玉树临枫 阅读(75) 评论(0)

之前有在弄监控服务器这块的工作,今天来整体总结下。因为有些服务器(路由器、交换机等都是基于snmp协议的)必须使用snmp协议去监控采集和接收信息,所以必须去了解snmp相关内容,以及如何在基于java上开发。关于了解snmp相关内容,必看《SNMP简单网络管理协议》这本书里面介绍的很详细,另外推荐这位前辈的博文写的很到位 《snmp学习总结》。关于snmp4j的介绍也可以看看前面这位前辈关于 《snmp学习总结》的最后一篇博文《snmp4j介绍》。当然本篇主要记录如何基于Java如何使用snmp4j去开发实现监控与采集,下面我们直接结合源码以及实例讲解:

一、针对源码进行分析:

  1、核心对象SNMP的初始化。

  源码中有四种初始化方法及四个构造函数,其实都大同小异:参数少的就必须后续添加,参数多的必须提前初始化。
       

  我们先看看第一个无参构造函数,源码很简单,但是注释很多,所以看源码必须要先看注释。

 1 /**
 2    * Creates a {@code Snmp} instance that uses a
 3    * {@code MessageDispatcherImpl} with no message processing
 4    * models and no security protols (by default). You will have to add
 5    * those by calling the appropriate methods on
 6    * {@link #getMessageDispatcher()}.
 7    * <p>
 8    * At least one transport mapping has to be added before {@link #listen()}
 9    * is called in order to be able to send and receive SNMP messages.
10    * <p>
11    * To initialize a {@code Snmp} instance created with this constructor
12    * follow this sample code:
13    * <pre>
14    * Transport transport = ...;
15    * Snmp snmp = new Snmp();
16    * SecurityProtocols.getInstance().addDefaultProtocols();
17    * MessageDispatcher disp = snmp.getMessageDispatcher();
18    * disp.addMessageProcessingModel(new MPv1());
19    * disp.addMessageProcessingModel(new MPv2c());
20    * snmp.addTransportMapping(transport);
21    * OctetString localEngineID = new OctetString(
22    *    MPv3.createLocalEngineID());
23    *    // For command generators, you may use the following code to avoid
24    *    // engine ID clashes:
25    *    // MPv3.createLocalEngineID(
26    *    //   new OctetString("MyUniqueID"+System.currentTimeMillis())));
27    * USM usm = new USM(SecurityProtocols.getInstance(), localEngineID, 0);
28    * disp.addMessageProcessingModel(new MPv3(usm));
29    * snmp.listen();
30    * </pre>
31    */
32   public Snmp() {
33     this.messageDispatcher = new MessageDispatcherImpl();
34     if (SNMP4JSettings.getSnmp4jStatistics() != SNMP4JSettings.Snmp4jStatistics.none) {
35       counterSupport = CounterSupport.getInstance();
36     }
37   }

  从上面注释中可以看出要初始化snmp需要设置messageDispatcher里面的参数和TransportMapping参数,如果没有设置好这个两个参数,发送报文时会报错(见下面案例).所以我们可以直接使用第三个构造函数。

  接下来我们来看第二个构造函数Snmp(TransportMapping<? extends Address> transportMapping):

 1 /**
 2    * Creates a <code>Snmp</code> instance that uses a
 3    * <code>MessageDispatcherImpl</code> with all supported message processing
 4    * models and the default security protols for dispatching.
 5    * <p>
 6    * To initialize a <code>Snmp</code> instance created with this constructor
 7    * follow this sample code:
 8    * <pre>
 9    * Transport transport = ...;
10    * Snmp snmp = new Snmp(transport);
11    * OctetString localEngineID =
12    *   new OctetString(snmp.getMPv3().getLocalEngineID());
13    * USM usm = new USM(SecurityProtocols.getInstance(), localEngineID, 0);
14    * SecurityModels.getInstance().addSecurityModel(usm);
15    * snmp.listen();
16    * </pre>
17    *
18    * @param transportMapping TransportMapping
19    *    the initial <code>TransportMapping</code>. You can add more or remove
20    *    the same later.
21    */
22   public Snmp(TransportMapping<? extends Address> transportMapping) {
23     this();
24     initMessageDispatcher();
25     if (transportMapping != null) {
26       addTransportMapping(transportMapping);
27     }
28   }
protected final void initMessageDispatcher() {
    this.messageDispatcher.addCommandResponder(this);
    this.messageDispatcher.addMessageProcessingModel(new MPv2c());
    this.messageDispatcher.addMessageProcessingModel(new MPv1());
    this.messageDispatcher.addMessageProcessingModel(new MPv3());
    SecurityProtocols.getInstance().addDefaultProtocols();
}

