If you're a network engineer deploying on your own x86 hardware, my default recommendation is OPNsense. But there is one important exception: if your priority is routing/automation/network-OS functionality rather than a traditional firewall appliance experience, VyOS may actually be the better choice.

My ranking

1. 🥇 OPNsense — best overall

OPNsense is what I'd choose for most custom-hardware deployments.

It gives you:

• Stateful IPv4/IPv6 firewall
• NAT and extensive VLAN support
• Multi-WAN/load balancing/failover
• WireGuard, IPsec and OpenVPN
• IDS/IPS
• DNS services
• Traffic shaping
• HA/failover
• Excellent web UI
• FreeBSD-based appliance architecture
• Runs directly on commodity amd64 hardware

OPNsense explicitly supports x86-64 hardware, and its current recommended baseline is a multi-core CPU, 8 GB RAM and a 120 GB SSD, although substantially smaller systems can work depending on the feature set.

Why I'd pick it: It's a particularly good balance between serious firewall functionality and not having to hand-build the entire networking stack. The GUI is also useful when you're managing hundreds of firewall rules, VPNs, NAT policies, aliases, etc.

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2. 🥇 VyOS — best if you're actually thinking like a network engineer

VyOS is a different beast.

It's Linux-based and much more like a traditional network operating system. It supports things such as BGP, OSPF, IS-IS, PIM, VRFs, WireGuard, IPsec, policy routing, automation APIs and configuration commit/rollback.

That's extremely attractive if your firewall is also going to be your:

• Internet edge router
• BGP router
• Site-to-site VPN router
• WAN edge
• VRF router
• Lab routing platform
• Automated infrastructure component

It runs on essentially arbitrary x86-64 hardware, and VyOS publishes hardware/NIC compatibility information.

The tradeoff: OPNsense feels like a firewall appliance; VyOS feels like a network router that happens to have a very capable firewall.

For someone comfortable with Cisco/Juniper-style CLI, I would seriously consider VyOS over OPNsense.

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3. pfSense

pfSense remains a very capable choice. It's FreeBSD-based, supports custom hardware, has a mature web interface and extensive firewall/VPN/routing functionality. The project explicitly supports building your own hardware rather than requiring Netgate appliances.

I'd choose it when:

• You already have pfSense expertise.
• Your organization already standardizes on it.
• You want its particular ecosystem/support options.
• You're migrating an existing pfSense environment.

For a new deployment, however, I'd personally lean OPNsense unless there's a specific pfSense requirement.

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4. IPFire

IPFire is worth considering if you want something relatively lightweight. It supports x86-64 and ARM64 and can run on everything from small appliances to rack servers.

It's just not my first choice for a network-engineering-oriented deployment.

What I'd build

For a custom appliance, I'd probably use:

x86-64 CPU + Intel NICs + 8–16 GB ECC RAM + SSD + OPNsense

Intel NICs are particularly sensible here; OPNsense's hardware documentation specifically recommends Intel NICs because of their driver reliability and throughput characteristics.

For something more like a miniature enterprise router, I'd instead build:

x86-64 + Intel 10/25 GbE NICs + VyOS

and manage it through configuration/automation rather than a GUI.

Bottom line

If you want a firewall appliance: → OPNsense

If you want a network operating system that happens to provide firewalling: → VyOS

If you already know pfSense: → pfSense is still perfectly viable

For a network engineer specifically, I'd shortlist OPNsense and VyOS, and the deciding question is whether you want GUI-centric firewall management (OPNsense) or CLI/API-centric network infrastructure (VyOS).

For a network engineer deploying on custom hardware, the best open-source firewall platform depends on your preferred management style, but OPNsense and VyOS stand out as the top choices. OPNsense dominates for engineers who want a modern, feature-rich Next-Generation Firewall (NGFW) with a robust web GUI, API, and plugin ecosystem. VyOS is preferred by enterprise and data center engineers who favor a traditional, CLI-driven, Cisco/Juniper-style routing and security workflow.

While pfSense Community Edition (CE) remains widely deployed, industry momentum for custom hardware has notably shifted toward OPNsense due to commercial licensing changes, feature development trajectories, and API availability.

