What is the difference between "active" and "passive" IDS?

Active Intrusion Detection Systems (IDS) and passive IDS differ fundamentally in their approach to threat management. Active IDS are designed to take proactive measures in response to detected threats. This means that when the system identifies a potential intrusion or an attack, it can take immediate actions such as blocking the malicious traffic, alerting administrators, or even reconfiguring network devices to mitigate the threat. This active response enhances the security posture by preventing potential breaches from occurring or escalating.

On the other hand, passive IDS focus solely on monitoring and detecting suspicious activities. They log events and generate alerts for security personnel to review, providing essential data for response and analysis. However, they do not take direct actions to prevent or mitigate attacks. The monitoring capabilities of passive IDS help organizations understand their security landscape and prepare for potential threats, but they rely on human intervention or other security measures to address those threats.

This distinction between active and passive systems is significant for an organization’s security strategy, as it defines the level of automation and immediate response capabilities available in protecting against intrusions.