As we have discussed, Traps are like events. This is a way the SNMP agent pushes the information to client. Asynchronously, events can be fired to client from server (agent).
Example:
SNMP Trap Receiver:
package com.G2.SNMP.Trap.receiver;
import java.io.IOException;
import org.snmp4j.CommandResponder;
import org.snmp4j.CommandResponderEvent;
import org.snmp4j.CommunityTarget;
import org.snmp4j.MessageDispatcher;
import org.snmp4j.MessageDispatcherImpl;
import org.snmp4j.MessageException;
import org.snmp4j.PDU;
import org.snmp4j.Snmp;
import org.snmp4j.mp.MPv1;
import org.snmp4j.mp.MPv2c;
import org.snmp4j.mp.StateReference;
import org.snmp4j.mp.StatusInformation;
import org.snmp4j.security.Priv3DES;
import org.snmp4j.security.SecurityProtocols;
import org.snmp4j.smi.OctetString;
import org.snmp4j.smi.TcpAddress;
import org.snmp4j.smi.TransportIpAddress;
import org.snmp4j.smi.UdpAddress;
import org.snmp4j.transport.AbstractTransportMapping;
import org.snmp4j.transport.DefaultTcpTransportMapping;
import org.snmp4j.transport.DefaultUdpTransportMapping;
import org.snmp4j.util.MultiThreadedMessageDispatcher;
import org.snmp4j.util.ThreadPool;
public class TrapReceiver implements CommandResponder {
public static void main(String[] args) {
TrapReceiver snmp4jTrapReceiver = new TrapReceiver();
try {
snmp4jTrapReceiver.listen(new UdpAddress("localhost/162"));
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* Trap Listner
*/
public synchronized void listen(TransportIpAddress address)
throws IOException {
AbstractTransportMapping transport;
if (address instanceof TcpAddress) {
transport = new DefaultTcpTransportMapping((TcpAddress) address);
} else {
transport = new DefaultUdpTransportMapping((UdpAddress) address);
}
ThreadPool threadPool = ThreadPool.create("DispatcherPool", 10);
MessageDispatcher mDispathcher = new MultiThreadedMessageDispatcher(
threadPool, new MessageDispatcherImpl());
// add message processing models
mDispathcher.addMessageProcessingModel(new MPv1());
mDispathcher.addMessageProcessingModel(new MPv2c());
// add all security protocols
SecurityProtocols.getInstance().addDefaultProtocols();
SecurityProtocols.getInstance().addPrivacyProtocol(new Priv3DES());
// Create Target
CommunityTarget target = new CommunityTarget();
target.setCommunity(new OctetString("public"));
Snmp snmp = new Snmp(mDispathcher, transport);
snmp.addCommandResponder(this);
transport.listen();
System.out.println("Listening on " + address);
try {
this.wait();
} catch (InterruptedException ex) {
Thread.currentThread().interrupt();
}
}
/**
* This method will be called whenever a pdu is received on the given port
* specified in the listen() method
*/
public synchronized void processPdu(CommandResponderEvent cmdRespEvent) {
System.out.println("Received PDU...");
PDU pdu = cmdRespEvent.getPDU();
if (pdu != null) {
System.out.println("Trap Type = " + pdu.getType());
System.out.println("Variables = " + pdu.getVariableBindings());
}
}
}
Version 1 Trap Sender:
package com.G2.SNMP.Trap.Sender;
import org.snmp4j.CommunityTarget;
import org.snmp4j.PDU;
import org.snmp4j.PDUv1;
import org.snmp4j.Snmp;
import org.snmp4j.TransportMapping;
import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.smi.IpAddress;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.OctetString;
import org.snmp4j.smi.UdpAddress;
import org.snmp4j.transport.DefaultUdpTransportMapping;
public class TrapSenderVersion1 {
public static final String community = "public";
// Sending Trap for sysLocation of RFC1213
public static final String Oid = ".1.3.6.1.2.1.1.8";
//IP of Local Host
public static final String ipAddress = "127.0.0.1";
