Firewall

What is Firewall?

CISA advises installing a firewall at the boundary of your home network to defend against external threats, and keeping it enabled, since some are off by default. A firewall looks at connections and decides which to allow. Typically it permits traffic that you started and drops traffic that arrives unasked. Software firewalls run on a computer and hardware firewalls run in a router or a separate box.

A firewall is not antivirus. It watches the doors and does not scan files.

Rules can be simple or detailed. A home firewall mostly follows one rule: let replies in, keep unasked visitors out.

Why does it matter on a fixed wireless connection?

Your router's firewall works together with NAT. The antenna and radio on your roof are not a firewall, and the company has not published a firewall feature in its service, so keep your own router's protection on. If you use the wireless link for a small business, a stronger firewall may be worth buying. See secure a small business network.

Port forwards and UPnP rules make holes in a firewall on purpose. See port forwarding.

A business with a card reader, cameras or a shared file server has more to protect than a household with a few phones. Our guide card readers and point of sale notes what to ask your card processor about network setup.

What should I do about it?

Log in to your router and look for a firewall or security page. Make sure it is on, change the default admin password, turn off remote management unless you need it, and update the firmware. CISA lists these steps on its home network security page. The guide secure your home network shows them in order.

An old router that no longer receives updates should be replaced. Read end-of-life routers.