This is a step by step instruction set for installing OpenNMS on Debian based Linux systems. I chose to use Ubuntu 18.04 LTS Server. The original installation includes the iptables installation and rulebase. I decided to add a separate document for migration instead of altering the original documentation. Once iptables is completely EOL/EOS, I'll updated the primary instructions.

I've added notes for the dependency problems with libgetopt-mixed-perl and syslog repo update in the Ubuntu 20.04 addendum.