📊 Direct Comparison

🔎 Top Open-Source Firewall Options

🌟 OPNsense: Best Overall for GUI & NGFW Capabilities

OPNsense has become the go-to alternative for network engineers deploying custom hardware. Its open development model provides access to advanced features without proprietary lock-in.

• Advanced Networking: Supports enterprise protocols like VXLAN and EVPN natively.
• Modern Security Stack: Features a redesigned rules interface, Suricata for inline IPS/IDS, and native WireGuard.
• Automation Ready: Includes a built-in REST API making it vastly superior to pfSense for Infrastructure-as-Code (IaC) workflows.
• Hardware Compatibility: Runs efficiently on generic x86_64 multi-NIC hardware, providing rapid security updates and kernel refreshes.

📈 VyOS: Best for Enterprise CLI, Routing, and Automation

VyOS is a specialized, open-source routing and security platform engineered specifically for data center, service provider, and large enterprise environments.

• Command-Line Dominance: Uses a unified, hierarchical CLI that mimics corporate enterprise systems, appealing directly to traditional network engineers.
• Linux Core: Powered by the Debian Linux kernel, offering superior hardware compatibility with odd or ultra-modern NICs compared to BSD-based systems.
• Heavy Routing Stack: Excel at massive routing loads, supporting complex BGP topologies, OSPF, and Virtual Routing and Forwarding (VRF) effortlessly.
• Total Automation: Highly scriptable platform designed for zero-touch deployment via HTTP/Git configurations.

📌 pfSense CE: The Legacy Stalwart

Historically the standard for open-source firewalls, pfSense Community Edition remains viable but faces strategic headwinds.

• Massive Community: Enormous documentation base, troubleshooting threads, and third-party tutorials.
• Stability: Highly reliable core packet filtering and NAT mechanics.
• Strategic Risk: Netgate's focus on its commercial pfSense Plus branch means the free Community Edition receives slower feature updates.

💡 IPFire: Best for Minimal Attack Surface

If you require a strict, hardened perimeter security appliance rather than an advanced enterprise router, IPFire is an exceptional choice.

• Security Focus: A streamlined Linux-based firewall designed with a modular structure to limit vulnerability vectors.
• Pakfire Package Manager: Easy, secure updates to add packages like web filtering and IPS.

⚠️ Hidden Hardware & Deployment Costs

Before deploying open-source software on your own custom hardware, watch out for these network engineering variables:

• NIC Selection: Always prioritize authentic Intel NICs (e.g., i225-V, i226-V, or X520/X710 for 10GbE+). Realtek and cheap generic NIC chipsets frequently suffer from driver instability under FreeBSD-based operating systems like OPNsense and pfSense.
• Crypto Offloading: Ensure your custom CPU explicitly supports Intel AES-NI or AMD CCP instructions. Without hardware-accelerated cryptography, your VPN throughput (OpenVPN/IPsec) will bottleneck performance severely.
• IDS/IPS Throughput: Running deep packet inspection tools like Suricata requires significant single-core CPU frequency and plenty of RAM. If you plan to run 1GbE or 10GbE line-rate inspection, budget for an active-cooled desktop-grade CPU rather than an ultra-low-power Intel Celeron or Atom chip.

To help narrow this down, could you tell me more about your deployment? Let me know the target throughput (1Gbps, 10Gbps+), your custom hardware specs (especially CPU and NICs), and whether your priority leans toward a web GUI interface or a programmable CLI.

For a network engineer deploying a firewall on custom hardware, the best choice depends on whether you mean “best firewall appliance” or “best network operating system.” The short answer:

1. Best overall: OPNsense
2. Best for routing-heavy engineering environments: VyOS
3. Best conservative enterprise/homelab choice: pfSense

Big Iron NexusSec## My recommendation: OPNsense for most custom appliances

OPNsense is usually the best fit if you are building a bare-metal x86 firewall appliance with:

• Intel NICs
• Multiple VLANs
• Multi-WAN
• Site-to-site VPNs
• IDS/IPS
• Web filtering
• Network segmentation
• A requirement for a manageable GUI

Strengths:

• Modern web interface
• Strong plugin ecosystem
• Built-in support for common firewall/VPN features
• Good fit for custom hardware
• Open-source licensing model
• Active development cadence

Weaknesses:

• Less ideal if your goal is pure routing automation
• Some advanced carrier-grade networking features are not its focus

NexusSec KnowledgeXchange## Choose VyOS if you think like a router engineer

VyOS is the better answer when the firewall is also your router.