  从源码中可以看到它帮我们设置了messageDispatcher里面的参数,只要我们提供TransportMapping参数即可。第四个构造函数Snmp(MessageDispatcher messageDispatcher)其实跟第一个类似同样需要提供两个参数,所以第三个和第四个就列出来了。其中涉及到接口有MessageDispatcher接口、MessageProcessingModel接口,涉及到的类有MPv1、MPv2和MPv3分别对应snmp版本v1、v2c和v3。

/**
 * @description MessageDispatcher接口定义了处理传入的SNMP消息并将其分派到感兴趣的CommandResponder实例的实例的公共服务。它还提供了一个发送出去的SNMP消息的服务。
 */
public interface MessageDispatcher extends TransportListener {}
/**
 * @description MessageProcessingModel 接口为所有SNMP消息处理模型定义了通用方法。
 */
public interface MessageProcessingModel {}
/**
 * @description TransportMapping定义了SNMP传输映射的公共接口。传输映射只能支持单个传输协议。
 */
public interface TransportMapping<A extends Address> {}

  2、核心对象Target

  我们先看下Target对象下的继承关系。其中主要用到的子对象是CommunityTarget和UserTarget,CommunityTarget用于SNMPv1和SNMPv2c这两个版本,而UserTarget用于SNMPV3版本。

       

  在初始化CommunityTarget时默认使用的是snmpv1(适用于snmpv2).

/**
   * Default constructor.
   */
  public CommunityTarget() {
    setVersion(SnmpConstants.version1);
    setSecurityLevel(SecurityLevel.NOAUTH_NOPRIV);
    setSecurityModel(SecurityModel.SECURITY_MODEL_SNMPv1);
  }

  3、核心对象PDU

  

  跟Target一样,针对snmp的不同版本是使用不同的子类去实现。PDUv1用于SNMPv1和SNMPv2c这两个版本,而ScopedPDU用于SNMPV3版本。

二、案例分析:

  1、snmpGet功能测试:

  第一步:要初始snmp并开启监听。其中有点不同的是,为了支持snmpv3版本的处理需要增加用户并设置安全名称和加密算法。(关于那些静态变量的值,最好放到配置文件中显得灵活点)。

另外再说明下:snmp是基于udp协议发送报文的,且snmp端口默认为161。

 1 public class SnmpUtil {
 2     private static Logger log = LoggerFactory.getLogger(SnmpUtil.class);
 3     public static Snmp snmp = null;
 4     private static String community = "public";
 5     private static String ipAddress = "udp:10.10.112.105/";
 6     
 7     /**
 8      * @description 初始化snmp
 9      * @author YuanFY
10      * @date 2017年12月16日 上午10:28:01
11      * @version 1.0
12      * @throws IOException 
13      */
14     public static void initSnmp() throws IOException{
15             //1、初始化多线程消息转发类
16             MessageDispatcher messageDispatcher = new MessageDispatcherImpl(); 
17             //其中要增加三种处理模型。如果snmp初始化使用的是Snmp(TransportMapping<? extends Address> transportMapping) ,就不需要增加 
18             messageDispatcher.addMessageProcessingModel(new MPv1());
19             messageDispatcher.addMessageProcessingModel(new MPv2c());
20             //当要支持snmpV3版本时,需要配置user
21             OctetString localEngineID = new OctetString(MPv3.createLocalEngineID());
22             USM usm = new USM(SecurityProtocols.getInstance().addDefaultProtocols(), localEngineID, 0);
23             UsmUser user = new UsmUser(new OctetString("SNMPV3"), AuthSHA.ID, new OctetString("authPassword"), 
24                 PrivAES128.ID, new OctetString("privPassword"));
25             usm.addUser(user.getSecurityName(), user);
26             messageDispatcher.addMessageProcessingModel(new MPv3(usm));
27             //2、创建transportMapping
28             UdpAddress updAddr = (UdpAddress) GenericAddress.parse("udp:10.10.112.177/161");
29             TransportMapping<?> transportMapping = new DefaultUdpTransportMapping(updAddr);
30             //3、正式创建snmp
31             snmp = new Snmp(messageDispatcher, transportMapping);
32             //开启监听
33             snmp.listen();
34     }
35 }

