This paper describes an approach to secure previously deployed vehicles by using bus monitoring and segmentation to remove malicious messages from the CAN bus. Modern automotive buses were designed for reliability rather than security. This lack of security means that any node on the bus can transmit a message to any other node and the receiver cannot verify the sender or that the message is unaltered. The intrusion detection and prevention system seeks to solve that issue by actively monitoring traffic on all connected busses, alerting an operator when an error is detected and removing flagged messages from the bus. The system will eventually be installed on an Interim Armored Vehicle (IAV) Stryker.