What action does Intrusion Prevention take when a packet matches a security rule?

When a packet matches a security rule in an Intrusion Prevention System (IPS), the primary action taken is to drop the packet from the network. This is a critical function of intrusion prevention as it aims to protect the network from potentially harmful or malicious traffic. By dropping the packet, the IPS prevents it from reaching its intended destination, thereby stopping the threat before it can execute any harmful actions or exploit vulnerabilities in the system.

The other options involve actions that are not typical for a functioning IPS when a security rule is matched. For instance, changing the packet's direction is not a common response since it may inadvertently redirect the threat without neutralizing it. Alerting the user about the packet can be part of logging or monitoring activity, but it does not actively prevent the threat from entering the network. Quarantining the packet is more characteristic of endpoint security solutions rather than the immediate actions of an IPS. The primary goal is to take preemptive measures against threats, which is effectively done by dropping the packet.