What is a Firewall?
Firewalls safeguard networks and prevent cyber attacks by establishing a border between your internal systems and outside threats, examining all data packets that enter and leave your computer network. The firewall checks each packet to determine its legitimacy and whether it should enter the protected system using a pre-configured set of rules. If it does not match the rules, a packet is dropped and cannot enter.
Firewall technology comes in several forms, ranging from basic packet-filtering to advanced next-generation firewalls with enhanced features. Choosing the right firewall solution for your network requires a full understanding of your organizational needs and security objectives. It is also imperative to regularly review and adjust settings to prevent unintended openings for attackers.
Like a wall around a castle or city, a firewall establishes a boundary to protect your internal network. The firewall monitors incoming and outgoing data packets and grants access to users or devices based on a set of criteria. This includes filtering based on source and destination IP addresses, ports, packet protocols, and more. A firewall can even block unauthorized traffic like viruses, denial-of-service attacks, macros, remote logins, and spam.
The firewall can be compared to a guard at a gate. It looks at each person entering or exiting, evaluating where they came from and where they are going and if it is safe to admit them. The firewall works in much the same way, evaluating each incoming/outgoing data packet and deciding whether it should be accepted, denied, or dropped (delivered back to where it originated). Modern firewall solutions include stateful inspection, DNS security, and other innovative capabilities that help to defend against advanced threats.