Choose it for:

• BGP
• OSPF
• MPLS
• EVPN/VXLAN
• Infrastructure-as-code workflows
• Git-managed configurations
• Automated deployments

It feels closer to a Juniper/Cisco-style router OS than a traditional firewall appliance. The tradeoff is that it is CLI-first; there is no pfSense/OPNsense-style administration experience.

A network engineer running:

• multiple sites,
• dynamic routing,
• cloud connectivity,
• lab environments,
• or automation pipelines

will often prefer VyOS.

Choose pfSense if you value maturity and ecosystem

pfSense remains a very capable option.

Advantages:

• Extremely mature
• Large user base
• Extensive documentation
• Long history in small business and lab deployments
• Strong commercial ecosystem

It is a particularly good choice if:

• you already know pfSense,
• your organization already uses it,
• you want Netgate appliance support,
• or you value the existing knowledge base.

Hardware recommendations

For a custom appliance, I would prioritize:

• CPU: modern Intel x86-64 (Core i3/i5/i7, Xeon-D, N-series, etc.)
• NICs: Intel i210/i225/i226/X520/X710-class adapters
• RAM: - 8 GB minimum
• 16 GB+ if running IDS/IPS, Zenarmor, heavy logging, or multiple services
• Storage: - small SSD/NVMe
• avoid USB flash drives for production
• Form factor: - 1U rackmount
• mini-PC appliance
• embedded x86 box

Avoid cheap Realtek NICs for serious firewall deployments; Intel adapters generally have better driver support and reliability.

Quick decision matrix

Big Iron parse.glIf I were building a new custom x86 firewall appliance today, I would install OPNsense unless I specifically needed VyOS-style routing and automation. For a network engineer who wants to treat the box as infrastructure code, I would lean VyOS.

For a network engineer deploying on custom hardware, the "best" open-source firewall depends heavily on whether your background leans toward a traditional GUI/BSD appliance model or a Cisco/Juniper-style CLI routing model.

The top three industry-standard contenders for custom hardware deployments stand out with distinct advantages:

• OPNsense — Best overall for a modern GUI, security cadence, and true open-source governance. It is a fork of pfSense with a heavily refactored, cleaner MVC-based web interface, faster API integration, and a transparent update model. It supports modern features (like WireGuard, Sensei/Suricata integrations, and advanced traffic shaping) out of the box without commercial licensing gatekeeping.
• VyOS — Best for network engineers who prefer a CLI-first, enterprise router/firewall workflow . Based on Debian, VyOS features a unified configuration syntax heavily inspired by Vyatta and Cisco IOS/JUNOS (commit/rollback mechanics, multi-vendor feature sets). If you manage your firewalls via automation (Ansible) or think in terms of BGP/OSPF routing tables rather than firewall alias tabs, VyOS on custom x86_64 hardware is exceptionally powerful.
• pfSense (CE - Community Edition) — The battle-tested historical giant built on FreeBSD. While its core packet filter (pf) engine remains rock solid and performance is stellar, the project's stewardship by Netgate has shifted heavily toward their proprietary pfSense Plus commercial ecosystem, leaving the Community Edition with a more stagnant feature/update roadmap compared to OPNsense.

Feature Comparison Matrix

Recommendation Summary

• Go with OPNsense if you want an appliance-style deployment with a clean web interface, rapid vulnerability patching, and an intuitive layout for managing rules, VPN tunnels, and IDS/IPS.
• Go with VyOS if your daily vernacular is routed subnets, dynamic routing daemons, programmatic configuration generation, and strict CLI control.

If you'd like to narrow this down, tell me:

• What kind of hardware specs (CPU, RAM, NIC count/vendor like Intel i350) you are working with?
• Are you routing at multi-gigabit line rates or requiring heavy VPN/BGP integration?

