nagios(3)

Documentation of

Topic: Nagios Core 3.3.1 Network Monitoring

YYFMarch 1, 2012GZZ

Ministry of Education, Youth and Sport, #201, Norodom Blvd., Phnom Penh Kingdom of Cambodia

website: www.moeys.gov.kh, Email: [email protected]

Fax: +855 23 210 134

Kingdom of Cambodia

National Religion King

YYZZMinistry of Education, Youth and Sport

Department of Information and ASEAN Affairs

ICT in Education Office

Ministry of Education, Youth and Sports.#201, Norodom Blvd.,

Phnom Penh, Kingdom of Cambodia

Website: www.moeys.gov.khFax: +855 23 210 134

CentOS6_Nagios_Core_3.3.x_V0.0.docx

March 1, 2012 By Vannath KANN Page 2 of 77

VERSION DATE DESCRIPTION

V1.0 FEBROURY 01, 2012 NAGIOS CORE AND PLUGINS INSTALATION

V1.0 FEBROURY 02, 2012

Document History






1. About Nagios Core .......................................................................................................................... 6

1.1. What is Nagios Core? ...........................................................................................................................................6

1.2. Downloading the Latest Version .........................................................................................................................6

2. Quick Start Installation Guide....................................................................................................... 6

2.1. Introduction ..........................................................................................................................................................6

2.2. What You Will End Up? ......................................................................................................................................7

2.3. Prerequisites..........................................................................................................................................................7

2.4. Step 1: Create Account Information ...................................................................................................................7

2.5. Step 2: Download Nagios and the Plugins ..........................................................................................................8

2.6. Step 3: Compile and Install Nagios .....................................................................................................................8

2.7. Step 4: Customize Configuration ........................................................................................................................9

2.8. Step 5: Configure the Web Interface ..................................................................................................................9

2.9. Step 6: Compile and Install the Nagios Plugins ...............................................................................................11

2.10. Step 7: Start Nagios ............................................................................................................................................11

2.11. Step 8: Modify SELinux Setting ........................................................................................................................12

2.12. Step 9: Login to the Web Interface ...................................................................................................................13

2.13. Step 10: Other Modifications.............................................................................................................................14

2.14. Step 11:Your Done ............................................................................................................................................15

2.15. Nagios Virtual Host ............................................................................................................................................15

3. How to monitor a Linux/Unix machine (NRPE addon) ............................................................ 18

3.1. Introduction ........................................................................................................................................................18

3.2. Overview..............................................................................................................................................................19

3.3. Installation and Setup NRPE on Remote Server .............................................................................................19

3.4. SetupNagios Monitoring Host Server ...............................................................................................................23

3.5. Customizing Your Configuration......................................................................................................................31

3.5.1. Remote Host Configuration .............................................................................................................................31

3.5.2. Monitoring Host Configuration .......................................................................................................................32

3.6. NRPE Option Help .............................................................................................................................................33

4. How to monitor a Windows machine .......................................................................................... 35

4.1. Introduction ........................................................................................................................................................35

Table of Content






4.2. Overview..............................................................................................................................................................35

4.3. What's Already Done For You ..........................................................................................................................36

4.4. Prerequisites........................................................................................................................................................36

4.5. Installing the Windows Agent............................................................................................................................37

4.6. Configuring Nagios.............................................................................................................................................40

4.7. Password Protection ...........................................................................................................................................43

4.8. Restarting Nagios................................................................................................................................................44

5. How to monitor a router/switch................................................................................................... 45

5.1. Introduction ........................................................................................................................................................45

5.2. Overview..............................................................................................................................................................45

5.3. Steps .....................................................................................................................................................................46


5.5. Prerequisites........................................................................................................................................................47


5.7. Monitoring Services............................................................................................................................................48

5.8. Monitoring Packet Loss and RTA.....................................................................................................................48

5.9. Monitoring SNMP Status Information .............................................................................................................48

5.10. Monitoring Bandwidth / Traffic Rate...............................................................................................................49


6. How to monitor a network printer .............................................................................................. 51

6.1. Introduction ........................................................................................................................................................51

6.2. Overview..............................................................................................................................................................51

6.3. Steps .....................................................................................................................................................................52


6.5. Prerequisites........................................................................................................................................................52



7. How to monitor a publicly available service (HTTP,FTP,SSH,etc.) ........................................ 55

7.1. Introduction ........................................................................................................................................................55

7.2. Plugins For Monitoring Service.........................................................................................................................55

7.3. Creating A Host Definition ................................................................................................................................56

7.4. Creating Service Definitions ..............................................................................................................................56






7.5. Monitoring HTTP...............................................................................................................................................56

7.6. Monitoring FTP ..................................................................................................................................................62

7.7. Monitoring SSH ..................................................................................................................................................63

7.8. Monitoring SMTP...............................................................................................................................................64

7.9. Monitoring POP3................................................................................................................................................66

7.10. Monitoring IMAP ...............................................................................................................................................67

7.11. Restarting Nagios ss............................................................................................................................................69

8. Parent and Childs Relationship................................................................................................... 70

8.1. Introduction ........................................................................................................................................................70

5.2. Configuration......................................................................................................................................................70

9. Icon Images.................................................................................................................................... 72

10. Trouble shooting ........................................................................................................................... 76

10.1. Verifying Your Configuration ...........................................................................................................................76

11. Reference........................................................................................................................................ 77






1. About Nagios Core

1.1. What is Nagios Core?

Nagios Core is an Open Source system and network monitoring application. It watches

hosts and services that you specify, alerting you when things go bad and when they get better.

Nagios Core was originally designed to run under Linux, although it should work under most

other unices as well.

Some of the many features of Nagios Core include:

Monitoring of network services (SMTP, POP3, HTTP, NNTP, PING, etc.) Monitoring of host resources (processor load, disk usage, etc.) Simple plugin design that allows users to easily develop their own service checks Parallelized service checks Ability to define network host hierarchy using "parent" hosts, allowing detection of and

distinction between hosts that are down and those that are unreachable

Contact notifications when service or host problems occur and get resolved (via email, pager, or user-defined method)

Ability to define event handlers to be run during service or host events for proactive problem resolution

Automatic log file rotation Support for implementing redundant monitoring hosts Optional web interface for viewing current network status, notification and problem history,

log file, etc.

1.2. Downloading the Latest Version

FYou can check for new versions of Nagios Core at http://www.nagios.org/download.

