Q & A: What’s a firewall? Do I need one?

Q: I’m not quite sure what a firewall is. Is it really that important?

A: You probably saw this one coming, but the short answer is: Yes! A firewall is a critical part of your home networking setup, regardless of the network’s size or complexity.

Think of the firewall as a big, blazing curtain of flames with a bucket of water on either side. Data packets sent out through your system to the Internet get dunked before they movethrough the conflagration, passing unscathed. Packets coming into your private network get baptized, too, but first they have to pass a sniff test. The firewall checks to see what doorway they’re trying to enter. If they try to enter through the front, they get dipped, move through the inferno, and arrive unharmed. But data addressed to an entry point, or port, that it shouldn’t have access to — such as traffic trying to push through a port meant for SSH (secure) transfers — bypasses the soaking and gets fried to a crisp.

That’s the simplified description of how the firewall on a consumer router works. The router opens and closes ports automatically to ensure that illegitimate messages arriving at your system’s door meet an impregnable barrier instead of an open gateway.

To be clear, a typical consumer-grade router doesn’t double as a true firewall. A true firewall filters both incoming and outgoing traffic to ensure that any internal systems that may be compromised don’t send out data and intruding systems can’t get data in. Consumer-grade routers typically ignore outbound traffic in favor of a rigid defense against inbound trouble.

There’s a lot more technology within a router that protects against intruders, and we’ll explore it in subsequent posts. Understanding how data gets from point A to point B will help you better configure your own router and networking setup to do exactly what you want it to do — and keep your system and data safe.

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