I can give you a tailored recommendation and initial setup considerations.

For a network engineer deploying on custom x86 hardware, my top choice is OPNsense.

My ranking

1. OPNsense — best overall

OPNsense gives you the combination I'd want on a custom appliance: stateful IPv4/IPv6 firewalling, VLANs, multi-WAN, IPsec/OpenVPN/WireGuard, traffic shaping, IDS/IPS with Suricata, DNS/DHCP, NetFlow, high availability/CARP, and an API/plugin architecture.

It's also genuinely well suited to building your own appliance. It runs on standard amd64 hardware, with official installation images for USB, ISO and serial-console deployments. The current documentation recommends a multi-core CPU, 8 GB RAM and a 120 GB SSD for a typical full-featured installation.

The BSD 2-Clause license is another nice advantage if you're building something customized or integrating it into your own infrastructure.

I'd pick OPNsense if: this is a perimeter firewall, edge router, VPN concentrator, lab firewall, branch appliance, or general-purpose security gateway.

2. VyOS — potentially better if you're a network engineer first

VyOS is fundamentally different. Rather than being primarily a GUI firewall appliance, it's a Linux network operating system with routing, firewalling, VPNs and automation as first-class functions. It supports BGP, OSPF, IS-IS, PIM, WireGuard, IPsec, configuration commit/rollback, and HTTP/scripting APIs.

If you're comfortable with Cisco/Juniper-style CLI workflows and want something you can manage through Git, automation, Ansible, APIs and infrastructure-as-code, I'd seriously consider VyOS over OPNsense.

I'd pick VyOS if: you're building a router/firewall for a data center, ISP/edge environment, lab routing fabric, or heavily automated network.

3. pfSense CE

pfSense remains a very capable choice and has a huge ecosystem. If your organization already has extensive pfSense knowledge, documentation, configurations or operational experience, there's little reason to migrate simply for the sake of switching.

For a new custom-hardware build in 2026, though, I'd lean OPNsense unless you have a specific pfSense requirement.

What I'd actually deploy

For a custom appliance with, say, an Intel/AMD x86-64 CPU and 4–8 Intel NICs:

Firewall/security appliance: → OPNsense

Router + firewall + BGP/OSPF + automation: → VyOS

Traditional GUI-managed firewall where the team already knows pfSense: → pfSense CE

One particularly important hardware consideration: use Intel NICs where possible. OPNsense's documentation specifically recommends Intel NICs because of their reliability and throughput/CPU characteristics.

If you tell me your CPU, RAM, NIC model/count, expected WAN speed (1/2.5/10/25/40/100 GbE), and whether you need IDS/IPS, BGP, WireGuard, HA, etc., I can recommend the specific platform and a custom-hardware design rather than just the software.

For a network engineer deploying on custom x86 or appliance hardware, the "best" open-source firewall comes down to a fundamental philosophy: Do you want a firewall with routing features, or a router with firewall features?

The three undisputed leaders in the open-source space cater to very different operational styles.

1. OPNsense — Best for Feature-Rich, Modern Web GUI Management

If you prefer a polished, responsive web interface, regular security updates, and a transparent open-source model, OPNsense is the top choice. It is a fork of pfSense that diverged over governance, and it has largely outpaced it in modern UI design and plugin architecture.

• Under the Hood: FreeBSD kernel, utilizing pf (Packet Filter) for stateful inspection.
• Why Network Engineers Like It:
  • First-class plugin ecosystem (tightly integrated with tools like Zenarmor for L7 application visibility and deep packet inspection, and Suricata for inline IPS/IDS).
  • Modern, API-driven architecture with a clean, logically organized layout.
  • Completely open-source core without the commercial split-brain pressures facing its predecessor.
• The Catch: It’s an interface-first firewall. If you want to manage everything via an enterprise-style CLI or treat your configs like code, the shell capabilities are relatively constrained.

“OPNsense is still the answer. The plugins are vast, the community is active, Deciso folks are amazing and they ship updates like clockwork, and the UI remains the gentlest on-ramp to serious home networking I know of.”

