1.1.1.17.1.10,1.3.6.1.2.1.31.1.1” is a table.
1.3.6.1.2.1.31.1.1.1.17.1.10,1.3.6.1.2.1.31.1.1.1 would then be the table entry and
1.3.6.1.2.1.31.1.1.1.17.1.10,1.3.6.1.2.1.31.1.1.1.17 could the be a column in the table.

Then 1.3.6.1.2.1.31.1.1.1.17.1.10,1.3.6.1.2.1.31.1.1.1.17.20 could be a row in the table.

But 1.3.6.1.2.1.31.1.1.1.17.1.10,1.3.6.1.2.1.31.1.1.1.17.20 could never be a scalar because scalar instances must end with a zero instance identifier like 1.3.6.1.2.1.31.1.1.1.17.1.10,1.3.6.1.2.1.31.1.1.1.17.0

10

Hi Frank. Thanks for your help. It works very well.