Ubuntu install Nagios Core 3.31

sudo apt-get install apache2

sudo apt-get install libapache2-mod-php5

sudo apt-get install build-essential

sudo apt-get install libgd2-dev

sudo apt-get install libgd2-xpm-dev

sudo –s                                       

/usr/sbin/useradd -m -s /bin/bash nagios               

passwd nagios                                   

/usr/sbin/groupadd nagios                          

/usr/sbin/usermod -G nagios nagios                  

/usr/sbin/groupadd nagcmd

/usr/sbin/usermod -a -G nagcmd nagios

/usr/sbin/usermod -a -G nagcmd www-data

mkdir ~/downloads

cd ~/downloads

wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.3.1.tar.gz
wget http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.15.tar.gz
cd ~/downloads

tar xzvf nagios-3.3.1.tar.gz
cd nagios
./configure --with-command-group=nagcmd

sed -i 's:for file in includes/rss/\*;:for file in includes/rss/\*.\*;:g' ./html/Makefile

sed -i 's:for file in includes/rss/extlib/\*;:for file in includes/rss/extlib/\*.\*;:g' ./html/Makefile

make all

make install

make install-init

make install-config

make install-commandmode

make install-webconf

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

/etc/init.d/apache2 reload

cd ~/downloads

tar xzvf nagios-plugins-1.4.15.tar.gz

cd nagios-plugins-1.4.15

./configure --with-nagios-user=nagios --with-nagios-group=nagios

Make

make install

ln -s /etc/init.d/nagios /etc/rcS.d/S99nagios

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

/etc/init.d/nagios start

Finish: http://localhost/nagios/