Getting Nagios3 to work properly on Ubuntu
To get the check_host_alive working:
chmod u+s /bin/ping
To get external commands working:
chmod g+x /var/lib/nagios3/rw
To get check_smart working:
chown root:root /usr/lib/nagios/plugins/check_ide_smart
chmod u+s /usr/lib/nagios/plugins/check_ide_smart
chmod o+x /usr/lib/nagios/plugins/check_ide_smart