Nagios Monitoring System

How Nagios Works

Nagios functions as a monitoring service and host. But its own well does not include this part of the function. All the monitoring and testing functions are done by various plugins. After the Nagios is started, it periodically automatically calls the hammer to detect the server state, while Nagios maintains a queue, all the status information returned by the plug-in is queued, and Nagios reads the information from the first team, processes it, and then displays the status results over the web. This is the so-called passive mode, often used to monitor the host system resources, such as system load, disk utilization, memory utilization, network status, number of system processes and so on. The other is active mode, mainly Nagios server actively to obtain data, often used to detect URL monitoring and service status monitoring. Compared to the active mode of the server actively to be monitored by the monitoring machine to obtain monitoring data, a great advantage is that the other work to remove data processing is placed on the monitor (including the transmission of data), to avoid the large number of monitors, a polling time is too long and lead to monitoring reaction delay, This is also the key to the passive mode to assume a greater amount of monitoring. Nagios provides a number of plug-ins that allow you to easily monitor many service statuses. After the installation is complete, there are all the plugins available in Nagios's/libexec in the Nagios Sunday record, such as Check_disk is the plug-in that checks the disk space, Check_load is the plug-in that checks the CPU load, and so on. Each plugin can be used to view its usage and functionality by running the./check_xxx-h command.

Nagios Four monitoring states

Nagios can identify four status return messages: 0 (OK) indicates a normal/green state. 1 (WARNING) indicates that a warning appears/xxx,2 (critcal) indicates a very serious error/red, 3 (UNKNOWN) indicates an unknown error/deep xxx. Nagios determines the state of the monitored object based on the value returned by the plug-in, and displays it through the Web for administrators to detect faults in a timely manner.

Nagios manages services remotely via the Nrpe plugin

• Nagios executes the Check_nrpe plugin installed inside it and tells Check_nrpe to detect which services.
• Connect the Nrpe daemon on the remote machine via the Ssl,check_nrpe.
• Nrpe runs a variety of local plugins to detect local service and status (Check_disk,.. etc).
• Nrpe the results of the test to the host side of the Check_nrpe, Check_nrpe and then send the results to the Nagios state queue.
• Nagios reads the information in the queue, then displays the results.

Case Environment

监控主机：192.168.10.128被控主机：192.168.10.142

Case implementation Build Nagios Surveillance System 1, turn off firewalls and SELinux

systemctl stop firewalld.servicesetenforce 0

2. Install related software packages

yum install -y gcc glibc glibc-common gd gd-devel xinetd openssl-devel

3. Create Nagios users and user groups

useradd -s /sbin/nologin nagios

4, create the working directory, set the genus belong to the main group

mkdir /usr/local/nagioschown -R nagios.nagios /usr/local/nagiosll -d /usr/local/nagios/      //查看权限

5. Compiling and installing Nagios

tar -zxvf nagios-4.0.1.tar.gz -C /optcd /opt/nagios-4.0.1./configure --prefix=/usr/local/nagios       //指定安装目录make allmake installmake install-initmake install-commandmodemake install-configchkconfig --add /etc/rc.d/init.d/nagioschkconfig --level 35 nagios onchkconfig --list nagioscd /usr/local/nagios        //检查是否存在etc、bin、sbin、share、var 这五个目录

6. Install Nagios Plugin

The various monitoring functions provided by Nagios are basically done via plugins.

tar xvzf nagios-plugins-1.5.tar.gz -C /optcd /opt/nagios-plugins-1.5./configure --prefix=/usr/local/nagios       //指定安装目录make && make install

7. Install lamp

Recommended to manually compile and install lamp, here I save time with yum install

yum install -y httpd* mysql* php

8. Modify the httpd configuration file

Vim/etc/httpd/conf/httpd.conf found: User Apache group Apache modified to user Nagios group Nagios and then found <ifmodule dir_module> DirectoryIndex index.html </IfModule> modified to <ifmodule dir_module> directoryindex index.html index.php </If Module> then adds the following: AddType application/x-httpd-php. php for security reasons, it is common for nagios web monitoring pages to be authorized for access, which requires an additional authentication configuration, That is, the following information is added at the end of the httpd.conf file: #setting for Nagios scriptalias/nagios/cgi-bin "/usr/local/nagios/sbin" <directory "/usr/ Local/nagios/sbin "> AuthType Basic Options execcgi allowoverride None Order allow,deny allow F Rom All authname "Nagios Access" authuserfile/usr/local/nagios/etc/htpasswd Require valid-use R </Directory> Alias/nagios "/usr/local/nagios/share" <directory "/usr/local/nagios/share" > AuthType Bas      IC Options None allowoverride none Order Allow,deny allow from all AuthName "Nagios Access" authuserfile/usr/local/nagios/etc/htpasswd     Require Valid-user </Directory>  

