EmDash00
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Joined: Fri May 17, 2019 1:44 pm

Is it possible to do secure file transfers over USB-TTL?

Mon May 20, 2019 2:22 pm

Basically the question above.

I think it's possible with minicom. Are there other methods?

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thagrol
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Location: Darkest Somerset, UK
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Re: Is it possible to do secure file transfers over USB-TTL?

Tue May 21, 2019 12:39 pm

There are many but it depends on what you mean by secure, what control you have over both ends of the link, and how much you want to do manually.

Unlike a LAN (or the internet) serial is point to point, you don't usually go through multiple devices to get to the other end.

Her's a couple of suggections:
  1. Set up a PPP/SLIP link between the two ends then use any relevant network tool (vpn, sftp, scp, etc)
    • Configure both serial ports with identical settings
    • On the receiving end

      Code: Select all

      cat /dev/serial_port > some_file
    • On the sending end:

      Code: Select all

      cat some_file > /dev/serial_port
  2. ftp. Though that may involve some config on both ends. Don't ask, it's been a couple of decades since I've had to do that.
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hippy
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Location: UK

Re: Is it possible to do secure file transfers over USB-TTL?

Tue May 21, 2019 1:48 pm

thagrol wrote:
Tue May 21, 2019 12:39 pm
Unlike a LAN (or the internet) serial is point to point, you don't usually go through multiple devices to get to the other end.
Generally - and I note your "usually" - but it could be serial over GSM, Bluetooth, or something similar which can be tapped without physical access.

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thagrol
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Re: Is it possible to do secure file transfers over USB-TTL?

Tue May 21, 2019 5:25 pm

hippy wrote:
Tue May 21, 2019 1:48 pm
thagrol wrote:
Tue May 21, 2019 12:39 pm
Unlike a LAN (or the internet) serial is point to point, you don't usually go through multiple devices to get to the other end.
Generally - and I note your "usually" - but it could be serial over GSM, Bluetooth, or something similar which can be tapped without physical access.
Indeed. In those cases I'd go with a PPP/SLIP link over serial and sftp/scp or a VPN on top of that as a minimum if tight security was paramount.

And don't forget good old serial over POTS (Plain Old Telephone System). While that's circuit switched there are plenty of places between the ends it can be (and has been) tapped.

However, most of that won't apply with "USB-TTL".
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