2. VyOS — Best for CLI-Centric Engineers & Complex Routing

If your background is in enterprise routing (Cisco IOS, Juniper JunOS) and you break out in hives when forced to click around a web GUI, VyOS is built for you. It is a Linux-based network operating system providing a vendor-style CLI with atomic commits, rollbacks, and programmatic APIs.

• Under the Hood: Debian Linux using FRRouting (FRR) for dynamic routing protocols and nftables or iptables for packet filtering.
• Why Network Engineers Like It:
  • Industry-standard operational model: full support for BGP, OSPF (v2/v3), MPLS, VXLAN, and advanced policy-based routing.
  • commit-confirm safety nets (apply a risky firewall/routing change with a mandatory rollback timer if you lose connectivity).
  • Blazing-fast packet forwarding performance on custom bare-metal x86 hardware, especially with multi-gigabit/10G+ Intel NICs.
• The Catch: It is a router first and a firewall second. It lacks native Layer 7 application classification out of the box, and there is no default web GUI—you live in the shell. While community source code and nightly builds are open, official binary container/ISO releases require a support subscription or registration.

“I became the user who wants his firewall to behave like a git repository. I became the user who gets a small thrill from typing commit-confirm 60 before pushing a risky change... Welcome to the big boys firewall. Bring your own CLI.”

3. pfSense Community Edition (CE) — Best for Legacy Documentation & Massive Community

pfSense is the grandfather of open-source edge firewalls. While its corporate steward (Netgate) has shifted primary commercial focus toward pfSense Plus (which requires paid licenses or specific hardware), the Community Edition remains free.

• Under the Hood: FreeBSD kernel, stateful packet filtering via pf.
• Why Network Engineers Like It:
  • The largest community footprint and an unmatched backlog of troubleshooting documentation accumulated over two decades.
  • Extremely stable, conservative release cadence that prioritizes rock-solid production uptimes.
  • Robust add-ons like pfBlockerNG for region-based and DNSBL filtering.
• The Catch: The gap between the commercial Plus tier and the free Community Edition has widened, raising long-term questions about how aggressively CE will be prioritized for new feature development.

Summary Recommendation

• Choose OPNsense if you want a robust, transparent, GUI-managed firewall with powerful UTM/L7 plugins (Zenarmor/Suricata) running on your custom white-box appliance.
• Choose VyOS if you treat infrastructure as code, require heavy dynamic routing (BGP/OSPF) , and want a proper JunOS/Cisco-style CLI experience.

To help narrow down your choice, let me know:

• What is your target hardware configuration (CPU cores, RAM, and NIC manufacturer like Intel vs. Realtek)?
• Do you have complex routing requirements (like BGP or multi-site VPN meshes) or is this primarily a perimeter firewall/NAT setup?

For a network engineer deploying custom bare-metal hardware, the "best" open-source firewall depends entirely on your background and operational philosophy: whether you prefer a firewall-first GUI experience (managing rules via a polished web dashboard) or a router-first CLI experience (managing the box like a traditional Juniper or Cisco device).

The top industry contenders for custom hardware deployments split cleanly along these lines:

• OPNsense — Best overall for a feature-rich, GUI-driven Next-Generation Firewall (NGFW). Forked originally from pfSense, OPNsense has won significant momentum due to its modern, responsive web UI, frequent bi-weekly update cadence, hardened security foundation (HardenedBSD), and fully open-source plugin ecosystem . For network engineers wanting comprehensive traffic shaping, integrated Suricata-based IDS/IPS, robust API integration, and easy third-party package expansion (like Zenarmor) without worrying about commercial licensing shifts, OPNsense is the leading choice.
• VyOS — Best for network engineers with a traditional enterprise/telecom background. VyOS is a Linux-based network operating system (forked long ago from Vyatta) that is completely CLI-driven. If you think in terms of candidate configurations, commit/rollback syntax, and native advanced routing protocols (like BGP, OSPF, MPLS, and VXLAN), VyOS feels like working on commercial hardware. It excels at high-throughput bare-metal performance and text-based automation workflows.
• pfSense (Community Edition - CE) — Best for massive community documentation and legacy familiarity. Maintained by Netgate, pfSense CE is a battle-tested FreeBSD firewall with an immense user base. While it remains reliable, its commercial evolution toward pfSense Plus has left the community edition with less prioritized development and fewer modern UI/API niceties compared to OPNsense. However, its forum history and how-to guides cover almost any edge-case integration imaginable.
• IPFire — Best lightweight, security-hardened Linux alternative. Built directly on top of Linux Netfilter rather than FreeBSD, IPFire is modular, clean, and ideal for constrained custom hardware or strict network segmentation using its color-coded zone system (Green, Red, Blue, Orange). It has a smaller footprint and a dedicated following who prefer a Linux kernel core.

