What feature does a firewall provide in network security?

A firewall primarily functions to monitor and control incoming and outgoing network traffic based on predetermined security rules. One of the essential features of a firewall is its ability to filter traffic by TCP/UDP port number. This means that the firewall can allow or block traffic based on the specific ports that communication is using, which helps in permitting or restricting access to certain services. For example, web traffic typically uses TCP port 80 for HTTP and TCP port 443 for HTTPS. By filtering on these port numbers, the firewall can enforce security policies to allow legitimate traffic while blocking potentially harmful connections.

This capability is crucial for protecting the network from unauthorized access and malicious attacks, as it ensures only designated traffic types are permitted based on their port assignment. In doing so, the firewall maintains the integrity and security of the network. Other options, such as encrypting traffic or providing Wi-Fi access, do not characterize the core function of a firewall. Additionally, while IP address filtering is a feature, it is the combination of filtering by IP address and port number that provides a more robust security posture.