2. Quick Start Installation Guide

2.1. Introduction

This guide is intended to provide you with simple instructions on how to install Nagios from

source (code) on Fedora and have it monitoring your local machine inside of 20 minutes. No

advanced installation options are discussed here - just the basics that will work for 95% of users

who want to get started.

These instructions were written based on a standard CentOS 6.0 version Linux distribution.






2.2. What You Will End Up?

If you follow these instructions, here's what you'll end up with:

Nagios and the plugins will be installed underneath /usr/local/nagios Nagios will be configured to monitor a few aspects of your local system (CPU load, disk

usage, etc.)

The Nagios web interface will be accessible at http://localhost/nagios/

2.3. Prerequisites

During portions of the installation you'll need to have root access to your machine.

You also need to give it a static IP address.

Make sure you've installed the following packages on your Fedora installation before

continuing.

Apache PHP GCC compiler GD development libraries

You can use yum to install these packages by running the following commands (as root):

[root@cent60 ~]# yum install httpdphp [root@cent60 ~]# yum install gccglibcglibc-common

[root@cent60 ~]# yum install gdgd-devel

2.4. Step 1: Create Account Information

Become the root user.

[vannath@cent60 ~]$ su -l

Password:

[root@cent60 ~]#

Create a new nagios user account and give it a password.

[root@cent60 ~]# useradd -m nagios

[root@cent60 ~]# passwdnagios

Changing password for user nagios.

New password:

BAD PASSWORD: it is too simplistic/systematic

BAD PASSWORD: is too simple

Retype new password:






passwd: all authentication tokens updated successfully.

[root@cent60 ~]#

Create a new nagcmd group for allowing external commands to be submitted through the web

interface. Add both the nagios user and the apache user to the group.

[root@cent60 ~]# groupaddnagcmd

[root@cent60 ~]# usermod -a -G nagcmdnagios

[root@cent60 ~]# usermod -a -G nagcmd apache

[root@cent60 ~]#

2.5. Step 2: Download Nagios and the Plugins

Create a directory for storing the Nagios Core from downloads.

[root@cent60 ~]#

[root@cent60 ~]# mkdir -p /opt/NagiosCore3.3

[root@cent60 ~]# cd /opt/NagiosCore3.3/

[root@cent60 NagiosCore3.3]#

Download the source code tarballs of both Nagios and the Nagios plugins (visit

http://www.nagios.org/download/ for links to the latest versions). These directions were tested

with Nagios 3.3.1 and Nagios Plugins 1.4.15.

Make that you Server can access to internet.

[root@cent60 NagiosCore3.3]# wgethttp://prdownloads.sourceforge.net/

sourceforge/nagios/ nagios-3.3.1.tar.gz

[root@cent60 NagiosCore3.3]# wgethttp://prdownloads.sourceforge.net/

sourceforge/nagiosplug/nagios-plugins-1.4.15.tar.gz

2.6. Step 3: Compile and Install Nagios

Extract the Nagios source code tarball.

[root@cent60 NagiosCore3.3]# ll

total 3724

-rw-r--r--. 1 root root 1714630 Dec 14 14:56 nagios-3.3.1.tar.gz

-rw-r--r--. 1 root root 2095419 Dec 14 14:57 nagios-plugins-1.4.15.tar.gz

[root@cent60 NagiosCore3.3]# tar xvf nagios-3.3.1.tar.gz


total 3728

drwxr-xr-x. 16 nagiosnagios 4096 Jul 26 2011nagios








[root@cent60 NagiosCore3.3]# cdnagios

[root@cent60 nagios]#

Run the Nagios configure script, passing the name of the group you created earlier like so:

[root@cent60 nagios]# ./configure --with-command-group=nagcmd

Compile the Nagios source code.

[root@cent60 nagios]# make all

Install binaries, init script, sample config files and set permissions on the external command

directory.

[root@cent60 nagios]# make install

[root@cent60 nagios]# make install-init

[root@cent60 nagios]# make install-config

[root@cent60 nagios]# make install-commandmode

Don't start Nagios yet - there's still more that needs to be done......

2.7. Step 4: Customize Configuration

Sample configuration files have now been installed in the /usr/local/nagios/etc directory. These

sample files should work fine for getting started with Nagios. You'll need to make just one

change before you proceed.....

Edit the /usr/local/nagios/etc/objects/contacts.cfgconfig file with your favorite editor and

change the email address associated with the nagiosadmin contact definition to the address

you'd like to use for receiving alerts.

[root@cent60 nagios]# vim /usr/local/nagios/etc/objects/contacts.cfg

# emailnagios@localhost ;






[root@cent60 nagios]# make install-webconf


Create a nagiosadmin account for logging into the Nagios web interface. Remember the

password you assign to this account - you'll need it later.

[root@cent60 nagios]# htpasswd -c /usr/local/nagios/htpasswd.usersnagiosadmin

New password:

Re-type new password:

Adding password for user nagiosadmin


Restart Apache to make the new settings take effect.

[root@cent60 nagios]# servicehttpd restart

Stopping httpd: [ OK ]

Starting httpd: httpd: apr_sockaddr_info_get() failed for cent60

httpd: Could not reliably determine the server's fully qualified domain name,

using 127.0.0.1 for ServerName

[ OK ]

[root@cent60 nagios]# servicehttpd status

httpd (pid 1610) is running...


You will experience with above httpd error message so fix is issue we have go and edit file

/etc/httpd/conf/httpd.conf

[root@cent60 conf]# pwd

/etc/httpd/conf

[root@cent60 conf]# vimhttpd.conf

# redirections work in a sensible way.

#

#ServerName www.example.com:80

ServerName*:80

#

# UseCanonicalName: Determines how Apache constructs self-referencing

[root@cent60 nagios]# servicehttpd restart

Stopping httpd: [ OK ]

Starting httpd: [ OK ]







2.9. Step 6: Compile and Install the Nagios Plugins

Extract the Nagios plugins source code tarball.

[root@cent60 NagiosCore3.3]# tar xvf nagios-plugins-1.4.15.tar.gz


total 3732

drwxr-xr-x. 16 nagiosnagios 4096 Feb 1 23:08 nagios


drwxrwxrwx. 16 nagios root 4096 Jul 28 2010nagios-plugins-1.4.15


[root@cent60 NagiosCore3.3]#cd nagios-plugins-1.4.15

Compile and install the plugins.

[root@cent60 nagios-plugins-1.4.15]# ./configure --with-nagios-user=nagios --

with-nagios-group=nagios

[root@cent60 nagios-plugins-1.4.15]# make

[root@cent60 nagios-plugins-1.4.15]# make install

2.10. Step 7: Start Nagios

Add Nagios to the list of system services and have it automatically start when the system boots.

