I'm smiling reading your comment, having fought with jails/iocage and networking in the past. The counterpoint is that you likely didn't have inbound connection

I'm smiling reading your comment, having fought with jails/iocage and networking in the past. The counterpoint is that you likely didn't have inbound connection problems with Docker because it seems to quite effectively bypass all of the iptables rules on the host. I didn't dig too deep into it, but I had iptables rules set up to only allow inbound 22 and 443, but all of the exposed ports on the containers were still externally available.