RHEL 8 / RHEL 9

To keep the system safe, some hardening is required. For information regarding using firewalls with RHEL 8 / RHEL 9, refer to:

https://docs.redhat.com/en/documentation/Red_Hat_Enterprise_Linux/9#Security 

https://docs.redhat.com/en/documentation/Red_Hat_Enterprise_Linux/8#Security