For some security jobs, yes; for the office firewall itself, usually not. A mini PC makes a good security lab, a network monitoring sensor, a log collector or a test bed for open-source firewalls such as OPNsense and pfSense. As the main firewall for a business, a purpose-built appliance like a Fortinet FortiGate 30G (S$766.80, hardware only) or FortiGate 50G (S$1,168.80, listed 3 Nov 2026) is simpler to run and support, because it combines dedicated security processors, a subscription that keeps its threat signatures current and vendor support. The deciding details on a mini PC are network ports, memory and who will maintain it. We have not tested these setups ourselves; this is based on the OPNsense, pfSense, Security Onion and Fortinet documentation and ASUS's specifications.
What do the open-source tools need?
| Tool | Published requirement | ASUS NUC fit |
|---|---|---|
| OPNsense | Minimum 1 GHz dual-core, 3GB RAM, 4GB storage; recommended 1.5 GHz multi-core, 8GB RAM, 120GB SSD; Intel NICs described as reliable | Any current NUC meets it; NUC 16 Pro uses Intel I226 NICs |
| pfSense | 64-bit x86, at least 1GB RAM, 8GB disk; IDS packages need at least 1GB more RAM, sometimes 2GB+; CPU is "the first bottleneck" | Fine on CPU and memory |
| Security Onion 2.4 | Standalone: 4 cores, 24GB RAM (32GB+ suggested), 200GB, 2 NICs; sensor: 4 cores, 12GB, 2 NICs; x86-64 only | Needs two NICs and plenty of RAM: NUC 16 Pro with 32GB+ |
| Network ports | A firewall needs at least two networks (WAN and LAN), as separate ports or VLANs | NUC 15 Pro: one 2.5GbE port; NUC 16 Pro: two 2.5GbE ports |
From the OPNsense hardware manual, Netgate's pfSense minimum requirements (Aug 2025) and sizing guide (Dec 2025), Security Onion 2.4 hardware requirements, and ASUS's NUC 15 Pro and NUC 16 Pro specifications.
Where does a mini PC work well?
- A security lab. Run OPNsense, pfSense or a SIEM in virtual machines, break things and learn. Our three-NUC home lab post covers the platform side.
- A monitoring sensor. Security Onion's sensor role needs four cores, 12GB of RAM and two network interfaces, one of them dedicated to sniffing with no IP address. The NUC 16 Pro's two 2.5GbE ports suit that, fed from a mirror port on a managed switch.
- A small branch or home firewall for someone who already knows OPNsense or pfSense and will patch it.
- A jump box or log collector in a locked cabinet, using the Kensington slot and, on vPro models, Intel AMT for remote access.
Choose two network ports from the start. The NUC 15 Pro has one 2.5GbE port, so as a firewall it needs a USB or Thunderbolt adapter or VLANs on a managed switch. The NUC 16 Pro has two. Netgate's sizing guide notes that inexpensive network cards "consume significantly more CPU than better quality cards such as Intel", which favours the NUC's Intel I226 controllers.
A mini PC can run a firewall. The question is who will look after it at 2am when the signatures are out of date.
Why not use one as the company firewall?
Three reasons. First, throughput under inspection: Fortinet's hardware acceleration guide explains that FortiGate security processors offload network traffic, antivirus, attack detection and encryption from the main CPU, and Fortinet's October 2026 product matrix lists 1.1 Gbps of threat-protection throughput for the FortiGate 50G. On a mini PC, all of that falls on the CPU, which pfSense's own guide names as the first bottleneck. Second, updates: a FortiGate's FortiGuard subscription keeps its intrusion prevention, antivirus and web filtering signatures current, while an open-source firewall depends on whoever maintains it. Third, support: when an appliance fails, there is a vendor and a replacement path. See Buying a FortiGate Without FortiGuard and Why Your S$200 Router Isn't a Replacement for a Business Firewall.
What about running a mini PC alongside a FortiGate?
That is often the best combination. The FortiGate sits at the edge and enforces policy; a NUC on the inside runs Security Onion as a sensor or collects logs, so you have a second view of what crosses the network. Whatever you deploy, treat the mini PC itself as a server: keep its BIOS and operating system patched, disable unused services and record it in your asset list. Forgotten boxes are a classic way in; see A Cyber Incident Can Start With a Forgotten Device in Your Office.
Buying in Singapore
SourceIT supplies the ASUS NUC 16 Pro Ultra 5 325 barebone (S$700.53) and Ultra 7 356H barebone (S$885.65), both with two 2.5GbE ports, G.SKILL 32GB DDR5-5600 SO-DIMMs (S$811.25), and the FortiGate 30G (S$766.80) and FortiGate 50G (S$1,168.80), hardware prices listed 3 Nov 2026; FortiGuard bundles are quoted separately. Browse the FortiGate firewall collection and ASUS NUC collection. For a quotation, use Request for Quotation on the product page, call (65) 6978 3502, email Sales@sourceit.com.sg or use our contact page.
Frequently asked questions
Can an ASUS NUC run OPNsense or pfSense? Yes. Both need modest x86 hardware, well within any current NUC. As a firewall it needs two networks, so the dual-port NUC 16 Pro is the easier choice.
Is a mini PC firewall as good as a FortiGate? Not for most businesses. A FortiGate offloads inspection to security processors and keeps signatures current through FortiGuard; a mini PC relies on its CPU and on whoever maintains it.
What does Security Onion need? Version 2.4 needs at least 4 cores, 12GB RAM and two network interfaces for a sensor, or 24GB RAM for a standalone install, on x86-64 hardware.
How many network ports does an ASUS NUC have? The NUC 15 Pro has one 2.5GbE port and the NUC 16 Pro has two.
How much is a FortiGate in Singapore? At SourceIT on 3 Nov 2026, the FortiGate 30G hardware is S$766.80 and the 50G S$1,168.80; FortiGuard subscriptions are extra.
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