关闭selinux
注意：（如没有，可跳过）
修改selinux配置：
getenforce
setenforce 0

如果要使用selinux，需要修改如下
chcon -R -t https_sys_content_t /usr/local/nagios/sbin
chcon -R -t https_sys_content_t /usr/local/nagios/share

1、安装必备软件：
yum -y install httpd php gcc glibc glibc-common gd gd-devel openssl-devel xinetd

2、下载相关程序：
wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.2.3.tar.gz
wget http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.15.tar.gz
wget http://prdownloads.sourceforge.net/sourceforge/nagios/nrpe-2.12.tar.gz

创建Nagios用户及组：
/usr/sbin/useradd nagios -s /bin/bash

创建一个名为nagcmd的用户组，用于从web接口执行外部命令。将Nagios用户和Apache用户加入组中：
/usr/sbin/groupadd nagcmd
/usr/sbin/usermod -G nagcmd nagios
/usr/sbin/usermod -G nagcmd apache

注：上面的apache是Apache用户所属的组，如有不同请自行调整。

编译安装nagios：
tar zxf nagios-3.2.3.tar.gz
cd nagios-3.2.3
./configure --with-command-group=nagcmd
make all
make install
make install-init
make install-config
make install-commandmode
make install-webconf

注：make install 用于安装主要的程序、CGI及HTML文件
　　　　make install-init 用于生成init启动脚本
　　　　make install-config 用于安装示例配置文件
　　　　make install-commandmode 用于设置相应的目录权限
　　　　make install-webconf 用于安装Apache配置文件

配置Nagios Web界面登陆帐号及密码：
htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

安装nagios插件：
tar xzf nagios-plugins-1.4.15.tar.gz
cd nagios-plugins-1.4.15
./configure --with-nagios-user=nagios --with-nagios-group=nagios
make && make install

启动前先检查下配置文件是否正确:
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

启动nagios服务：
/usr/local/nagios/bin/nagios -d /usr/local/nagios/etc/nagios.cfg

查看Nagios运行状态：
/usr/local/nagios/bin/nagiostats

加入nagios到启动组：
chkconfig --add nagios
chkconfig nagios on

注意：如果运行/etc/init.d/nagios restart 出现Starting nagios:This account is currently not available.
执行：
usermod -s /bin/bash nagios
给用户指定默认shell。

登陆nagios：
重启apache服务：
/etc/init.d/httpd restart
http://localhost/nagios

安装NRPE：
注意：由于NRPE是通过SSL方式在监控和被监控主机上进行数据传输的，所以必须先安装ssl相关的软件包。

tar zxf nrpe-2.12.tar.gz
cd nrpe-2.12
./configure
make all
make install-plugin
make install-daemon
make install-daemon-config
make install-xinetd

编辑：
vi /etc/xinetd.d/nrpe
only_from       = 127.0.0.1 #修改成nagios服务器的地址

添加nrpe后台服务端口到/etc/services文件中：
vi /etc/services
nrpe 5666/tcp #NRPE

重启xinetd服务：
service xinetd restart

注意：
如果开启了防火墙，打开防火墙规则：
iptables -I RH-Firewall-1-INPUT -p tcp -m tcp --dport 5666 -j ACCEPT
保存新规则：
service iptabls save

验证NRPE是否正确安装：
/usr/local/nagios/libexec/check_nrpe -H localhost
注：如果成功，会返回NRPE的版本号。

监控主机上的操作：
安装nagios插件和nrpe，步骤同上。

nagios服务器添加nrpe命令模板：
vi /usr/local/nagios/etc/objects/commands.cfg
define command{
    command_name    check_nrpe
    command_line    $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$ -t 60
}

新建存放主机文件的目录：
vi /usr/local/nagios/etc/nagios.cfg
cfg_dir=/usr/local/nagios/etc/servers

mkdir /usr/local/nagios/etc/servers
chown -R nagios.nagios /usr/local/nagios/etc/servers

在模板里添加一个host主机模板包含pnp：
vi /usr/local/nagios/etc/objects/templates.cfg
define host{
        name                            linux-server    ; The name of this host template
        use                             generic-host,hosts-pnp  ; This template inherits other values from the generic-host template
        check_period                    24x7            ; By default, Linux hosts are checked round the clock
        check_interval                  5               ; Actively check the host every 5 minutes
        retry_interval                  1               ; Schedule host check retries at 1 minute intervals
        max_check_attempts              10              ; Check each Linux host 10 times (max)
        check_command                   check-host-alive ; Default command to check Linux hosts
        notification_period             workhours       ; Linux admins hate to be woken up, so we only notify during the day
                                                        ; Note that the notification_period variable is being overridden from
                                                        ; the value that is inherited from the generic-host template!
        notification_interval           120             ; Resend notifications every 2 hours
        notification_options            d,u,r           ; Only send notifications for specific host states
        contact_groups                  admins          ; Notifications get sent to the admins by default
        register                        0               ; DONT REGISTER THIS DEFINITION - ITS NOT A REAL HOST, JUST A TEMPLATE!
        }

在模板里添加一个pnp服务模板：
vi /usr/local/nagios/etc/objects/templates.cfg
define service{
        name                            pnp-service           ; The name of this service template
        use                             generic-service,services-pnp            ; Inherit default values from the generic-service definition
        max_check_attempts              4                       ; Re-check the service up to 4 times in order to determine its final (hard) state
        normal_check_interval           5                       ; Check the service every 5 minutes under normal conditions
        retry_check_interval            1                       ; Re-check the service every minute until a hard state can be determined
        register                        0                       ; DONT REGISTER THIS DEFINITION - ITS NOT A REAL SERVICE, JUST A TEMPLATE!
        }
       
创建一个主机配置文件：
vi /usr/local/nagios/etc/servers/192.168.56.151.cfg

修改联系人信息：
vi /usr/local/nagios/etc/objects/contacts.cfg
define contact{
        contact_name                    backkom ; Short name of user
        use                             generic-contact     ; Inherit default values from generic-contact template (defined above)
        alias                           system Admin       ; Full name of user
        email                           backkom@mail.com ;<<***** CHANGE THIS TO YOUR EMAIL ADDRESS ******
        }

把用户加入admin组：
define contactgroup{
        contactgroup_name       admins
        alias                   Nagios Administrators
        members                 nagiosadmin,backkom
        }
       
创建主机组：
vi /usr/local/nagios/etc/objects/groups.cfg
cfg_file=/usr/local/nagios/etc/objects/groups.cfg
define hostgroup{
        hostgroup_name  server; The name of the hostgroup
        alias           App server; Long name of the group
        members         server1,server2,app1,app2,db1,db2  }