Design and implementation of a network diode

OData support
Dr. Holczer Tamás
Department of Networked Systems and Services

In the computer world, one of the most important field is the network security, because of the great value of the information. Nobody wants his secret data to leak out. This main data is stored on own servers, in private networks, that need high defense. To avoid the leak-out, one solution is to use a data diode. The data diode is an electrical equipment, which allows the dataflow only in one direction. That's why our private network can receive information, but can't send data to the public network.

On the computing market we can buy data diodes, but their prices are extremely high. My task was to build a data diode from cheap components, write drivers to them, and test the speed and reliability of the resulting data diode.

Only an unidirectional dataflow can exist because of the hardware: two Raspberry PIs are connected with an optocoupler. The two mini computers divide the network to two parts: to the sending and receiving networks. The sending network collects data from the public hosts, transmits it through the optocoupler to the other Raspberry, who routes the received data to it's destination in the private network. Due to the physical attributes of the optocoupler, the dataflow in the opposite direction is impossible.

The completed data diode is able to transmit data with high reliability from the sending to the receiving network, and offers complete security against data leaks.


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