Setup Nagios 4 in Ubuntu 20.04

You can install nagios 4 using apt-get under Ubutu 20.04.

1. Install nagios 4 and apache2 packages with snmp support.

sudo apt-get install nagios4 nagios-plugins-contrib nagios-snmp-plugins snmp-mibs-downloader apache2

2. Enable apache2's cgi module.

sudo a2enmod cgi

3. Restart both nagios and apache2 service.

sudo systemctl restart apache2sudo systemctl restart nagios4

4.  Remember to comment out mibs: under /etc/snmp/snmp.conf.

5. Access the nagios 4 webpage via http://xxx.xxx.xxx.xxx/nagios4