A method and apparatus for verifying the integrity of devices on a target network. The apparatus has security subsystems and a master security system hierarchically connected to the security subsystems via a secure link. The target network includes various intrusion detection devices, which may be part of the security subsystem. Each intrusion detection device generates a plurality of event messages when an attack on the network is detected. The security subsystem collects these event messages, correlates, and analyzes them, and performs network scanning processes. If certain events warrant additional scrutiny, they are uploaded to the master security system for review.