I received a response from S. Geissler at TheImagingSource.
He instructed me to build tiscamera from sources, and then to
    $ sudo cp build/data/udev/80-theimagingsource-cameras.rules /etc/udev/rules.d/
    $ sudo service udev restart
Unluckily, this didn't enable me to take exposures.
Mr Geissler warned me that this woudn't help if my camera was already recognized by the system, and it did, but as a DFx 21BU04 instead of a DMK 31AU03.AS, and, indeed, the suggested procedure didn't change anything.
So, I think this is the end of the story. I'll continue to take videos of the Sun and Moon and, maybe, revive a Windows laptop to take exposures.
Thanks a lot to both of you for having tried to help me.