Tuesday, February 5, 2008

And then nagios asked "Hi servers, how are you today?"

There are quite a numbers of Network or Health Monitoring System. Being an opensource user I have shortlisted several of them; nagios, zabbix, zenoss, opennms. If you really need a quick one, choose zabbix, then you got yourself a car. If you got time, learn nagios. You'll be given an engine, then you have to choose the type of body, rear wheel drive or 4 wheel drive, how many doors do you want and so on, until finally you got yourself a car. OpenNMS has the enterprise look but like zabbix, quite dependant on SNMP but not as easy to install. Zenoss has gained a good position in term of ranking at sourceforge.net and currently is ranked at no 9. I might wanna try to look at this(and openNMS) later on but in the meantime, nagios, i choose you.

This guide is intended for those using Redhat,Fedora,Centos and I have added some steps to fit my needs. This steps works for me but I am not responsible for what you are going to do to your system. Like any other system admins, you should always have and setup a test server before put it into production.

refer http://nagios.sourceforge.net/docs/3_0/quickstart-fedora.html for original quickstart documentation


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 Fedora Core 6 Linux distribution.

What You'll End Up With

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/


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

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

* Apache
* GCC compiler
* GD development libraries
* RRDtool

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

# yum install httpd
# yum install gcc
# yum install glibc glibc-common
# yum install gd gd-devel gd-progs
# yum install rrdtool

1) Create Account Information

Become the root user.

# su -l

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

# /usr/sbin/useradd nagios
# passwd nagios

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.

# /usr/sbin/groupadd nagcmd
# /usr/sbin/usermod -G nagcmd nagios
# /usr/sbin/usermod -G nagcmd apache

2) Download Nagios and the Plugins

Create a directory for storing the downloads.

# mkdir ~/downloads
# cd ~/downloads

Download the source code tarballs of both Nagios and the Nagios plugins (visit http://www.nagios.org/download/ for links to the latest versions). At the time of writing, the latest versions of Nagios and the Nagios plugins were 3.0rc1 and 1.4.11, respectively.

# wget http://osdn.dl.sourceforge.net/sourceforge/nagios/nagios-3.0rc1.tar.gz
# wget http://osdn.dl.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.11.tar.gz

3) Compile and Install Nagios

Extract the Nagios source code tarball.

# cd ~/downloads
# tar xzf nagios-3.0rc1.tar.gz
# cd nagios-3.0rc1

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

# ./configure --with-command-group=nagcmd

Compile the Nagios source code.

# make all

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

# make install
# make install-init
# make install-config
# make install-commandmode

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

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.cfg config 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.

# vi /usr/local/nagios/etc/objects/contacts.cfg

5) Configure the Web Interface

Install the Nagios web config file in the Apache conf.d directory.

# 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.

# htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

create a file called .htaccess in /usr/local/nagios/sbin containing:

AuthUserFile /usr/local/nagios/etc/htpasswd.users
AuthName "Welcome To Nagios"
AuthType Basic
Require valid-user

Restart Apache to make the new settings take effect.

service httpd restart

6) Compile and Install the Nagios Plugins

Extract the Nagios plugins source code tarball.

# cd ~/downloads
# tar xzf nagios-plugins-1.4.11.tar.gz
# cd nagios-plugins-1.4.11

Compile and install the plugins.

# ./configure --with-nagios-user=nagios --with-nagios-group=nagios
# make
# make install

7) Start Nagios

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

# chkconfig --add nagios
# chkconfig nagios on

Verify the sample Nagios configuration files.

# /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

If there are no errors, start Nagios.

# service nagios start

8) Modify SELinux Settings

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.


Put SELinux into Permissive mode.

setenforce 0

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

# chcon -R -t httpd_sys_content_t /usr/local/nagios/sbin/
# 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 NagiosCommunity.org wiki at http://www.nagioscommunity.org/wiki.

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.


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.

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 NagiosCommunity.org wiki for specific instructions on configuring your system to send email messages to external addresses. More information on notifications can be found here.

11) You're Done(Well, I'm not)

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, so check out the following docs...

* Monitoring Windows machines
* Monitoring Linux/Unix machines
* Monitoring Netware servers
* Monitoring routers/switches
* Monitoring publicly available services (HTTP, FTP, SSH, etc.)

12) Beautify it a lil bit

Download nuvola style front-end from nagiosexchange.org.
Browse also for some other interesting logo package available there.
Previously, I used whiteline.zip and extract it into /usr/local/nagios/share/images/logos
# mkdir /usr/local/nuvola
# cd /usr/local/nuvola
# tar -zxvf ~/downloads/nagios-nuvola-1.0.3.tar.gz

Backup(just in case)
# cp /usr/local/nagios/share /usr/local/nagios/share.old
# cp -rf html/ /usr/local/nagios/share
edit /usr/local/nagios/share/config.js to make sure cgi-bin pointing to the right path and some other option


13) Replace nagios logo with your custom logo in statusmap

make sure you have install gd-progs package
turn your logo into gif or png format(eg mine.gif) and put it in /usr/local/nagios/share/images/logos
# cd /usr/local/nagios/share/images/logos
use pngtogd2 tool or giftogd2 tools to convert it into gd2 format
# ls -al mine.gif
-rw-r--r-- 1 root root 1536 Jan 24 12:24 mine.gif

# giftogd2 mine.gif mine.gd2 1536 1

backup old and replace with new logo
# cp nagios.gd2 nagios.gd2.old
# cp mine.gd2 nagios.gd2


14) Nagiosgraph

http://www.novell.com/coolsolutions/feature/19843.html provides good details

# cd /usr/local/
# tar -zxvf ~/downloads/nagiosgraph-0.9.0.tgz
read the INSTALL file carefully
you might need to create nagiosgraph.log and /var/spool/perfdata.log
and can manipulate the data like in serviceextinfo.cfg like:

define serviceextinfo {
service_description PING
notes_url show.cgi?host=$HOSTNAME$&service=$SERVICEDESC$&db=ping,losspct&db=ping,rta
icon_image graph.gif
icon_image_alt View graphs
so it gives a clearer picture by separating the data in 2 different graph

any problem refer here:

15) SMS Notification

download smstools and buy GSM Modem Wavecom 1306b

Now there's your car.


peter said...

Hi, you might also consider just installing GroundWork Monitor. Nagios is one of the many open source components it unifies: GroundWork Monitor has a point-n-click GUI for configuration, contains RRDtool for trending data, and integrates with Cacti and other extensions. And you can always go back to stand-alone Nagios if you want.

yoe said...

Thanks Peter. Groundwork Monitor sure looks very interesting especially on the component integration part. Although the comparison page is quite scary looking at the huge gap between opensource and professional version. Still, a must read, learn and maybe try.

Anonymous said...

Dude! see if you could setup something like "print the article" link or something but apart from that yeah nice work !

yoe said...

Will look into it, thanks Osman