NRPE介绍

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。

wKioL1Qm3NLBZZSnAAHCItyFxXI201.jpg

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

wKioL1Qm2krywnxLAACf2VJUtQI655.jpg

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

1. [root@ClientNrpe ~]# useradd -s /sbin/nologin nagios

2、安装nagios-plugins，因为NRPE依赖此插件

1. [root@ClientNrpe ~]# yum -y install gcc gcc-c++ make openssl openssl-devel
3. [root@ClientNrpe ~]# tar xf nagios-plugins-2.0.3.tar.gz
4. [root@ClientNrpe ~]# cd nagios-plugins-2.0.3
5. [root@ClientNrpe nagios-plugins-2.0.3]# ./configure --with-nagios-user=nagios --with-nagios-group=nagios
6. [root@ClientNrpe nagios-plugins-2.0.3]# make && make install
8. #注意：如何要监控mysql 需要添加 --with-mysql

3、安装NRPE

1. [root@ClientNrpe ~]# tar xf nrpe-2.15.tar.gz
2. [root@ClientNrpe ~]# cd nrpe-2.15
3. [root@ClientNrpe nrpe-2.15]# ./configure --with-nrpe-user=nagios \
4. > --with-nrpe-group=nagios \
5. > --with-nagios-user=nagios \
6. > --with-nagios-group=nagios \
7. > --enable-command-args \
8. > --enable-ssl
9. [root@ClientNrpe nrpe-2.15]# make all
10. [root@ClientNrpe nrpe-2.15]# make install-plugin
11. [root@ClientNrpe nrpe-2.15]# make install-daemon
12. [root@ClientNrpe nrpe-2.15]# make install-daemon-config

4、配置NRPE

1. [root@ClientNrpe ~]# grep -v '^#' /usr/local/nagios/etc/nrpe.cfg |sed '/^$/d'
2. log_facility=daemon
3. pid_file=/var/run/nrpe.pid
4. server_port=5666 #监听的端口
5. nrpe_user=nagios
6. nrpe_group=nagios
7. allowed_hosts=192.168.0.105 #允许的地址通常是Nagios服务器端
9. dont_blame_nrpe=0
10. allow_bash_command_substitution=0
11. debug=0
12. command_timeout=60
13. connection_timeout=300
14. command[check_users]=/usr/local/nagios/libexec/check_users -w 5 -c 10
15. command[check_load]=/usr/local/nagios/libexec/check_load -w 15,10,5 -c 30,25,20
16. command[check_hda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p /dev/hda1
17. command[check_zombie_procs]=/usr/local/nagios/libexec/check_procs -w 5 -c 10 -s Z
18. command[check_total_procs]=/usr/local/nagios/libexec/check_procs -w 150 -c 200

5、启动NRPE

1. #以守护进程的方式启动
2. [root@ClientNrpe ~]# /usr/local/nagios/bin/nrpe -c /usr/local/nagios/etc/nrpe.cfg -d
3. [root@ClientNrpe ~]# netstat -tulpn | grep nrpe
4. tcp 0 0 0.0.0.0:5666 0.0.0.0:* LISTEN 22597/nrpe
5. 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：

1. -i # Run as a service under inetd or xinetd
2. -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：

1. [root@ClientNrpe ~]# cat /etc/init.d/nrped
2. #!/bin/bash
3. # chkconfig: 2345 88 12
4. # description: NRPE DAEMON
6. NRPE=/usr/local/nagios/bin/nrpe
7. NRPECONF=/usr/local/nagios/etc/nrpe.cfg
9. case "$1" in
10. start)
11. echo -n "Starting NRPE daemon..."
12. $NRPE -c $NRPECONF -d
13. echo " done."
14. ;;
15. stop)
16. echo -n "Stopping NRPE daemon..."
17. pkill -u nagios nrpe
18. echo " done."
19. ;;
20. restart)
21. $0 stop
22. sleep 2
23. $0 start
24. ;;
25. *)
26. echo "Usage: $0 start|stop|restart"
27. ;;
28. esac
29. exit 0
30. [root@ClientNrpe ~]# chmod +x /etc/init.d/nrped
31. [root@ClientNrpe ~]# chkconfig --add nrped
32. [root@ClientNrpe ~]# chkconfig nrped on
34. [root@ClientNrpe ~]# service nrped start
35. Starting NRPE daemon... done.
36. [root@ClientNrpe ~]# netstat -tnlp
37. Active Internet connections (only servers)
38. Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
39. tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1031/sshd
40. tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 1108/master
41. tcp 0 0 0.0.0.0:5666 0.0.0.0:* LISTEN 22597/nrpe
42. tcp 0 0 :::22 :::* LISTEN 1031/sshd
43. tcp 0 0 ::1:25 :::* LISTEN 1108/master
44. tcp 0 0 :::5666 :::* LISTEN 22597/nrpe