[root@cent60 nagios-plugins-1.4.15]# chkconfig --add nagios

[root@cent60 nagios-plugins-1.4.15]# chkconfignagios on

[root@cent60 nagios-plugins-1.4.15]#

Verify the sample Nagios configuration files.

[root@cent60 nagios-plugins-1.4.15]# /usr/local/nagios/bin/nagios -v

/usr/local/nagios/etc/nagios.cfg

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


If there are no errors, start Nagios.


[root@cent60 nagios-plugins-1.4.15]# servicenagios start

Starting nagios: done.

[root@cent60 nagios-plugins-1.4.15]# servicenagios restart

Running configuration check...done.

Stopping nagios: done.



2.11. Step 8: Modify SELinux Setting

Fedora ships with SELinux (Security Enhanced Linux) installed and in Enforcing mode by

default. This can result in "Internal Server Error" messages when you attempt to access the

Nagios CGIs.

See if SELinux is in Enforcing mode.

[root@cent60 nagios-plugins-1.4.15]# getenforce

Enforcing


Put SELinux into Permissive mode.

[root@cent60 nagios-plugins-1.4.15]# getenforce 0

Enforcing


To make this change permanent, you'll have to modify the settings in /etc/selinux/config and

reboot.

[root@cent60 nagios-plugins-1.4.15]# vim /etc/selinux/config

# disabled - No SELinux policy is loaded.

#SELINUX=enforcing

SELINUX=disabled

# SELINUXTYPE= can take one of these two values:

[root@cent60 nagios-plugins-1.4.15]# reboot






Instead of disabling SELinux or setting it to permissive mode, you can use the following

command to run the CGIs under SELinux enforcing/targeted mode:

[root@cent60 nagios-plugins-1.4.15]# chcon -R -t httpd_sys_content_t

/usr/local/nagios/sbin

[root@cent60 nagios-plugins-1.4.15]# chcon -R -t httpd_sys_content_t

/usr/local/nagios/share/


For information on running the Nagios CGIs under Enforcing mode with a targeted policy, visit

the Nagios Support Portal or Nagios Community Wiki.

2.12. Step 9: Login to the Web Interface

You should now be able to access the Nagios web interface at the URL below. You'll be

prompted for the username (nagiosadmin) and password you specified earlier.

Open web browser enter http://192.168.10.1/nagios

If you still cannot access no Nagios Server check your firewall and disable it.

[root@cent60 ~]#

[root@cent60 ~]# system-config-firewall-tui






Click on the "Service Detail" navbar link to see details of what's being monitored on your local

machine. It will take a few minutes for Nagios to check all the services associated with your

machine, as the checks are spread out over time.

2.13. Step 10: Other Modifications

Make sure your machine's firewall rules are configured to allow access to the web server if you

want to access the Nagios interface remotely.

Configuring email notifications is out of the scope of this documentation. While Nagios is

currently configured to send you email notifications, your system may not yet have a mail

program properly installed or configured. Refer to your system documentation, search the web,

or look to the Nagios Support Portal or Nagios Community Wiki for specific instructions on

configuring your system to send email messages to external addresses. More information on

notifications can be found here.






2.14. Step 11:Your Done

Congratulations! You sucessfully installed Nagios. Your journey into monitoring is just

beginning. You'll no doubt want to monitor more than just your local machine.

2.15. Nagios Virtual Host

We dont want to access to Nagios with 192.168.10.1/nagiso we want to use domain name

instead like nagios.vannath.lab

The Virtual Host configuration file will create during installing Nagios in

/etc/httpd/conf.d/nagios.conf

[root@cent60 conf.d]# pwd

/etc/httpd/conf.d

[root@cent60 conf.d]# vimnagios.conf

# SAMPLE CONFIG SNIPPETS FOR APACHE WEB SERVER

# Last Modified: 11-26-2005

#

# This file contains examples of entries that need

# to be incorporated into your Apache web server

# configuration file. Customize the paths, etc. as

# needed to fit your system.

ScriptAlias /nagios/cgi-bin "/usr/local/nagios/sbin"

# SSLRequireSSL

Options ExecCGI

AllowOverride None

Order allow,deny

Allow from all

# Orderdeny,allow

# Deny from all

# Allow from 127.0.0.1

AuthName "Nagios Access"

AuthType Basic

AuthUserFile /usr/local/nagios/etc/htpasswd.users

Require valid-user

Alias /nagios "/usr/local/nagios/share"






# SSLRequireSSL

Options None

AllowOverride None

Order allow,deny

Allow from all

# Orderdeny,allow

# Deny from all



AuthType Basic


Require valid-user

And then edit this file as the following:

# SAMPLE CONFIG SNIPPETS FOR APACHE WEB SERVER

# Last Modified: 11-26-2005

#

# This file contains examples of entries that need

# to be incorporated into your Apache web server

# configuration file. Customize the paths, etc. as

# needed to fit your system.

ServerAdmin [email protected]

DocumentRoot /usr/local/nagios/share

ServerNamenagios.vannath.lab

ErrorLog logs/dummy-host.example.com-error_log

CustomLog logs/dummy-host.example.com-access_log common

ScriptAlias /nagios/cgi-bin "/usr/local/nagios/sbin"

# SSLRequireSSL

Options ExecCGI

AllowOverride None

Order allow,deny

Allow from all

# Orderdeny,allow

# Deny from all








AuthType Basic


Require valid-user

Alias /nagios "/usr/local/nagios/share"

# SSLRequireSSL

Options None

AllowOverride None

Order allow,deny

Allow from all

# Orderdeny,allow

# Deny from all



AuthType Basic


Require valid-user

The next thing to do is add CNAME record on your DNS Server

[root@cent60 conf.d]# vim /var/named/vannath.lab.zone

$TTL 1D

@ IN SOA cent60.vannath.lab. root.vannath.lab. (

0 ; serial

1D ; refresh

1H ; retry

1W ; expire

3H ) ; minimum

NS cent60.vannath.lab.

cent60 A 192.168.10.1

nagios CNAME cent60.vannath.lab.

OK now let try access to nagios using domain name nagios.vannath.lab






Alright, now we can access Nagios with domain name

3. How to monitor a Linux/Unix machine (NRPE addon)

3.1. Introduction

This document describes how you can monitor "private" services and attributes of Linux/UNIX

servers, such as:

CPU load Memory usage






Disk usage Logged in users Running processes etc.

