How Firewalls Work
Firewalls are the guards that protect our devices and data from unwanted connections. They control what is – and more importantly – allowed to flow in and out of our devices, checking the ID of everything that tries to connect to your computer or home network. Firewalls can be software or hardware, and are a vital part of your cybersecurity toolkit.
Firewall technologies have evolved over the years to meet increasing threat landscapes. Many are now powered by AI and ML algorithms to offer superior anomaly detection, threat intelligence, and adaptive policy enforcement. These new, advanced firewalls are often referred to as “cloud-native” and can be delivered as a service (FWaaS).
How Firewalls Work
Firewals typically have multiple layers of security that operate together to provide comprehensive protection for your device, data, and network. Each layer performs a specific function and works with other layers to detect, block or allow traffic.
The first layer of most firewalls is known as packet filtering, which evaluates the headers of data packets based on pre-defined rules that determine whether a packet should be allowed or blocked. These rules are nested and evaluated in order of priority and are primarily based on communication protocols such as IP, TCP or UDP and their associated ports, or on the source and destination of the data packet.
A more sophisticated technology called stateful inspection is also used by some firewalls to further enhance the protection they can provide. Instead of evaluating data on a packet-by-packet basis, stateful inspection examines the behavior of existing connections and catalogs them over time, allowing for more effective threat detection.