java - 带有 snmpv3 响应和错误的 SNMP4j 为空

Question

我正在使用 snmp4j 3.4.2 在我的 Java 应用程序中(完整代码如下)
我正在尝试执行 snmpget 使用 snmpv3，安全性 DES 和授权 MD5 和自定义 OID(python 脚本，由 snmp 的扩展功能执行)。为了更好地理解，我在下面的示例中使用了 SnmpConstants.sysUpTime。
SNMP 资源配置了此用户:

defSecurityName demo
defSecurityLevel authPriv
defAuthType MD5
defPrivType DES
defAuthPassphrase pass
defPrivPassphrase pass

我已经在使用这个用户和资源来成功地使用 执行 snmpget python (pysnmp) 和 bash (snmpget)，所以我可以肯定地说我的设置是有效的，而 java 代码是问题所在。
我有两个 Java 类(Listener.java 和 ServerStatusHelper.java)
Listener.java 包含 main 并调用 ServerStatusHelper.java 中的 snmpGet，其他 Listener 代码因不需要而被排除在外。

import org.snmp4j.PDU;
import org.snmp4j.ScopedPDU;
import org.snmp4j.Snmp;
import org.snmp4j.Target;
import org.snmp4j.event.ResponseEvent;
import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.security.AuthMD5;
import org.snmp4j.security.AuthSHA;
import org.snmp4j.security.PrivAES128;
import org.snmp4j.security.PrivDES;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.VariableBinding;

public class Listener {

    public static void main(String[] args) {

        ServerStatusHelper agent = new ServerStatusHelper("host.tld", "udp", 161, "demo", "demo",
                "pass", "pass", new AuthMD5(), new PrivDES(), true);

        try {
            agent.startAgent();
            ResponseEvent response = agent.snmpGetOperation(SnmpConstants.sysUpTime);
            if (response != null) {
                System.out.println(
                        "response null - error: "+ response.getError() +
                        "peerAddress: " + response.getPeerAddress() +
                        "source: " + response.getSource().toString() +
                        "request: " + response.getRequest());
            }

        } catch (

        IOException e) {
            e.printStackTrace();

        }
    }

}

ServerStatusHelper.java

import java.io.IOException;

import org.snmp4j.CommunityTarget;
import org.snmp4j.PDU;
import org.snmp4j.ScopedPDU;
import org.snmp4j.Snmp;
import org.snmp4j.TransportMapping;
import org.snmp4j.UserTarget;
import org.snmp4j.event.ResponseEvent;
import org.snmp4j.mp.MPv3;
import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.security.AuthGeneric;
import org.snmp4j.security.AuthMD5;
import org.snmp4j.security.PrivDES;
import org.snmp4j.security.PrivacyGeneric;
import org.snmp4j.security.SecurityLevel;
import org.snmp4j.security.SecurityModels;
import org.snmp4j.security.SecurityProtocols;
import org.snmp4j.security.USM;
import org.snmp4j.security.UsmUser;
import org.snmp4j.smi.Address;
import org.snmp4j.smi.GenericAddress;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.OctetString;
import org.snmp4j.smi.TransportIpAddress;
import org.snmp4j.smi.VariableBinding;
import org.snmp4j.transport.DefaultTcpTransportMapping;
import org.snmp4j.transport.DefaultUdpTransportMapping;

public class ServerStatusHelper {

    private Address nmsIP;
    private String user;
    private String securityName;
    private String privacyPassword;
    private String authorizationPassword;
    private AuthGeneric authProtocol;
    private PrivacyGeneric privacyProtocol;
    private String protocol;
    private boolean encryption;

    private long timeOut = 1000;
    private int noOfRetries = 10;

    private Snmp snmp;
    private UserTarget target;
    private CommunityTarget v1target;
    
    ServerStatusHelper(String ip, String protocol, int snmpPort, String username, String securityName,
            String privacyPassword, String authPassowrd, AuthGeneric authProtocol, PrivacyGeneric privacyProtocol,
            boolean encryption) {

        nmsIP = GenericAddress.parse(protocol + ":" + ip + "/" + snmpPort);
        System.out.println("NMS IP set : " + nmsIP.toString());

        this.protocol = protocol;
        this.user = username;
        this.securityName = securityName;
        this.privacyPassword = privacyPassword;
        this.authorizationPassword = authPassowrd;
        this.authProtocol = authProtocol;
        this.privacyProtocol = privacyProtocol;
        this.encryption = encryption;
        
        SecurityProtocols.getInstance().addAuthenticationProtocol(new AuthMD5());
        SecurityProtocols.getInstance().addPrivacyProtocol(new PrivDES());

    }

    public void startAgent() throws IOException {
        if (snmp == null) {

            TransportMapping<? extends TransportIpAddress> transport = null;

            if (protocol.equalsIgnoreCase("udp")) {
                System.out.println("UDP Protocol selected.");
                transport = new DefaultUdpTransportMapping();
            } else {
                System.out.println("TCP Protocol selected.");
                transport = new DefaultTcpTransportMapping();
            }

            snmp = new Snmp(transport);

