Security & privacy

Firewall

The short version

A firewall checks data moving into or out of a network and uses rules to allow or block connections.

A gate for online connections

Like a guarded gate, a firewall checks connections against rules. It might let people open a website while blocking direct access to its customer database.

A web application firewall (WAF) checks requests to websites and APIs for signs of attack.

Firewalls need other safeguards

A firewall cannot fix flaws in an app and may not stop someone using a stolen password. Old rules can also leave openings. Teams still need sign-in checks and software fixes.