Publicly available services that are provided by Linux servers (HTTP, FTP, SSH, SMTP, etc.)

can be monitored easily by following the documentation on monitoring publicly available

services.

3.2. Overview

There are several different ways to monitor attributes or remote Linux/Unix servers. One is by

using shared SSH keys and the check_by_ssh plugin to execute plugins on remote servers. This

method will not be covered here, but can result in high load on your monitoring server if you

are monitoring hundreds or thousands of services. The overhead of setting up/destroying SSH

connections is the cause of this.

Another common method of monitoring remote Linux/Unix hosts is to use the NRPE addon.

NRPE allows you to execute plugins on remote Linux/Unix hosts. This is useful if you need to

monitor local resources/attributes like disk usage, CPU load, memory usage, etc. on a remote

host.

Use th NRPE daemon to execute Nagios plugins on the remote server and report back to the

monitoring host server.

3.3. Installation and Setup NRPE on Remote Server

1. Create Nagios user account on remote server to monitored

[root@cent61 ~]# useraddnagios

[root@cent61 ~]# passwdnagios

Changing password for user nagios.

New password:

BAD PASSWORD: it is too simplistic/systematic

BAD PASSWORD: is too simple






Retype new password:

passwd: all authentication tokens updated successfully.

[root@cent61 ~]#

2. Download and Install Nagios Plugins

from http://www.nagios.org/download/download.php

[root@cent61 ~]# mkdir -p /opt/Nagios

[root@cent61 ~]# cd /opt/Nagios/

[root@cent61 Nagios]#

Save file to directory /opt/Nagios. As of this writing Nagios 3.3.1 (Stable) and Nagios Plugins

1.4.15 (Stable)

Extract Files:

[root@cent61 Nagios]# tarxvf nagios-plugins-1.4.15.tar.gz

[root@cent61 Nagios]# ll

total 2456

drwxrwxrwx. 16 501 root 4096 Jul 28 2010 nagios-plugins-1.4.15


-rw-r--r--. 1 root root 411768 Jan 29 14:02 nrpe-2.13.tar.gz

[root@cent61 Nagios]# cd nagios-plugins-1.4.15


3. Compile and Configure Nagios Plugins

You need the openssl-devel,GCC compiler and GD development libraries package installed to

compile plugins with ssl support.






[root@cent61 nagios-plugins-1.4.15]# yum install openssl-devel [root@cent61 nagios-plugins-1.4.15]# yum install gccglibcglibc-common

[root@cent61 nagios-plugins-1.4.15]# yum install gdgd-devel Install Plugin:

[root@cent61 nagios-plugins-1.4.15]# ./configure --with-nagios-user=nagios --

with-nagios-group=nagios

[root@cent61 nagios-plugins-1.4.15]# make

[root@cent61 nagios-plugins-1.4.15]# make install

The permissions on the plugin directory and the plugins will need to be changed to nagios user

[root@cent61 nagios-plugins-1.4.15]# chownnagios.nagios /usr/local/nagios/

[root@cent61 nagios-plugins-1.4.15]# chown -R nagios.nagios

/usr/local/nagios/libexec/


Package xinted is needed

[root@cent61 nagios-plugins-1.4.15]# yum install xinetd

4. Download and Install NRPE Daemon

As of this writing NRPE 2.13 (Stable)

Extract the Files:

[root@cent61 Nagios]# tar xvf nrpe-2.13.tar.gz

[root@cent61 Nagios]# ll

total 2460

drwxrwxrwx. 16 501 root 4096 Feb 2 19:32 nagios-plugins-1.4.15


drwxr-xr-x. 8 nagiosnagios 4096 Nov 12 01:50 nrpe-2.13


[root@cent61 Nagios]# cd nrpe-2.13

5. Compile and configure NRPE

[root@cent61 nrpe-2.13]# ./configure

*** Configuration summary for nrpe 2.13 11-11-2011 ***:

General Options:

-------------------------

NRPE port: 5666

NRPE user: nagios

NRPE group: nagios

Nagios user: nagios

Nagios group: nagios






Review the options above for accuracy. If they look okay,

type 'make all' to compile the NRPE daemon and client.

[root@cent61 nrpe-2.13]#

[root@cent61 nrpe-2.13]# make all

[root@cent61 nrpe-2.13]# make install-plugin

[root@cent61 nrpe-2.13]# make install-daemon

[root@cent61 nrpe-2.13]# make install-daemon-config

[root@cent61 nrpe-2.13]# make install-xinetd

6. Post NRPE Configuration

Edit Xinetd NRPE entry:

Add Nagios Monitoring server to the only_from directive

[root@cent61 nrpe-2.13]# vim /etc/xinetd.d/nrpe

# default: on

# description: NRPE (Nagios Remote Plugin Executor)

servicenrpe

{

flags = REUSE

socket_type = stream

port = 5666

wait = no

user = nagios

group = nagios

server = /usr/local/nagios/bin/nrpe

server_args = -c /usr/local/nagios/etc/nrpe.cfg --inetd

log_on_failure += USERID

disable = no

only_from = 127.0.0.1 192.168.10.1

}

Edit services file entry ,Add entry for nrpe daemon

[root@cent61 nrpe-2.13]# vim /etc/services

sfmsso 5635/tcp # SFM Authentication Subsystem

sfm-db-server 5636/tcp # SFMdb - SFM DB server

nrpe5666/tcp# NRPE

amqps 5671/tcp # amqp protocol over TLS/SSL

Restart Xinetd and Set to start at boot:






[root@cent61 nrpe-2.13]# chkconfigxinetd on

[root@cent61 nrpe-2.13]# servicexinetd restart

Stopping xinetd: [ OK ]

Starting xinetd: [ OK ]


7. Test NRPE Daemon Install

Check NRPE daemon is running and listening on port 5666: Output should be: as here

[root@cent61 nrpe-2.13]# netstat -at | grepnrpe

tcp 0 0 *:nrpe *:* LISTEN


Check NRPE daemon is functioning: Output should be NRPE version:

[root@cent61 nrpe-2.13]# /usr/local/nagios/libexec/check_nrpe -H localhost

NRPE v2.13


8. Open Port 5666 on Firewall

Make sure to open port 5666 on the firewall of the remote server so that the Nagios monitoring

server can access the NRPE daemon.

