因此，我尝试使用Java库SNMP4j在本地计算机上运行代理模拟。我一直在使用此示例程序来尝试使一切正常运行。
https://www.jitendrazaa.com/blog/java/snmp/creating-snmp-agent-server-in-java-using-snmp4j/
设置环境时遇到了一些麻烦，因此我参考了这篇帖子RunTimeException in SNMP4J agent来寻求帮助。导入他的项目后，我遇到了与他同样的约束问题。
要解决此问题，我刚刚将模拟代理的IP地址从0.0.0.1/161更改为127.0.0.1/16000。现在，我收到此运行时错误：
Exception in thread "main" java.lang.NullPointerException
at org.snmp4j.agent.mo.DefaultMOTableModel.addRow(DefaultMOTableModel.java:44)
at org.snmp4j.agent.mo.DefaultMOMutableTableModel.addRow(DefaultMOMutableTableModel.java:285)
at org.snmp4j.agent.mo.DefaultMOTable.addRow(DefaultMOTable.java:191)
at org.bihe.SNMPAgent.addCommunities(SNMPAgent.java:87)
at org.snmp4j.agent.BaseAgent.init(BaseAgent.java:175)
at org.bihe.SNMPAgent.start(SNMPAgent.java:166)
at org.bihe.TestSNMPAgent.init(TestSNMPAgent.java:44)
at org.bihe.TestSNMPAgent.main(TestSNMPAgent.java:19)
我将范围缩小到baseAgent类尝试使用SNMPAgent类中重载的addCommunities函数时。在此函数中，由于SNMP4j库提供的DefaultMOTable类中的这段代码，MOTableRow行变量被分配为null。
不是获取SNMP_Error_Success代码“ 0”，而是获取rowEvent.getVetoStatus（）为“ 18”。这样就得到了NULL的返回值
public R createRow(OID index, Variable[] initialValues) {
if (model instanceof MOMutableTableModel) {
Variable[] values = initialValues;
if (values.length < getColumnCount()) {
values = getDefaultValues();
System.arraycopy(initialValues, 0, values, 0, initialValues.length);
}
R row =
((MOMutableTableModel<R>)model).createRow(index, values);
MOTableRowEvent rowEvent =
new MOTableRowEvent(this, this, row, MOTableRowEvent.CREATE, true);
fireRowChanged(rowEvent);
//this is where things go wrong
System.out.println(rowEvent.getVetoStatus());
if (rowEvent.getVetoStatus() == SnmpConstants.SNMP_ERROR_SUCCESS) {
return row;
}
}
return null;
}
我在SNMPConstants.class文件中查找了此错误代码，发现错误状态为18表示“ SNMP_ERROR_INCONSISTENT_NAME = 18”。我很难弄清楚这到底是什么意思，是什么导致此错误以及如何修复它。我正在使用与上述项目“ snmp4j-2.2.3.jar”和“ snmp4j-agent-2.0.10a.jar”完全相同的罐子。
如果有帮助，这是我正在使用的代码：
package org.bihe;
import java.io.IOException;
import org.snmp4j.agent.CommandProcessor;
import org.snmp4j.mp.MPv3;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.OctetString;
import org.snmp4j.mp.SnmpConstants;
public class TestSNMPAgent {
static final OID sysDescr = new OID(".1.3.6.1.2.1.1.1.0");
public static void main(String[] args) throws IOException {
//not really sure what the use of this ipaddress is as it't not used anywhere in the code.
TestSNMPAgent client = new TestSNMPAgent("udp:127.0.0.1/161");
System.out.println("Hello this is a client");
client.init();
}
SNMPAgent agent = null;
/**
* This is the client which we have created earlier
*/
SNMPManager client = null;
String address = null;
/**
* Constructor
*
* @param add
*/
public TestSNMPAgent(String add) {
address = add;
}
private void init() throws IOException {
System.out.println("Hello before Agent");
OctetString testoct = new OctetString("public2public");
//ipaddress changed from 0.0.0.1/161 to 127.0.0.1/16000
agent = new SNMPAgent("127.0.0.1/16000");
agent.start();
//code execution doesn't make it past the agent.start() statement.
