What role does a firewall play in network security?

A firewall is a crucial component of network security that functions primarily to monitor and control incoming and outgoing network traffic based on predetermined security rules. By inspecting the data packets that are transmitted across a network, a firewall has the capability to block unauthorized access attempts, ensuring that malicious traffic does not infiltrate a system while allowing legitimate traffic to pass through.

This monitoring and blocking mechanism can be applied at various levels, including the network layer or application layer, depending on the type of firewall being used. Firewalls can be hardware-based, software-based, or a combination of both, and they are essential in creating a barrier between a trusted internal network and untrusted external networks, such as the internet.

The other options describe functions that are generally not associated with firewalls. For example, encrypting data, storing backups, or managing user access and permissions involve different specific security measures and tools within an overall cybersecurity strategy. Each of these functions is important, but they do not align with the fundamental role of a firewall in protecting network integrity and preventing unauthorized access.