Firewalls

“ A network security system that monitors and controls incoming and outgoing internet traffic, acting as a barrier to prevent unauthorized access and malicious activity. It functions by allowing or blocking data packets based on a set of pre-defined security rules. ”

A firewall, which can be hardware or software, is a security device that guards for your computer or network. Its job is to monitor the incoming and outgoing traffic and decide what should be allowed or blocked. There are out-of-the-box setups that have predetermined lists of what to block and allow, but it’s a good idea to configure your firewall based on your unique network needs. Customizing your firewall rules prevents legitimate activities from being blocked. Just as a security guard checks who can enter a building, a firewall checks which data packets can enter your device or network. Without a firewall, your computer is more exposed to hackers, malware, and other threats lurking on the internet.

Firewalls can be hardware-based, software-based, or a combination of both. Hardware firewalls are usually built into routers or dedicated devices and protect entire networks, while software firewalls run directly on your computer or mobile device, controlling traffic for that specific device. Most modern operating systems, like Windows or macOS, come with a built in firewall that you can enable for basic protection.

One of the main ways firewalls work is by setting rules. These rules define what types of traffic are allowed in or out. For example, your firewall might allow web browsing on port 80 or 443 but block incoming connections on other ports that hackers commonly exploit. You don’t need to memorize ports or protocols to benefit from a firewall, the software usually comes with documentation that helps you identify what you regularly need access to and what can be shut down. This way you can filter suspicious connections while letting legitimate ones pass, keeping your home network safer. Firewalls are also valuable for controlling outgoing traffic. Some malware doesn’t just enter your computer, it tries to send your data to hackers or join a network of infected devices called a botnet.¹ A firewall can block these outgoing connections before they can do damage, acting as a proactive layer of defense, not just a reactive one.

Companies rely heavily on firewalls to protect sensitive data and maintain business continuity. Corporate firewalls are usually much more sophisticated, combining multiple security features. They filter traffic based on content, check for viruses, block malicious websites, and sometimes even monitor user behavior. An industrial firewall might prevent employees from accessing risky sites or stop an intruder from gaining access to internal servers. As with most things, the increased functionality here comes at a higher dollar cost.

On the previous page we talked about using a VPN connect to a company network from far away, and firewalls play a part in this process. When a remote worker connects to the company network through a VPN, the company firewall ensures that only authorized traffic comes through the tunnel.² It helps maintain security for the company network even when employees are working from coffee shops, airports, or home offices.

Has your computer ever asked for permission to let an application connect to the internet? That popup is your firewall asking whether it should allow or block traffic. This helps prevent unknown or malicious applications from sending or receiving data without your knowledge. With a properly configured firewall, you shouldn’t be getting these popups often because your regular network activities are already allowed by the rules you defined in the configuration. If this is your first time hearing about this technology or you haven’t gotten around to setting it up on your own devices, I strongly recommend you look into it. Firewalls are an included tool in nearly every operating system now, including Windows, Mac, and Linux. They don’t take long to setup, you don’t need technical knowledge to understand what to allow and block, and once it has been configured, you’ll rarely have to go back in to make changes. It’s a nice layer of defense that runs for without much work on the user’s end.

It’s important to mention that firewalls are not a silver bullet. Like all of the other cybersecurity defenses discussed on this site, they work best as part of a multi-layered security approach. Antivirus software, strong passwords, regular updates, and safe browsing habits all complement firewalls. Together, these measures create a robust shield against threats, both for individual users at home and for large corporate networks. By monitoring traffic, enforcing rules, and blocking dangerous connections while letting legitimate activity continue, firewalls play a vital role in the overall defense stategy.

¹ “A Survey on Botnets, Issues, Threats, Methods, Detection and Prevention”, by Owen, H, Zarrin, J, and Pour, S, February 2022
² “Firewalls and VPNs: How They Work Together to Secure Remote Access”, OutsourceIT Security, July 2024