snmp 协议开发之SNMP4J-SNMPv1/v2

ゝ一世哀愁。 2023-10-16 21:52 7阅读 0赞

使用SNMP4J可以很方便的实现一个SNMP NMS的功能。  
对于SNMPv1/SNMPv2，简单的说，只需要以下几个步骤  
1) 创建Snmp对象snmp  
  
2) 创建CommunityTarget对象target，并指定community, version, address, timeout, retry等参数。  
  
3) 创建PDU对象pdu，并指定操作类型(GET/GETNEXT/GETBULK/SET)， 添加VariableBinding(也就是待操作的OID),  
 如果是GETBULK操作，还可以指定MaxRepetitions和NonRepeaters。  
 注意一定要指定MaxRepetitions，默认值是0，那样不会返回任何结果。  
  
4) 调用snmp.send(pdu, target)方法，发送请求请返回结果。  
  
此外，SNMP4J提供了TableUtils类，可以很轻松的实现一个SNMP Walk的功能，比如一次返回一个表格下面的所有MIB值。  
TableUtils类还支持指定ower bound index 和 upper bound index， 得到更小范围的结果以提高性能。这一点对于从一个很多行的表中取一部分行的数据来说很重要。  
  
Snmp还支持异步的send方法。  
  
下面的代码实例实现了GET, GETNEXT, GETBULK, Walk, SET操作，  
以及一个利用异步send方法实现的agent discovery： 对一个广播地址发送请求，等待agent返回的应答。

如果需要对一个范围内的IP进行扫描，可以稍加改进，反复调用异步send多次发送给不同IP。

package com.snmp.demo;
    
    import org.snmp4j.CommunityTarget;
    import org.snmp4j.PDU;
    import org.snmp4j.Snmp;
    import org.snmp4j.event.ResponseEvent;
    import org.snmp4j.event.ResponseListener;
    import org.snmp4j.mp.SnmpConstants;
    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;
    import org.snmp4j.util.DefaultPDUFactory;
    import org.snmp4j.util.TableEvent;
    import org.snmp4j.util.TableUtils;
    
    import java.io.IOException;
    import java.util.List;
    import java.util.Vector;
    
    /**
     * Created by vixuan-008 on 2015/7/9.
     */
    public class SNMPv1 {
        public static void main(String[] args) throws Exception {
            Snmp snmp = new Snmp(new DefaultUdpTransportMapping());
            snmp.listen();
    
            CommunityTarget target = new CommunityTarget();
            target.setCommunity(new OctetString("public"));
            target.setVersion(SnmpConstants.version2c);
            target.setAddress(new UdpAddress("127.0.0.1/161"));
            target.setTimeout(3000);    //3s
            target.setRetries(1);
    
            sendRequest(snmp, createGetPdu(), target);
            sendRequest(snmp, createGetNextPdu(), target);
            sendRequest(snmp, createGetBulkPdu(), target);
            snmpWalk(snmp, target);()
    
            target.setCommunity(new OctetString("public"));
            sendRequest(snmp, createSetPdu(), target);
    
            CommunityTarget broadcastTarget = new CommunityTarget();
            broadcastTarget.setCommunity(new OctetString("public"));
            broadcastTarget.setVersion(SnmpConstants.version2c);
            broadcastTarget.setAddress(new UdpAddress("192.168.0.204/161"));
            broadcastTarget.setTimeout(5000);   //5s
            sendAsyncRequest(snmp, createGetNextPdu(), broadcastTarget);
            Thread.sleep(6000); //main thread wait 6s for the completion of asynchronous request
        }
        private static PDU createGetPdu() {
            PDU pdu = new PDU();
            pdu.setType(PDU.GET);
            pdu.add(new VariableBinding(new OID("1.3.6.1.2.1.1.3"))); //sysUpTime
            pdu.add(new VariableBinding(new OID("1.3.6.1.2.1.1.5.0"))); //sysName
            pdu.add(new VariableBinding(new OID("1.3.6.1.2.1.1.5")));   //expect an no_such_instance error
            return pdu;
        }
    
        private static PDU createGetNextPdu() {
            PDU pdu = new PDU();
            pdu.setType(PDU.GETNEXT);
            pdu.add(new VariableBinding(new OID("1.3.6.1.2.1.1.3")));   //sysUpTime
            pdu.add(new VariableBinding(new OID("1.3.6.1.2.1.1.5")));   //sysName
    
            return pdu;
        }
    
        private static PDU createGetBulkPdu() {
            PDU pdu = new PDU();
            pdu.setType(PDU.GETBULK);
            pdu.setMaxRepetitions(10);  //must set it, default is 0 .1.3.6.1.2.1.1.1.0
            pdu.setNonRepeaters(0);
            pdu.add(new VariableBinding(new OID("1.3.6.1.2.1.1")));     //system
            return pdu;
        }
    
        private static PDU createSetPdu() {
            PDU pdu = new PDU();
            pdu.setType(PDU.SET);
            pdu.add(new VariableBinding(new OID("1.3.6.1.2.1.1.5.0"), new OctetString("sysname"))); //sysName
            return pdu;
        }
    
        private static void sendRequest(Snmp snmp, PDU pdu, CommunityTarget target)
                throws IOException {
            ResponseEvent responseEvent = snmp.send(pdu, target);
            PDU response = responseEvent.getResponse();
    
            if (response == null) {
                System.out.println("TimeOut...");
            } else {
                if (response.getErrorStatus() == PDU.noError) {
                    Vector<? extends VariableBinding> vbs = response.getVariableBindings();
                    for (VariableBinding vb : vbs) {
                        System.out.println(vb + " ," + vb.getVariable().getSyntaxString());
                    }
                } else {
                    System.out.println("Error:" + response.getErrorStatusText());
                }
            }
        }
    
        private static void sendAsyncRequest(Snmp snmp, PDU pdu, CommunityTarget target)
                throws IOException {
            snmp.send(pdu, target, null, new ResponseListener(){
    
                @Override
                public void onResponse(ResponseEvent event) {
                    PDU response = event.getResponse();
                    System.out.println("Got response from " + event.getPeerAddress());
                    if (response == null) {
                        System.out.println("TimeOut...");
                    } else {
                        if (response.getErrorStatus() == PDU.noError) {
                            Vector<? extends VariableBinding> vbs = response.getVariableBindings();
                            for (VariableBinding vb : vbs) {
                                System.out.println(vb + " ," + vb.getVariable().getSyntaxString());
                            }
                        } else {
                            System.out.println("Error:" + response.getErrorStatusText());
                        }
                    }
                }});
        }
    
        private static void snmpWalk(Snmp snmp, CommunityTarget target) {
            TableUtils utils = new TableUtils(snmp, new DefaultPDUFactory(PDU.GETNEXT));//GETNEXT or GETBULK
            utils.setMaxNumRowsPerPDU(5);   //only for GETBULK, set max-repetitions, default is 10
            OID[] columnOids = new OID[] {
                    new OID("1.3.6.1.2.1.1.9.1.2"), //sysORID
                    new OID("1.3.6.1.2.1.1.9.1.3"), //sysORDescr
                    new OID("1.3.6.1.2.1.1.9.1.5")  //wrong OID, expect an null in in VariableBinding array
            };
            // If not null, all returned rows have an index in a range (lowerBoundIndex, upperBoundIndex]
            List<TableEvent> l = utils.getTable(target, columnOids, new OID("3"), new OID("10"));
            for (TableEvent e : l) {
                System.out.println(e);
            }
        }
    }