What Is a Firewall?
Firewall: Part barrier, part screening mechanism, firewalls regulate incoming and outgoing data to strengthen your cybersecurity defenses against hacking and other threats. Learn what a firewall is, how it works to prevent data breaches, and the different types of firewalls available for businesses.
A firewall is a piece of software that examines snippets of information (data packets) that travel to and from a device on the internet. It looks at the packets to determine if they match predetermined rules and then allows or denies them based on the results. This enables it to stop unauthorized access to networks and limit the impact of malicious code or malware on your systems.
There are multiple types of firewalls, categorized by their level at which they operate and the way they filter data packets. First-generation firewalls, also known as packet-filtering firewalls, operate at the OSI network layer and look at individual data packets to identify them based on their source and destination. This type of firewall is limited in its ability to detect malicious content, however, since it only checks the data packets themselves without evaluating the context that may be attached to them.
Next-generation firewalls, on the other hand, are more sophisticated and operate at the application layer. They monitor applications and network traffic to look for suspicious behavior like SQL injection or cross-site scripting, as well as to evaluate the level of security risk associated with each. They are capable of identifying and stopping complex attacks, including zero-day threats, and can improve performance by reducing firewall rule sets.