三、监控端安装NRPE

1、安装NRPE

1. [root@Nagios ~]# tar xf nrpe-2.15.tar.gz
2. [root@Nagios ~]# cd nrpe-2.15
3. [root@Nagios nrpe-2.15]# ./configure
4. > --with-nrpe-user=nagios \
5. > --with-nrpe-group=nagios \
6. > --with-nagios-user=nagios \
7. > --with-nagios-group=nagios \
8. > --enable-command-args \
9. > --enable-ssl
10. [root@Nagios nrpe-2.15]# make all
11. [root@Nagios nrpe-2.15]# make install-plugin
13. #安装完成后，会在Nagios安装目录的libexec下生成check_nrpe的插件
14. [root@Nagios ~]# cd /usr/local/nagios/libexec/
15. [root@Nagios libexec]# ll -d check_nrpe
16. -rwxrwxr-x. 1 nagios nagios 76769 9月 28 08:07 check_nrpe

2、check_nrpe的用法

1. [root@Nagios libexec]# ./check_nrpe -h
3. NRPE Plugin for Nagios
4. Copyright (c) 1999-2008 Ethan Galstad (nagios@nagios.org)
5. Version: 2.15
6. Last Modified: 09-06-2013
7. License: GPL v2 with exemptions (-l for more info)
8. SSL/TLS Available: Anonymous DH Mode, OpenSSL 0.9.6 or higher required
10. Usage: check_nrpe -H <host> [ -b <bindaddr> ] [-4] [-6] [-n] [-u] [-p <port>] [-t <timeout>] [-c <command>] [-a <arglist...>]
12. Options:
13. -n = Do no use SSL
14. -u = Make socket timeouts return an UNKNOWN state instead of CRITICAL
15. <host> = The address of the host running the NRPE daemon
16. <bindaddr> = bind to local address
17. -4 = user ipv4 only
18. -6 = user ipv6 only
19. [port] = The port on which the daemon is running (default=5666)
20. [timeout] = Number of seconds before connection times out (default=10)
21. [command] = The name of the command that the remote daemon should run
22. [arglist] = Optional arguments that should be passed to the command. Multiple
23. arguments should be separated by a space. If provided, this must be
24. the last option supplied on the command line.
26. Note:
27. This plugin requires that you have the NRPE daemon running on the remote host.
28. You must also have configured the daemon to associate a specific plugin command
29. with the [command] option you are specifying here. Upon receipt of the
30. [command] argument, the NRPE daemon will run the appropriate plugin command and
31. send the plugin output and return code back to *this* plugin. This allows you
32. to execute plugins on remote hosts and 'fake' the results to make Nagios think
33. the 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：

1. check_nrpe -H <host> [-n] [-u] [-p <port>] [-t <timeout>] [-c <command>] [-a <arglist...>]
3. [root@Nagios libexec]# ./check_nrpe -H 192.168.0.81
4. NRPE v2.15

3、定义命令

1. [root@Nagios ~]# cd /usr/local/nagios/etc/objects/
2. [root@Nagios objects]# vim commands.cfg
3. #增加到末尾行
4. define command{
5. command_name check_nrpe
6. command_line $USER1$/check_nrpe -H "$HOSTADDRESS$" -c "$ARG1$"
7. }

