[Ashly Jackson]

Firewalls are critical components of a secure network infrastructure. A firewall is a security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. According to the text and video materials, there are two main types: network-based firewalls and host-based firewalls. Network-based firewalls protect entire networks, while host-based firewalls protect individual devices.

Characteristics of firewalls include packet filtering, stateful inspection, proxy functionality, and application-layer filtering. For example, stateful inspection tracks the state of active connections and makes decisions based on the context of the traffic, unlike simple packet filtering that only inspects individual packets.

An additional source, the National Institute of Standards and Technology (NIST), emphasizes that firewalls enforce security policies by preventing unauthorized access to sensitive data. This is crucial for security officers to understand, as firewalls are a frontline defense against threats like malware, unauthorized access, and data exfiltration. By implementing properly configured firewalls, security officers help ensure the confidentiality, integrity, and availability of network resources.