What is the main function of a firewall in network security?

The main function of a firewall in network security is to monitor and control network traffic. Firewalls serve as a barrier between trusted and untrusted networks, allowing only authorized traffic to pass through while blocking potentially harmful traffic. This ensures that unauthorized access attempts and malicious activities are thwarted, thereby protecting the internal network from external threats.

Firewalls operate using predefined security rules that dictate which types of traffic are allowed or denied based on various parameters such as source and destination IP addresses, port numbers, and protocols. By actively managing incoming and outgoing traffic, firewalls help maintain the integrity and security of a network. This capability makes them a fundamental element in any organization's cybersecurity strategy.

Although encrypting sensitive data, scanning for viruses, and backing up data are crucial cybersecurity functions, they serve different purposes and do not directly relate to the core function of monitoring and controlling network traffic, which is the essence of what a firewall does.