Nagios

Nagios -network monitoring system offers complete monitoring and alerting for servers, switches, applications, and services.

Installation

Web server

Decide which web server will be to used and set it up:

Apache with PHP
Lighttpd with PHP
Nginx with PHP and fcgiwrap

Once finished return here to and continue reading.

USE flags

Set the proper USE flags for Nagios before it emerging it:

USE flags for net-analyzer/nagios-core Nagios core – monitoring daemon, web GUI, and documentation

`apache2`	Add Apache2 support
`classicui`	use the classic web theme
`lighttpd`	install www-servers/lighttpd config
`perl`	Add optional support/bindings for the Perl language
`vim-syntax`	Pulls in related vim syntax scripts
`web`	enable web interface

Data provided by the Gentoo Package Database · Last update: 2020-01-15 03:54More information about USE flags

Do not forget to enable the right USE flags for Nagios plugins (net-analyzer/nagios-plugins).

Emerge

Finally install net-analyzer/nagios:root #emerge --ask net-analyzer/nagios

Configuration

Apache

Enable the Nagios module for Apache: FILE /etc/conf.d/apache2

'"`UNIQ--pre-00000001-QINU`"'

Since Nagios requires PHP for its web interface, it may needed to be enabled as well if it has not been previously. One way is to simply add -D PHP5 to APACHE2_OPTS and edit /etc/php/apache2-php<YOUR_PHP_VERSION>/php.ini This should be fine unless PHP is needed for purposes other than hosting Nagios.

If using Apache 2.4 (which is still marked unstable as of April 2015) the /etc/apache2/modules.d/99_nagios3.conf file may need to be modified to fit the new authorization directives of Apache 2.4.

Remember to add the apache user to group nagios:root #usermod -a -G nagios apache

Restart the Apache service to have it recognize the group change:root #rc-service apache2 restart

Lighttpd

Enable the Nagios configuration for Lighttpd: FILE /etc/lighttpd/lighttpd.conf

include "nagios.conf"

Configure authentication. More information on how to set this up can be found in the Lighttpd documentation. FILE /etc/lighttpd/nagios.conf

$HTTP["url"] =~ "nagios" {
    auth.backend ="plain"    # The password is stored as plain text as user:password in...
    auth.backend.plain.userfile = "/etc/nagios/passwd"  # this file
    auth.require = ( "" => (
        "method" => "digest",
        "realm" => "nagios",
        "require" => "user=nagiosadmin"
        )
    )
    setenv.add-environment = ( "REMOTE_USER" => "user" )
}

Restart the Lighttpd service:root #rc-service lighttpd restart

Nginx

See the Nginx guide before continuing if you don’t have it already setup.

Emerge www-servers/spawn-fcgi and www-misc/fcgiwrap:root #emerge --ask www-servers/spawn-fcgi www-misc/fcgiwrap

Next, create an init script for a spawn-fcgi instance dedicated to nagios:root #ln -s /etc/init.d/spawn-fcgi /etc/init.d/spawn-fcgi.nagiosroot #cp /etc/conf.d/spawn-fcgi /etc/conf.d/spawn-fcgi.nagios

Then, configure our spawn-fcgi instance to launch fcgiwrap and listen on a unix socket: FILE /etc/conf.d/spawn-fcgi.nagios

# edit these variables:
FCGI_SOCKET=/run/fcgiwrap.nagios.socket
FCGI_USER=nagios
FCGI_GROUP=nginx
FCGI_EXTRA_OPTIONS="-M 0660"
FCGI_PORT= # must be empty for the socket to work
FCGI_PROGRAM=/usr/sbin/fcgiwrap

Don’t forget to add spawn-fcgi.nagios to the default runlevel and start it:root #rc-update add spawn-fcgi.nagios defaultroot #rc-service spawn-fcgi.nagios start

You may need to change the owner of the /var/nagios folder, so fcgiwrap can access it:root #chown nagios:nagios /var/nagios

Nginx can now be configured to serve our nagios instance. Here’s an example configuration snippet for nginx, assuming you have defined a php upstream: FILE /etc/nginx/nginx.conf

location /nagios {
        alias /usr/share/nagios/htdocs;

        location ~ \.php$ {
                # Filter out arbitrary code execution
                location ~ \..*/.*\.php$ {return 404;}
                fastcgi_pass php;
                include fastcgi.conf;
                fastcgi_param SCRIPT_FILENAME $request_filename;
        }

        location /nagios/cgi-bin/ {
                root /usr/lib/;
                include /etc/nginx/fastcgi_params;
                fastcgi_param  AUTH_USER nagiosadmin;
                fastcgi_param  REMOTE_USER nagiosadmin;
                if ($uri ~ "\.cgi$"){
                        fastcgi_pass unix:/run/fcgiwrap.nagios.socket-1;
                }
        }
}

Permissions

Add the user name(s) to the nagios group, whom are allowed access to the Nagios service:root #gpasswd -a <USER_NAME> nagios

Once done, completely sign out from all shells and re-login for the update to apply.

Boot service

Start Nagios:root #rc-service nagios start

To start Nagios at boot time, add it the default runlevel:root #rc-update add nagios default

Testing

Open a browser and navigate to http://localhost/nagios

Troubleshooting

nagios troubleshooting

Nagios Open Source Network Monitoring System(NMS)