Nagios (Centos 6) Easy way

Nagios (Centos 6) Easy way

I decided to write this post because I am currently implementing a massive Nagios installation.
Which includes two Data Centres and two offices.
My next post will be on how to configure a server to be monitored by Nagios.

Centos 6 Easier way to install Nagios Server

Install Epel Repository GPG key
# rpm --import http://ftp.riken.jp/Linux/fedora/epel/RPM-GPG-KEY-EPEL-6

Install Epel Repository Package
# rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm

Search and Install Nagios Packages
Required Packages:
nagios.x86_64
nagios-plugins.x86_64
nagios-plugins-all.x86_64
httpd.x86_64

Install the packages
# yum install httpd.x86_64 nagios.x86_64 nagios-plugins.x86_64 nagios-plugins-all.x86_64 -y
Note: on my brand new system I had 78 packages installed.
It might be different on your system, depends on how many packages you already have installed.

Configuring Apache
# chkconfig --level 35 httpd on
# service httpd start

Test Apache Install
Open your broser and navigate to your server IP address to test Apache works
If it doesn't we need to open up the firewall

# vi /etc/sysconfig/iptables

Add the line below:
-A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT

Save the file and restart iptables
# service iptables restart

Test acessing your Nagios IP address once again
http://192.168.1.23
Note: If you see the Apache Test Page your Apache is working fine
Replace 192.168.1.23 with your server's IP address

Setup Nagios Apache Virtual Host
# cd /etc/httpd/conf.d/
# vi nagios.conf

The file should look as per below:

ScriptAlias /nagios/cgi-bin/ "/usr/lib64/nagios/cgi-bin/"

<Directory "/usr/lib64/nagios/cgi-bin/">
#  SSLRequireSSL
   Options ExecCGI
   AllowOverride None
   Order allow,deny
   Allow from all
   AuthName "Nagios Access"
   AuthType Basic
   AuthUserFile /etc/nagios/passwd
   Require valid-user
</Directory>

Alias /nagios "/usr/share/nagios/html"

<Directory "/usr/share/nagios/html">
   Options None
   AllowOverride None
   Order allow,deny
   Allow from all
   AuthName "Nagios Access"
   AuthType Basic
   AuthUserFile /etc/nagios/passwd
   Require valid-user
</Directory>

Restart Apache
# service httpd restart

Set an User Name and Password to protect Nagios access
# htpasswd -c /etc/nagios/passwd nagiosadmin
New password: TYPE in a Password
Re-type new password: Type the same password again

Test the Nagios web Interface access
http://192.168.1.23/nagios/
Type in: nagiosadmin and your password

Note: If you see the Nagios Web Interface, things are looking good and Nagios is installed correctly.

We need to start Nagios service
# chkconfig --level 35 nagios on

Start Nagios
# service nagios start

Navigate to the Nagios web Interface at: http://192.168.1.23/nagios/
Enter username and password and click on: * Services
Note: by Now you should see the localhost being monitored and some default services.

Httpd service will display a warning: HTTP WARNING: HTTP/1.1 403 Forbidden
Note: Just create an empty index.html page.
# touch /var/www/html/index.html
That should take care of the warning.

Nagios 3.4.4 looks a a lot better than previous versions.

That is it folks, that was easy.

by Renato de Oliveira

Installing and configuring Nagios NRPE from source

Install and configure Nagios NRPE and NPRE Plugins

Before you start some dependencies:

zlib-devel             
libsepol-devel         
libselinux-devel       
keyutils-libs-devel    
e2fsprogs-devel        
krb5-devel             
openssl-devel 

# cd /usr/local

# wgethttp://downloads.sourceforge.net/project/nagios/nrpe-2.x/nrpe-2.14/nrpe-2.14.tar.gz?r=http%3A%2F%2Fsourceforge.net%2Fprojects%2Fnagios%2Ffiles%2Fnrpe-2.x%2Fnrpe-2.14%2F&ts=1361216535&use_mirror=garr

# tar -zxvf nrpe-2.14.tar.gz

# cd nrpe-2.14


# ./configure --prefix=/usr/local/nagios


# make all

# adduser nagios

# mkdir /usr/local/nagios

# mkdir /usr/local/nagios/libexec

# mkdir /usr/local/nagios/share

# cp /usr/local/nrpe-2.14/src/nrpe /usr/local/nagios

# cp /usr/local/nrpe-2.14/src/check_nrpe /usr/local/nagios/libexec/

# cp /usr/local/nrpe-2.14/sample-config/nrpe.cfg /usr/local/nagios

# chown -R nagios: /usr/local/nagios

# add the line below to /etc/services on all servers to be monitored
nrpe 5666/tcp #NRPE



Modify /etc/xinetd.d/nrpe
Note: Do it on all servers and add the lines below:
# default: on
# description: NRPE
service nrpe
{
        flags           = REUSE
        socket_type     = stream
        wait            = no
        user            = nagios
        server          = /usr/local/nagios/nrpe
        server_args     = -c /usr/local/nagios/nrpe.cfg --inetd
        log_on_failure  += USERID
        disable         = no
        only_from       = <IPADDRESS of your Nagios Server>
}


# /etc/init.d/xinetd restart


# netstat -ant |grep 5666

Note: you should see a similar output as the one below
tcp     0    0 0.0.0.0:5666       0.0.0.0:* LISTEN

Installing Nagios NRPE plugins

# cd /usr/local

# wget http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.16.tar.gz

# tar -zxvf nagios-plugins-1.4.16.tar.gz

# cd nagios-plugins-1.4.16

# ./configure --prefix=/usr/local/nagios

# make all

# make install

NOTE: All plugins will be compiled and copied to /usr/local/nagios/libexec/

# chown nagios: -R /usr/local/nagios/libexec/

I will be writing about how to Install and configure Nagios server on next posts.

Something I would like to draw your attention to; once you have compiled the NRPE addon, you can simply tar the whole /usr/local/nagios folder and copy to remaining servers.

#tar -cvf nagios.tar /usr/local/nagios

by Renato