Chapter 9. The Proxmox VE Firewall

The Proxmox VE firewall is a security feature that allows easy and effective protection of a virtual environment for both internal and external network traffic. By leveraging this firewall, we can protect VMs, host nodes, or the entire cluster by creating firewall rules. By creating rules at the virtual machine level, we can provide total isolation for VM-to-VM network traffic, including VM-to-external traffic. Prior to the Proxmox VE firewall, security and isolation were not possible at the hypervisor level. Keep in mind that the built-in Proxmox firewall should not be a substitute for a VM-level firewall. We must still apply a firewall policy inside a guest VM, but the hypervisor-level firewall provides an added layer of protection should the VM operating system firewall be misconfigured or not configured at all. This also creates added management overhead because network administrators or managers must now open or close ports or apply firewall policies...