> Both devices run custom scripts designed to handle data transmission reliably rather than quickly. This approach limits throughput, but reliability is paramount for critical monitoring, where losing data is unacceptable. The scripts are finely tuned to ensure that every log entry is transmitted securely without risk of cross-contamination between networks.
This goes through an opto coupler
On the other end there a python script listening on GPIO16, it takes a string of binary data, decodes, checks it's valid, then creates a tagged syslog message. Syslog is configured to forward everything onto a central location for folks to monitor.
Hope that makes sense.
But I guess it's not the same as being asked "where's the air gap" pointing at the optocoupler, and saying "there it is"
In the past I have worked in defence, for highly sensitive stuff they wouldn't even allow a common ground between two networks.
That's why I chose an option iolsator, it ensures the two devices are electrically isolated.
It's overkill for this application, but I wanted to set something up right, and if I ever have another project like this that needs to be more secure, it's ready to go.
I actually agree very much with this. If you're looking for strong assurance that there is no possible back-channel, devices like optocouplers help significantly. It's not hard for me to think of a way to surreptitiously send data backwards through a common ground, or normal silicon diode, or a magnetic coupler like an Ethernet transformer, but optoisolators make it significantly more challenging.