Final answer:
An intrusion detection system (IDS) is the type of firewall described, which can detect and alert users about suspicious activity as soon as it happens.
Step-by-step explanation:
The type of firewall you are describing is called an intrusion detection system (IDS).
IDS is a network security tool that monitors network traffic for suspicious activity and alerts users or administrators when it detects potential threats or attacks. It can be integrated into a firewall or exist as a standalone device.
IDS is powerful enough to be used by large corporations, as it provides real-time monitoring and can help prevent unauthorized access, malware infections, and other security breaches.