snmp学习笔记之二trap——分析notification.c文件
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
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安装notification:
./configure --with-mib-modules="examples/notification" make sudo make install
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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
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验证netSnmpExampleNotifications mib库是否正常加载:
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 -
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
- 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
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启动snmptrapd
sudo snmptrapd –d –f –Lo
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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
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notification.c 源码如下:
/** @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: * * 可以通过 --with-mib-modules="examples/notification" 把这个模块 * 编译到agent模块中，snmptrapd可以接收到他发送的traps, 接收到的信息 * 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
#include #include /* * contains prototypes */ #include "notification.h" /* * our initialization routine 初始化 * (to get called, the function name must match init_FILENAME() * 函数的名字必须是 init_FILENAME() 这种格式 */ 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秒发送一个trap*/ send_example_notification, /* our callback 我们的回调函数 */ 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(¬ification_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(¬ification_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(¬ification_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); // 发送snmpv2的trap /* * free the created notification variable list */ DEBUGMSGTL(("example_notification", "cleaning up/n")); snmp_free_varbind(notification_vars); }
- 参考:
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- How can I get the agent to generate a trap http://www.net-snmp.org/wiki/index.php/FAQ:Coding_15
- http://www.net-snmp.org/docs/mibs/NET-SNMP-EXAMPLES-MIB.txt
- http://www.net-snmp.org/dev/agent/notification_8c-example.html
- http://www.net-snmp.org/wiki/index.php/FAQ:Agent_17
- By: Bian Jiang ([email protected])
- From: http://www.b0rder.com
- Date: 2008.11.11