Nagios是一款开源的免费网络监视工具，能有效监控Windows、Linux和Unix的主机状态，交换机路由器等网络设置，打印机等。在系统或服务状态异常时发出邮件或短信报警第一时间通知网站运维人员，在状态恢复后发出正常的邮件或短信通知。下面是如何配置nagios监控linux主机。
Linux被监控主机配置
安装nagios插件
# yum -y install nagios-plugins nagios-plugins-all
安装nrpe插件
# yum -y install nrpe
修改nrpe配置
# vim /etc/nagios/nrpe.cfg allowed_hosts=127.0.0.1,1.2.3.4
启动nrpe服务
# service nrpe start
设置nrpe开机启动
# chkconfig nrpe on
检查nrpe是否正常启动
# netstat -an | grep 5666
如果出现如下：
tcp 0 0 0.0.0.0:5666 0.0.0.0:* LISTEN
说明nrpe启动成功
防火墙中打开5666端口
# vim /etc/sysconfig/iptables -A INPUT -m state --state NEW -m tcp -p tcp -s 1.2.3.4 --dport 5666 -j ACCEP
重启防火墙
# service iptables restart
Nagios 监控主机配置
安装nrpe插件
# yum -y install nagios-plugins-nrpe
安装好的check_nrpe插件位置为：/usr/lib64/nagios/plugins/check_nrpe
定义check_nrpe监控命令
# vim /etc/nagios/objects/commands.cfg
在最后面添加如下内容：
# 'check_nrpe' command definition
define command{
command_name check_nrpe
command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$
}
添加远程主机配置文件目录
# cd /etc/nagios
新建远程主机监控配置文件目录
# mkdir servers
修改nagios.cfg配置文件，将servers目录添加到配置文件中
# vim nagios.cfg
添加如下一行：
cfg_dir=/etc/nagios/servers
配置远程主机监控对象
# cd servers
假如被监控主机ip为1.2.3.4
新建1.2.3.4.cfg，在里面添加如下监控内容
###############################################################################
# LOCALHOST.CFG - SAMPLE OBJECT CONFIG FILE FOR MONITORING THIS MACHINE
#
# Last Modified: 05-31-2007
#
# NOTE: This config file is intended to serve as an *extremely* simple
# example of how you can create configuration entries to monitor
# the local (Linux) machine.
#
###############################################################################
###############################################################################
###############################################################################
#
# HOST DEFINITION
#
###############################################################################
###############################################################################
# Define a host for the local machine
define host{
use linux-server,host-pnp ; Name of host template to use
; This host definition will inherit all variables that are defined
; in (or inherited by) the linux-server host template definition.
host_name lvs01
alias lvs01
address 1.2.3.4
}
###############################################################################
###############################################################################
#
# HOST GROUP DEFINITION
#
###############################################################################
###############################################################################
# Define an optional hostgroup for Linux machines
#define hostgroup{
# hostgroup_name linux-servers ; The name of the hostgroup
# alias Linux Servers ; Long name of the group
# members lvs01 ; Comma separated list of hosts that belong to this group
# }
###############################################################################
###############################################################################
#
# SERVICE DEFINITIONS
#
###############################################################################
###############################################################################
# Define a service to "ping" the local machine
define service{
use local-service,srv-pnp; Name of service template to use
host_name lvs01
service_description PING
check_command check_ping!100.0,20%!500.0,60%
}
# Define a service to check the disk space of the root partition
# on the local machine. Warning if < 20% free, critical if
# < 10% free space on partition.
define service{
use local-service,srv-pnp; Name of service template to use
host_name lvs01
service_description Root Partition
check_command check_nrpe!check_disk
}
# Define a service to check the number of currently logged in
# users on the local machine. Warning if > 20 users, critical
# if > 50 users.
define service{
use local-service,srv-pnp; Name of service template to use
host_name lvs01
service_description Current Users
check_command check_nrpe!check_users
}
# Define a service to check the number of currently running procs
# on the local machine. Warning if > 250 processes, critical if
# > 400 users.
define service{
use local-service ; Name of service template to use
host_name lvs01
service_description Total Processes
check_command check_nrpe!check_total_procs
}
define service{
use local-service ; Name of service template to use
host_name lvs01
service_description Zombie Processes
check_command check_nrpe!check_zombie_procs
}
# Define a service to check the load on the local machine.
define service{
use local-service,srv-pnp; Name of service template to use
host_name lvs01
service_description Current Load
check_command check_nrpe!check_load
}
# Define a service to check the swap usage the local machine.
# Critical if less than 10% of swap is free, warning if less than 20% is free
define service{
use local-service,srv-pnp; Name of service template to use
host_name lvs01
service_description Swap Usage
check_command check_nrpe!check_swap
}
# Define a service to check SSH on the local machine.
# Disable notifications for this service by default, as not all users may have SSH enabled.
#define service{
# use local-service ; Name of service template to use
# host_name lvs01
# service_description SSH
# check_command check_ssh
# notifications_enabled 0
# }
# Define a service to check HTTP on the local machine.
# Disable notifications for this service by default, as not all users may have HTTP enabled.
#define service{
# use local-service ; Name of service template to use
# host_name lvs01
# service_description HTTP
# check_command check_tcp!80
# }
define service{
use local-service,srv-pnp; Name of service template to use
host_name lvs01
service_description Disk IO
check_command check_nrpe!check_diskstat
}
验证nagios配置文件
# nagios -v /etc/nagios/nagios.cfg
或者
# service nagios checkconfig
测试check_nrpe插件与被监控机nrpedaemon之间能否正常通信
# /usr/lib64/nagios/plugins/check_nrpe -H 1.2.3.4
如果返回NRPE v2.13，说明正常
或者也可以用如下命令测试，看下是否有数据返回
# /usr/lib64/nagios/plugins/check_nrpe -H 1.2.3.4 -c check_load
重启nagios
# service nagios restart
这样子就完成了对远程主机的监控，登录web界面即可看到相应信息。