A firewall is a security protocol that protects your internal network from the threats of the internet. It keeps an eye on the data that comes in and out of your home network.
Without a firewall, your trusted private network could be at risk of cyberattacks, data breaches, and malware from the public.
The technical side of what a firewall does
To get to grips with how a firewall works, you need to understand how data travels between internet networks.
Basically, data moves across the internet in the form of information-filled packets. A firewall inspects these data packets to analyze their:
- Content: The information each data packet contains, such as an image, text, or video.
- Protocol: The language of the data packet, for example, HTTP or TCP.
- Port: The medium that the data is traveling through, such as email, web, or a social media network.
- Source: Where the data is coming from, for example, the IP address or hostname of incoming traffic.
- Destination: Where the data is headed, including the IP address, hostname, and other information that describes where the traffic is going.
Afterwards, the firewall determines whether to let the data packet pass or, instead, to block it based on a set of predefined rules.
To ensure that dangerous data packets are blocked, it’s crucial that you properly set up your firewall, create effective rules, and keep it up to date.
SEE: Learn the fundamentals of computer networking.
Hardware firewalls
Hardware firewalls are dedicated physical devices, often integrated into routers or standalone appliances, that act as a barrier between a private network and the internet. They offer robust, centralized protection, making them ideal for organizations and businesses that need to secure multiple devices or high volumes of network traffic.
Although they are typically more expensive than software firewalls, hardware firewalls provide scalability and consistent performance, protecting an entire network without relying on the resources of individual devices.
Software firewalls
Software firewalls are applications installed on individual devices to monitor and control network traffic at the endpoint level. They are included by default in most operating systems, such as Windows and macOS, and some routers also incorporate software firewall capabilities.
These firewalls can be customized to block specific applications, filter outbound and inbound traffic, and provide alerts for suspicious activities. The specific capabilities will depend on what type of software firewall you are using. A Next-Generation Firewall (NGFW), for example, may provide tools for access control, intrusion prevention, advanced threat intelligence, and deep packet inspection.
What a firewall does to protect your home network
1. Blocks unauthorized traffic
To reiterate, a firewall blocks threats coming from restricted sources or ports.
This means your firewall will block any data packets coming from a restricted IP address or website. It will also reduce your home network’s visibility to potentially risky protocols.
Firewalls can also block data packets that have malicious content.
Basically, firewall users can set predefined rules to give a firewall access control of their data. Based on these rules, the firewall will shut out intruders. For instance, parents may set rules in the firewall to deny access to certain applications or block out content based on certain keywords.
2. Defends against threats
A firewall serves as a checkpoint for all data packets, so it protects your home’s internet system from several threats, including:
- Cyberattacks coming from hackers who want to damage your system or steal and erase data.
- Malware that infects not just software but also hardware, possibly destroying applications and devices.
- Ransomware that locks important files, seeking funds from you to release it.
Instead of just sniffing out these malicious invaders, a firewall neutralizes them in case they do enter your network. This way, it prevents the threats from spreading through your network infrastructure, further decreasing the scope of the damage.
Learn more about the latest threats to network security and how to defend against each one.
3. Prevents application intrusion
Even if you expect untrusted applications to act out of line, sometimes your most-trusted apps will try to access and extract sensitive data from your device.
This can happen when the application is outdated, infected, or a hacker tries to use it to get into your system.
Thankfully, your firewall observes an application’s behavior to make sure there are no attempts to enter unauthorized resources. Doing so, it protects your sensitive data.
For example, if an application tries to access a location or photos on your device even though you haven’t allowed it to do so, the firewall will act immediately to stop it. Along with protecting your data, it will also inform you of unusual activity.
4. Improves network performance
Firewalls are more than security guards. Since they monitor the flow of traffic and keep an eye on who’s accessing your devices, they free up valuable resources. By doing so, they reduce network congestion and improve your performance online.
Apart from filtering out unnecessary traffic volume, a firewall also keeps the network’s functioning in check by increasing your security.
What’s more, firewalls prevent crashes that can occur due to cyber attacks, misconfiguration, or bugs in your system.
