Hardware Firewalls vs. Software Firewalls: Which to Use and When

Quick Definition: Firewalls are essential for network and system security. Hardware firewalls protect corporate networks with high performance, extended features, and scalability. Software firewalls are flexible, cost-effective solutions for individual devices when not connected to the corporate network.

Network security is more necessary than ever, full stop. Our work, our lives, and our culture are now inseparably intertwined with the digital landscape, so protecting these assets and systems is absolutely critical work.

Firewalls are the first level of protection between our systems and threats, whether those are curious but harmless users, lone-wolf black hats, or nation-state hacker groups. For IT pros and decision-makers, deciding how and where to implement firewalls is the first step to building a multilayer defense against all of these sources of harmful traffic. Those decisions begin with understanding one fundamental distinction between firewall types: hardware versus software.

Today, we'll explore the definitions, capabilities, and ideal use cases of firewalls and the specific differences between hardware and software firewalls. They each have their own challenges that we'll also address. To get started, let’s talk about what firewalls are. 

What is a Firewall?

A firewall is a security device or application that monitors and controls incoming and outgoing traffic based on a set of predetermined security rules. It acts as a gatekeeper, blocking unwanted traffic to safeguard applications and data.

Early firewalls worked on a simple ruleset involving blocking and allowing traffic based on ports or IP addresses. Let's take a web server as an example. To access a hosted site, users would need to connect on TCP port 443 for an HTTPS connection. A typical firewall ruleset for this case would be to allow connections from any source IP on port 443, and block connections to any other port. 

This is to allow access to the website but blocks public access to other ports like SSH (TCP 22) or Remote Desktop (TCP 3389). The public doesn't need access to these services, and in fact, it would be dangerous to allow access as it invites hackers.

Later firewalls added more advanced features, such as deep packet inspection (DPI) to examine the traffic and apply specific policies, instruction detection prevention (IDP) to block potential hacking, and web application firewalls (WAF) specifically for websites to detect and block common web app attacks. The humble firewall performs all these and many more protections for your networks.

What are Hardware Firewalls?

Hardware firewalls are standalone devices that secure entire networks. They are physical appliances, like a switch or router, that sit between the internet and your internal network. Typically, they will be connected directly to your ISP's equipment, so literally all the bits must go through them before hitting any other gear. They have a WAN port to connect to the ISP, and a LAN port to connect to your network.

Hardware firewalls are dedicated appliances, so their hardware is optimized for performance and high-speed processing of large volumes of network traffic, usually rated for a specific max amount of bandwidth. They offer comprehensive protection of all devices within the network, and have advanced features like intrusion prevention, load balancing, and VPN servers.

The Cisco ASA is the classic firewall of choice, scaling from capacity from small offices to huge enterprises. Other common make and models include Fortinet FortiGate, the Palo Alto PA series, and the Juniper SRX series.

What are Software Firewalls?

Software firewalls are applications installed on individual computers to filter, permit, and deny traffic on that specific device. They operate at the host level only; in other words, they only protect the one computer they are installed on.

They are customizable for individual devices, where individualized configurations are needed. They are cost-effective, especially considering that most OSes have a built-in software firewall. This also leads to ease of deployment, as the setup of these built-in firewalls is simple. There are more powerful third-party software firewalls, though, like ZoneAlarm and BitDefender.

The number one advantage of software firewalls over their hardware counterparts is remote workers. Hardware is intended to protect all the devices on a physical network. This is fine, if all your users are on a network controlled by your organization, like your headquarters or a branch office. 

For workers at home, in coffee shops, or at airports, the hardware firewall is useless (unless VPNs are in play, but that's a whole other topic). Software firewalls protect the device no matter where the user is working.

Comparing Hardware vs. Software Firewalls

Now that we understand how each type of firewall works, let’s compare the differences between hardware and software firewalls on a more granular level. 

Performance and Scalability

Hardware firewalls offer superior performance for high-volume traffic, as the hardware is specially built for this use. They are easily scalable, with either software licenses or hardware updates to increase capacity. Software firewalls, while limited to the resources of their host, only need to deal with the traffic of that single host, so comparing performance with hardware firewalls isn't a fair deal.

Security Features

The features available on either hardware or software firewalls vary widely depending on the solution you choose. For example, next-gen hardware firewalls can block ports, inspect SSL traffic for malware or vulnerability exploits, perform website content filtering, act as VPN servers, and many other advanced features. More simple models, however, may only let you open a few ports. Software firewalls generally don't have these high-level features, with similar basic functionality of port blocking.

Deployment and Management

Hardware firewalls require dedicated physical setup and maintenance, with rack space, power and cable management, and hardware lifecycles to consider. Software firewalls are simpler to deploy but might require updates and the complications of managing software consistently across multiple devices.

When to Choose a Hardware Firewall

Hardware firewalls are ideal in scenarios where high performance and robust network-wide protection are required. Ideally, a single firewall can handle the traffic and security for an entire network, whether your headquarters, corporate campus, or individual branch offices.

They have the advantages of processing data through high-bandwidth links, centralized control for even the largest LANs, and simplified management. They can also protect hosted services, like applications, web, or email servers, with robust traffic monitoring and intrusion detection and prevention features.

When to Choose a Software Firewall

Software firewalls are best for protecting individual devices used outside the office and beyond the protection of a hardware firewall. They are easily deployable and customizable (with appropriate device management tools already in place), very cost-effective, and provide portable protection for remote workers and frequent travelers.

Final Thoughts 

Both hardware and software firewalls bring their unique strengths to the table. Hardware firewalls are ideal for high performance, protecting many users and servers at once. Software firewalls provide flexible protection for individual devices out in the world. 

The choice for you depends on your needs and budget. Weigh these factors carefully, and hopefully, a choice becomes clear to protect your networks, your users, and your servers.

Want to learn more about firewalls? Check out our online training on Network Firewall Fundamentals with Keith Barker.