Abstract: Communication apparatus includes a one-way, hardware-actuated data relay, which includes a first hardware interface configured to receive a command from a communications network and a second hardware interface configured to convey the received command to a protected destination when the relay is actuated. A decoder includes a third hardware interface configured to receive a digital signature for the command from the communications network and hardware decoding logic coupled to verify the digital signature and to actuate the relay upon verifying the digital signature, whereby the command is conveyed via the second hardware interface to the protected destination.

Abstract: Communication apparatus includes a one-way, hardware-actuated data relay, which includes a first hardware interface configured to receive a command from a communications network and a second hardware interface configured to convey the received command to a protected destination when the relay is actuated. A decoder includes a third hardware interface configured to receive a digital signature for the command from the communications network and hardware decoding logic coupled to verify the digital signature and to actuate the relay upon verifying the digital signature, whereby the command is conveyed via the second hardware interface to the protected destination.

Abstract: Communication apparatus includes a one-way, hardware-actuated data relay, which includes a first hardware interface configured to receive a command from a communications network and a second hardware interface configured to convey the received command to a protected destination when the relay is actuated. A decoder includes a third hardware interface configured to receive a digital signature for the command from the communications network and hardware decoding logic coupled to verify the digital signature and to actuate the relay upon verifying the digital signature, whereby the command is conveyed via the second hardware interface to the protected destination.

Abstract: Communication apparatus includes at least first and second communication interfaces, configured for digital communication with first and second nodes. At least one processor is coupled between the communication interfaces, and is configured, upon receiving a message from one of the first and second nodes that is directed to the other of the first and second nodes, to carry out the following actions: when the message contains a command, to convey the command to the other of the first and second nodes; when the message contains status information, to convey the status information to the other of the first and second nodes; when the message contains a response to a command, to discard the response; and when the message contains a query, to block the query from reaching the other of the first and second nodes.

Abstract: Communication apparatus includes a one-way, hardware-actuated data relay, which includes a first hardware interface configured to receive a command from a communications network and a second hardware interface configured to convey the received command to a protected destination when the relay is actuated. A decoder includes a third hardware interface configured to receive a digital signature for the command from the communications network and hardware decoding logic coupled to verify the digital signature and to actuate the relay upon verifying the digital signature, whereby the command is conveyed via the second hardware interface to the protected destination.