yum install httpd php
yum install gcc glibc glibc-common
yum install gd gd-devel
1) Create Account Information
Become the root user.
su -l
Create a new nagios user account and give it a password.
/usr/sbin/useradd -m 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 -a -G nagcmd nagios
/usr/sbin/usermod -a -G nagcmd apache
2) Download Nagios and the Plugins
Create a directory for storing the downloads.
mkdir /opt/nagios
cd /opt/nagios
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.
wget http://sourceforge.net/projects/nagios/files/nagios-3.x/nagios-3.3.1/nagios-3.3.1.tar.gz/download
wget http://sourceforge.net/projects/nagiosplug/files/nagiosplug/1.4.15/nagios-plugins-1.4.15.tar.gz/download
3) Compile and Install Nagios
Extract the Nagios source code tarball.
cd /opt/nagios
tar xzf nagios-3.3.1.tar.gz
cd nagios
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
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
Restart Apache to make the new settings take effect.
/etc/init.d/httpd restart
6) Compile and Install the Nagios Plugins
Extract the Nagios plugins source code tarball.
cd /opt/nagios
tar xzf nagios-plugins-1.4.15.tar.gz
cd nagios-plugins-1.4.15
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.
/sbin/chkconfig --add nagios
/sbin/chkconfig nagios on
/sbin/chkconfig httpd 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.
/etc/init.d/nagios start
8) Modify SELinux Settings
CentOS 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.
To make this change permanent, you'll have to modify the settings in /etc/selinux/config and reboot.
nano /etc/selinux/config
SELINUX=enforcing change to SELINUX=permissive
reboot
or
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/
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.
http://localhost/nagios/