What is a Firewall?
Firewalls monitor, filter, and control incoming and outgoing network traffic based on predefined security rules. They’re the primary line of defense against external threats like hacks, malware, hijacking software, and other cyber attacks. Firewalls are available in both hardware and software form. They can be installed on the perimeter of a network, between different network segments, or even in the cloud environment. The firewall’s rule set is based on a variety of criteria including protocol type, source and destination addresses, port number, and application. Firewalls keep a log of each event and can be updated to cover new vulnerabilities as they emerge.
When evaluating firewall hardware devices, it’s important to understand the unique environment an enterprise operates in and how it will use its firewall. This will help ensure the solution meets and exceeds its cybersecurity needs. For example, consider whether your organization uses multi-cloud, hybrid-cloud, or virtualization technologies, or if you’re looking for a firewall that integrates with advanced security strategies like Zero Trust.
As a general rule, most network traffic is sent via TCP or UDP packets. Each packet has a unique address that indicates where it’s coming from and going to, along with other information like the message content. Firewalls match each packet against its own list of rules and then take an associated action (e.g., permit or deny). In a home network with a simple router and basic firewall, this is usually enough to protect against obvious malicious content like websites with hijacking software and viruses.