一、简介
1、NRPE介绍
NRPE是Nagios的一个功能扩展，它可在远程Linux/Unix主机上执行插件程序。通过在远程服务器上安装NRPE插件及Nagios插件程序来向Nagios监控平台提供该服务器的本地情况，如CPU负载，内存使用，磁盘使用等。这里将Nagios监控端称为Nagios服务器端，而将远程被监控的主机称为Nagios客户端。
Nagios监控远程主机的方法有多种，其方式包括SNMP，NRPE,SSH,NCSA等。这里介绍其通过NRPE监控远程Linux主机的方式。
NRPE（Nagios Remote Plugin Executor）是用于在远端服务器上运行监测命令的守护进程，它用于让Nagios监控端基于安装的方式触发远端主机上的检测命令，并将检测结果返回给监控端。而其执行的开销远低于基于SSH的检测方式，而且检测过程不需要远程主机上的系统账号信息，其安全性也高于SSH的检测方式。
2、NRPE的工作原理
NRPE有两部分组成
check_nrpe插件：位于监控主机上
nrpe daemon：运行在远程主机上，通常是被监控端agent
注意：nrpe daemon需要Nagios-plugins插件的支持，否则daemon不能做任何监控
详细的介绍NRPE的工作原理
当Nagios需要监控某个远程Linux主机的服务或者资源情况时：
首先：Nagios会运行check_nrpe这个插件，告诉它要检查什么；
其次：check_nrpe插件会连接到远程的NRPE daemon，所用的方式是SSL；
然后：NRPE daemon 会运行相应的Nagios插件来执行检查；
最后：NRPE daemon 将检查的结果返回给check_nrpe 插件，插件将其递交给nagios做处理。
二、被监控端安装Nagios-plugins插件和NRPE
1、添加nagios用户
[root@ClientNrpe ~]# useradd -s /sbin/nologin nagios
2、安装nagios-plugins，因为NRPE依赖此插件
[root@ClientNrpe ~]# yum -y install gcc gcc-c++ make openssl openssl-devel[root@ClientNrpe ~]# tar xf nagios-plugins-2.0.3.tar.gz [root@ClientNrpe ~]# cd nagios-plugins-2.0.3[root@ClientNrpe nagios-plugins-2.0.3]# ./configure --with-nagios-user=nagios --with-nagios-group=nagios[root@ClientNrpe nagios-plugins-2.0.3]# make && make install#注意：如何要监控mysql 需要添加 --with-mysql
3、安装NRPE
[root@ClientNrpe ~]# tar xf nrpe-2.15.tar.gz [root@ClientNrpe ~]# cd nrpe-2.15[root@ClientNrpe nrpe-2.15]# ./configure --with-nrpe-user=nagios \> --with-nrpe-group=nagios \> --with-nagios-user=nagios \> --with-nagios-group=nagios \> --enable-command-args \> --enable-ssl[root@ClientNrpe nrpe-2.15]# make all[root@ClientNrpe nrpe-2.15]# make install-plugin[root@ClientNrpe nrpe-2.15]# make install-daemon[root@ClientNrpe nrpe-2.15]# make install-daemon-config
4、配置NRPE
[root@ClientNrpe ~]# grep -v '^#' /usr/local/nagios/etc/nrpe.cfg |sed '/^$/d'log_facility=daemonpid_file=/var/run/nrpe.pidserver_port=5666 #监听的端口nrpe_user=nagiosnrpe_group=nagiosallowed_hosts=192.168.0.105 #允许的地址通常是Nagios服务器端 dont_blame_nrpe=0allow_bash_command_substitution=0debug=0command_timeout=60connection_timeout=300command[check_users]=/usr/local/nagios/libexec/check_users -w 5 -c 10command[check_load]=/usr/local/nagios/libexec/check_load -w 15,10,5 -c 30,25,20command[check_hda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p /dev/hda1command[check_zombie_procs]=/usr/local/nagios/libexec/check_procs -w 5 -c 10 -s Zcommand[check_total_procs]=/usr/local/nagios/libexec/check_procs -w 150 -c 200
5、启动NRPE
#以守护进程的方式启动[root@ClientNrpe ~]# /usr/local/nagios/bin/nrpe -c /usr/local/nagios/etc/nrpe.cfg -d[root@ClientNrpe ~]# netstat -tulpn | grep nrpetcp 0 0 0.0.0.0:5666 0.0.0.0:* LISTEN 22597/nrpe tcp 0 0 :::5666 :::* LISTEN 22597/nrpe
有两种方式用于管理nrpe服务，nrpe有两种运行模式：
-i # Run as a service under inetd or xinetd-d # Run as a standalone daemon
可以为nrpe编写启动脚本，使得nrpe以standard alone方式运行：
