Bare Metal vs Virtualized Firewall

Quick Answer

Choose a bare-metal firewall if your priorities are a simpler architecture, dedicated operation, and fewer software dependencies.

Choose a virtualized firewall if your priorities are hardware consolidation, flexible resource allocation, and building a home lab.

Neither architecture is inherently better. The main difference is whether a virtualization layer exists between the firewall and the underlying hardware.

Bare Metal

Firewall Hardware → OPNsense / pfSense → Network

Virtualized

Hardware → Hypervisor → Firewall VM → Network

OPNsense officially supports virtualized deployments, including KVM environments, which means it can run on virtualization platforms such as Proxmox VE.

For most users, the decision can start with four questions:

• Is the firewall a critical network service?
• Are you already using Proxmox?
• Do you want to run other services on the same machine?
• Are you comfortable troubleshooting virtualization and virtual networking?

1. What Is a Bare-Metal Firewall?

Bare metal means:

Installing the firewall operating system directly on the physical hardware.

For example:

CWWK Firewall Mini PC
↓
OPNsense
↓
Network

There is no hypervisor between the firewall OS and the hardware.

The system can directly use the CPU, RAM, storage, and network interfaces, making this the simplest deployment model for a dedicated firewall appliance.

2. Why Choose Bare Metal?

Simpler Architecture

A bare-metal deployment has fewer software layers. You only need to manage the physical hardware, firewall operating system, and firewall configuration.

As a result, there are fewer components to troubleshoot when a network problem occurs.

Dedicated Hardware Resources

The firewall has dedicated access to the CPU and RAM.

For example, if the system has 8 GB of memory and a 4-core CPU, those resources can be used entirely by the firewall rather than being shared with other virtual machines or containers.

More Direct Recovery

If the firewall provides internet access for an entire home or office, separating it from experimental services prevents home-lab server reboots, upgrades, or network changes from affecting network availability.

This generally makes recovery and maintenance more straightforward.

A Clearer Failure Domain

The failure chain of a dedicated firewall is relatively simple:

Firewall Hardware
↓
Firewall Service

If a separate NAS or virtualization server has a problem, the dedicated firewall can continue operating.

When network availability matters more than hardware consolidation, this type of isolation can be especially valuable.

3. What Is a Virtualized Firewall?

A virtualized firewall runs the firewall OS as a virtual machine on a hypervisor.

For example:

CWWK Mini PC
↓
Proxmox
├── OPNsense VM
├── DNS
├── Monitoring
├── Home Assistant
└── Other VMs

OPNsense officially supports VM deployments, including KVM environments.

Its current virtualization guidance specifies the following for the OPNsense VM itself:

• At least 3 GB of RAM
• At least 8 GB of virtual disk space recommended

It is important to note that these requirements apply only to the:

OPNsense guest VM.

Therefore, a system that is perfectly adequate for a dedicated firewall may require significantly more hardware once multiple VMs are added.

Related Guide: Proxmox Firewall Hardware Requirements: CPU, RAM, Storage & NICs

4. Why Virtualize a Firewall?

The main value of a virtualized firewall is not simply higher firewall performance. It is:

Hardware Consolidation + Flexibility

Hardware Consolidation

A single physical machine can run multiple services, reducing the number of physical systems, power adapters, cables, and the amount of rack or desk space required.

For a home lab, a sufficiently capable system can run both the firewall and other services on the same hardware.

Better Hardware Utilization

Because a dedicated firewall often operates at relatively low CPU utilization, virtualization allows otherwise unused CPU and memory resources to run services such as AdGuard, monitoring tools, and other lightweight workloads.

This prevents a higher-performance CPU from being used only for firewall duties.

A More Flexible Lab Environment

Virtualization is also well suited to:

• Test VMs
• Isolated virtual networks
• Temporary services
• Multiple operating systems
• Staging environments

You can test different services and network architectures without adding more physical machines.

For this reason, a virtualized firewall is particularly useful for home-lab users who are already running Proxmox.

