Airgapped devices and networks


I can’t help noticing how the term airgapped has morphed over time, and it’s implied security and isolation has been eroded.

In my past life doing process control and SCADA, airgapped meant exactly what it sounds like: a physical space between two devices separated by air or another physical barrier. This wasn’t a security consideration like it is in IT—or at least, not primarily—it was usually the result of two devices or cables being physically or electrically incompatible, or to prevent serious problems with equipment if inadvertently connected. I’m talking about electrical fundamentals like connecting two discrete AC sources, or real-time networks with different protocols.

In IT we mostly discuss airgapped devices and networks as a security feature. A sensitive device deliberately not connected to the Internet would be a classic—and dare I say, increasingly and disturbingly rare—example. The term loses some of its literal meaning when we start talking about wireless networks, and there have been academic examples of using speakers to take control of airgapped devices. But it still ultimately refers to deliberately-isolated gear.

But now I’m starting to see the term employed in the industry for logically separated, as opposed to physical. I’ve seen devices connected over a VLAN, or a VPN, or a separate port on the same NIC, as being described as airgapped in proposals and architecture diagrams. This doesn’t pass mustard for me; a deliberate conflation of two English idioms because that’s exactly what these pseudo-airgapped devices are doing.

While I concede physical separation is no panacea, that airgapped devices can still be attacked in other ways, and VPNs/VLANs/etc are robust and proven, I think we’re losing the meaning of the term using it more broadly like this.

Author bio and support


Ruben Schade is a technical writer and infrastructure architect in Sydney, Australia who refers to himself in the third person. Hi!

The site is powered by Hugo, FreeBSD, and OpenZFS on OrionVM, everyone’s favourite bespoke cloud infrastructure provider.

If you found this post helpful or entertaining, you can shout me a coffee or send a comment. Thanks ☺️.