Use snmp to monitor Linux hosts

1. Introduction to snmp protocol

SNMP (Simple Network Management Protocol) is also a protocol at the application layer. The default port number is 161. We usually monitor Linux hosts by installing an agent client for monitoring, but some companies also need to monitor network devices and Windows hosts. When you have to use the snmp protocol to monitor the equipment

SNMP has a MIB library. This MIB library stores the oid of each monitoring indicator. The so-called oid is the object id. Each monitoring indicator will have an oid and it is stored in the MIB library to ensure that all the oids of the monitoring indicators are Will not repeat

Take an example: For example, the monitoring item of CPU, a CPU has many monitoring indicators, such as kernel state, user state, etc., these indicators will be stored in the MIB library in order, for example, the user state is .1.1 then the user state is. 1.2 Push backwards in turn, if there are various indicators under the kernel state, then it is .1.1.1, and finally form a form similar to a tree structure

You need to enter the community password when connecting with the snmp protocol. If you do not set a password, the network device will be exposed to the entire network

The idea of using snmp monitoring is:

1. Install the snmp server program on the controlled end, configure the community password, and configure the range of indicators

2. Install the snmp client program on the monitoring side, and connect with the snmp server program to obtain monitoring indicators

snmp MIB library view address: https://blog.csdn.net/weixin_44953658/article/details/110986875

snmp is UDP protocol

2. Use snmp to monitor Linux hosts

2.1. Obtain the percentage OID used by the CPU user system in the MIB library

Visit https://blog.csdn.net/weixin_44953658/article/details/110986875

.1.3.6.1.4.1.2021.11.9.0 User CPU ratio.
1.3.6.1.4.1.2021.11.10.0 System CPU ratio

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2.2. Install the snmp server on the controlled end and configure it

1.安装snmp
[root@192_168_81_230 ~]# yum -y install net-snmp

2.配置snmp
[root@192_168_81_230 ~]# vim /etc/snmp/snmpd.conf 	
 41 com2sec notConfigUser  default       jiangxl				//设置密码口令
 55 view    systemview    included   .1				//设置允许的指标范围

3.启动snmp
[root@192_168_81_230 ~]# systemctl start snmpd
[root@192_168_81_230 ~]# systemctl enable snmpd

4.查看端口，注意一定要加上u，因为snmp是udp协议
[root@192_168_81_230 ~]# netstat -lnptu | grep snmp
tcp        0      0 127.0.0.1:199           0.0.0.0:*               LISTEN      10746/snmpd         
udp        0      0 0.0.0.0:161             0.0.0.0:*                           10746/snmpd

2.3. Install the snmp client on the monitoring side and test

1.安装snmp客户端
[root@zabbix-server ~]# yum install net-snmp-utils.x86_64 -y

2.测试获取CPU系统态的使用情况
[root@zabbix-server ~]# snmpwalk -v 2c -c jiangxl 192.168.81.240 .1.3.6.1.4.1.2021.11.10.0
UCD-SNMP-MIB::ssCpuSystem.0 = INTEGER: 0

-v：表示指定版本
-c：指定密码口令
最后面的就是指标oid