When first migrating to version 7 of CentOS I failed to understand the working of the new default firewalld product and kept with iptables/ufw. I am finally embracing the new methodology, and found an exellent article Understanding Firewalld in Multi-Zone Configurations. I hope this note helps you if you seek knowledge.
This morning I tweeted a quote by Henry Thoreau, "There are a thousand hacking at the branches of evil to one who is striking at the root." It piqued my interest, so I set out to determine what the renowned author believed to be the root of all evil. I found a good description of his quote on the quora website. After reading that analysis I found myself searching for information related to his political leanings, which led me to this Wall Street Journal article . Perhaps you'll find those items as interesting as I have.