Epson scanner lost permissions

[Hansl]

Suddenly I cannot access my Epson Perfection V800 anymore, using Vuescan on LMDE.
sudo vuescan works, so it has to be a permissions problem. (Have had this some years ago, needed then to add myself to group 'scanner' which was not necessary before).
My /etc/group has been changed two days ago, obviously by one of the many recent updates…
Which group do I need to add now? And why? Can't see an obvious candidate.

Hans

[pdc_2]

I am always impressed how capable VueScan is ........ it seems to work for everything; if one were installing it new to your system, I imagine it would cope with whatever is the latest thing that has de-stabilised your scanner;

I just wonder if you remove and then re-install VueScan; there may well be a newer version you could download as well; if it does not update by itself ..... I apologise if this seems an inappropriate suggestion, but I thought to make; the other thing is to email them directly and ask them what to do; they seem very "on to things ........."

[Hansl]

Looking with lsusb, I found my scanner at /dev/bus/usb/003/005 with permissions 664 / root:root .
Changing its group to 'scanner', it works again… till next reboot.
Now what has changed last week?  How do I get my permissions back again?  What were they before?
Funny: another machine with the same current LMDE2/Mate and Vuescan but another Epson scanner still works as usual — have to look after its permissions.

[Hansl]

@pdc_2 Reinstalling / upgrading vuescan did not help — as expected, since Vuescan does make no install or changes to the OS.  One just copies its four files (just 14 MB total) to an arbitrary path, in my case /usr/local/bin.

Yes, Vuescan is very powerful — a bit difficult to understand and master at first, but the best scan software I know.  Unfortunately not FOSS but worth every € (I bought the perpetual Pro version many years ago). There are not many scanners it cannot use, and Ed Hamrick is responsive to bug reports and proposals.

Hans

[Hansl]

Still not working… But I've another different machine with the same current LMDE2, same vuescan and a different Epson scanner (V33) — that machine still works as both used to!
On the “good” machine the permissions for the scanner's /dev/bus/usb/00?/00? are the same root:root rw-rw-r-- except for a trailing plus sign signalling extended attributes. Wow, I wasn't aware that my system has ACLs enabled (turns out that this is standard for ext4) and uses them.
And lo!  getfacl  does show extended permissions as user:<me>:rw- and group:scanner:rw- like needed for it to work.

So — what does set these needed extended permissions on my “good” machine?
And why aren't they set anymore on my “bad” machine?
And how do I get them back again?  Probably some udev rule, but which?