Related Guide: Proxmox Firewall Hardware Requirements: CPU, RAM, Storage & NICs

5. The Biggest Tradeoff: Failure Domain

Virtualization provides more flexibility, but it also increases the firewall's dependency on other parts of the system.

With bare metal:

Firewall Hardware Problem
↓
Firewall Down

With a virtualized host:

Hypervisor Problem
↓
Firewall VM Down
+
Other VMs May Be Down

The same applies to host maintenance.

If you need to reboot the Proxmox host because of hardware maintenance, network configuration changes, kernel updates, or platform upgrades, the firewall VM running on that host will also be interrupted.

That does not mean virtualization is unsuitable for firewall deployment.

The real issue is that:

The hypervisor becomes part of the network's critical path.

For a home lab, this may be completely acceptable.

However, if an entire office or several people in a household depend on the same network connection, a dedicated firewall is often easier to maintain.

Related Guide: Running a Firewall on Proxmox: Reboots, Downtime and Failure Risks

6. Bare Metal Does Not Automatically Mean Better Performance

It is easy to assume that bare metal is always faster and virtualization is always slower, but the reality is more nuanced.

Modern virtualization can still provide strong network performance when the host, virtual networking, CPU allocation, and NIC configuration are set up properly.

The more useful comparison is architectural.

Bare Metal

• Fewer software layers
• Dedicated resources
• Simpler network architecture
• More direct troubleshooting

Virtualized

• Shared / allocated resources
• More networking options
• Greater configuration flexibility
• Ability to run additional VMs and services
• More software layers to manage

The actual performance difference still depends on the workload.

If you choose a virtualized firewall, you also need to consider how the firewall VM connects to the physical NICs.

Common approaches include:

• Virtual Bridge
• PCI Passthrough

Neither option is universally better. The right choice depends on the host networking design, the number of NICs available, and how much separation you want between the firewall and the hypervisor.

Related Guide: OPNsense on Proxmox: Virtual Bridge vs PCI Passthrough

7. Bare Metal vs Virtualized Firewall Comparison

FAQ

Can OPNsense Run on Proxmox?

Yes.

OPNsense supports KVM virtualization, and Proxmox VE is based on KVM, so OPNsense can run as a virtual machine on Proxmox.

Is Bare Metal Always Faster Than a Virtualized Firewall?

Not necessarily.

Actual performance depends on CPU allocation, NIC configuration, virtual networking, and the firewall workload.

The main advantages of bare metal are a simpler architecture and more direct access to hardware resources.

Should OPNsense Use PCI Passthrough?

Not necessarily.

PCI passthrough allows an OPNsense VM to control a dedicated physical NIC more directly, but it also increases hardware and configuration complexity.

A virtual bridge can also be used for a virtualized firewall.

The right choice depends on the network architecture, number of NICs, and management requirements.

Read More: OPNsense on Proxmox: Virtual Bridge vs PCI Passthrough

Is a Virtualized Firewall Suitable for Home Use?

Yes.

The key question is not whether it can run, but whether you are comfortable making the firewall dependent on the virtualization host.

Which Is Better for Beginners?

If your main goal is simply to run OPNsense or pfSense reliably for routing, firewall, and VPN services, bare metal is generally easier to understand and troubleshoot.

If you are already familiar with Proxmox and virtual networking, then a virtualized firewall becomes a more reasonable option.

Choose the Deployment Model Around Your Network

If the machine only needs to serve as a firewall, bare metal keeps the network architecture simpler, more direct, and easier to maintain and troubleshoot.

If your goal is to build a compact multi-service home lab and consolidate the firewall, DNS, monitoring, and other services on the same system, virtualization can make better use of the available hardware while providing greater flexibility.

The real question is not:

Which technology is more advanced?

It is:

Does your network actually need the flexibility of virtualization, and are you willing to accept the additional host dependency and management complexity?

Related Guide: CWWK Firewall Mini PC Guide

Related Guide: OPNsense Hardware Requirements

Related Guide: N100 vs N305 for Firewall

Explore CWWK Firewall Hardware for Bare-Metal and Virtualized Deployments →