Dokku didn't - and still does not - do anything re: firewalls. Thats up to the server administrator to handle. For instance, you might choose to have this on a

Dokku didn't - and still does not - do anything re: firewalls. Thats up to the server administrator to handle. For instance, you might choose to have this on a VPC in AWS, in which case you wouldn't need much of a firewall. Or if you're using this on Digital Ocean where there aren't Security Groups, it would be up to you to setup ipfw or iptables. As far as magic, I'm not sure what you are getting at. The entire source is there for you to look at, and is actually quite readable. I don't write bash all day, but it was quite easy for me to jump in as a maintainer of dokku.