  其中要注意的是UdpAddress updAddr = (UdpAddress) GenericAddress.parse("udp:10.10.112.177/161"); 只能指定本机ip,要么不要设置地址。请看DefaultUdpTransportMapping的源码

 1 /**
 2    * Creates a UDP transport on the specified address. The address will not be
 3    * reused if it is currently in timeout state (TIME_WAIT).
 4    *
 5    * @param udpAddress
 6    *    the local address for sending and receiving of UDP messages.
 7    * @throws IOException
 8    *    if socket binding fails.
 9    */
10   public DefaultUdpTransportMapping(UdpAddress udpAddress) throws IOException {
11     super(udpAddress);
12     socket = new DatagramSocket(udpAddress.getPort(),
13                                 udpAddress.getInetAddress());
14   }

  第二步: 根据snmp版本创建Target对象,其中针对snmpV3版本需要设置安全级别和安全名称,其中安全名称是创建snmp指定user设置的new OctetString("SNMPV3"),针对snmpv1和snmpv2c需要设置团体名。另外必须设置ipAddress,且对应的主机要配置snmp否则获取不到值。如下:

 1 private static Target createTarget(int version, int port) {
 2         Target target = null;
 3         if (!(version == SnmpConstants.version3 || version == SnmpConstants.version2c || version == SnmpConstants.version1)) {
 4             log.error("参数version异常");
 5             return target;
 6         }
 7         if (version == SnmpConstants.version3) {
 8             target = new UserTarget();
 9             //snmpV3需要设置安全级别和安全名称,其中安全名称是创建snmp指定user设置的new OctetString("SNMPV3")
10             target.setSecurityLevel(SecurityLevel.AUTH_PRIV);
11             target.setSecurityName(new OctetString("SNMPV3"));
12         } else {
13             //snmpV1和snmpV2需要指定团体名名称
14             target = new CommunityTarget();
15             ((CommunityTarget)target).setCommunity(new OctetString(community));
16             if (version == SnmpConstants.version2c) {
17                 target.setSecurityModel(SecurityModel.SECURITY_MODEL_SNMPv2c);
18             }
19         }
20         target.setVersion(version);
21         //必须指定,没有设置就会报错。
22         target.setAddress(GenericAddress.parse(ipAddress+port));
23         target.setRetries(5);
24         target.setTimeout(3000);
25         return target;
26     }

  第三步:创建报文。其中要注意的是pdu可以设置类型,如果想要用snmpget方法,就设置PDU.GET.

 1     private static PDU createPDU(int version, int type, String oid){
 2         PDU pdu = null;
 3         if (version == SnmpConstants.version3) {
 4             pdu = new ScopedPDU();
 5         }else {
 6             pdu = new PDUv1();
 7         }
 8         pdu.setType(type);
 9         //可以添加多个变量oid
10         pdu.add(new VariableBinding(new OID(oid)));
11         return pdu;
12     }

  最后一步发送报文也是最重要的一步,需要前面三步的支撑才能进行。如下:

 1 public static void snmpGet(String oid){
 2         try {
 3             //1、初始化snmp,并开启监听
 4             initSnmp();
 5             //2、创建目标对象
 6             Target target = createTarget(SnmpConstants.version2c, SnmpConstants.DEFAULT_COMMAND_RESPONDER_PORT);
 7             //3、创建报文
 8             PDU pdu = createPDU(SnmpConstants.version2c, PDU.GET, oid);
 9             System.out.println("-------> 发送PDU <-------"); 
10             //4、发送报文,并获取返回结果
11             ResponseEvent responseEvent = snmp.send(pdu, target);
12             PDU response = responseEvent.getResponse();
13             System.out.println("返回结果:" + response);
14         }
15         catch (IOException e) {
16             e.printStackTrace();
17         }
18     }

