Skroo🦄 is a user on octodon.social. You can follow them or interact with them if you have an account anywhere in the fediverse.
If you don't, you can sign up here.
Admins running docker and using ufw to manage iptables, docker messes directly with the rules. There's a fix at the end of this post. #admin
http://blog.viktorpetersson.com/post/101707677489/the-dangers-of-ufw-docker
Better article on this if you are running 16.04.
http://blog.samcater.com/how-to-set-docker-1-12-to-not-interfere-with-iptables-firewalld/