You are saying that if one installs containers or VMs with Qemu or VirtualBox or OpenVZ or LXC or Kubernetes or VMware these technologies will all punch holes to the outside by default despite the iptables setup of the host machine ?
So-called “bridged networking” is not the default for VirtualBox but it is recommended for Qemu, yes. In that case only the routing rules on the bridge apply, not the filtering rules on your host’s interface.
You are saying that if one installs containers or VMs with Qemu or VirtualBox or OpenVZ or LXC or Kubernetes or VMware these technologies will all punch holes to the outside by default despite the iptables setup of the host machine ?
So-called “bridged networking” is not the default for VirtualBox but it is recommended for Qemu, yes. In that case only the routing rules on the bridge apply, not the filtering rules on your host’s interface.