  测试如下:

    public static void main(String[] args) {
        snmpGet("1.3.6.1.2.1.1.1.0");
    }

  output

-------> 发送PDU <-------
返回结果:RESPONSE[requestID=1344419162, errorStatus=Success(0), errorIndex=0, VBS[1.3.6.1.2.1.1.1.0 = Linux localhost.localdomain 3.10.0-327.36.2.el7.x86_64 #1 SMP Mon Oct 10 23:08:37 UTC 2016 x86_64]]

  从中可以得知,snmpget是可以根据指定的oid获取其对应的内容的。

  2、SNMPWalk功能测试

  查看了下PDU的源码,发现没有对应snmpwalk的类型,所以使用getNext类型来实现snmpwalk功能。
  

 1 public static void snmpWalk(String oid) {
 2         try {
 3             //1、初始化snmp,并开启监听
 4             initSnmp();
 5             //2、创建目标对象
 6             Target target = createTarget(SnmpConstants.version2c, SnmpConstants.DEFAULT_COMMAND_RESPONDER_PORT);
 7             //3、创建报文
 8             PDU pdu = createPDU(SnmpConstants.version2c, PDU.GETNEXT, oid);
 9             System.out.println("-------> 发送PDU <-------"); 
10             //4、发送报文,并获取返回结果
11             boolean matched = true;
12             while (matched) {
13                 ResponseEvent responseEvent = snmp.send(pdu, target);
14                 if (responseEvent == null || responseEvent.getResponse() == null) {
15                     break;
16                 }
17                 PDU response = responseEvent.getResponse();
18                 String nextOid = null;
19                 Vector<? extends VariableBinding> variableBindings = response.getVariableBindings();
20                 for (int i = 0; i < variableBindings.size(); i++) {
21                     VariableBinding variableBinding = variableBindings.elementAt(i);
22                     Variable variable = variableBinding.getVariable();
23                     nextOid = variableBinding.getOid().toDottedString();
24                     //如果不是这个节点下的oid则终止遍历,否则会输出很多,直到整个遍历完。
25                     if (!nextOid.startsWith(oid)) {
26                         matched = false;
27                         break;
28                     }
29                     //System.out.println(variable);
30                 }
31                 if (!matched) {
32                     break;
33                 }
34                 pdu.clear();
35                 pdu.add(new VariableBinding(new OID(nextOid)));
36                 System.out.println("返回结果:" + response);
37             }
38         }
39         catch (IOException e) {
40             // TODO Auto-generated catch block
41             e.printStackTrace();
42         }
43     }

  测试如下:

1     public static void main(String[] args) {
2         //snmpGet("1.3.6.1.2.1.1.1.0");
3         snmpWalk("1.3.6.1.2.1.25.3.3.1.2");//CPU的当前负载,N个核就有N个负载4     }
-------> 发送PDU <-------

返回结果:RESPONSE[requestID=1014693266, errorStatus=Success(0), errorIndex=0, VBS[1.3.6.1.2.1.25.3.3.1.2.196608 = 1]]
返回结果:RESPONSE[requestID=1014693268, errorStatus=Success(0), errorIndex=0, VBS[1.3.6.1.2.1.25.3.3.1.2.196609 = 0]]

  用命令获取的结果是跟代码输出的结果是一样的,如下:

 

  3、前面两个案例都是跟采集有关,接下来介绍如何监控接收服务器发过来的故障然后提示个用户,这就需要用到snmptrap了。接下来我们直接看案例:

  处理流程:

