Improvements in intrusion detection are disclosed by providing integrated intrusion detection services. Preferably, these services are integrated into a system or server that is the potential target of attack. Stack-based security processing is leveraged for access to cleartext data within the layers of the protocol stack. Layer-specific attacks may therefore be processed efficiently. Evaluation of incoming traffic for an intrusion is preferably performed only after an error condition of some type has been detected. This approach reduces the overhead of intrusion detection by reducing the number of packets to be inspected, and at the same time allows more efficient packet inspection through use of context-specific information that may be used to direct the inspection to particular candidate attacks. Generic attack class capability is also disclosed. Intrusion detection policy information may be used to direct the actions to be taken upon detecting an attack.