3.4. SetupNagios Monitoring Host Server

1. Downlad and Install NRPE Plugin

From http://www.nagios.org/download/download.php

As of this writing NRPE 2.13 (Stable)

Save file to directory /opt/NagiosCore3.3


total 4136

drwxr-xr-x. 16 nagiosnagios 4096 Feb 1 23:08 nagios


drwxrwxrwx. 16 nagios root 4096 Feb 2 00:09 nagios-plugins-1.4.15



[root@cent60 NagiosCore3.3]#

Extract the Files:

[root@cent60 NagiosCore3.3]# tar xvf nrpe-2.13.tar.gz

[root@cent60 NagiosCore3.3]# cd nrpe-2.13

2. Compile and Configure NRPE






You need the openssl-devel package installed to compile NRPE with ssl support.

[root@cent60 nrpe-2.13]# yum install openssl-devel

[root@cent60 nrpe-2.13]# ./configure

*** Configuration summary for nrpe 2.13 11-11-2011 ***:

General Options:

-------------------------

NRPE port: 5666

NRPE user: nagios

NRPE group: nagios

Nagios user: nagios

Nagios group: nagios

Review the options above for accuracy. If they look okay,

type 'make all' to compile the NRPE daemon and client.

[root@cent60 nrpe-2.13]# make all

[root@cent60 nrpe-2.13]# make install-plugin

3. Test Connection to NRPE daemon on Remote Server

Lets now make sure that the NRPE on our Nagios server can talk to the NRPE daemon on the

remote server we want to monitor. Replace with the remote servers IP

address.

[root@cent60 nrpe-2.13]# /usr/local/nagios/libexec/check_nrpe -H 192.168.10.2

NRPE v2.13


If you encounter a problem check firewall on the remote Server.

[root@cent60 nrpe-2.13]# /usr/local/nagios/libexec/check_nrpe -H 192.168.10.2

Connection refused or timed out


Make sure that the firewall is disable on the remote linux Server

[root@cent61 nrpe-2.13]# system-config-firewall-tui

Firewall Configuration

A firewall protects against unauthorized






network intrusions. Enabling a firewall blocks

all incoming connections. Disabling a firewall

allows all connections and is not recommended.

Firewall: [ ] Enabled

OK Customize Cancel

4. Create NRPE Command Definition

A command definition needs to be created in order for the check_nrpe plugin to be used by

nagios. Add the following:

[root@cent60 nrpe-2.13]# vim /usr/local/nagios/etc/objects/commands.cfg

##################################################################################

# NRPE CHECK COMMAND #

# Command to use NRPE to check remote host systems

##################################################################################

define command{

command_namecheck_nrpe

command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$

}

D

5. Create Linux Object template

In order to be able to add the remote linux machine to Nagios we need to create an object

template file adn add some object definitions.

Create new linux-box-remote object template file:

[root@cent60 nrpe-2.13]# vim /usr/local/nagios/etc/objects/linux-box-remote.cfg

Add the following and replace the values host_name alias address with the values that

match your setup:

The host_name you set for the define_host section must match the host_name in the

define_service section






define host{

namelinux-box-remote ; Name of this template

use generic-host ; Inherit default values

check_period 24x7

check_interval 5

retry_interval 1

max_check_attempts 10

check_command check-host-alive

notification_period 24x7

notification_interval 30

notification_optionsd,r

contact_groups admins

register 0 ; DONT REGISTER THIS - ITS A TEMPLATE

}

define host{

uselinux-box-remote ; Inherit default values from a template

host_name Cent61 ; The name we're giving to this server

alias Cent61 ; A longer name for the server

address 192.168.10.2 ; IP address of the server

}

define service{

use generic-service

host_name Cent61

service_description CPU Load

check_commandcheck_nrpe!check_load

}

define service{

use generic-service

host_name Cent61

service_description Current Users

check_commandcheck_nrpe!check_users

}

define service{

use generic-service

host_name Cent61

service_description /dev/hda1 Free Space

check_command check_nrpe!check_hda1

}






define service{

use generic-service

host_name Cent61

service_description Total Processes

check_commandcheck_nrpe!check_total_procs

}

define service{

use generic-service

host_name Cent61

service_description Zombie Processes

check_commandcheck_nrpe!check_zombie_procs

Activate the linux-box-remote.cfg template:

[root@cent60 ~]# vim /usr/local/nagios/etc/nagios.cfg

####### Definitions for monitoring remote Linux machine #########

cfg_file=/usr/local/nagios/etc/objects/linux-box-remote.cfg

################

Verify Nagios Configuration Files

[root@cent60 ~]# /usr/local/nagios/bin/nagios -v


Checking obsessive compulsive processor commands...


Total Warnings: 0

Total Errors: 0


check

[root@cent60 ~]#

Restart Nagios:

[root@cent60 ~]# servicenagios restart




[root@cent60 ~]#






Check Nagios Monitoring server that the remote linux box was added and is being monitored !

6. Trouble Shooting

On Status Information you will encounter error message DISK CRITICAL - /dev/hda1 is not

accessible: No such file or directory






Solution you need you check you systems hard disk architecture on the remote server

[root@cent61 ~]# df -h

FilesystemSize Used Avail Use% Mounted on

/dev/sda2 9.9G 382M 9.0G 4% /

tmpfs 504M 0 504M 0% /dev/shm

/dev/sda1 97M 24M 69M 26% /boot

/dev/sda5 3.9G 973M 2.7G 27% /usr

/dev/sr0 4.4G 4.4G 0 100% /mnt/iso/dvd

[root@cent61 ~]#

As you can the systems hard disk architecture is sda not hda so change it to fix this.

[root@cent61 ~]# vim /usr/local/nagios/etc/nrpe.cfg

#command[check_hda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p

/dev/hda1

command[check_hda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -

p/dev/sda2

OK now the problem is fixed






You see on Service manu it display /dev/hda1 it is not really on exactly systems Change

command to the right one. This is done on the remote server

[root@cent61 ~]# vim /usr/local/nagios/etc/nrpe.cfg

#command[check_hda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p

/dev/hda1

command[check_disk_root]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p

/dev/sda2

And thenon Nagios Server change as the following

[root@cent60 objects]# pwd

/usr/local/nagios/etc/objects

[root@cent60 objects]# vimlinux-box-remote.cfg

define service{

use generic-service

host_name Cent61

# service_description /dev/hda1 Free Space

# check_command check_nrpe!check_hda1

service_description Root Partition

check_commandcheck_nrpe!check_disk_root

}

Then restart nagios service

[root@cent60 objects]# servicenagios restart









[root@cent60 objects]#

Atfter that is should look as the following

3.5. Customizing Your Configuration

You'll might want to monitor more services on the remote Linux/Unix box than those that are

described in thisdocumentation. This is easy to accomplish

Anytime you want to monitor a new service on a remote host using the NRPE addon, you have

to do two things:

Add a new command definition to the nrpe.cfg file on the remote host Add a new service definition to your Nagios configuration on the monitoring

host

Let's say you want to monitor the swap usage on the remote Linux/Unix host. Here are the steps

you'd need tofollow...

