The firewall configuration can be changed with an already included package.
Call the TUI version with system-config-firewall-tui
The only open port will be 22/tcp for SSH Access
Disable password authentication. See ssh
Using ISO Storage on "/" or subdirectories on the same partition is not really viable, as only 18GiB are assigned to this mountpoint by default.
Instead use the local EXT mapper device. This is mounted under /run/sr-mount/(id)
Create a new "ISO" directory.
If you want to still use an easier to remember path, create a symbolic link. For example ln -s /run/sr-mount/69d19d8e-f0dd-92d8-41bc-3d974b20f4f8/ISO/ /root/ISO. You'll be able to use the path /root/ISO in the webinterface as local ISO storage.