(Slackware 14.1, 14.0 & 13.37)

1. Create the nagios group and user:

   # groupadd -g 213 nagios
   # useradd -u 213 -d /dev/null -s /bin/false -g nagios nagios

2. Add the 'apache' user to the 'nagios' group, so that it can write to the /var/nagios/rw directory ('a' option prevents the user to be removed from other groups, the member of which he is already):

   # usermod -aG nagios apache

3. Install the Nagios::Plugin Perl module:

        cpan -i Nagios::Plugin

4. Use sbopkg or install the individual packages using scripts from SlackBuilds.org, and install the following in this order:
   • RRDTool
   • nagios (currently, the package which can be built using a SlackBuilds.org script is nagios-3.3.1)
   • nagios-plugin package
   • nagios-graphing
5. Edit /etc/nagios/nagios.conf and turn off the logging:

   CHANGE:
        use_syslog=1
   TO:
        use_syslog=0
   CHANGE:
        log_notifications=1
   TO:
        log_notification=0

6. Edit /etc/httpd/extra/nagios.conf, after the <Directory “/var/www/htdocs/nagios”> line:

   CHANGE:
        Options None
   TO:
        Options FollowSymLinks

7. Edit /etc/httpd/http.conf

   UNCOMMENT:
        #LoadModule cgi_module lib64/httpd/modules/mod_cgi.so
        
        (or #LoadModule cgi_module lib/httpd/modules/mod_cgi.so which ever applies)
        
   CHANGE:
        <IfModule dir_module>
        DirectoryIndex index.html
        </IfModule>
   TO:
        <IfModule dir_module>
        DirectoryIndex index.html index.php
        </IfModule>
   CHANGE:
        # Uncomment the following line to enable PHP:
        #
        # Include /etc/httpd/mod_php.conf
   TO:
        # Uncomment the following line to enable PHP:
        #
        Include /etc/httpd/mod_php.conf
        
   RIGHT AFTER:
        DocumentRoot /srv/httpd/htdocs
   ADD:
        Include /etc/httpd/extra/nagios.conf

8. Make sure apache starts at boot and start/restart apache:

   # chmod 755 /etc/rc.d/rc.httpd
   # /etc/rc.d/rc.httpd restart

9. Set the password for nagiosadmin :

   # htpasswd -c /etc/nagios/htpasswd.users nagiosadmin

10. (Not sure if this is necessary but, leaving it in until I can test)
    Make sure nagios starts at boot and start/restart nagios:
    1. Edit /etc/rc.d/rc.local and add:

       # Start nagios:
       if [ -x /etc/rc.d/rc.nagios ]; then
         echo "Starting nagios..."
         /etc/rc.d/rc.nagios start
       fi

    2. Edit /etc/rc.d/rc.local_shutdown (you may have to create this file if it does not exist, and make it executable) and add:

       # Stop nagios:
       if [ -x /etc/rc.d/rc.nagios ]; then
         echo "Stopping nagios..."
         /etc/rc.d/rc.nagios stop
       fi

11. Make rc.nagios executable:

    # chmod 755 /etc/rc.d/rc.nagios

12. Start nagios:

    # /etc/rc.d/rc.nagios restart

Goto http://YOUR_MACHINE/nagios/ and you should see Nagios working.

1. Run the htpasswd command for each user:

   # htpasswd -c /etc/nagios/htpasswd.users bob
   # htpasswd -c /etc/nagios/htpasswd.users sue

2. Edit /etc/nagios/cgi.cfg and add the user(s) too:

   authorized_for_all_services=nagiosadmin,bob,sue
   authorized_for_all_hosts=nagiosadmin,bob,sue

   (or add “*” to allow all authenticated users)

ERROR: When browsing to the nagios webpage (as nagiosadmin) you get “You do not have permission” HINT: Check /var/log/httpd/error_log to see what is failing.

FIX1: Make sure that /srv/www/htdocs/nagios is “drwxrwxr-x nagios nagios”

FIX2: In /etc/http/httpd.conf make sure:

  UNCOMMENT: Include /etc/httpd/mod_php.conf
  DO THE "<IfModule dir_module>" CHANGE LISTED ABOVE
  

ERROR: “stderr: execvp(/usr/libexec/monitoring-plugins/check_ping, …) failed. errno is 2: No such file or directory”

FIX: vi /etc/nagios/resource.cfg

   CHANGE: $USER1$=/usr/libexec/monitoring-plugins
   TO: $USER1$=/usr/libexec/nagios

* Originally written by arfon