To help narrow down which platform fits your custom hardware build, tell me:

• Do you prefer a Web GUI or a Cisco/Juniper-style CLI?
• What are your expected throughput requirements (e.g., 1 Gbps, 10 Gbps+)?
• Will you need advanced routing protocols like BGP or OSPF running natively on the device?

For a network engineer deploying on custom x86 hardware, my default recommendation is OPNsense—but VyOS is arguably better if your appliance is primarily a router rather than a stateful edge firewall.

My ranking

🥇 OPNsense — best overall

For a custom-built firewall appliance, I'd probably start here.

OPNsense runs on standard amd64/x86-64 hardware, supports everything from embedded systems to rack servers, and its documented recommended configuration is only a multicore ~1.5 GHz CPU, 8 GB RAM, and a 120 GB SSD. It specifically recommends Intel NICs for reliability and throughput.

It gives you:

• Stateful firewalling
• VLANs / 802.1Q
• NAT
• IPv6
• WireGuard / IPsec / OpenVPN
• Multi-WAN
• CARP-based HA
• DHCP/DNS
• IDS/IPS
• Traffic shaping
• Extensive logging/monitoring
• API and plugins
• FRR for BGP, OSPF, BFD, etc.

There's also a major advantage for a network engineer: you get a very usable GUI without sacrificing access to the underlying FreeBSD environment.

One caveat

OPNsense is optimized around the firewall-appliance model. If your mental model is more:

"I want to build my own Juniper/Cisco-style router on commodity hardware"

then I'd seriously consider VyOS instead.

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🥈 VyOS — best for a network engineer who thinks in CLI/configuration

VyOS is particularly compelling if your appliance needs to do serious routing.

It supports BGP, OSPF/OSPFv3, BFD, IS-IS, policy routing, multicast routing, MPLS LDP, WireGuard, IPsec, OpenVPN, HAProxy, and other networking functions. It can run directly on commodity x86-64 hardware.

Its configuration model is also much closer to what you'd expect from a dedicated network OS:

configure
set interfaces ethernet eth0 address ...
set protocols bgp ...
set firewall ...
commit
save

That makes it particularly attractive for:

• BGP edge routers
• WAN routers
• Internet gateways
• ISP equipment
• SD-WAN-ish appliances
• Automated network infrastructure
• High-throughput routing
• Custom network appliances

VyOS also supports technologies such as DPDK/VPP for higher-performance deployments; its platform documentation describes scaling to 100G+ environments on suitable hardware.

Important distinction

VyOS is not quite the same product philosophy as OPNsense.

OPNsense:

"I'm building a firewall appliance."

VyOS:

"I'm building a network operating system."

For a network engineer, that distinction matters.

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🥉 OpenWrt — fantastic if you want to own the entire appliance

OpenWrt is the choice I'd make if you're interested in building something more embedded or Linux-centric.

Modern OpenWrt uses firewall4 with nftables and gives you access to the underlying Linux networking stack.

It's particularly attractive for:

• ARM/x86 appliances
• Very small hardware
• Custom embedded products
• Wi-Fi routers
• Cellular gateways
• Extremely customized networking
• Developers comfortable with Linux

The downside is that you're assembling more of the solution yourself. OPNsense gives you a much more complete firewall appliance experience out of the box.

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What I'd build

If you said:

"Give me a custom hardware firewall for a serious home lab, small business, branch office, or edge network."

