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What is a Firewall?

When you need a security system to monitor and filter the traffic moving in and out of a network, you need a firewall. These security structures work by applying specific rules, which determine the connections that are allowed vs. the ones that get blocked. 

Internet-connected devices can be reached by other systems that are connected to the same network. A firewall is like a gatekeeper who sits between your device (or network) and the outside world. When incoming traffic arrives on a port, the firewall checks it against its rules and makes a decision on whether or not to let it through. 

Firewalls can be hardware-based, software-based, or both. Your home router likely includes a basic, built-in firewall as part of its hardware, but you may also have protection via operating systems like Windows and macOS. Business and organizational firewalls typically run more advanced security systems that can inspect traffic in greater detail. 

Firewalls can be configured in endless ways. They may be set up to restrict access to certain ports, flag traffic from suspicious IP addresses, or prevent specific types of connections from leaving your network altogether. 

A firewall isn’t going to be successful if it’s your only approach to network security, but it plays a fundamental role in protecting your networks and devices.