What Is a Firewall?
Firewall is a network security tool that filters, blocks, and verifies data packets to prevent threats. It is an integral part of any cybersecurity solution, and can be deployed on-premises or in the cloud. Depending on the product, firewalls can be hardware appliances that plug into a networking infrastructure or software solutions that run on general-purpose and dedicated hardware or virtual machines.
Different types of firewalls filter data packets based on criteria like source and destination IP addresses, port numbers, and packet protocols. Some operate at a single layer of the Open Systems Interconnection (OSI) network model, while others read and filter application protocols like HTTP. The best firewalls combine these features to provide a comprehensive defense against complex and ever-changing attacks.
The first commercially successful firewall technology was the PIX (Private Internet eXchange) firewall from Network Translation Inc., developed in 1994. Recognizing the impending depletion of IPv4 addresses, the PIX firewall was designed to securely connect private networks to the internet using a limited number of registered IPv4 addresses. It later became one of Cisco’s flagship firewall products.
The latest versions of firewalls bolster their capabilities with advanced features such as user identification and contextual machine learning to improve threat detection and prevention. Some feature a Zero Trust architecture to segment and secure IoT devices, while others offer synchronized protection via integrated IPS, ATP, and DTP that works together to stop known and unknown malware threats in real time.