[root@ClientNrpe ~]# cat /etc/init.d/nrped #!/bin/bash# chkconfig: 2345 88 12# description: NRPE DAEMONNRPE=/usr/local/nagios/bin/nrpeNRPECONF=/usr/local/nagios/etc/nrpe.cfgcase "$1" in start) echo -n "Starting NRPE daemon..." $NRPE -c $NRPECONF -d echo " done." ;; stop) echo -n "Stopping NRPE daemon..." pkill -u nagios nrpe echo " done." ;; restart) $0 stop sleep 2 $0 start ;; *) echo "Usage: $0 start|stop|restart" ;; esacexit 0[root@ClientNrpe ~]# chmod +x /etc/init.d/nrped [root@ClientNrpe ~]# chkconfig --add nrped[root@ClientNrpe ~]# chkconfig nrped on[root@ClientNrpe ~]# service nrped startStarting NRPE daemon... done.[root@ClientNrpe ~]# netstat -tnlpActive Internet connections (only servers)Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1031/sshd tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 1108/master tcp 0 0 0.0.0.0:5666 0.0.0.0:* LISTEN 22597/nrpe tcp 0 0 :::22 :::* LISTEN 1031/sshd tcp 0 0 ::1:25 :::* LISTEN 1108/master tcp 0 0 :::5666 :::* LISTEN 22597/nrpe
三、监控端安装NRPE
1、安装NRPE
[root@Nagios ~]# tar xf nrpe-2.15.tar.gz [root@Nagios ~]# cd nrpe-2.15[root@Nagios nrpe-2.15]# ./configure > --with-nrpe-user=nagios \> --with-nrpe-group=nagios \> --with-nagios-user=nagios \> --with-nagios-group=nagios \> --enable-command-args \> --enable-ssl[root@Nagios nrpe-2.15]# make all[root@Nagios nrpe-2.15]# make install-plugin#安装完成后，会在Nagios安装目录的libexec下生成check_nrpe的插件[root@Nagios ~]# cd /usr/local/nagios/libexec/[root@Nagios libexec]# ll -d check_nrpe -rwxrwxr-x. 1 nagios nagios 76769 9月 28 08:07 check_nrpe
2、check_nrpe的用法
[root@Nagios libexec]# ./check_nrpe -hNRPE Plugin for NagiosCopyright (c) 1999-2008 Ethan Galstad (nagios@nagios.org)Version: 2.15Last Modified: 09-06-2013License: GPL v2 with exemptions (-l for more info)SSL/TLS Available: Anonymous DH Mode, OpenSSL 0.9.6 or higher requiredUsage: check_nrpe -H[ -b ] [-4] [-6] [-n] [-u] [-p ] [-t ] [-c ] [-a ]Options: -n = Do no use SSL -u = Make socket timeouts return an UNKNOWN state instead of CRITICAL = The address of the host running the NRPE daemon = bind to local address -4 = user ipv4 only -6 = user ipv6 only [port] = The port on which the daemon is running (default=5666) [timeout] = Number of seconds before connection times out (default=10) [command] = The name of the command that the remote daemon should run [arglist] = Optional arguments that should be passed to the command. Multiple arguments should be separated by a space. If provided, this must be the last option supplied on the command line.Note:This plugin requires that you have the NRPE daemon running on the remote host.You must also have configured the daemon to associate a specific plugin commandwith the [command] option you are specifying here. Upon receipt of the[command] argument, the NRPE daemon will run the appropriate plugin command andsend the plugin output and return code back to *this* plugin. This allows youto execute plugins on remote hosts and 'fake' the results to make Nagios thinkthe plugin is being run locally.
