What does a restrictive firewall do?

A restrictive firewall is designed to enhance security by following the principle of least privilege. This means that it prohibits all traffic that is not explicitly permitted through pre-defined rules. In practical terms, this ensures that only authorized communications can occur, reducing the risk of unauthorized access or attacks from malicious sources.

For instance, in a network where a restrictive firewall is applied, an administrator would need to create specific rules that allow certain types of traffic—such as web browsing or file transfers—while all other traffic, by default, would be denied. This contrasts with permissive firewalls, which allow all traffic unless specifically blocked. The approach taken by a restrictive firewall makes it an effective tool for organizations that prioritize security and wish to minimize vulnerabilities.

Additionally, this method requires careful planning and ongoing management, as legitimate traffic may also be inadvertently blocked if not properly accounted for, which underscores the importance of a thoughtful configuration process.