  1、必须实现CommandResponder接口

  2、初始化snmp并开启监听。这步跟上面初始化一样,只是面对并发的情况使用MultiThreadedMessageDispatcher进行信息处理。

  3、将当前实现CommandResponder的对象添加至snmp的addCommandResponder才能接收到信息。

  4、处理接收到信息,通知用户。

 1 package com.yuanfy.study.snmp;
 2 
 3 import java.io.IOException;
 4 
 5 import org.slf4j.Logger;
 6 import org.slf4j.LoggerFactory;
 7 import org.snmp4j.CommandResponder;
 8 import org.snmp4j.CommandResponderEvent;
 9 import org.snmp4j.MessageDispatcher;
10 import org.snmp4j.MessageDispatcherImpl;
11 import org.snmp4j.PDU;
12 import org.snmp4j.Snmp;
13 import org.snmp4j.TransportMapping;
14 import org.snmp4j.mp.MPv1;
15 import org.snmp4j.mp.MPv2c;
16 import org.snmp4j.mp.MPv3;
17 import org.snmp4j.security.AuthSHA;
18 import org.snmp4j.security.PrivAES128;
19 import org.snmp4j.security.SecurityProtocols;
20 import org.snmp4j.security.USM;
21 import org.snmp4j.security.UsmUser;
22 import org.snmp4j.smi.GenericAddress;
23 import org.snmp4j.smi.OctetString;
24 import org.snmp4j.smi.UdpAddress;
25 import org.snmp4j.transport.DefaultUdpTransportMapping;
26 import org.snmp4j.util.MultiThreadedMessageDispatcher;
27 import org.snmp4j.util.ThreadPool;
28 
29 public class SnmpTrapHandler implements CommandResponder{
30     private static Logger log = LoggerFactory.getLogger(SnmpTrapHandler.class);
31     private static int threadNum = 200;
32     private static String ipAddress = "udp:10.10.112.177/162";
33     private Snmp snmp = null;
34     public void init(){
35         //1、初始化多线程消息转发类
36         ThreadPool threadPool = ThreadPool.create("SnmpTrap", threadNum);
37         MessageDispatcher messageDispatcher = new MultiThreadedMessageDispatcher(threadPool, new MessageDispatcherImpl()); 
38         //其中要增加三种处理模型。如果snmp初始化使用的是Snmp(TransportMapping<? extends Address> transportMapping) ,就不需要增加 
39         messageDispatcher.addMessageProcessingModel(new MPv1());
40         messageDispatcher.addMessageProcessingModel(new MPv2c());
41         OctetString localEngineID = new OctetString(MPv3.createLocalEngineID());
42         USM usm = new USM(SecurityProtocols.getInstance().addDefaultProtocols(), localEngineID, 0);
43         UsmUser user = new UsmUser(new OctetString("SNMPV3"), AuthSHA.ID, new OctetString("authPassword"), 
44             PrivAES128.ID, new OctetString("privPassword"));
45         usm.addUser(user.getSecurityName(), user);
46         messageDispatcher.addMessageProcessingModel(new MPv3(usm));
47         //2、创建transportMapping
48         TransportMapping<?> transportMapping = null;
49         try {
50             UdpAddress updAddr = (UdpAddress) GenericAddress.parse(System.getProperty("snmp4j.listenAddress", ipAddress));
51             transportMapping = new DefaultUdpTransportMapping(updAddr);
52             //3、正式创建snmp
53             snmp = new Snmp(messageDispatcher, transportMapping);
54             //开启监听
55             snmp.listen();
56         } catch (IOException e) { 
57             log.error("初始化transportMapping失败:", e.getMessage());
58             e.printStackTrace();
59         }
60     }
61     
62     public void start() {
63         init();
64         //一定要将当前对象添加至commandResponderListeners中
65         snmp.addCommandResponder(this);
66         System.out.println("开始监听trap信息:");
67     }
68     /**
69      * 处理信息方法
70      */
71     @Override
72     public void processPdu(CommandResponderEvent event) {
73         String version = null ;
74         String community = null;
75         if (event.getPDU().getType() == PDU.V1TRAP) {
76             version = "v1";
77             community = new String(event.getSecurityName());
78         } else if (event.getPDU().getType() == PDU.TRAP){
79             if (event.getSecurityModel() == 2) {
80                 version = "v2";
81                 community = new String(event.getSecurityName());
82             }else {
83                 version = "v3";
84             }
85         }
86         System.out.println("接收到的trap信息:[发送来源="+event.getPeerAddress()+",snmp版本="+version+",团体名="+community+", 携带的变量="+event.getPDU().getVariableBindings()+"]");
87     }
88     public static void main(String[] args) {
89         SnmpTrapHandler handler = new SnmpTrapHandler();
90         handler.start();
91     }
92 }

  测试如下: