Q: What does a firewall do, and is it something I need to get?
A: In the early days of the internet, we often connected through a dial-up modem or some other form of direct connection.
When you connected in this way, your computer was assigned a public IP address, which meant that it was directly accessible by others on the internet.
It was important to install a software firewall to block direct access to your computer when you were connected to the internet. Popular consumer-focused firewalls such as Zone Alarm also monitored outgoing traffic to alert the user when suspicious activity was detected.
Today, we generally connect through a wired or wireless router, which allows lots of devices to share a single internet connection.
The router also provides hardware-based firewall protection by assigning every device connected to it a local IP address, which is only accessible by other devices on that local network.
Consider it your first layer of protection against unauthorized access from the outside world.
Windows firewall
If your computer is running the Windows operating system, there’s also a firewall built into Microsoft Defender.
It adds an additional layer of protection for inbound traffic, and also monitors outgoing traffic for suspicious activity.
If you want to see if it’s enabled, go to the Settings → Update & Security → Windows Security → Firewall & Network Protection.
You’ll see three different network types listed — Domain, Private and Public — with an indication of whether the firewall is enabled for each one.
Domain networks are when you are part of a business network controlled by an IT department that would generally determine and control whether this firewall is used.
Private networks are those that don’t use domain services and represent the typical home or small business network.
Public networks like those at coffee shops, hotels and airports are where having the firewall enabled is important, since you won’t have the protection provided by your router.
For the best protection when on public networks, it’s best to connect using a VPN (Virtual Private Network).
MacOS firewall
Apple computer users also have a firewall built into the operating system, which can be accessed by going to System Preferences → Security & Privacy and click on the Firewall tab at the top.
If you want to make a change, you’ll need to click on the lock in the bottom left corner and enter your OS password.
Internet security software firewalls
Just about every internet security software program these days includes firewall protection, which can be more sophisticated than the ones built into operating systems.
You can run into some problems if both are running, so you’ll need to specifically search the support section of your product’s website to see whether you need to disable it.
In some cases, your built-in firewall can be disabled during the installation process of your security software, so don’t be alarmed if that happens.
If your computer connects to a business network, it’s important to contact the IT department to discuss changes before you make them, to avoid conflicting security issues.