4、定义服务

1. [root@Nagios objects]# cp windows.cfg linhost.cfg
2. [root@Nagios objects]# grep -v '^#' linhost.cfg |sed '/^$/d'
3. define host{
4. use linux-server
5. host_name linhost
6. alias My Linux Server
7. address 192.168.0.81
8. }
9. define service{
10. use generic-service
11. host_name linhost
12. service_description CHECK USER
13. check_command check_nrpe!check_users
14. }
15. define service{
16. use generic-service
17. host_name linhost
18. service_description Load
19. check_command check_nrpe!check_load
20. }
21. define service{
22. use generic-service
23. host_name linhost
24. service_description SDA1
25. check_command check_nrpe!check_hda1
26. }
27. define service{
28. use generic-service
29. host_name linhost
30. service_description Zombie
31. check_command check_nrpe!check_zombie_procs
32. }
33. define service{
34. use generic-service
35. host_name linhost
36. service_description Total procs
37. check_command check_nrpe!check_total_procs
38. }

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

wKioL1QnZhGQMN-ZAAM_Km8AoXQ787.jpg

5、启动所定义的命令和服务

1. [root@Nagios ~]# vim /usr/local/nagios/etc/nagios.cfg
2. #增加一行
3. cfg_file=/usr/local/nagios/etc/objects/linhost.cfg

6、配置文件语法检查

1. [root@Nagios ~]# service nagios configtest
3. Nagios Core 4.0.7
4. Copyright (c) 2009-present Nagios Core Development Team and Community Contributors
5. Copyright (c) 1999-2009 Ethan Galstad
6. Last Modified: 06-03-2014
7. License: GPL
9. Website: http://www.nagios.org
10. Reading configuration data...
11. Read main config file okay...
12. Read object config files okay...
14. Running pre-flight check on configuration data...
16. Checking objects...
17. Checked 20 services.
18. Checked 3 hosts.
19. Checked 2 host groups.
20. Checked 0 service groups.
21. Checked 1 contacts.
22. Checked 1 contact groups.
23. Checked 26 commands.
24. Checked 5 time periods.
25. Checked 0 host escalations.
26. Checked 0 service escalations.
27. Checking for circular paths...
28. Checked 3 hosts
29. Checked 0 service dependencies
30. Checked 0 host dependencies
31. Checked 5 timeperiods
32. Checking global event handlers...
33. Checking obsessive compulsive processor commands...
34. Checking misc settings...
36. Total Warnings: 0
37. Total Errors: 0
39. Things look okay - No serious problems were detected during the pre-flight check
40. Object precache file created:
41. /usr/local/nagios/var/objects.precache

7、重新启动nagios服务

1. [root@Nagios ~]# service nagios restart
2. Running configuration check...
3. Stopping nagios: done.
4. 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

wKiom1Qm8WfyoR-sAAF5rctJNZ8410.jpg

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

wKiom1Qm8WfCZrd-AAb-FyGH-V4273.jpg

在监控Linhost主机时出现一个CRITICAL的警告，查找解决办法

wKioL1Qm8jyzbPBcAAEWP2KVKxc476.jpg

1. ###被监控端修改NRPE配置文件并重启NRPE服务
2. [root@ClientNrpe etc]# vim nrpe.cfg
3. command[check_sda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p /dev/sda1
4. [root@ClientNrpe etc]# service nrped restart
6. ###监控端修改linhost.cfg配置文件并重启nagios和httpd服务
7. [root@Nagios objects]# vim linhost.cfg
8. #注释：原来这里是hda1，现在修改成sda1
9. define service{
10. use generic-service
11. host_name linhost
12. service_description SDA1
13. check_command check_nrpe!check_sda1
14. }
15. [root@Nagios ~]# service nagios restart
16. Running configuration check...
17. Stopping nagios: done.
18. Starting nagios: done.
19. [root@Nagios ~]# service httpd restart
20. 停止 httpd： [确定]
21. 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：

wKioL1Qm9JKADd8SAAa9TVtAuVc417.jpg