A firewall is an app or a physical device that protects you when you're using a local computer network. It can block attempts to gain unauthorized access to the network, and it can block unauthorized communication by hidden and/or malicious software that's running on your device.
- Do you already have a firewall?Before you buy a standalone firewall app, check whether you already have protection:
- Firewalls in Windows: Windows PCs from version XP onward have software firewalls built into the operating system. The Windows' firewall only attempts to protect you from things getting in, and it does so in silence, so don't feel bad if you've never noticed it.
- Firewalls in Mac: MacOS also has a built-in software firewall. It's disabled by default, but then MacOS doesn't have Windows-grade security concerns in most home-user scenarios.
- Firewalls in routers, modems, and antivirus apps: Almost all home network routers have a built-in firewall, and so do many high-speed modems. Premium antivirus software also frequently bundles a decent firewall.
- Do you need a firewall if you're on public Wi-Fi?
While your home or workplace may be well-protected against digital intrusion, your local coffee shop may not have the best wireless security. Someone may also try to trick you into connecting to an unsafe public wireless network. In those scenarios, it's not a bad idea to have third-party firewall software running alongside or in place of Windows' built-in firewall.
Public Wi-Fi users may also want to consider a VPN, which will create a private encrypted tunnel between you and the website you're visiting. That makes it hard for other people on the public network to snoop on your activities. Check out our VPN buyer's guide. For the best experience, you will probably have to pay a subscription fee to access a VPN designed for personal use.
- Do firewalls fully protect you from malicious websites?While firewalls help protect your local network, a website can still trick you into giving it sensitive information. This is chiefly done by the site masking itself as a legitimate-looking bank or social media site. The URL may also be spelled similarly to the legit website. When you transmit your username and password to log in to an account on the fake website, its owners now have access (unless your account is set up with two-step verification).
- Do firewalls anonymize you on the Internet?A router with a firewall uses a system called Network Address Translation (NAT) so that only the router's IP address is visible to the Internet, rather than the device that's connecting via the router. However, the router's IP address is still assigned by your Internet service provider, which keeps a log of when this IP was assigned and where. So if you want privacy, you'll still need an encrypted connection (indicated by the HTTPS prefix in your browser address bar) or a relay like the Tor network ( Windows, Mac, iOS, and Android).