dialout group

Lutz Vieweg lvml at 5t9.de
Sat Oct 18 09:48:02 PDT 2014

On 10/18/2014 05:56 PM, Salvo Tomaselli wrote:
> I was showing to my brother in law (who uses ubuntu) how to use subsurface.
> And the device (ttyUSB0) created for his suunto vyper has permissions
> 660 root dialout
> And naturally, subsurface was failing to work because his user didn't belong
> to the dialout group.

Yes, a situation so common that I found it worth addressing in my tutorial video.

> I think that:
> A: subsurface should detect the situation and provide meaningful error, able
> to help users to fix the problem.

I agree - it should be fairly easy to probe the selected device for accessability
even before entering any libdivecomputer function. Displaying some explanatory
text on the situation if access is not granted should be helpful to get people started.

> B: The user should have access to the device, but I am not sure how this
> should work. I imagine subsurface might come with some udev rules. I am not
> very familiar with udev.

This is kind of dependent on the distribution and its security policy - making
every detected device (even very generic ones such as serial devices) readable/writeable
to any logged on user can be a security risk.

But otherwise, sure, most Linux distributions today seem to use udev, some use mdev, and
configuration files suitable for the "detectable" amongst the dive computers
could be provided in distribution specific Subsurface packages.

> I don't know if a similar situation can also happen on other platforms, but I
> would imagine it is entirely possible.

Every operating system that is concerned about security would not just randomly
expose devices to unpriviledged users, I'm sure you'll find the same situation with
NetBSD, FreeBSD etc.


Lutz Vieweg

More information about the subsurface mailing list