An active network defense system is provided that is operable to monitor and block traffic in an automated fashion. This active network defense system is placed in-line with respect to the packet traffic data flow as a part of the network infrastructure. In this configuration, inspection and manipulation of every passing packet is possible. An algorithmic filtering operation applies statistical threshold filtering to the data flow in order to identify threats existing across multiple sessions. A trigger filtering operation applies header and content match filtering to the data flow in order to identify threats existing within individual sessions. Threatening packet traffic is blocked and threatening sessions are terminated. Suspicious traffic is extracted from the data flow for further examination with more comprehensive content matching as well as asset risk analysis. A flow control mechanism is provided to control passage rate for packets passing through the data flow.