A firewall controls network connections. It decides which traffic can reach your device or leave it, while antivirus focuses on scanning files and programs for malicious code. The two protect different parts of the same system.
Does this affect you?
Use this for Windows PCs, Macs, and home routers, all of which normally include a firewall of some kind.
Understand what a firewall actually does
A firewall is about connection rules, not reading every file.
- It blocks unsolicited incoming connections so random devices on the internet cannot directly connect to services running on your computer.
- It uses rules based on ports, apps, and network types. Web browsing, file sharing, email, and other services use different network paths that can be allowed or blocked.
- Your router provides a network firewall for devices on your home Wi-Fi, while Windows and macOS can run software firewalls on each individual computer.
- It does not replace antivirus. A firewall may block unwanted connections, but it usually will not stop you from downloading and opening a malicious file yourself.
- Modern firewalls can also watch outgoing connections and warn when a program tries to send data to an unusual server.
Think of the firewall as traffic control for connections and antivirus as inspection for suspicious files and behavior.
Check that your firewall is actually on
It is usually enabled already, but a quick check is worth doing.
- On Windows, open Settings > Privacy & security > Windows Security > Firewall & network protection. Domain, Private, and Public networks should show On.
- On Mac, open System Settings > Network > Firewall and turn it on if needed. Some Mac setups leave it off by default.
- On a home router, sign in to the router admin page, often 192.168.1.1 or 192.168.0.1, and look for Firewall or Security. It is usually enabled.
- Do not disable the firewall as a general fix for connection problems. If troubleshooting requires it, turn it back on quickly.
- If a legitimate app is blocked, add an exception for that specific app instead of opening the whole firewall.
More control
The internet is constantly scanned
Automated tools probe public addresses looking for exposed services. A firewall blocks much of that background noise before it reaches your device.
It cannot stop social engineering
If you approve a remote support session, click a phishing link, or install a malicious app, the firewall may not intervene because you initiated the action.
Public Wi-Fi makes device firewalls more important
At home, your router blocks many outside connections. On public Wi-Fi, your computer may be near strangers on the same network, so the device firewall matters more.
Sources
- CISA – Understanding Firewalls for Home and Small Office Use (2025)
- Microsoft Support – Turn Microsoft Defender Firewall on or off (2025)
- Apple Support – Change firewall settings on Mac (2025)