3.5.1. Remote Host Configuration

You can use the check_swap plugin to monitor swap usage on the machine. Assuming you

followed theinstallation instructions in this document, the check_swap plugin should already be

installed in/usr/local/nagios/libexec






Login as the nagios user on the remote host.

Run the check_swap plugin manually and tweak the command line options to specify the

desired warning andcritical free swap space thresholds. Make sure the full command line

returns the expected output you want fromthe plugin. For this example, let's say you want a

critical alert if swap free space is less than 10% and a warning iffree space is less than 20%.

Here's the command line that would accomplish that:

[root@cent61 etc]# /usr/local/nagios/libexec/check_swap -w 20% -c 10%

SWAP OK - 100% free (1023 MB out of 1023 MB) |swap=1023MB;204;102;0;1023

[root@cent61 etc]#

Now that you know the command line that should be execute, open the NRPE configuration

file.

[root@cent61 etc]# pwd

/usr/local/nagios/etc

[root@cent61 etc]# vimnrpe.cfg

Add a new check_swap command definition that uses the command line from above and save

the file.

command[check_total_procs]=/usr/local/nagios/libexec/check_procs -w 150 -c

200

command[check_swap]=/usr/local/nagios/libexec/check_swap -w 20% -c 10%

# The following examples allow user-supplied arguments and can

If you're running the NRPE daemon as a standalone daemon you'll need to restart it. If you're

running it under theinetd/xinetdsuperserver you don't need to do anything more.

3.5.2. Monitoring Host Configuration

On the monitoring host, you need to define a new service for monitoring the swap usage on the

remote host. Addthe following entry to one of your object configuration files

define service{

use generic-service

host_name Cent62

service_description Swap Partition

check_commandcheck_nrpe!check_swap

}.

Notice that the check commands is passing check_swap to check_nrpe command definition.

This will cause the NRPE daemon to run the check_swap command that was definded in the

nrpe.cfg file on the remote host in the previous step.






Next, verify your Nagios configuration files and restart Nagios.

[root@cent60 etc]# /usr/local/nagios/bin/nagios -v



Total Warnings: 0

Total Errors: 0


check

[root@cent60 etc]#

[root@cent60 etc]# servicenagios restart




[root@cent60 etc]#

Thats it! You are now monitoring a new service on the remote host using the NRPE addon

3.6. NRPE Option Help

For more option about NRPE you can use -h when executed NRPE script

[root@cent61 libexec]# cd /usr/local/nagios/libexec/

[root@cent61 libexec]# ls






check_aptcheck_flexlmcheck_mailqcheck_oraclecheck_ssmtp

check_breezecheck_ftpcheck_mrtgcheck_overcrcheck_swap

check_by_sshcheck_httpcheck_mrtgtrafcheck_pingcheck_tcp

check_clamdcheck_icmpcheck_nagioscheck_popcheck_time

check_clustercheck_ide_smartcheck_nntpcheck_procscheck_udp

check_dhcpcheck_ifoperstatuscheck_nntpscheck_realcheck_ups

check_digcheck_ifstatuscheck_nrpecheck_rpccheck_users

check_diskcheck_imapcheck_ntcheck_sensorscheck_wave

check_disk_smbcheck_ircdcheck_ntpcheck_simap negate

check_dnscheck_jabbercheck_ntp_peercheck_smtpurlize

check_dummycheck_loadcheck_ntp_timecheck_spop utils.pm

check_file_agecheck_logcheck_nwstatcheck_ssh utils.sh

[root@cent61 libexec]#

[root@cent61 libexec]# ./check_dhcp -h

check_dhcp v1.4.15 (nagios-plugins 1.4.15)

Copyright (c) 2001-2004 Ethan Galstad ([email protected])

Copyright (c) 2001-2007 Nagios Plugin Development Team

This plugin tests the availability of DHCP servers on a network.

Usage:

check_dhcp [-v] [-u] [-s serverip] [-r requestedip] [-t timeout]

[-i interface] [-m mac]

Options:

-h, --help

Print detailed help screen

-V, --version

Print version information

-v, --verbose

Show details for command-line debugging (Nagios may truncate output)

-s, --serverip=IPADDRESS

IP address of DHCP server that we must hear from

-r, --requestedip=IPADDRESS

IP address that should be offered by at least one DHCP server

-t, --timeout=INTEGER

Seconds to wait for DHCPOFFER before timeout occurs

-i, --interface=STRING

Interface to to use for listening (i.e. eth0)

-m, --mac=STRING






MAC address to use in the DHCP request

-u, --unicast

Unicast testing: mimic a DHCP relay, requires -s

Send email to [email protected] if you have questions

regarding use of this software. To submit patches or suggest improvements,

send email to [email protected]

[root@cent61 libexec]#

4. How to monitor a Windows machine

4.1. Introduction

This document describes how you can monitor "private" services and attributes of Windows

machines, such as:

Memory usage CPU load Disk usage Service states Running processes etc.

Publicly available services that are provided by Windows machines (HTTP, FTP, POP3, etc.)

can be monitored easily by following the documentation on monitoring publicly available

services.

4.2. Overview

Monitoring private services or attributes of a Windows machine requires that you install an

agent on it. This agent acts as a proxy between the Nagios plugin that does the monitoring and

the actual service or attribute of the Windows machine. Without installing an agent on the

Windows box, Nagios would be unable to monitor private services or attributes of the Windows

box.

For this example, we will be installing the NSClient++ (http://sourceforge.net/projects/nscplus/)

addon on the Windows machine and using the check_nt plugin to communicate with the

NSClient++ addon. The check_nt plugin should already be installed on the Nagios server if you

followed the quickstart guide.






The NSClient++ agent must be installed on the target Windows machine and configured before

Nagios can monitor system metrics, services, processes, or performance data on the target

machine

4.3. What's Already Done For You

To make your life a bit easier, a few configuration tasks have already been done for you:

A check_nt command definition has been added to the commands.cfg file. This allows you to use the check_nt plugin to monitor Window services.

