snmp笔记(2)

snmp学习笔记之二trap——分析notification.c文件 November 19th, 2008 BianJiang Leave a comment Go to comments

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By: Bian Jiang (borderj@gmail.com) From: http://www.b0rder.com Date: 2008.11.11

需要文件:

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

这两个文件都在net-snmp源码包里，我的版本是5.4.1

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

1. 安装notification:

2. 3.

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

sudo make install

4. 配置snmp.conf文件，在文件中增加NET-SNMP-EXAMPLES-MIB mib库

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

在文件中增加： mibs +NET-SNMP-EXAMPLES-MIB

5. 验证netSnmpExampleNotifications mib库是否正常加载:

6. 7.

snmptranslate -IR -Tp netSnmpExampleNotifications +--netSnmpExampleNotifications(3)

8. 9.

|

+--netSnmpExampleNotificationPrefix(0)

10. | |

11. | +--netSnmpExampleHeartbeatNotification(1) 12. |

13. +-- ---N String netSnmpExampleNotification(1) 14. | Textual Convention: SnmpAdminString 15. | Size: 0..255 16. |

17. +--netSnmpExampleNotificationObjects(2) 18. |

19. +-- ---N Integer32 netSnmpExampleHeartbeatRate(1) 20. +-- ---N String netSnmpExampleHeartbeatName(2) 21. Textual Convention: SnmpAdminString Size: 0..255

22. 配置snmptrapd.conf

建立/usr/share/snmp/snmptrapd.conf（我的机器上是这个，不同机器不同，可能有的放在/etc/snmp,/usr/local/share/snmp/下，视不同情况慢慢实验），加入以下一行:

authcommunity execute,log,net public

设置所有用户的访问权限：可执行，记录，传递，

如果相对接受到的信息处理可以增加:

traphandle .1.3.6.1.4.1.2021.251.2 page_me down # 默认处理函数

traphandle default log_it

1. agent自动产生trap

配置agent的snmpd.conf，加入以下几行：(参考:

http://www.net-snmp.org/wiki/index.php/FAQ:Agent_17 ):

# 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. 启动snmptrapd

sudo snmptrapd –d –f –Lo

2. 启动snmpd

sudo snmpd -f -L

snmpd 会每隔30秒给snmptrapd发送一个信息。收到的信息如下:

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 .+........@.....

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 源码如下:

2. 3.

/** @example notification.c

* This example shows how to send a notification from inside the

4. * agent. In this case we do something really boring to decide

5. * whether to send a notification or not: we simply sleep for 30

6. * seconds and send it, then we sleep for 30 more and send it again.

7. * We do this through the snmp_alarm mechanisms (which are safe to

8. * use within the agent. Don't use the system alarm() call, it won't

9. * work properly). Normally, you would probably want to do something

10. * to test whether or not to send an alarm, based on the type of mib

11. * module you were creating. 12. *

13. * When this module is compiled into the agent (run configure with

14. * --with-mib-modules=\"examples/notification\") then it should send

15. * out traps, which when received by the snmptrapd demon will look

16. * roughly like: 17. *

18. * 可以通过 --with-mib-modules=\"examples/notification\" 把这个模块

19. * 编译到agent模块中，snmptrapd可以接收到他发送的traps, 接收到的信息 20. * 如下: 21. *

22. * 2002-05-08 08:57:05 localhost.localdomain [udp:127.0.0.1:32865]:

23. * sysUpTimeInstance = Timeticks: (3803) 0:00:38.03 \\ 24. * snmpTrapOID.0 = OID: netSnmpExampleNotification 25. * 26. */ 27. 28. /*

29. * start be including the appropriate header files

30. */

31. #include 32. #include

33. #include 34. 35. /*

36. * contains prototypes 37. */

38. #include \"notification.h\" 39. 40. /*

41. * our initialization routine 初始化

42. * (to get called, the function name must match init_FILENAME()

43. * 函数的名字必须是 init_FILENAME() 这种格式 44. */ 45. void

46. init_notification(void) 47. {

48. DEBUGMSGTL((\"example_notification\

49. \"initializing (setting callback alarm)\\n\")); 50. snmp_alarm_register(30, /* seconds, 秒 */

51. SA_REPEAT, /* repeat (every 30 seconds). 每隔30秒发送一个trap*/

52. send_example_notification, /* our callback 我们的回调函数 */

53. NULL /* no callback data needed */ 54. ); 55. } 56.

57. /** here we send a SNMP v2 trap (which can be sent through snmpv3 and

58. * snmpv1 as well) and send it out. 59. *

60. * The various \"send_trap()\" calls allow you to specify traps in different

61. * formats. And the various \"trapsink\" directives allow you to specify

62. * destinations to receive different formats.