9. Create Access authentication files

htpasswd -c /usr/local/nagios/etc/htpasswd jack#用户名：jack          密码：123123     （自行定义）cat /usr/local/nagios/etc/htpasswd   //查看文件信息，密码为加密信息

10. Start httpd Service

systemctl start httpd.service

Configuring the Nagios Monitoring System

After Nagios is installed, the default configuration file is in the/usr/local/nagios/etc/directory

Configuration file Introduction and modification

cd /usr/local/nagios/etc/

1.objects/templates.cfg

主要用于监控主机资源以及服务，在nagios配置中称为对象，为了不必重复定义一些监控对象，Nagios引入了一个模板配置文件，将一些共性的属性定义成模板，以便于多次引用。vim objects/templates.cfgcontact_groups  联系组属性改成 ts,ts将在后面的contacts.cfg文件中定义

2.resource.cfg file

resource.cfg是nagios的变量定义文件 一般无需更改$USER1$=/usr/local/nagios/libexec

3.objects/commands.cfg file

此文件默认是存在的，无需修改即可使用，当然如果有新的命令需要加入时，在此文件进行添加即可

4. objects/hosts.cfg file

此文件默认不存在，需要手动创建，hosts.cfg主要用来指定被监控的主机地址以及相关属性信息（不能有任何空格）vim objects/hosts.cfgdefine host{           use                     linux-server       #引用主机linux-server的属性信息，linux-server主机在templates.cfg文件中进行了定义。        host_name               Nagios-Linux     #主机名        alias                   Nagios-Linux     #主机别名        address                 192.168.10.142     #被监控的主机地址，这个地址可以是ip，也可以是域名。        }   #定义一个主机组   define hostgroup{              hostgroup_name          bsmart-servers     #主机组名称，可以随意指定。        alias                   bsmart servers     #主机组别名        members                 Nagios-Linux    #主机组成员，其中“Nagios-Linux”就是上面定义的主机。             }

5.objects/localhost.cfg file

Used to monitor the machine generally without changes

6.objects/windows.cfg file

Used to monitor windows here without using

7.objects/services.cfg file

This file does not exist by default and needs to be created manually, primarily for defining monitored services and host resources

define service{          use                     local-service      #引用local-service服务的属性值，local-service在templates.cfg文件中进行了定义。        host_name               Nagios-Linux      #指定要监控哪个主机上的服务，“Nagios-Server”在hosts.cfg文件中进行了定义。        service_description     check-host-alive      #对监控服务内容的描述，以供维护人员参考。        check_command           check-host-alive      #指定检查的命令。        }  

8.objects/contacts.cfg file

Contacts.cfg is a configuration file that defines contacts and contact groups (no spaces)

define contact{        contact_name                    jack     #联系人的名称,这个地方不要有空格        use                             generic-contact     #引用generic-contact的属性信息，其中“generic-contact”在templates.cfg文件中进行定义        alias                           Nagios Admin        email                           [email protected]        }define contactgroup{        contactgroup_name       ts     #联系人组的名称,同样不能空格        alias                   Technical Support     #联系人组描述        members                 jack    #联系人组成员，其中“jack”就是上面定义的联系人，如果有多个联系人则以逗号相隔        }

9.cgi.cfg file

This file is used to control the associated CGI script, because the Nagios Web monitoring interface verifies that the user is Jack, so simply add the user's execute permission in the Cgi.cfg file, and in the end add

default_user_name=jackauthorized_for_system_information=nagiosadmin,jack  authorized_for_configuration_information=nagiosadmin,jack  authorized_for_system_commands=jackauthorized_for_all_services=nagiosadmin,jack  authorized_for_all_hosts=nagiosadmin,jackauthorized_for_all_service_commands=nagiosadmin,jack  authorized_for_all_host_commands=nagiosadmin,jack

. nagios.cfg file

Nagios master configuration file, referencing the object profile in the Nagios.cfg file

cfg_file=/usr/local/nagios/etc/objects/hosts.cfgcfg_file=/usr/local/nagios/etc/objects/services.cfg

command_check_interval=10s       //该变量用于设置nagios对外部命令检测的时间间隔

11. Check the configuration file

/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg         //验证配置文件

Log in to Nagios

systemctl restart httpd.service浏览器输入http://192.168.10.128/nagios/

Log in using the Jack User and 123123 password that you started to set up.

Log in to the page

View monitored hosts, native and Nagios-linux

View the services on the monitored host

View specific status information for monitored hosts

Nagios Monitoring System