通过NRPE监控远程Linux主机要使用chech_nrpe插件进行，其语法格式如下：check_nrpe -H[-n] [-u] [-p ] [-t ] [-c ] [-a ][root@Nagios libexec]# ./check_nrpe -H 192.168.0.81NRPE v2.15
3、定义命令
[root@Nagios ~]# cd /usr/local/nagios/etc/objects/[root@Nagios objects]# vim commands.cfg #增加到末尾行define command{ command_name check_nrpe command_line $USER1$/check_nrpe -H "$HOSTADDRESS$" -c "$ARG1$"} 4、定义服务
[root@Nagios objects]# cp windows.cfg linhost.cfg [root@Nagios objects]# grep -v '^#' linhost.cfg |sed '/^$/d'define host{ use linux-server host_name linhost alias My Linux Server address 192.168.0.81 }define service{ use generic-service host_name linhost service_description CHECK USER check_command check_nrpe!check_users }define service{ use generic-service host_name linhost service_description Load check_command check_nrpe!check_load }define service{ use generic-service host_name linhost service_description SDA1 check_command check_nrpe!check_hda1 }define service{ use generic-service host_name linhost service_description Zombie check_command check_nrpe!check_zombie_procs }define service{ use generic-service host_name linhost service_description Total procs check_command check_nrpe!check_total_procs } 这里重点说下，Nagios服务端定义服务的命令完全是根据被监控端NRPE中内置的监控命令，如下图所示
5、启动所定义的命令和服务
[root@Nagios ~]# vim /usr/local/nagios/etc/nagios.cfg #增加一行cfg_file=/usr/local/nagios/etc/objects/linhost.cfg
6、配置文件语法检查
[root@Nagios ~]# service nagios configtestNagios Core 4.0.7Copyright (c) 2009-present Nagios Core Development Team and Community ContributorsCopyright (c) 1999-2009 Ethan GalstadLast Modified: 06-03-2014License: GPLWebsite: http://www.nagios.orgReading configuration data... Read main config file okay... Read object config files okay...Running pre-flight check on configuration data...Checking objects... Checked 20 services. Checked 3 hosts. Checked 2 host groups. Checked 0 service groups. Checked 1 contacts. Checked 1 contact groups. Checked 26 commands. Checked 5 time periods. Checked 0 host escalations. Checked 0 service escalations.Checking for circular paths... Checked 3 hosts Checked 0 service dependencies Checked 0 host dependencies Checked 5 timeperiodsChecking global event handlers...Checking obsessive compulsive processor commands...Checking misc settings...Total Warnings: 0Total Errors: 0Things look okay - No serious problems were detected during the pre-flight checkObject precache file created:/usr/local/nagios/var/objects.precache
7、重新启动nagios服务
[root@Nagios ~]# service nagios restartRunning configuration check...Stopping nagios: done.Starting nagios: done.
8、打开Nagios web监控页面
1）首先点击【Hosts】查看监控主机状态是否为UP
2）其次点击【Services】查看各监控服务的状态是否为OK
注意：在监控新添加的主机linhost；出现状态为CRITICAL，提示没有那个文件或目录。下面是解决办法
在监控Linhost主机时出现一个CRITICAL的警告，查找解决办法
###被监控端修改NRPE配置文件并重启NRPE服务[root@ClientNrpe etc]# vim nrpe.cfg command[check_sda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p /dev/sda1[root@ClientNrpe etc]# service nrped restart###监控端修改linhost.cfg配置文件并重启nagios和httpd服务[root@Nagios objects]# vim linhost.cfg #注释：原来这里是hda1，现在修改成sda1define service{ use generic-service host_name linhost service_description SDA1 check_command check_nrpe!check_sda1 }[root@Nagios ~]# service nagios restartRunning configuration check...Stopping nagios: done.Starting nagios: done.[root@Nagios ~]# service httpd restart停止 httpd： [确定]正在启动 httpd： [确定] 再次点击【services】即为刷新页面，查看如下图所示：
时间：2014-12-26
更新一个监控httpd服务的错误
今天在看日志的时候，在nginx的错误日志中发现很多一样的错误日志，起初是因为其它php程序的bug呢，后来跟开发人员讨论，排除了这个问题，于是就到Google上搜索，才知道原来是监控上配置文件的问题？
错误日志截图：
解决办法参考这篇文章：