A Windows server host template (called windows-server) has already been created in the templates.cfg file. This allows you to add new Windows host definitions in a simple

manner.

The above-mentioned config files can be found in the /usr/local/nagios/etc/objects/ directory.

You can modify the definitions in these and other definitions to suit your needs better if you'd

like. However, I'd recommend waiting until you're more familiar with configuring Nagios

before doing so. For the time being, just follow the directions outlined below and you'll be

monitoring your Windows boxes in no time.

4.4. Prerequisites

The first time you configure Nagios to monitor a Windows machine, you'll need to do a bit of

extra work. Remember, you only need to do this for the *first* Windows machine you monitor.

Edit the main Nagios config file.

[root@cent60 ~]# vim /usr/local/nagios/etc/nagios.cfg

Remove the leading pound (#) sign from the following line in the main configuration file:

# Definitions for monitoring a Windows machine

cfg_file=/usr/local/nagios/etc/objects/windows.cfg

Save the file and exit.






What did you just do? You told Nagios to look to the /usr/local/nagios/etc/objects/windows.cfg

to find additional object definitions. That's where you'll be adding Windows host and service

definitions. That configuration file already contains some sample host, hostgroup, and service

definitions. For the *first* Windows machine you monitor, you can simply modify the sample

host and service definitions in that file, rather than creating new ones.

4.5. Installing the Windows Agent

Before you can begin monitoring private services and attributes of Windows machines, you'll

need to install an agent on those machines. I recommend using the NSClient++ addon, which

can be found at http://sourceforge.net/projects/nscplus. These instructions will take you through

a basic installation of the NSClient++ addon, as well as the configuration of Nagios for

monitoring the Windows machine.

Download the NSClient++ installer package to the target machine you wish to install it on.

Run the NSClient++ MSI installer package to initiate the installation. The welcome screen will

appear. Click Next to continue to the next step

Read through the End User License Agreement. Once you have agreed to its terms, check the

acceptance box and click Next to continue.






You may customize the installation options on the next screen if you wish. No changes are

required for an working installation of the agent. Click Next to continue.

If an existing NSClient++ installation exists on the target machine, you will have the option of

using the old configuration file. This option is not enable if this is the first time you are

installing the client. Click Next to continue






In the next step you will need to configure the NSClient++ agent. These steps are important!

Make sure you:

Enter the IP address of the Nagios Core server in the Allowed hosts box. Enter a password in the NSClient password box that will be required for

communication between the Nagios server and the Windows machine.

Check the following boxes in the Modules to load section: Enable common check plugins Enable nsclient server (check_nt)

Click Next to continue.

Click the Install button on the next screen to begin the installation.






When the installation completes, make sure to check the Start service option and click Finish

to complete the setup.

The NSClient++ agent will now be running as a service, which means the Windows machine is

ready to be monitored with Nagios.

4.6. Configuring Nagios

Now it's time to define some object definitions in your Nagios configuration files in order to

monitor the new Windows machine.






Open the windows.cfg file for editing.

[root@cent60 ~]# vim /usr/local/nagios/etc/objects/windows.cfg

Add a new host definition for the Windows machine that you're going to monitor. If this is the

*first* Windows machine you're monitoring, you can simply modify the sample host definition

in windows.cfg. Change the host_name, alias, and address fields to appropriate values for the

Windows box.

# Change the host_name, alias, and address to fit your situation

define host{

use windows-server ; Inherit default values from a

template

host_name w2k81 ; The name we're giving to this host

alias Windows Server 2008; A longer name associated with the

host

address 192.168.10.3 ; IP address of the host

}

Good. Now you can add some service definitions (to the same configuration file) in order to tell

Nagios to monitor different aspects of the Windows machine. If this is the *first* Windows

machine you're monitoring, you can simply modify the sample service definitions in

windows.cfg.

Note: Replace "w2k81" in the example definitions below with the name you specified in the

host_name directive of the host definition you just added.

Add the following service definition to monitor the version of the NSClient++ addon that is

running on the Windows server. This is useful when it comes time to upgrade your Windows

servers to a newer version of the addon, as you'll be able to tell which Windows machines still

need to be upgraded to the latest version of NSClient++.

define service{

use generic-service

# host_name winserver

host_name w2k81

service_description NSClient++ Version

check_command check_nt!CLIENTVERSION

}

Add the following service definition to monitor the uptime of the Windows server.






define service{

use generic-service


host_name w2k81

service_description Uptime

check_command check_nt!UPTIME

}

Add the following service definition to monitor the CPU utilization on the Windows server and

generate a CRITICAL alert if the 5-minute CPU load is 90% or more or a WARNING alert if

the 5-minute load is 80% or greater.

define service{

use generic-service


host_name w2k81

service_description CPU Load

check_command check_nt!CPULOAD!-l 5,80,90

}

Add the following service definition to monitor memory usage on the Windows server and

generate a CRITICAL alert if memory usage is 90% or more or a WARNING alert if memory

usage is 80% or greater.

define service{

use generic-service


host_name w2k81

service_description Memory Usage

check_command check_nt!MEMUSE!-w 80 -c 90

}

Add the following service definition to monitor usage of the C:\ drive and D:\drive on the

Windows server and generate a CRITICAL alert if disk usage is 90% or more or a WARNING

alert if disk usage is 80% or greater.

define service{

use generic-service


host_name w2k81

service_description C:\ Drive Space

check_command check_nt!USEDDISKSPACE!-l c -w 80 -c 90

}






define service{

use generic-service


host_name w2k81

service_description D:\ Drive Space

check_command check_nt!USEDDISKSPACE!-l d -w 80 -c 90

}

Add the following service definition to monitor the W3SVC service state on the Windows

machine and generate a CRITICAL alert if the service is stopped.

define service{

use generic-service


host_name w2k81

service_description W3SVC

check_command check_nt!SERVICESTATE!-d SHOWALL -l W3SVC

}

Add the following service definition to monitor the Explorer.exe process on the Windows

machine and generate a CRITICAL alert if the process is not running.

define service{

use generic-service


host_name w2k81

service_description Explorer

check_command check_nt!PROCSTATE!-d SHOWALL -l Explorer.exe

}

That's it for now. You've added some basic services that should be monitored on the Windows

box. Save the configuration file.

4.7. Password Protection

If you specified a password in the NSClient++ configuration file on the Windows machine,

you'll need to modify the check_nt command definition to include the password. Open the

commands.cfg file for editing.

