Abstract: A cross-domain guard is disclosed that includes a field programmable gate array (FPGA). The FPGA includes a rule database containing one or more rules, a memory interconnect configured to send control data or rule processing data, media access control logic, and a plurality of filter engines configured to receive an incoming message and generate a processed message. Each of the plurality of filter engines may contain a message processing allocation element configured to receive and distribute the incoming message, and a plurality of rule processor kernels. Each of the plurality of rule processor kernels includes a rule processor kernel control element, a plurality of data operator kernels configured to perform a data comparison operation, a ternary lookup table processor configured to perform a logic operation based upon a result of the data comparison operation, and a processed message arbiter. A method for filtering incoming messages is also disclosed.