What does a firewall primarily help protect against?

A firewall primarily helps protect against unauthorized access to a network or individual devices within that network. It acts as a barrier between trusted internal networks and untrusted external networks, such as the internet. By monitoring and controlling incoming and outgoing network traffic based on predetermined security rules, a firewall can effectively prevent unauthorized users or malicious software from gaining access to sensitive data and systems.

The functionality of a firewall is crucial in safeguarding network resources from external threats, which is a significant aspect of overall network security management. It ensures that only legitimate traffic is allowed through and blocks potential intruders, making it an essential component of any secure networking strategy. This focus on controlling access is what makes the option of unauthorized access the correct choice for what a firewall primarily protects against.