[root@cent60 ~]# vim /usr/local/nagios/etc/objects/commands.cfg

[root@cent60 ~]#

Change the definition of the check_nt command to include the "-s " argument

(where PASSWORD is the password you specified on the Windows machine) like this:






# 'check_nt' command definition

define command{

command_name check_nt

command_line $USER1$/check_nt -H $HOSTADDRESS$ -p 12489 -s 1234567 -

v $ARG1$ $ARG2$

}

Save the file.

4.8. Restarting Nagios

You're done with modifying the Nagios configuration, so you'll need to verify your

configuration files and restart Nagios.

If the verification process produces any errors messages, fix your configuration file before

continuing. Make sure that you don't (re)start Nagios until the verification process completes

without any errors!

[root@cent60 ~]# /usr/local/nagios/bin/nagios -v



Total Warnings: 0

Total Errors: 0


check

[root@cent60 ~]#

[root@cent60 ~]# service nagios restart




[root@cent60 ~]#

Ok now we monitor it !






5. How to monitor a router/switch

5.1. Introduction

This document describes how you can monitor the status of network switches and routers. Some

cheaper "unmanaged" switches and hubs don't have IP addresses and are essentially invisible on

your network, so there's not any way to monitor them. More expensive switches and routers

have addresses assigned to them and can be monitored by pinging them or using SNMP to

query status information.

I'll describe how you can monitor the following things on managed

switches, hubs, and routers:

Packet loss, round trip average SNMP status information Bandwidth / traffic rate

5.2. Overview

Monitoring switches and routers can either be easy or more involved - depending on what

equipment you have and what you want to monitor. As they are critical infrastructure

components, you'll no doubt want to monitor them in at least some basic manner.

Switches and routers can be monitored easily by "pinging" them to determine packet loss, RTA,

etc. If your switch supports SNMP, you can monitor port status, etc. with the check_snmp

plugin and bandwidth (if you're using MRTG) with the check_mrtgtraf plugin.






The check_snmp plugin will only get compiled and installed if you have the net-snmp and net-

snmp-utils packages installed on your system. Make sure the plugin exists in

/usr/local/nagios/libexec before you continue. If it doesn't, install net-snmp and net-snmp-utils

and recompile/reinstall the Nagios plugins.

5.3. Steps

There are several steps you'll need to follow in order to monitor a new router or switch. They

are:

Perform first-time prerequisites Create new host and service definitions for monitoring the device Restart the Nagios daemon

5.4. What's Already Done For You

To make your life a bit easier, a few configuration tasks have already been done for you:

Two command definitions (check_snmp and check_local_mrtgtraf) have been added to the commands.cfg file. These allows you to use the check_snmp and check_mrtgtraf

plugins to monitor network routers.

A switch host template (called generic-switch) has already been created in the templates.cfg file. This allows you to add new router/switch host definitions in a simple

manner.

The above-mentioned config files can be found in the /usr/local/nagios/etc/objects/ directory.

You can modify the definitions in these and other definitions to suit your needs better if you'd

like. However, I'd recommend waiting until you're more familiar with configuring Nagios






before doing so. For the time being, just follow the directions outlined below and you'll be

monitoring your network routers/switches in no time.

5.5. Prerequisites

The first time you configure Nagios to monitor a network switch, you'll need to do a bit of extra

work. Remember, you only need to do this for the *first* switch you monitor.

Edit the main Nagios config file.

[root@cent60 etc]# vim /usr/local/nagios/etc/nagios.cfg

# Definitions for monitoring a router/switch

cfg_file=/usr/local/nagios/etc/objects/switch.cfg

Save the file and exit.

What did you just do? You told Nagios to look to the /usr/local/nagios/etc/objects/switch.cfg to

find additional object definitions. That's where you'll be adding host and service definitions for

routers and switches. That configuration file already contains some sample host, hostgroup, and

service definitions. For the *first* router/switch you monitor, you can simply modify the

sample host and service definitions in that file, rather than creating new ones.

5.6. Configuring Nagios

You'll need to create some object definitions in order to monitor a new router/switch.

Open the switch.cfg file for editing.

[root@cent60 etc]# vim /usr/local/nagios/etc/objects/switch.cfg

Add a new host definition for the switch that you're going to monitor. If this is the *first* switch

you're monitoring, you can simply modify the sample host definition in switch.cfg. Change the

host_name, alias, and address fields to appropriate values for the switch.

# Define the switch that we'll be monitoring

define host{

use generic-switch ; Inherit default values from a template

# host_name linksys-srw224p ; The name we're giving to this switch

host_name icteo-sw01 ; The name we're giving to this switch

alias ICTEO Switch 01 ; A longer name associated with the

switch

address 192.168.10.10 ; IP address of the switch

hostgroups switches ; Host groups this switch is associated with

}






5.7. Monitoring Services

Now you can add some service definitions (to the same configuration file) to monitor different

aspects of the switch. If this is the *first* switch you're monitoring, you can simply modify the

sample service definition in switch.cfg.

Note: Replace "linksys-srw224p" in the example definitions below with the name you specified

in the host_name directive of the host definition you just added.

5.8. Monitoring Packet Loss and RTA

Add the following service definition in order to monitor packet loss and round trip average

between the Nagios host and the switch every 5 minutes under normal conditions.

# Create a service to PING to switch

define service{

use generic-service ; Inherit values from a template

# host_name linksys-srw224p ; The name of the host the

service is associated with


service_description PING ; The service description

check_command check_ping!200.0,20%!600.0,60% ; The command

used to monitor the service

normal_check_interval 5 ; Check the service every 5 minutes under

normal conditions

retry_check_interval 1 ; Re-check the service every minute until

its final/hard state is determined

}

This service will be:

CRITICAL if the round trip average (RTA) is greater than 600 milliseconds or the packet loss is 60% or more

WARNING if the RTA is greater than 200 ms or the packet loss is 20% or more OK if the RTA is less than 200 ms and the packet loss is less than 20%

5.9. Monitoring SNMP Status Information

If your switch or router supports SNMP, you can monitor a lot of information by using the

check_snmp plugin. If it doesn't, skip this section.

Add the following service definition to monitor the uptime of the switch.






# Monitor uptime via SNMP

define service{

use generic-service ; Inherit values from a template

# host_name linksys-srw224p


service_description Uptime

check_command check_snmp!-C public -o sysUpTime.0

}

In the check_command directive of the service definition above, the "-C public" tells the plugin

that the SNMP community name to be used is "public" and the "-o sysUpTime.0" indicates

which OID should be checked.

nagios(3)

Documents