A "diode" is not an air gap. If there is any flow in either direction, you don't have an air gap. This isn't hard to understand.
Last I checked, light does indeed cross gaps of air, so "air gapped" is at least more appropriate than your comment.
Creating a bespoke data diode for air‑gapped networks
21–30 of 86 posts
Re: Creating a bespoke data diode for air‑gapped networks
#22Earlier quoted context omitted.
How confident are you that a compromised receiving machine able to send arbitrary voltages on 8 of the 9 pins wouldn't be able to trigger some unexpected behavior on the airgapped machine?
Pretty confident, if the recieving machine is compromised, it is only connected to the opto coupler, that ensures only one way traffic, on one pin. Somehow you would have to get a receive pin to transmit, and then get through the opto coupler and then it just hits a pin that's designed to only send data.
Pins on modern hardware like that are all bidirectional you set the direction in software normally.
Re: Creating a bespoke data diode for air‑gapped networks
#23A "diode" is not an air gap. If there is any flow in either direction, you don't have an air gap. This isn't hard to understand.
Last I checked, light does indeed cross gaps of air, so "air gapped" is at least more appropriate than your comment.
By that logic, an open wifi router would be considered air gapped, n’est pas?
Re: Creating a bespoke data diode for air‑gapped networks
#24A "diode" is not an air gap. If there is any flow in either direction, you don't have an air gap. This isn't hard to understand.
Unless the mossad is after you one way light based coms may as well be
Re: Creating a bespoke data diode for air‑gapped networks
#25Could've used a speaker and microphone with an appropriate noise-resistant digital encoding.
I think the benefit of a discrete optocoupler is in keeping the communication point-to-point, so no other device (malicious or otherwise) can "listen in". A low-power light signal won't penetrate a solid enclosure; it's much harder to prevent mechanical vibrations from leaking information beyond the coupler - you'd need to keep the speaker and microphone on some kind of suspension (springs and shock absorbers) acting as a low-pass filter.
Re: Creating a bespoke data diode for air‑gapped networks
#26A "diode" is not an air gap. If there is any flow in either direction, you don't have an air gap. This isn't hard to understand.
yes, but if your adversary is capable of exploiting a one-way diode to RCE, you might as well just give up.
Re: Creating a bespoke data diode for air‑gapped networks
#27Earlier quoted context omitted.
Pretty confident, if the recieving machine is compromised, it is only connected to the opto coupler, that ensures only one way traffic, on one pin. Somehow you would have to get a receive pin to transmit, and then get through the opto coupler and then it just hits a pin that's designed to only send data.
Pins on modern hardware like that are all bidirectional you set the direction in software normally.
Ohhh that's a good point, you can set the Rx pin to Tx, then it still has to get through the opto isolator, and then it's talking to a port that's set to Tx.
Re: Creating a bespoke data diode for air‑gapped networks
#28I don't see how this is airgapped. You literally connect a full Pi to the RXing computer. What audit has RX Pi device gone through?
Two separate networks, completely isolated, the only bit connecting the two is the opto coupler. Was all audited by their internal sec department. They are happy, it was an interesting problem, they need a bunch of seriously old kit well away from their network, so put it on its own isolated network, but then they realised they also wanted to get some info out of the old kit. Therefore this project was launched. Luck…
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Re: Creating a bespoke data diode for air‑gapped networks
#29A "diode" is not an air gap. If there is any flow in either direction, you don't have an air gap. This isn't hard to understand.
Whether you want to define it as a true air gap or not, this is effectively how most "air gapped" clouds work, with diodes.
Re: Creating a bespoke data diode for air‑gapped networks
#30Earlier quoted context omitted.
Very curious what the hinted at issues were with using regular unidirectional serial before introducing the pair of Pis.
The problems was all my fault :-) I was trying to use a port that was not designed for serial data. When data was sent across it was getting mashed. I think it's because both ports were not uart, therefore when the binary data was sent if they were not perfectly in sync it would get mashed, I might have been able to solve it by sending a clock as well. But the easier option was to just change everything to the uart p…
It was probably due to the lack of flow control. Serial doesn't work well when it's one-way. I did something similar to send logs waaaay back in the day, and it would constantly flip bits or send characters out of sequence, etc. I had to transmit very slowly to get it to work stably without any flow control. I want to say that I limited it to 9600 kbps before it started to become reliable.