5. Maintains privacy
Imagine a stranger watching you through your window. Creepy, right?
This is something hackers may do to keep an eye on your data and browsing habits. They might even use your private information against you.
A firewall stops this from happening by using rules to filter network traffic, blocking unauthorized attempts to access your system or monitor your activities. It inspects data packets for suspicious patterns, ensuring sensitive information stays secure.
Advanced firewalls use features like deep packet inspection and stateful packet filtering to detect and prevent unauthorized data transfers or malicious activity. They also monitor outgoing traffic, stopping applications or malware from transmitting private data to untrusted sources, providing a crucial layer of protection against data breaches.
6. Logs and audits data
Firewalls don’t merely observe the traffic coming in and out of the network. They can also be configured to log information about this traffic.
This data is critical in order to check the information later in case an unfortunate event arises and you need to go back and analyze what happened.
A firewall can track the timestamps, size, protocols, ports, IP addresses, and other details of a given packet. This information can help you investigate network activity. For instance, if a bug enters your system and ends up disturbing it, you can access the firewall’s log to track exactly where it came from.
Apart from being useful in tracking activity, these logs are also helpful in identifying system or security issues in the long run. Learn how to perform a firewall audit.
7. Scans for vulnerabilities
Some firewalls can also scan weaknesses in your network’s connected devices. This allows the firewall to alert you of outdated or misconfigured software.
They can also integrate with other vulnerability scanning programs to give you an idea of your network’s security position.
This isn’t all, though. Since firewalls can also analyze the severity of your vulnerabilities, you’ll be in a better place to prioritize important security upgrades or changes in the future.
What doesn’t a firewall do?
While a firewall is an important part of a security system, it is still just a part. It’s far from the only type of network security protection you need.
For example, you should have good antivirus software to protect your network. Antivirus software protects against malware by detecting and removing harmful files that the firewall doesn’t block. Firewalls only inspect network traffic, and malware hiding within applications, files, or devices may go undetected.
Skilled hackers can also slip through a firewall’s guard by using port hopping, spoofing, and other sneaky techniques to deliver malicious payloads. All these tricks can fool the firewall into believing that a hacker is transferring legitimate data packets from trusted sources, ports, or protocols.
Along with a firewall, antivirus software creates a layered defense, constantly monitoring your system for threats that pass through the firewall.
These are just two of the most important technologies to use when you are setting up network security — a firewall is one of several layers that play an important role in keeping your devices and personal data secure. Here are some of the other common tools people use:
- Anti-phishing software: Blocks malicious websites, links, and content.
- VPN: Encrypts and secures your connection by masking your online activity and covering your IP address.
- Antivirus software: Defends against malicious software by scanning individual files, downloads, applications, and network traffic.
- Intrusion detection system: Filters network traffic to protect against cyber hackers by blocking them before they can enter your system.
Installing a firewall in combination with these solutions can protect you from online scams, attacks, malware, tracking, and sensitive data extraction.
SEE: Learn about common network security configuration mistakes.
There are also limitations of firewalls to be aware of:
- Firewalls may block legitimate traffic.
- Firewalls may fail to catch harmful traffic or alert you about threats.
- Misconfigured firewalls can create new vulnerabilities.
- Overly restrictive firewall rules can negatively impact user experience.
Firewalls for consumers are typically easy to install and require minimal configuration. There are many different types of firewalls. I would recommend using one that fits your confidence level with computer networking. Setting rules for firewalls is certainly something you can teach yourself how to do, but as I mentioned, misconfigured firewalls can cause a host of problems or accidentally open the door to hackers.
Firewalls for businesses manage and monitor network traffic on a larger scale, protecting against external threats while supporting advanced features like intrusion detection/protection and deep packet inspection. Unlike consumer firewalls, which typically secure single devices or small home networks, business firewalls are designed to handle high traffic volumes and support complex networks.
However, even powerful business firewalls are only one piece of an effective network security strategy, which should also include endpoint protection, employee training, and regular system monitoring to guard against evolving cyber threats. Learn more about how to secure a network and the best network security tools available today.
