What Are They, When to Use Them, and How to Choose
Most people using personal computers have at least heard the word “firewall” in an IT context. For those not deeply familiar with cybersecurity, a firewall might seem like some mysterious tool running quietly in the background, magically protecting your PC from cyber threats. While this description contains some truth, the concept of a firewall is usually more nuanced—especially when it comes to industrial applications.
In this article, we’ll explore industrial firewalls step by step:
- Step 1: Difference between hardware and software firewalls
- Step 2: Difference between industrial and commercial hardware firewalls
- Step 3: Difference between boundary and LAN industrial hardware firewalls
- Step 4: Selection guide for MOXA industrial firewall types
Let’s begin our journey!
What Is a Network Firewall, and What’s the Difference Between Software and Hardware Versions?
A firewall, in general terms, is a network security system that monitors, filters, and controls incoming and outgoing network traffic based on predefined security rules. It functions as a barrier between trusted and untrusted networks. Imagine a cyber threat as a fire in an adjacent building, and your firewall as a fire-resistant wall — this visualization neatly explains the role of a firewall in cybersecurity.
In typical scenarios, a “trusted” network refers to internal networks (such as home or enterprise), while an “untrusted” network usually means the Internet. However, in more complex environments, such as industrial applications (factories or smart grids), even neighbouring local networks can pose threats. Thus, firewalls often act as barriers even between VLANs within a single internal network.
From a conceptual and functional standpoint, there is no fundamental difference between hardware and software firewall implementations; the distinction lies in their deployment. A software firewall is an application installed directly on your computer, typically running as a background service. A hardware firewall, by contrast, is a standalone physical device resembling an Ethernet switch or router.
In simple terms, a software firewall is ideal for individual computers or small groups of powerful computers since firewall applications can consume considerable computing resources.
In industrial environments, however, most devices aren’t traditional computers but rather network remote I/O, controllers, IoT gateways, and embedded systems with limited computational resources. For these environments, hardware firewalls are typically more practical and widely used. The reasons include:
- Cost-efficiency and simplicity: Deploying one hardware firewall between a router and a large network of devices is far easier and more economical than installing dedicated software firewalls on every device.
- Resource limitations: Most industrial devices simply can’t handle the computational demands of a firewall application, making external hardware solutions a necessity.
Since APulsar specialises in cybersecurity solutions for industrial applications, we will focus exclusively on hardware firewalls for the remainder of this article.
Difference Between Industrial and Commercial Hardware Firewalls
Previously, we mentioned that a firewall “monitors, filters, and controls incoming and outgoing network traffic based on predefined security rules.” These rules determine whether to permit or deny traffic based on criteria such as source and destination IP addresses, port numbers, and protocol types. More advanced firewalls can inspect packets deeply — up to the application layer (Layer 7 of the OSI model) — to perform filtering, threat detection, and policy enforcement at a granular level.
It would be misleading to claim that industrial-grade firewalls are inherently “better” than commercial firewalls. Both types often feature advanced capabilities like Deep Packet Inspection (DPI) and Intrusion Prevention Systems (IPS). However, industrial firewalls are designed with specialized cybersecurity functions specifically tailored for operational technology (OT) environments — functions that would be redundant in most commercial IT use cases.
As discussed in our article Defense-in-Depth Security Architecture, industrial firewalls such as those from MOXA provide capabilities like OT protocol inspection for Modbus, DNP3, IEC-104, and others. The ability to inspect the payloads of industrial protocols is critical in OT environments but unnecessary for typical IT infrastructure.
Industrial Protocol Support for DPI in MOXA Firewalls
| Protocol | Vertical Market | Available Now |
|---|---|---|
| DNP3 | Power/Water | ✓ |
| EtherNet/IP | Automation | ✓ |
| IEC 60870-5-104 | Power/Water | ✓ |
| IEC 61850 MMS | Power | ✓ |
| MELSEC | Automation | ✓ |
| Modbus TCP | General | ✓ |
| Modbus UDP | General | ✓ |
| Omron FINS | Automation | ✓ |
| OPC UA | Automation | ✓ |
| Siemens S7 Comm. | Automation | ✓ |
| Siemens S7 Comm. Plus | Automation | ✓ |
🔗 For the most up-to-date list of supported industrial protocols, please visit MOXA’s Network Security Appliance section on their official website.
