Hardware

Data diodes are based on hardware, so they are immune to remote tampering. Here we provide resources for building your own data diode.

Data Diode With Commodity Hardware

A data diode can be built using fiber-optic network equipment. As shown below, the Ethernet media converter on the left sends data to the media converter on the right. The converter on the right physically cannot transfer data in the reverse direction, since its transmit port is taped over.

Two Ethernet fiber media converters, connected by a fiber-optic splitter. The sender is on the left, and the receiver is on the right. The receiver's transmit port is covered by electrical tape.

As of Spring 2023, the components cost about $80 on Amazon:

2x Cat 6 Ethernet cable
2x Gigabit Ethernet copper to single mode fiber media converter (TP-Link MC210CS)
1x SC/UPC single mode fiber-optic splitter

The splitter’s input should be connected to the TX port of the sender. One of the splitter’s two outputs should be connected to the sender’s RX port, and the other to the receiver’s RX port. Finally, use electrical tape to cover the TX port of the receiver.

Note: At the time these photos were taken, we were mistakenly using APC connectors (green). However, the media converters require UPC connectors (blue). APC and UPC connectors are not compatible. We will updated our photos soon!

Credit: OSDD Project

Data Diode Enclosure

Our lab designed an enclosure to make data diodes portable. Data physically cannot leave the air-gapped laptop, since its wireless radios, speakers, and USB ports are disabled: the laptop can only receive data through the data diode.

An internet-connected laptop connected to an air-gapped laptop through a data diode. The data diode is contained in an enclosure under the air-gapped laptop.

The internals of the data diode enclosure. The data diodes are powered by a USB Ethernet adapter, which also connects the receiver data diode to the laptop.

The enclosure consists of these components:

1x 90-degree USB 3.0 adapter
1x TP-Link USB 3.0 to Ethernet adapter
2x DC 5V to DC 9V converter cable with 5.5mm barrel jack (center positive)
1x Ethernet keystone
4x 3D-printed corners
4x 3D-printed screws
1x 3D-printed Ethernet keystone slot
1x 3D-printed bracket for media converters
6x laser-cut acrylic walls

You should customize the top of the enclosure so that your laptop’s USB port exactly matches the cutout for the 90-degree USB adapter. Currently, the enclosure is sized for a MacBook Pro (13-inch, Late 2013). We recommend attaching your laptop to the enclosure using Command Strips.

Download Parts

You may use our designs to manufacture your own enclosures. If you are a journalist, human rights worker, or public sector employee, we can provide you enclosures at cost. If you are an individual or commercial entity, please contact us for a quote.