需要檔案:

NET-SNMP-EXAMPLES-MIB.txt
notification.c

這兩個檔案都在net-snmp原始碼包裡，我的版本是5.4.1

NET-SNMP-EXAMPLES-MIB.txt net-snmp-5.4.1.2/mibs目錄下
notification.c net-snmp-5.4.1.2/agent/mibgroup/examples目錄下

1. 安裝notification:

   ./configure --with-mib-modules="examples/notification"
   make
   sudo make install

2. 配置snmp.conf檔案，在檔案中增加NET-SNMP-EXAMPLES-MIB mib庫

   sudo vim /usr/local/share/snmp/snmp.conf

   在檔案中增加： mibs +NET-SNMP-EXAMPLES-MIB

3. 驗證netSnmpExampleNotifications mib庫是否正常載入:

   snmptranslate -IR -Tp netSnmpExampleNotifications
   +--netSnmpExampleNotifications(3)
      |
      +--netSnmpExampleNotificationPrefix(0)
      |  |
      |  +--netSnmpExampleHeartbeatNotification(1)
      |
      +-- ---N String    netSnmpExampleNotification(1)
      |        Textual Convention: SnmpAdminString
      |        Size: 0..255
      |
      +--netSnmpExampleNotificationObjects(2)
         |
         +-- ---N Integer32 netSnmpExampleHeartbeatRate(1)
         +-- ---N String    netSnmpExampleHeartbeatName(2)
                  Textual Convention: SnmpAdminString
                  Size: 0..255

4. 配置snmptrapd.conf

   建立/usr/share/snmp/snmptrapd.conf（我的機器上是這個，不同機器不同，可能有的放在/etc/snmp,/usr/local/share/snmp/下，視不同情況慢慢實驗），加入以下一行:

   authcommunity execute,log,net public

設定所有使用者的訪問許可權：可執行，記錄，傳遞，

如果相對接受到的資訊處理可以增加:

traphandle .1.3.6.1.4.1.2021.251.2  page_me down
# 預設處理函式
traphandle default                  log_it

1. agent自動產生trap

# From: http://www.net-snmp.org/wiki/index.php/FAQ:Agent_17
# send v1 traps
trapsink   127.0.0.1:162
# also send v2 traps
trap2sink  127.0.0.1:162
informsink 127.0.0.1:162

1. 啟動snmptrapd

   sudo snmptrapd –d –f –Lo

2. 啟動snmpd

   sudo snmpd -f -L

snmpd 會每隔30秒給snmptrapd傳送一個資訊。收到的資訊如下:

Received 64 bytes from UDP: [127.0.0.1]:56929
0000: 30 3E 02 01  00 04 06 70  75 62 6C 69  63 A4 31 06    0>.....public.1.
0016: 09 2B 06 01  04 01 BF 08  02 03 40 04  AC 10 81 01    [email protected]
0032: 02 01 06 02  01 01 43 03  03 CC BC 30  13 30 11 06    ......C....0.0..
0048: 0C 2B 06 01  04 01 BF 08  02 03 02 01  00 02 01 1E    .+..............

2008-11-11 15:43:11 172.16.129.1(via UDP: [127.0.0.1]:56929) TRAP, SNMP v1, community public
        NET-SNMP-EXAMPLES-MIB::netSnmpExampleNotifications Enterprise Specific Trap
        (NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatNotification) Uptime: 0:41:30.20
        NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatRate.0 = INTEGER: 30

1. notification.c 原始碼如下:

   /** @example notification.c
    *  This example shows how to send a notification from inside the
    *  agent.  In this case we do something really boring to decide
    *  whether to send a notification or not: we simply sleep for 30
    *  seconds and send it, then we sleep for 30 more and send it again.
    *  We do this through the snmp_alarm mechanisms (which are safe to
    *  use within the agent.  Don't use the system alarm() call, it won't
    *  work properly).  Normally, you would probably want to do something
    *  to test whether or not to send an alarm, based on the type of mib
    *  module you were creating.
    *
    *  When this module is compiled into the agent (run configure with
    *  --with-mib-modules="examples/notification") then it should send
    *  out traps, which when received by the snmptrapd demon will look
    *  roughly like:
    *
    *   可以通過 --with-mib-modules="examples/notification" 把這個模組
    * 編譯到agent模組中，snmptrapd可以接收到他傳送的traps, 接收到的資訊
    * 如下:
    *
    *  2002-05-08 08:57:05 localhost.localdomain [udp:127.0.0.1:32865]:
    *      sysUpTimeInstance = Timeticks: (3803) 0:00:38.03 \
    *      snmpTrapOID.0 = OID: netSnmpExampleNotification
    *
    */
   
   /*
    * start be including the appropriate header files
    */
   #include <net-snmp/net-snmp-config.h>
   #include <net-snmp/net-snmp-includes.h>
   #include <net-snmp/agent/net-snmp-agent-includes.h>
   
   /*
    * contains prototypes
    */
   #include "notification.h"
   
