Firewall

A firewall monitors, and sometimes blocks, incoming and outgoing network traffic. Organizations establish security rules that dictate whether a firewall will permit or deny specific traffic based on its source address, source port, destination address, and destination port. Firewalls have been a first line of defense in network security for over 25 years, establishing a barrier between a secured and controlled internal network and an untrusted external network, such as the internet.

Modern firewalls such as Firewall-as-a-Service (FWaaS) are more sophisticated, offering additional functionality such as encrypted traffic inspection, intrusion detection and prevention systems (IDS/IPS), and the ability to identify and control applications.