What is a Firewall?
Firewall is a computer program (either on hardware or software, but usually running on a server or user computer) that constantly checks each and every network message against predefined rules to determine if it is a threat. This includes examining packet headers, looking at port numbers and ports, assessing the contents of each packet and the source or destination, and more.
Firewalls are critical in protecting the flow of data on private networks from external attacks. In education, firewalls can be used to limit student access to websites that are deemed inappropriate or unsafe for their age group. In the enterprise, firewalls can keep employees from being distracted by online advertising, gaming, social media, and other platforms that are not necessary for their jobs.
Network firewalls also serve to protect users by ensuring that the devices they are connecting from are secure. This can be accomplished by requiring multifactor authentication and limiting who can make changes to the firewall configuration. Firewalls can also be set to require users to change their password frequently to reduce the risk of cyberattacks on their device and ensure that it is updated regularly with the latest security patches.
The most common type of firewall is the packet filter, which operates as a sentry at the border. It examines each packet of data to see if it matches a certain rule, such as “Any employee from the Human Resources department cannot access data from the code server.” In contrast, stateful inspection maintains a record of existing connections and uses that history when assessing new network traffic requests. This allows for more detailed and accurate security assessments than packet filters can provide.