This guide is intended to provide you with simple instructions on how to install Nagios Core 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 using the Fedora 24 - Server Edition Linux distribution.
If you follow these instructions, here's what you'll end up with:
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.
You can use yum to install these packages by running the following commands (as root):
yum install httpd php yum install gcc glibc glibc-common yum install gd gd-devel
Become the root user.
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
Create a directory for storing the downloads.
mkdir ~/downloads cd ~/downloads
Download the source code tarballs of both Nagios Core and the Nagios plugins (visit https://www.nagios.org/download/ for links to the latest versions). These directions were tested with Nagios 4.2.1 and Nagios Plugins 2.1.3.
wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-4.2.1.tar.gz wget http://www.nagios-plugins.org/download/nagios-plugins-2.1.3.tar.gz
Extract the Nagios source code tarball.
cd ~/downloads tar xzf nagios-4.2.1.tar.gz cd nagios-4.2.1
Run the Nagios Core configure script, passing the name of the group you created earlier like so:
Compile the Nagios Core source code.
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 Core yet - there's still more that needs to be done ...
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 Core. 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.
Install the Nagios web config file in the Apache conf.d directory.
Create a nagiosadmin account for logging into the Nagios Core 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.
service httpd restart
Note: Consider implementing the ehanced CGI security measures described here to ensure that your web authentication credentials are not compromised.
Extract the Nagios plugins source code tarball.
cd ~/downloads tar xzf nagios-plugins-2.1.3.tar.gz cd nagios-plugins-2.1.3
Compile and install the plugins.
./configure --with-nagios-user=nagios --with-nagios-group=nagios make make install
Add Nagios Core 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 Core configuration files.
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
If there are no errors, start Nagios Core.
service nagios start
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.
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/
You should now be able to access the Nagios Core 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 Core to check all the services associated with your machine, as the checks are spread out over time.
Make sure your machine's firewall rules are configured to allow access to the web server if you want to access the Nagios Core interface remotely.
Configuring email notifications is out of the scope of this documentation. While Nagios Core 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.
Congratulations! You sucessfully installed Nagios Core. 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 ...