63. * But *all* traps are sent to *all* destinations, regardless of how they 64. * were specified. 65. * 66. *

67. * I.e. it's 68. * @verbatim

69. * ___ trapsink 70. * /

71. * send_easy_trap \\___ [ Trap ] ____ trap2sink 72. * ___ [ Generator ]

73. * send_v2trap / [ ] ----- informsink 74. * \\____

75. * trapsess

76. * 77. * *Not*

78. * send_easy_trap -------------------> trapsink 79. * send_v2trap -------------------> trap2sink 80. * ???? -------------------> informsink 81. * ???? -------------------> trapsess 82. * @endverbatim 83. */ 84. void

85. send_example_notification(unsigned int clientreg, void *clientarg) 86. { 87. /*

88. * define the OID for the notification we're going to send

89. * NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatNotification 90. */

91. oid notification_oid[] = 92. { 1, 3, 6, 1, 4, 1, 8072, 2, 3, 0, 1 };

93. size_t notification_oid_len = OID_LENGTH(notification_oid);

94. static u_long count = 0; 95. 96. /*

97. * In the notification, we have to assign our notification OID to

98. * the snmpTrapOID.0 object. Here is it's definition. 99. */

100. oid objid_snmptrap[] = { 1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0 };

101. size_t objid_snmptrap_len = OID_LENGTH(objid_snmptrap); 102. 103. /*

104. * define the OIDs for the varbinds we're going to include

105. * with the notification -

106. * NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatRate and

107. * NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatName 108. */

109. oid hbeat_rate_oid[] = { 1, 3, 6, 1, 4, 1, 8072, 2, 3, 2, 1, 0 };

110. size_t hbeat_rate_oid_len = OID_LENGTH(hbeat_rate_oid); 111. oid hbeat_name_oid[] = { 1, 3, 6, 1, 4, 1, 8072, 2, 3, 2, 2, 0 };

112. size_t hbeat_name_oid_len = OID_LENGTH(hbeat_name_oid); 113. 114. /*

115. * here is where we store the variables to be sent in the trap 116. */

117. netsnmp_variable_list *notification_vars = NULL;

118. const char *heartbeat_name = \"A girl named Maria\"; 119. #ifdef RANDOM_HEARTBEAT

120. int heartbeat_rate = rand() % 60; 121. #else

122. int heartbeat_rate = 30; 123. #endif 124.

125. DEBUGMSGTL((\"example_notification\\")); 126. 127. /*

128. * add in the trap definition object 129. */

130. snmp_varlist_add_variable(¬ification_vars, 131. /*

132. * the snmpTrapOID.0 variable 133. */

134. objid_snmptrap, objid_snmptrap_len,

135. /*

136. * value type is an OID 137. */

138. ASN_OBJECT_ID, 139. /*

140. * value contents is our notification OID

141. */

142. (u_char *) notification_oid, 143. /*

144. * size in bytes = oid length * sizeof(oid)

145. */

146. notification_oid_len * sizeof(oid)); 147. 148. /*

149. * add in the additional objects defined as part of the trap 150. */ 151.

152. snmp_varlist_add_variable(¬ification_vars,

153. hbeat_rate_oid, hbeat_rate_oid_len,

154. ASN_INTEGER,

155. (u_char *)&heartbeat_rate, 156. sizeof(heartbeat_rate)); 157. 158. /*

159. * if we want to insert additional objects, we do it here 160. */

161. if (heartbeat_rate < 30 ) {

162. snmp_varlist_add_variable(¬ification_vars,

163. hbeat_name_oid, hbeat_name_oid_len,

164. ASN_OCTET_STR,

165. heartbeat_name, strlen(heartbeat_name)); 166. } 167. 168. /*

169. * send the trap out. This will send it to all registered

170. * receivers (see the \"SETTING UP TRAP AND/OR INFORM DESTINATIONS\"

171. * section of the snmpd.conf manual page. 172. */ 173. ++count;

174. DEBUGMSGTL((\"example_notification\count));

175. send_v2trap(notification_vars); // 发送snmpv2的trap 176. 177. /*

178. * free the created notification variable list 179. */

180. DEBUGMSGTL((\"example_notification\181. snmp_free_varbind(notification_vars); }