//Ideally Port 162 should be used to send receive Trap, any other available Port can be used
public static final int port = 162;
public static void main(String[] args) {
TrapSenderVersion1 trapV1 = new TrapSenderVersion1();
trapV1.sendTrap_Version1();
}
/**
* This methods sends the V1 trap to the Localhost in port 162
*/
public void sendTrap_Version1() {
try {
// Create Transport Mapping
TransportMapping transport = new DefaultUdpTransportMapping();
transport.listen();
// Create Target
CommunityTarget cTarget = new CommunityTarget();
cTarget.setCommunity(new OctetString(community));
cTarget.setVersion(SnmpConstants.version1);
cTarget.setAddress(new UdpAddress(ipAddress + "/" + port));
cTarget.setTimeout(5000);
cTarget.setRetries(2);
PDUv1 pdu = new PDUv1();
pdu.setType(PDU.V1TRAP);
pdu.setEnterprise(new OID(Oid));
pdu.setGenericTrap(PDUv1.ENTERPRISE_SPECIFIC);
pdu.setSpecificTrap(1);
pdu.setAgentAddress(new IpAddress(ipAddress));
// Send the PDU
Snmp snmp = new Snmp(transport);
System.out.println("Sending V1 Trap... Check Wheather NMS is Listening or not? ");
snmp.send(pdu, cTarget);
snmp.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
Output:
Listening on 127.0.0.1/162
Received PDU…
Trap Type = -92
Variables = []
Version 2 Trap Sender:
package com.G2.SNMP.Trap.Sender;
import java.util.Date;
import org.snmp4j.CommunityTarget;
import org.snmp4j.PDU;
import org.snmp4j.Snmp;
import org.snmp4j.TransportMapping;
import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.smi.IpAddress;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.OctetString;
import org.snmp4j.smi.UdpAddress;
import org.snmp4j.smi.VariableBinding;
import org.snmp4j.transport.DefaultUdpTransportMapping;
public class TrapSenderVersion2 {
public static final String community = "public";
// Sending Trap for sysLocation of RFC1213
public static final String Oid = ".1.3.6.1.2.1.1.8";
//IP of Local Host
public static final String ipAddress = "127.0.0.1";
//Ideally Port 162 should be used to send receive Trap, any other available Port can be used
public static final int port = 162;
public static void main(String[] args) {
TrapSenderVersion2 trapV2 = new TrapSenderVersion2();
trapV2.sendTrap_Version2();
}
/**
* This methods sends the V1 trap to the Localhost in port 162
*/
public void sendTrap_Version2() {
try {
// Create Transport Mapping
TransportMapping transport = new DefaultUdpTransportMapping();
transport.listen();
// Create Target
CommunityTarget cTarget = new CommunityTarget();
cTarget.setCommunity(new OctetString(community));
cTarget.setVersion(SnmpConstants.version2c);
cTarget.setAddress(new UdpAddress(ipAddress + "/" + port));
cTarget.setRetries(2);
cTarget.setTimeout(5000);
// Create PDU for V2
PDU pdu = new PDU();
// need to specify the system up time
pdu.add(new VariableBinding(SnmpConstants.sysUpTime,
new OctetString(new Date().toString())));
pdu.add(new VariableBinding(SnmpConstants.snmpTrapOID, new OID(
Oid)));
pdu.add(new VariableBinding(SnmpConstants.snmpTrapAddress,
new IpAddress(ipAddress)));
pdu.add(new VariableBinding(new OID(Oid), new OctetString(
"Major")));
pdu.setType(PDU.NOTIFICATION);
// Send the PDU
Snmp snmp = new Snmp(transport);
System.out.println("Sending V2 Trap... Check Wheather NMS is Listening or not? ");
snmp.send(pdu, cTarget);
snmp.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
Output:
Listening on 127.0.0.1/162
Received PDU…
Trap Type = -89
Variables = [1.3.6.1.2.1.1.3.0 = Wed Feb 16 01:17:02 IST 2011, 1.3.6.1.6.3.1.1.4.1.0 = 1.3.6.1.2.1.1.6, 1.3.6.1.6.3.18.1.3.0 = 127.0.0.1, 1.3.6.1.2.1.1.6 = Major]
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