Some embodiments are directed to a cross-domain communication system and method. The system includes a data hub connectable to first domain and to a second domain, the first and second domains being isolated from one another. The data hub may be connected independently to the first domain and to the second domain, such that it is able to receive data from the first domain and transmit data to the second domain. The data hub includes a processor, and optionally a data diode, the processor being adapted to inspect packet data received from the first domain, and to run a set of user-defined rules, such that commands are applied to the packet data in accordance with the rules. When a command applied to packet data received from the first domain it creates packet data transmittable to the second domain in real time, such that the first and second domains communicate indirectly via the data hub.