How a Firewall Works and If You Need One

The firewall: How it protects computers, network devices & more

A firewall is a security system that acts like a digital barrier between connected devices and the outside world (the internet). Think of it like a security guard, checking who’s allowed to come in and who’s not. A firewall monitors the traffic (data) that flows between your devices and the internet, deciding whether to allow or block that data based on a set of predetermined security rules.

This simple yet powerful tool can prevent hackers from gaining access to personal data, protect you from malicious websites, and stop unauthorized applications from sending your data out to the internet. Whether it’s your computer, smartphone, or router—firewalls are crucial for maintaining a safe and secure network.

Does the average person really need a firewall?

When you think of cyberattacks and data breaches, it may seem like they only happen to big companies—since those stories tend to make the news. The fact is, cyberattacks and breaches can happen to anybody, anytime—and firewalls give you crucial protection against:

Hackers trying to break into your home network
Malware and viruses that can infect your personal devices
Phishing attacks and other online scams
Unauthorized access to your personal data

Simply put, a firewall is your first line of defense against the dangers lurking on the internet. By controlling and filtering the traffic that flows in and out of your devices—a firewall helps keep your personal information, data, and devices safe from hackers and malware.

How does a firewall work?

Now that we know what a firewall is, let’s break down exactly what it does. A good firewall will:

Check incoming and outgoing traffic. A firewall checks the data packets that travel between your device and the internet. (Think of data packets like little digital envelopes with important pieces of information in them.) It makes sure nothing harmful is coming in and that no sensitive information is being sent out.
Block unauthorized access. If a hacker tries to access your network or a suspicious app tries to send data without your permission, the firewall will block it, keeping your network safe.
Filter content. Many firewalls allow you to set up specific rules to block certain types of content or websites. If you want to prevent access to social media sites or block harmful content for kids, a firewall can do that.
Monitor activity. Firewalls also keep track of the activity happening on your network. They can detect unusual behavior, like an attempt to connect to a suspicious IP address, and alert you to potential threats.

In a nutshell, firewalls are the first line of defense for protecting your home internet network.

What is a stateless vs. stateful firewall?

When it comes to firewalls, not all are created equal. There are two main types: stateless and stateful firewalls. The difference between them can affect how well your network is protected and how much traffic can flow through.

Stateless firewall.

A stateless firewall works by checking each individual packet of data on its own, without "thinking" about the context or state of the connection. In other words, it looks at each piece of data and decides whether to allow it through based on predefined rules, without tracking the entire conversation between your device and the internet. This has some pros and cons:

Pros: Stateless firewalls are usually faster since they don’t have to keep track of the entire connection. They work well for basic tasks like blocking unwanted traffic or simple filtering.
Cons: Because they don’t track the state of connections, they can miss more sophisticated attacks or unauthorized access that tries to exploit multiple packets over time.

Stateful firewall.

A stateful firewall tracks the entire conversation between your device and the internet, making it much smarter. It can keep track of ongoing connections, so it can analyze the flow of traffic and make more informed decisions about whether to allow or block data. Think of it like a person who is keeping track of an entire conversation instead of just responding to each individual comment. Here are the pros and cons:

Pros: Stateful firewalls give you better security because they can understand the entire context of data packets. They are more effective at detecting complex attacks and malicious behavior over many data packets and sessions.
Cons: Because they’re more thorough, they can slow down devices or networks that don’t have the processing power to keep up. They also tend to cost more and are more complex to manage.

So, while both types of firewalls can protect your network, stateful firewalls give you the strongest, most reliable protection. However, they may be a bit of overkill for the average household—and they may slow things down.

Hardware vs. software firewalls

When it comes to firewalls, you’ll typically see two types: hardware firewalls and software firewalls. Here’s a closer look:

Hardware firewalls: These are actual physical devices that sit between your home network and the internet (in most homes, it’s a router or gateway.) They monitor and control all the traffic going in and out of your home network, giving you a centralized and higher level of protection. These are especially good for large homes—or homes with a lot of connected devices.
Software firewalls: These are programs installed directly on your individual devices, like your computer or smartphone (e.g., Windows Defender, McAfee Total Protection, Norton 360, etc.) They monitor and filter traffic just for that device. They’re great for personal protection on a per-device basis and are usually easy to set up.

Which one should you choose? Probably both.

If you have lots of devices like phones, laptops, gaming consoles, smart TVs, smart assistants, etc. and want a simple, centralized security solution, a hardware firewall is essential. Most modern routers and gateways come with a built-in firewall, so you likely already have one in place.
If you want even more protection for specific devices (such as your work computer), then adding a software firewall is probably a good idea, too.

In the end, these firewalls complement each other, giving you extra layers of protection for your home network.

T-Mobile is the fastest-growing Home Internet provider, delivering Advanced Cyber Security on its All-In Plan, as well as its Amplified Home Internet Plan, for added peace of mind. This gives you extra layers of security, including Safe Browsing to help block malicious links, along with Anomaly Detection to help protect your connected devices from cybercriminals. Best all, you can easily manage everything through the T-Life app. See which plans are available near you.