I'd build:

x86-64 + Intel NICs + OPNsense

Something like:

• Modern Intel/AMD x86-64 CPU
• 8–16 GB RAM
• 120+ GB SSD
• 4–8 Intel Ethernet ports
• Serial console
• Optional 10 GbE NIC
• Dedicated management interface

OPNsense explicitly identifies CPU, RAM, storage, and especially NIC quality as important factors for throughput, and Intel NICs are recommended.

If you're doing BGP, multiple full routing tables, high-speed WAN, MPLS, or treating the box primarily as a router, I'd instead build:

x86-64 + Intel/Mellanox NICs + VyOS

VyOS's documentation notes that routing workloads such as multiple BGP full tables can require substantially more RAM/CPU than its minimum requirements.

Bottom line

For firewalling: → OPNsense

For routing/network engineering: → VyOS

For embedded/custom Linux appliances: → OpenWrt

For the most appliance-like experience: → OPNsense

For the most "network OS" experience: → VyOS

If you're actually planning to build the hardware yourself, tell me your target WAN speed (1/2.5/10/25/40/100 GbE), number of ports, BGP/OSPF requirements, and whether you need IDS/IPS, and I can recommend a specific CPU, NICs, RAM, storage, and motherboard architecture.

For a network engineer deploying a firewall on custom hardware, my top choice is OPNsense—unless your priorities are heavily tilted toward routing, automation, or carrier/enterprise networking, in which case VyOS may be better.

My ranking

🥇 OPNsense — best overall

OPNsense is what I'd choose if the machine's primary job is being a firewall/security gateway.

It runs on FreeBSD and supports x86-64 hardware. The project officially supports installation on everything from embedded systems to rack servers. Its recommended baseline is a multicore 1.5 GHz+ CPU, 8 GB RAM, and a 120 GB SSD, although actual requirements depend heavily on throughput and enabled features.

The big advantage is that you get a proper firewall appliance experience without being tied to appliance hardware:

• Stateful firewall
• NAT
• VLANs
• IPv4/IPv6
• WireGuard/IPsec/OpenVPN
• DHCP/DNS
• IDS/IPS
• Traffic shaping
• Captive portal
• High availability
• Web UI + underlying FreeBSD system
• Plugin ecosystem
• Easy configuration backups/restoration

For custom hardware, I'd build around Intel NICs, preferably server-grade Intel Ethernet adapters. OPNsense specifically notes that Intel NICs provide reliable performance and reduced CPU load.

🥇 I'd pick OPNsense if:

Internet → firewall → VLANs → servers/workstations/APs

and you want the firewall to be easy to administer while still giving you plenty of room to get under the hood.

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🥈 VyOS — best if you're really a network engineer

VyOS is arguably the more interesting choice if you're thinking of the device as a router/network operating system that happens to provide a firewall, rather than a firewall appliance.

VyOS provides routing, firewall/NAT, QoS, load balancing, DHCP/DNS, VPNs, and other network functions through a unified CLI/API. It runs on commodity hardware, VMs, and cloud platforms.

Its feature set is particularly attractive for an engineer:

• BGP
• OSPF
• IS-IS
• VRRP
• Policy-based routing
• IPv6
• IPsec
• WireGuard
• VXLAN
• GRE/IPIP
• QoS
• NAT
• Zone-based firewall
• NetFlow/sFlow
• Ansible/Terraform/etc.
• Configuration commit/rollback
• API/automation

That's a killer combination for a custom x86 router.

I'd choose VyOS if:

Your architecture looks more like:

ISP → VyOS → BGP/OSPF → multiple routed networks → firewalls/servers

or you're building something involving routing protocols, VRFs, automation, redundant routers, or high-performance networking.

---

The important distinction

I'd frame it this way:

OPNsense = firewall first, router second.

VyOS = router/network OS first, firewall second.

Both can do either job, but their philosophies are different.

For example, if you want to sit down at a browser and configure:

WAN → NAT → VLAN 10 → DHCP → DNS → WireGuard → IDS

I'd strongly favor OPNsense.

