[8fingerlouie]

What about second firewalls ?

Hobbit jokes aside, yes, it pokes holes in the firewall on the machine hosting docker. It generally creates a lot of firewall rules to isolate or permit traffic to/from containers and expose ports.

Your "safest" bet is probably to only expose docker containers on the localhost interface, and use a reverse proxy (Nginx/Traefik/etc) to expose services. At least that's how i did it when i last ran Docker a few years ago.