Additionally, industrial firewalls like MOXA’s offer virtual patching — a feature that mitigates vulnerabilities directly at the firewall level without requiring updates to the protected devices behind it. This functionality is not always present in commercial firewalls. Furthermore, a specific product category like the “LAN firewall”, which we’ll explore later, doesn’t exist in the commercial firewall space at all.
Industrial firewalls also offer features like extended warranties, wide operating temperature ranges, resistance to dust and humidity, industry certifications, and support for DIN-rail mounting — all critical for industrial environments but unnecessary in most commercial settings. Additionally, MOXA’s firewalls feature simplified user interfaces tailored for OT engineers and integrate with centralized management platforms like MXsecurity, simplifying both deployment and compliance.
Difference Between Boundary and LAN Industrial Hardware Firewalls
Now that we understand the use and benefits of industrial hardware firewalls, we can move on to the two main categories MOXA offers: Boundary Firewalls and LAN Firewalls.
A boundary industrial firewall incorporates all the features mentioned earlier: IPS, DPI with OT-protocol support, and core functionalities like NAT. What distinguishes it is its placement and role. Boundary firewalls are deployed between private and public networks, or at the edge of internal zones. If your goal is to protect the network from external access or create a DMZ for secure data exchange, a boundary firewall is the right choice. Much of what we’ve covered in this article so far refers to boundary firewall functionality.
LAN firewalls, on the other hand, are where things get more interesting — and more unique to MOXA. These devices are designed to operate within a single subnet, which is not typical for traditional firewall deployments. LAN Firewalls are meant to safeguard important assets and clusters of field devices inside a control network, where traffic is exchanged over a single VLAN. One of their key benefits: they don’t require IP reconfiguration. You simply drop it into the network, and it’s good to go — almost plug-and-play.
For example, you can place one directly between two critical devices, or insert it just in front of a network switch inside a control cabinet — protecting field controllers, onboard AGVs, or other small groups of devices sharing that switch. But don’t be fooled by the simplicity: LAN firewalls still feature Deep Packet Inspection (DPI) and IPS/IDS, which are enabled by default. Sure, they don’t offer NAT or routing functions — but by now, you can probably guess why. Simply put, a LAN firewall is like a shepherd dog guarding a flock: you place it in the network segment, and it quietly watches over everything, ensuring nothing harmful slips through.
In this specific form — compact, rugged, and designed to operate within a single network segment without IP reconfiguration — the LAN firewall is a rare solution on the market. And in this field-ready format, MOXA is one of the very few vendors offering it.
Selection guide for MOXA industrial firewall types
Now that we’ve covered everything you need to know about the types of industrial firewalls, let’s wrap up with a quick selection guide.
Here’s a simple rule of thumb:
- If you need to route traffic between VLANs, require NAT or VPN, need redundancy protocols, or want multiple ports — go for a boundary firewall.
- If you need to protect a group of devices (especially legacy ones) within a single network segment, or want to filter traffic between just two devices — go for a LAN firewall.
Let’s do a quick recap and compare Boundary and LAN firewalls in the table below:
MOXA Industrial Firewall Types: Boundary vs. LAN
| Category | Boundary Firewall | LAN Firewall |
|---|---|---|
| Position | Inside or Between LANs | Inside one LAN |
| Traffic | South–North traffic | East–West traffic |
| Networks | Intranet, Internet, DMZ | Intranet |
| Network Operation | Layer 3 Routing / NAT / Redundancy | Layer 2 Bridge (Transparent) |
| IP Reconfiguration Needed | Yes | No |
| IPS/IDS | Yes | Yes |
| Firewall with DPI | Yes | Yes |
| VPN, NAT | Yes | No |
| Number of Ports | 4–10 | Only 2 Ports, In-and-Out |
| Applications |
|
|
| MOXA Solutions | EDR-G9010 EDR-G9004 EDR-8010 | EDF-G1002BP |
APulsar Technologies: Your Partner in Industrial Network and Security Solutions
At APulsar, we don’t just provide cutting-edge products; we offer end-to-end engineering services to design, plan, and implement robust industrial networks and security solutions tailored to your unique needs. Our expertise spans from creating secure architectures using firewalls to deploying technologies that ensure compliance with standards like IEC 62443.
Whether you need assistance with network segmentation, implementing firewalls and IDS/IPS, or integrating centralized management platforms like MXsecurity, our engineers provide hands-on support to ensure every layer of your network is optimized for both performance and security. With years of experience in industrial automation and OT cybersecurity, APulsar is your trusted partner for building secure, resilient infrastructures.
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