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
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[root@ClientNrpe ~]
# useradd -s /sbin/nologin nagios
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2、安装nagios-plugins，因为NRPE依赖此插件
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[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
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3、安装NRPE
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[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
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4、配置NRPE
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[root@ClientNrpe ~]
# grep -v '^#' /usr/local/nagios/etc/nrpe.cfg |sed '/^$/d'
log_facility=daemon
pid_file=
/var/run/nrpe
.pid
server_port=5666
#监听的端口
nrpe_user=nagios
nrpe_group=nagios
allowed_hosts=192.168.0.105
#允许的地址通常是Nagios服务器端
dont_blame_nrpe=0
allow_bash_command_substitution=0
debug=0
command_timeout=60
connection_timeout=300
command
[check_users]=
/usr/local/nagios/libexec/check_users
-w 5 -c 10
command
[check_load]=
/usr/local/nagios/libexec/check_load
-w 15,10,5 -c 30,25,20
command
[check_hda1]=
/usr/local/nagios/libexec/check_disk
-w 20% -c 10% -p
/dev/hda1
command
[check_zombie_procs]=
/usr/local/nagios/libexec/check_procs
-w 5 -c 10 -s Z
command
[check_total_procs]=
/usr/local/nagios/libexec/check_procs
-w 150 -c 200
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5、启动NRPE
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#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 nrpe
tcp 0 0 0.0.0.0:5666 0.0.0.0:* LISTEN 22597
/nrpe
tcp 0 0 :::5666 :::* LISTEN 22597
/nrpe
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有两种方式用于管理nrpe服务，nrpe有两种运行模式：
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-i
# Run as a service under inetd or xinetd
-d
# Run as a standalone daemon
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可以为nrpe编写启动脚本，使得nrpe以standard alone方式运行：
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[root@ClientNrpe ~]
# cat /etc/init.d/nrped
#!/bin/bash
# chkconfig: 2345 88 12
# description: NRPE DAEMON
NRPE=
/usr/local/nagios/bin/nrpe
NRPECONF=
/usr/local/nagios/etc/nrpe
.cfg
case
"$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"
;;
esac
exit
0
[root@ClientNrpe ~]
# chmod +x /etc/init.d/nrped
[root@ClientNrpe ~]
# chkconfig --add nrped
[root@ClientNrpe ~]
# chkconfig nrped on
[root@ClientNrpe ~]
# service nrped start
Starting NRPE daemon...
done
.
[root@ClientNrpe ~]
# netstat -tnlp
Active 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
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三、监控端安装NRPE
1、安装NRPE
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[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
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2、check_nrpe的用法
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[root@Nagios libexec]
# ./check_nrpe -h
NRPE Plugin
for
Nagios
Copyright (c) 1999-2008 Ethan Galstad (nagios@nagios.org)
Version: 2.15
Last Modified: 09-06-2013
License: GPL v2 with exemptions (-l
for
more
info)
SSL
/TLS
Available: Anonymous DH Mode, OpenSSL 0.9.6 or higher required
Usage: check_nrpe -H <host> [ -b <bindaddr> ] [-4] [-6] [-n] [-u] [-p <port>] [-t <timeout>] [-c <
command
>] [-a <arglist...>]
Options:
-n = Do no use SSL
-u = Make socket timeouts
return
an UNKNOWN state instead of CRITICAL
<host> = The address of the host running the NRPE daemon
<bindaddr> = 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
command
with the [
command
] option you are specifying here. Upon receipt of the
[
command
] argument, the NRPE daemon will run the appropriate plugin
command
and
send the plugin output and
return
code back to *this* plugin. This allows you
to execute plugins on remote hosts and
'fake'
the results to
make
Nagios think
the plugin is being run locally.
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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 <host> [-n] [-u] [-p <port>] [-t <timeout>] [-c <
command
>] [-a <arglist...>]
[root@Nagios libexec]
# ./check_nrpe -H 192.168.0.81
NRPE v2.15
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3、定义命令
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[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
"$ARG1$"
}
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4、定义服务
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[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
}
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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
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[root@Nagios ~]
# vim /usr/local/nagios/etc/nagios.cfg
#增加一行
cfg_file=
/usr/local/nagios/etc/objects/linhost
.cfg
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6、配置文件语法检查
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[root@Nagios ~]
# service nagios configtest
Nagios Core 4.0.7
Copyright (c) 2009-present Nagios Core Development Team and Community Contributors
Copyright (c) 1999-2009 Ethan Galstad
Last Modified: 06-03-2014
License: GPL
Website: http:
//www
.nagios.org
Reading 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 timeperiods
Checking global event handlers...
Checking obsessive compulsive processor commands...
Checking misc settings...
Total Warnings: 0
Total Errors: 0
Things
look
okay - No serious problems were detected during the pre-flight check
Object precache
file
created:
/usr/local/nagios/var/objects
.precache
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7、重新启动nagios服务
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[root@Nagios ~]
# service nagios restart
Running configuration check...
Stopping nagios:
done
.
Starting nagios:
done
.
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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
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###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sda1
define service{
use generic-service
host_name linhost
service_description SDA1
check_command check_nrpe!check_sda1
}
[root@Nagios ~]
# service nagios restart
Running 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]
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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：
http://forum.joomla.org/viewtopic.php?t=666220
本文转自zys467754239 51CTO博客，原文链接：http://blog.51cto.com/467754239/1558897，如需转载请自行联系原作者