            USM usm = new USM(SecurityProtocols.getInstance(), new OctetString(MPv3.createLocalEngineID()), 0);
            SecurityModels.getInstance().addSecurityModel(usm);

            transport.listen();

            snmp.getUSM().addUser(new OctetString(user),
                    new UsmUser(new OctetString(securityName), authProtocol.getID(),
                            new OctetString(authorizationPassword), privacyProtocol.getID(),
                            new OctetString(privacyPassword)));

            if (encryption)
                target = createUserTarget();
            else
                v1target = createUserTargetWithoutEncryption();
        }

    }

    public ResponseEvent snmpSetOperation(VariableBinding[] vars) throws IOException {
        PDU setPdu = new ScopedPDU();
        for (VariableBinding variableBinding : vars) {
            setPdu.add(variableBinding);
        }
        return snmp.send(setPdu, target);
    }

    public ResponseEvent snmpGetOperation(OID oid) throws IOException {

        if (encryption) {
            PDU getPdu = new ScopedPDU();
            getPdu.add(new VariableBinding(oid));
            getPdu.setType(ScopedPDU.GET);
            return snmp.get(getPdu, target);

        } else {
            PDU getPdu = new PDU();
            getPdu.add(new VariableBinding(oid));
            getPdu.setType(PDU.GET);
            return snmp.get(getPdu, v1target);

        }

    }

    private UserTarget createUserTarget() {
        UserTarget target = new UserTarget();
        target.setAddress(nmsIP);
        target.setRetries(noOfRetries);
        target.setTimeout(timeOut);
        target.setVersion(SnmpConstants.version3);
        target.setSecurityLevel(SecurityLevel.AUTH_PRIV);
        target.setSecurityName(new OctetString(securityName));
        return target;
    }

    private CommunityTarget createUserTargetWithoutEncryption() {
        CommunityTarget target = new CommunityTarget();
        target.setCommunity(new OctetString("public"));
        target.setAddress(nmsIP);
        target.setRetries(noOfRetries);
        target.setTimeout(timeOut);
        target.setVersion(SnmpConstants.version1);
        return target;
    }

    public long getTimeOut() {
        return timeOut;
    }

    public void setTimeOut(long timeOut) {
        this.timeOut = timeOut;
    }

    public int getNoOfRetries() {
        return noOfRetries;
    }

    public void setNoOfRetries(int noOfRetries) {
        this.noOfRetries = noOfRetries;
    }
}

程序的执行退出

NMS IP set : **IPREMOVED**/161
UDP Protocol selected.
response null - error: nullpeerAddress: **IPREMOVED**/161source: org.snmp4j.Snmp@e580929 request: GET[{contextEngineID=80:00:1f:88:80:5e:2e:49:07:2f:68:44:57:00:00:00:00, contextName=}, requestID=588252045, errorStatus=0, errorIndex=0, VBS[1.3.6.1.2.1.1.3.0 = Null]]

任何人都知道我做错了什么？
编辑:
从服务器系统日志我可以看到，请求到达资源:

Jul 31 11:52:46 loadbalancer snmpd[1219]: Connection from UDP: [IP REMOVED]:54734->[IP REMOVED]:161
Jul 31 11:52:46 loadbalancer snmpd[1219]: Connection from UDP: [IP REMOVED]:54734->[IP REMOVED]:161

Answer 1

@i-shm 我认为你做的一切都很好。
您代码中唯一的问题可能只是您评估 response 的那一行。多变的。您的意思是 response != null实际应该是什么时候response == null .我的意思是:

import org.snmp4j.PDU;
import org.snmp4j.ScopedPDU;
import org.snmp4j.Snmp;
import org.snmp4j.Target;
import org.snmp4j.event.ResponseEvent;
import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.security.AuthMD5;
import org.snmp4j.security.AuthSHA;
import org.snmp4j.security.PrivAES128;
import org.snmp4j.security.PrivDES;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.VariableBinding;

public class Listener {

    public static void main(String[] args) {

        ServerStatusHelper agent = new ServerStatusHelper("host.tld", "udp", 161, "demo", "demo",
                "pass", "pass", new AuthMD5(), new PrivDES(), true);

        try {
            agent.startAgent();
            ResponseEvent event = agent.snmpGetOperation(SnmpConstants.sysUpTime);
            final PDU response = event.getResponse();
            if (response == null) {
                System.out.println(
                        "response null - error: "+ event.getError() +
                        "peerAddress: " + event.getPeerAddress() +
                        "source: " + event.getSource().toString() +
                        "request: " + event.getRequest());
            } else {
              System.out.println("Response PDU:" + response.toString());
              // Process the response as you need, maybe something like this:
              long sysUpTime = response.get(0).getVariable().toLong();
              // You can find relevant information in the javadocs of the library:
              // https://agentpp.com/doc/snmp4j/index.html?org/snmp4j/package-summary.html
            }

        } catch (IOException e) {
            e.printStackTrace();

        }
    }

}

这就是为什么您没有在 java 代码中收到错误并且您的系统日志表明请求已实际发送的原因。