I'm running ASCII and attempting to get a Canon LiDE 220 scanner to
work. It is fully supported by SANE and I know that others are using
it. I've installed the packages: sane, libsane, libsane-common,
sane-utils, xsane, etc. In /etc/group I have:

        scanner:x:110:saned,haines
        saned:x:112:haines

The problem is that I can't access the device because it has
different device numbers on the bus.

    $ lsusb
      ...
      Bus 001 Device 051: ID 04a9:190f Canon, Inc.
      ...

Only one sg* interface has an ACL (cdrom):

    $ ls -l /dev/sg* 
    ...
    crw-rw----+ 1 root cdrom 21, 3 Jul 20 18:20 /dev/sg3

I go to see what device on the USB bus has an ACL. These two have
them:

    $ ls -l /dev/bus/usb/*/*
    ...
    crw-rw-r--+ 1 root lp   189,  48 Nov 10 11:49
          /dev/bus/usb/001/049
    crw-rw-r--+ 1 root root 189,  51 Nov 10 11:49
          /dev/bus/usb/001/052

Device 049 is my printer, and so I investigate device 052:

     $ getfacl /dev/bus/usb/001/052
        ...
        # owner: root
        # group: root
        user::rw-
        group::rw-
        group:scanner:rw-

So in fact the scanner is Bus 001 Device 052. But this is
contrary to what lsusb says. I appears that I can't access
the scanner because sane has the wrong device number.

The command # scanimage -L simply hangs. When run in authlog I
get:

Nov 10 13:05:15 ... USER=root ; COMMAND=/usr/bin/scanimage -v -L
Nov 10 13:05:15 ... session opened for user root by haines(uid=0)

Otherwise the logs say nothing.