What is a firewall?

We’re answering your question, “What is a firewall?”

It’s a tool to help keep cyber attackers out of your home or work, kind of like an air traffic controller for web traffic.

Here’s how it works.

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Firewalls

It sounds like a wall of fire. But a firewall is actually designed to keep fire out.

A firewall in a car, for example, keeps engine fires from burning your legs. On your computer, it blocks dangerous traffic, so — in theory — attackers can’t get through.

How does it work?

Computers send information to each other in packets. The firewall looks at the packets and may say, “Yes, that’s from a good IP address or Internet Protocol address, send it on through.” Or it may say, “No, bad address. It’s blocked.”

Some firewalls go even deeper, using ‘deep packet inspection’ to see what’s actually inside.

Laying Down the Law

You can set up rules for your firewall, deciding what to allow in and what to keep out.

Firewalls aren’t perfect.

For example, you could set up the rules wrong and allow bad traffic in by mistake.

That’s what happened at a group of hospitals in Britain in 2017. A misconfigured firewall allowed a ransomware infection, according to news reports.

One hospital network was shut down for four days and nearly 3,000 appointments were canceled.

In the Capital One hack, the attacker reportedly used a misconfigured firewall to get to credit applications, stealing info for as many as 100 million people.

Security Gaps

You may be watching what’s coming in, but you may forget to set rules to monitor what’s going out, allowing attackers to steal stuff right under your nose.

Also, attackers can find vulnerabilities in some firewalls and get through. Firewall makers often send out security updates to fix them. But people may delay or forget to update or patch, leaving a gaping security hole.

Plus, someone could pummel your system with web traffic in a DDoS — or distributed denial of service — attack to overload your firewall.

Still, experts say a firewall can be valuable, putting a barrier between you and attackers so they can’t burn your place down at will.

Do You Need a Firewall?

If you run a business, yes. At home? Also yes.

You probably already have a firewall in your router.

However, if your router comes from your service provider, some experts say it may not be sufficient. They recommend getting your own router — with a better firewall — and setting it up on your network as well.

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