Introduction to snmp4j

private void start() throws IOException {
        TransportMapping transport = new DefaultUdpTransportMapping();
	snmp = new Snmp(transport);
	// Do not forget this line!
	transport.listen();
}
public String getAsString(OID oid) throws IOException {
	ResponseEvent event = get(new OID[]{oid});
	return event.getResponse().get(0).getVariable().toString();
}

public ResponseEvent get(OID oids[]) throws IOException {
	PDU pdu = new PDU();
 	for (OID oid : oids) {
 	     pdu.add(new VariableBinding(oid));
 	}
 	pdu.setType(PDU.GET);
 	ResponseEvent event = snmp.send(pdu, getTarget(), null);
	if(event != null) {
             return event;
	}
	throw new RuntimeException("GET timed out");
}

private Target getTarget() {
	Address targetAddress = GenericAddress.parse(address);
	CommunityTarget target = new CommunityTarget();
	target.setCommunity(new OctetString("public"));
	target.setAddress(targetAddress);
	target.setRetries(2);
	target.setTimeout(1500);
	target.setVersion(SnmpConstants.version2c);
	return target;
}

SimpleSnmpClient client = new SimpleSnmpClient("udp:10.0.0.50/161");
String sysDescr = client.getAsString(new OID(".1.3.6.1.2.1.1.1.0"));
System.out.println(sysDescr);

   // package and imports removed
/**
 * This Agent contains mimimal functionality for running a version 2c snmp agent.
 */
public class Agent extends BaseAgent {

	// not needed but very useful of course
	static {
		LogFactory.setLogFactory(new Log4jLogFactory());
	}

	private String address;

	public Agent(String address) throws IOException {

		// These files does not exist and are not used but has to be specified
		// Read snmp4j docs for more info
		super(new File("conf.agent"), new File("bootCounter.agent"),
				new CommandProcessor(
						new OctetString(MPv3.createLocalEngineID())));
		this.address = address;
	}

	/**
	 * We let clients of this agent register the MO they
	 * need so this method does nothing
	 */
	@Override
	protected void registerManagedObjects() {
	}

	/**
	 * Clients can register the MO they need
	 */
	public void registerManagedObject(ManagedObject mo) {
		try {
			server.register(mo, null);
		} catch (DuplicateRegistrationException ex) {
			throw new RuntimeException(ex);
		}
	}

	public void unregisterManagedObject(MOGroup moGroup) {
		moGroup.unregisterMOs(server, getContext(moGroup));
	}

	/*
	 * Empty implementation
	 */
	@Override
	protected void addNotificationTargets(SnmpTargetMIB targetMIB,
			SnmpNotificationMIB notificationMIB) {
	}

	/**
	 * Minimal View based Access Control
	 *
	 * http://www.faqs.org/rfcs/rfc2575.html
	 */
	@Override
	protected void addViews(VacmMIB vacm) {

		vacm.addGroup(SecurityModel.SECURITY_MODEL_SNMPv2c, new OctetString(
				"cpublic"), new OctetString("v1v2group"),
				StorageType.nonVolatile);

		vacm.addAccess(new OctetString("v1v2group"), new OctetString("public"),
				SecurityModel.SECURITY_MODEL_ANY, SecurityLevel.NOAUTH_NOPRIV,
				MutableVACM.VACM_MATCH_EXACT, new OctetString("fullReadView"),
				new OctetString("fullWriteView"), new OctetString(
						"fullNotifyView"), StorageType.nonVolatile);

		vacm.addViewTreeFamily(new OctetString("fullReadView"), new OID("1.3"),
				new OctetString(), VacmMIB.vacmViewIncluded,
				StorageType.nonVolatile);
	}

	/**
	 * User based Security Model, only applicable to
	 * SNMP v.3
	 *
	 */
	protected void addUsmUser(USM usm) {
	}

	protected void initTransportMappings() throws IOException {
		transportMappings = new TransportMapping[1];
		Address addr = GenericAddress.parse(address);
		TransportMapping tm = TransportMappings.getInstance()
				.createTransportMapping(addr);
		transportMappings[0] = tm;
	}

	/**
	 * Start method invokes some initialization methods needed to
	 * start the agent
	 * @throws IOException
	 */
	public void start() throws IOException {

		init();
		// This method reads some old config from a file and causes
		// unexpected behavior.
		// loadConfig(ImportModes.REPLACE_CREATE);
		addShutdownHook();
		getServer().addContext(new OctetString("public"));
		finishInit();
		run();
		sendColdStartNotification();
	}

	protected void unregisterManagedObjects() {
		// here we should unregister those objects previously registered...
	}

	/**
	 * The table of community strings configured in the SNMP
	 * engine's Local Configuration Datastore (LCD).
	 *
	 * We only configure one, "public".
	 */
	protected void addCommunities(SnmpCommunityMIB communityMIB) {
		Variable[] com2sec = new Variable[] {
				new OctetString("public"), // community name
				new OctetString("cpublic"), // security name
				getAgent().getContextEngineID(), // local engine ID
				new OctetString("public"), // default context name
				new OctetString(), // transport tag
				new Integer32(StorageType.nonVolatile), // storage type
				new Integer32(RowStatus.active) // row status
		};
		MOTableRow row = communityMIB.getSnmpCommunityEntry().createRow(
				new OctetString("public2public").toSubIndex(true), com2sec);
		communityMIB.getSnmpCommunityEntry().addRow(row);
	}
}