System.out.println("Hello after agent");
// 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(MOCreator.createReadOnly(sysDescr,
"This Description is set By ShivaSoft"));
System.out.println("Hello before client");
// Setup the client to use our newly started agent
client = new SNMPManager("udp:127.0.0.1/2001");
client.start();
// Get back Value which is set
System.out.println(client.getAsString(sysDescr));
}
}
模拟代理的代码：
package org.bihe;
import java.io.File;
import java.io.IOException;
import org.snmp4j.TransportMapping;
import org.snmp4j.agent.BaseAgent;
import org.snmp4j.agent.CommandProcessor;
import org.snmp4j.agent.DuplicateRegistrationException;
import org.snmp4j.agent.MOGroup;
import org.snmp4j.agent.ManagedObject;
import org.snmp4j.agent.mo.MOTableRow;
import org.snmp4j.agent.mo.snmp.RowStatus;
import org.snmp4j.agent.mo.snmp.SnmpCommunityMIB;
import org.snmp4j.agent.mo.snmp.SnmpNotificationMIB;
import org.snmp4j.agent.mo.snmp.SnmpTargetMIB;
import org.snmp4j.agent.mo.snmp.StorageType;
import org.snmp4j.agent.mo.snmp.VacmMIB;
import org.snmp4j.agent.security.MutableVACM;
import org.snmp4j.mp.MPv3;
import org.snmp4j.security.SecurityLevel;
import org.snmp4j.security.SecurityModel;
import org.snmp4j.security.USM;
import org.snmp4j.smi.Address;
import org.snmp4j.smi.GenericAddress;
import org.snmp4j.smi.Integer32;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.OctetString;
import org.snmp4j.smi.Variable;
import org.snmp4j.transport.TransportMappings;
public class SNMPAgent extends BaseAgent {
private String address;
/**
*
* @param address
* @throws IOException
*/
public SNMPAgent(String address) throws IOException {
/**
* Creates a base agent with boot-counter, config file, and a
* CommandProcessor for processing SNMP requests. Parameters:
* "bootCounterFile" - a file with serialized boot-counter information
* (read/write). If the file does not exist it is created on shutdown of
* the agent. "configFile" - a file with serialized configuration
* information (read/write). If the file does not exist it is created on
* shutdown of the agent. "commandProcessor" - the CommandProcessor
* instance that handles the SNMP requests.
*/
super(new File("conf.agent"), new File("bootCounter.agent"),
new CommandProcessor(
new OctetString(MPv3.createLocalEngineID())));
this.address = address;
}
/**
* Adds community to security name mappings needed for SNMPv1 and SNMPv2c.
* */
@SuppressWarnings("unchecked")
@Override
protected void addCommunities(SnmpCommunityMIB communityMIB) {
OID testOct = new OctetString("public2public").toSubIndex(true);
Variable[] com2sec = new Variable[] { new OctetString("public"),
new OctetString("cpublic"), // security name
getAgent().getContextEngineID(), // local engine ID
new OctetString("public"), // default context name
new Integer32(StorageType.nonVolatile), // storage type
new Integer32(RowStatus.active) // row status
};
@SuppressWarnings("rawtypes")
//After the createRow function is called the variable, "row" is assigned to null
//due to the aformentioned DefaultMOTable class function, "createRow"
MOTableRow row = communityMIB.getSnmpCommunityEntry().createRow(
testOct.toSubIndex(true), com2sec);
/*
MOTableRow row = communityMIB.getSnmpCommunityEntry().createRow(
new OctetString("public2public").toSubIndex(true), com2sec);
*/
communityMIB.getSnmpCommunityEntry().addRow(row);
}
/**
* Adds initial notification targets and filters.
*/
@Override
protected void addNotificationTargets(SnmpTargetMIB arg0,
SnmpNotificationMIB arg1) {
// TODO Auto-generated method stub
}
/**
* Adds all the necessary initial users to the USM.
*/
@Override
protected void addUsmUser(USM arg0) {
// TODO Auto-generated method stub
}
/**
* Adds initial VACM configuration.
*/
@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);
}
/**
* Unregister the basic MIB modules from the agent's MOServer.
*/
@Override
protected void unregisterManagedObjects() {
// TODO Auto-generated method stub
}
/**
* Register additional managed objects at the agent's server.
*/
@Override
protected void registerManagedObjects() {
// TODO Auto-generated method stub
}
@SuppressWarnings("rawtypes")
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();
}
/**
* 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));
}
}
如果您希望将代码提供给MOCreator或SNMPManager类，我可以提供，但其与“ https://www.jitendrazaa.com/blog/java/snmp/creating-snmp-代理服务器在Java中使用snmp4j /“
编辑： 找到与错误有关的更多信息：
/**
* The specified object does not exists and presently it cannot be created,
* see error index.
*/
public static final int inconsistentName =
SnmpConstants.SNMP_ERROR_INCONSISTENT_NAME;