The following screenshot shows the Firewall option for the Datacenter zone through the Options tab by navigating to Datacenter | Firewall | Options:

As we can see in the preceding screenshot, by default the Proxmox firewall for the Datacenter zone is disabled with Input Policy set to DROP and Output Policy set to ACCEPT. If we did enable this firewall option right now, then all inbound access will be denied. You will have to be on the console to access the node. Before we enable this option, we must create two rules to allow the GUI on port 8006 and the SSH console on port 22.