   /*
    * our initialization routine 初始化
    * (to get called, the function name must match init_FILENAME()
    * 函式的名字必須是 init_FILENAME() 這種格式
    */
   void
   init_notification(void)
   {
       DEBUGMSGTL(("example_notification",
                   "initializing (setting callback alarm)\n"));
       snmp_alarm_register(30,     /* seconds, 秒 */
                           SA_REPEAT,      /* repeat (every 30 seconds). 每隔30秒傳送一個trap*/
                           send_example_notification,      /* our callback 我們的回撥函式 */
                           NULL    /* no callback data needed */
           );
   }
   
   /** here we send a SNMP v2 trap (which can be sent through snmpv3 and
    *  snmpv1 as well) and send it out.
    *
    *     The various "send_trap()" calls allow you to specify traps in different
    *  formats.  And the various "trapsink" directives allow you to specify
    *  destinations to receive different formats.
    *  But *all* traps are sent to *all* destinations, regardless of how they
    *  were specified.
    *
    *
    *  I.e. it's
    * @verbatim
    *                                           ___  trapsink
    *                                          /
    *      send_easy_trap \___  [  Trap      ] ____  trap2sink
    *                      ___  [ Generator  ]
    *      send_v2trap    /     [            ] ----- informsink
    *                                          \____
    *                                                trapsess
    *
    *  *Not*
    *       send_easy_trap  ------------------->  trapsink
    *       send_v2trap     ------------------->  trap2sink
    *       ????            ------------------->  informsink
    *       ????            ------------------->  trapsess
    * @endverbatim
    */
   void
   send_example_notification(unsigned int clientreg, void *clientarg)
   {
       /*
        * define the OID for the notification we're going to send
        * NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatNotification
        */
       oid             notification_oid[] =
           { 1, 3, 6, 1, 4, 1, 8072, 2, 3, 0, 1 };
       size_t          notification_oid_len = OID_LENGTH(notification_oid);
       static u_long count = 0;
   
       /*
        * In the notification, we have to assign our notification OID to
        * the snmpTrapOID.0 object. Here is it's definition.
        */
       oid             objid_snmptrap[] = { 1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0 };
       size_t          objid_snmptrap_len = OID_LENGTH(objid_snmptrap);
   
       /*
        * define the OIDs for the varbinds we're going to include
        *  with the notification -
        * NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatRate  and
        * NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatName
        */
       oid      hbeat_rate_oid[]   = { 1, 3, 6, 1, 4, 1, 8072, 2, 3, 2, 1, 0 };
       size_t   hbeat_rate_oid_len = OID_LENGTH(hbeat_rate_oid);
       oid      hbeat_name_oid[]   = { 1, 3, 6, 1, 4, 1, 8072, 2, 3, 2, 2, 0 };
       size_t   hbeat_name_oid_len = OID_LENGTH(hbeat_name_oid);
   
       /*
        * here is where we store the variables to be sent in the trap
        */
       netsnmp_variable_list *notification_vars = NULL;
       const char *heartbeat_name = "A girl named Maria";
       #ifdef  RANDOM_HEARTBEAT
       int  heartbeat_rate = rand() % 60;
       #else
       int  heartbeat_rate = 30;
       #endif
   
       DEBUGMSGTL(("example_notification", "defining the trap\n"));
   
       /*
        * add in the trap definition object
        */
       snmp_varlist_add_variable(&notification_vars,
                                 /*
                                  * the snmpTrapOID.0 variable
                                  */
                                 objid_snmptrap, objid_snmptrap_len,
                                 /*
                                  * value type is an OID
                                  */
                                 ASN_OBJECT_ID,
                                 /*
                                  * value contents is our notification OID
                                  */
                                 (u_char *) notification_oid,
                                 /*
                                  * size in bytes = oid length * sizeof(oid)
                                  */
                                 notification_oid_len * sizeof(oid));
   
       /*
        * add in the additional objects defined as part of the trap
        */
   
       snmp_varlist_add_variable(&notification_vars,
                                  hbeat_rate_oid, hbeat_rate_oid_len,
                                  ASN_INTEGER,
                                 (u_char *)&heartbeat_rate,
                                     sizeof(heartbeat_rate));
   
       /*
        * if we want to insert additional objects, we do it here
        */
       if (heartbeat_rate < 30 ) {
           snmp_varlist_add_variable(&notification_vars,
                                  hbeat_name_oid, hbeat_name_oid_len,
                                  ASN_OCTET_STR,
                                  heartbeat_name, strlen(heartbeat_name));
       }
   
       /*
        * send the trap out.  This will send it to all registered
        * receivers (see the "SETTING UP TRAP AND/OR INFORM DESTINATIONS"
        * section of the snmpd.conf manual page.
        */
       ++count;
       DEBUGMSGTL(("example_notification", "sending trap %ld\n",count));
       send_v2trap(notification_vars); // 傳送snmpv2的trap
   
       /*
        * free the created notification variable list
        */
       DEBUGMSGTL(("example_notification", "cleaning up\n"));
       snmp_free_varbind(notification_vars);
   }