// standard in RFC-1213
static final OID sysDescr = new OID(".1.3.6.1.2.1.1.1.0");

@BeforeClass
public static void setUp() throws Exception {
	agent = new Agent("0.0.0.0/2001");
	agent.start();

	// Since BaseAgent registers some mibs by default we need to unregister
	// one before we register our own sysDescr. Normally you would
	// override that method and register the mibs that you need
	agent.unregisterManagedObject(agent.getSnmpv2MIB());

	// Register a system description, use one from you product environment
	// to test with
	agent.registerManagedObject(MOScalarFactory.createReadOnly(sysDescr,"MySystemDescr"));

        // Setup the client to use our newly started agent
	client = new SimpleSnmpClient("udp:127.0.0.1/2001");
}

@AfterClass
public static void tearDown() throws Exception {
	agent.stop();
        client.stop();
}

@Test
public void verifySysDescr() throws IOException {
     assertEquals("MySystemDescr", client.getAsString(sysDescr));
}

/**
  * Uses asynchronous fetch and test it with Awaitility.
  */
@Test
public void verifySysDescrAsynch() throws Exception {
    final StringResponseListener listener = new StringResponseListener();
    client.getAsString(sysDescr, listener);
    await().until(callTo(listener).getValue(),equalTo("MySystemDescr"));
}

// standard in RFC-1213
static final OID interfacesTable = new OID(".1.3.6.1.2.1.2.2.1");

@BeforeClass
public static void setUp() throws Exception {
	agent = new Agent("0.0.0.0/2001");
	agent.start();
	// Build a table. This example is taken from TestAgent and sets up
	// two physical interfaces
	MOTableBuilder builder = new MOTableBuilder(interfacesTable)
		.addColumnType(SMIConstants.SYNTAX_INTEGER,MOAccessImpl.ACCESS_READ_ONLY)
		.addColumnType(SMIConstants.SYNTAX_OCTET_STRING,MOAccessImpl.ACCESS_READ_ONLY)
		.addColumnType(SMIConstants.SYNTAX_INTEGER,MOAccessImpl.ACCESS_READ_ONLY)
		.addColumnType(SMIConstants.SYNTAX_INTEGER,MOAccessImpl.ACCESS_READ_ONLY)
		.addColumnType(SMIConstants.SYNTAX_GAUGE32,MOAccessImpl.ACCESS_READ_ONLY)
		.addColumnType(SMIConstants.SYNTAX_OCTET_STRING,MOAccessImpl.ACCESS_READ_ONLY)
		.addColumnType(SMIConstants.SYNTAX_INTEGER,MOAccessImpl.ACCESS_READ_ONLY)
		.addColumnType(SMIConstants.SYNTAX_INTEGER,MOAccessImpl.ACCESS_READ_ONLY)
		// Normally you would begin loop over you two domain objects here
		.addRowValue(new Integer32(1))
		.addRowValue(new OctetString("loopback"))
		.addRowValue(new Integer32(24))
		.addRowValue(new Integer32(1500))
		.addRowValue(new Gauge32(10000000))
		.addRowValue(new OctetString("00:00:00:00:01"))
		.addRowValue(new Integer32(1500))
		.addRowValue(new Integer32(1500))
		//next row
		.addRowValue(new Integer32(2))
		.addRowValue(new OctetString("eth0"))
		.addRowValue(new Integer32(24))
		.addRowValue(new Integer32(1500))
		.addRowValue(new Gauge32(10000000))
		.addRowValue(new OctetString("00:00:00:00:02"))
		.addRowValue(new Integer32(1500))
		.addRowValue(new Integer32(1500));

	agent.registerManagedObject(builder.build());

	// Setup the client to use our newly started agent
	client = new SimpleSnmpClient("udp:127.0.0.1/2001");
}

/**
* Normally this would return domain objects or something else than this...
 */
public List> getTableAsStrings(OID[] oids) {
	TableUtils tUtils = new TableUtils(snmp, new DefaultPDUFactory());

	@SuppressWarnings("unchecked")
	List events = tUtils.getTable(getTarget(), oids, null, null);

	List> list = new ArrayList>();
	for (TableEvent event : events) {
		if(event.isError()) {
			throw new RuntimeException(event.getErrorMessage());
		}
		List strList = new ArrayList();
		list.add(strList);
		for(VariableBinding vb: event.getColumns()) {
			strList.add(vb.getVariable().toString());
		}
	}
	return list;
}

@Test
public void verifyTableContents() {

	// You retreive a table by suppling the columns of the table that
	// you need, here we use column 2,6 and 8 so we do not verify the complete
	// table
	List> tableContents = client.getTableAsStrings(new OID[]{
   		new OID(interfacesTable.toString() + ".2"),
    		new OID(interfacesTable.toString() + ".6"),
    		new OID(interfacesTable.toString() + ".8")});

	//and validate here
	assertEquals(2, tableContents.size());
	assertEquals(3, tableContents.get(0).size());
	assertEquals(3, tableContents.get(1).size());

	// Row 1
	assertEquals("loopback", tableContents.get(0).get(0));
	assertEquals("00:00:00:00:01", tableContents.get(0).get(1));
	assertEquals("1500", tableContents.get(0).get(2));
	// Row 2
	assertEquals("eth0", tableContents.get(1).get(0));
	assertEquals("00:00:00:00:02", tableContents.get(1).get(1));
	assertEquals("1500", tableContents.get(1).get(2));
}

Introduction to snmp4j

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