Поищите что-нибудь связанное с sane.
Файл должен содержать что-то вроде
# This file was automatically created based on description files (*.desc)
# by sane-desc 3.2 from sane-backends 1.0.18 on Mon Jan 8 19:41:55 2007
#
# udev rules file for supported USB devices
#
# To add a USB device, add a rule to the list below between the SUBSYSTEM...
# and LABEL... lines.
#
# To run a script when your device is plugged in, add RUN+="/path/to/script"
# to the appropriate rule.
#
# The following list already contains a lot of scanners. If your scanner
# isn't mentioned there, add it as explained above and mail the entry to
# the sane-devel mailing list (sane-devel@lists.alioth.debian.org).
#
ACTION!="add", GOTO="libsane_rules_end"
SUBSYSTEM!="usb_device", GOTO="libsane_rules_end"
# Hewlett-Packard ScanJet 4100C
SYSFS{idVendor}=="03f0", SYSFS{idProduct}=="0101", MODE="664", GROUP="scanner"
# Hewlett-Packard Photosmart S20 (C5101A) | Hewlett-Packard Photosmart S20xi (C7150A)
SYSFS{idVendor}=="03f0", SYSFS{idProduct}=="0102", MODE="664", GROUP="scanner"
# Hewlett-Packard ScanJet 4200C | Hewlett-Packard ScanJet 4200Cxi | Hewlett-Packard ScanJet 4200Cse_iscan.rules
SYSFS{idVendor}=="03f0", SYSFS{idProduct}=="0105", MODE="664", GROUP="scanner"
и т.д.
А есть файл /etc/udev/rules.d/025_iscan.rules ?