If you want to SSH in and configure:

BGP + OSPF + VRRP + policy routing + VRFs + IPsec + firewall policies + automation

I'd favor VyOS.

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What I'd put on custom hardware

For an OPNsense build, I'd aim for something roughly like:

• CPU: modern Intel x86-64, 4+ cores
• RAM: 8–16 GB
• Storage: 120+ GB SSD
• NICs: Intel Ethernet
• Boot: UEFI
• Console: serial + video if possible
• PSU: quality PSU, particularly for 24/7 operation
• Cooling: prioritize sustained cooling over peak CPU performance

OPNsense's own hardware guidance emphasizes that throughput is affected by CPU, RAM, storage, and especially NIC quality; IDS/IPS and other CPU-intensive features can materially change the hardware requirements.

For 10 GbE+, I'd stop sizing hardware based on the basic OPNsense recommendations and benchmark the exact combination of NICs, CPU, packet size, NAT, IDS/IPS, VPN encryption, and traffic profile you intend to run.

Bottom line

If you want one answer: OPNsense.

If you tell me "I'm a network engineer and want maximum control, routing, automation, and CLI": VyOS.

For a custom x86 firewall/router, I'd personally shortlist OPNsense and VyOS, then choose based primarily on whether the box is fundamentally a security appliance (OPNsense) or a network router (VyOS).

For a network engineer deploying on custom x86 hardware (such as a multi-NIC appliance from Protectli, Qotom, or a custom rackmount server), the "best" open-source firewall depends heavily on whether your background is rooted in GUI/enterprise appliance management or traditional vendor CLI routing.

The top open-source contenders tailored for custom hardware fit distinct use cases:

• OPNsense
  • Best for: Most modern deployments requiring a polished GUI and comprehensive feature set.
  • Why it shines for engineers: A fork of pfSense, OPNsense has rapidly outpaced it in UI design, code refactoring, and transparency. It features a clean, responsive API-driven web GUI, robust built-in stateful packet inspection, native multi-WAN load balancing/failover, and first-class integration with Suricata (for inline IDS/IPS) and Zenarmor (for deep packet inspection and web filtering). It is entirely open source under a BSD license with no hidden commercial gates.
• VyOS
  • Best for: Network engineers who live by the CLI and want a vendor-neutral routing operating system.
  • Why it shines for engineers: Unlike OPNsense or pfSense which rely heavily on web interfaces, VyOS is built from the ground up for CLI configuration using a unified, Juniper/Cisco-like operational and configuration mode (forked originally from the old Vyatta project) [5.0]. It runs on standard x86 hardware and provides enterprise-grade routing protocols (BGP, OSPFv2/v3, ISIS), advanced policy-based routing, stateful firewall rules, and robust VPN tunneling (IPsec, WireGuard, OpenVPN).
• pfSense (Community Edition - CE)
  • Best for: Legacy familiarity and maximum community documentation.
  • Why it shines for engineers: Historically the undisputed champion of open-source firewalls based on FreeBSD. It handles high-throughput routing, VLANs, and traffic shaping exceptionally well on bare-metal x86 hardware. Note: While pfSense CE remains free, the project's commercial shift toward "pfSense Plus" for official appliances has led many engineers to lean toward OPNsense for active, community-driven open-source innovation.
• IPFire
  • Best for: Lightweight, highly secure, modular Linux-based deployments.
  • Why it shines for engineers: Built directly on top of Linux Netfilter rather than FreeBSD, IPFire uses a rigid, color-coded zone system (Red for internet, Green for LAN, Blue for WLAN, Orange for DMZ) that makes strict boundary enforcement foolproof. It has a tiny footprint, making it ideal if your custom hardware is lower-powered or space-constrained.

Summary Recommendation

• Choose OPNsense if you want an enterprise-grade perimeter firewall managed through an exceptional web interface with rich plugin scalability.
• Choose VyOS if you treat your firewall like a core router and want a powerful, scriptable, CLI-first environment [5.0].

If you'd like to narrow this down, let me know:

• What kind of throughput and interfaces (e.g., 1GbE vs. 10GbE) your custom hardware has
• Whether you prefer managing via a Web GUI or a CLI