[cups.general] Appropriate permissions for printer device files?

[Michael Sweet]

Stefan Fiedler wrote:
> Hi all!
> 
> CUPS 1.2.5 works with my USB printer (a Canon S400) only if permissions on the 
> respective device file (/dev/usb/lp0) are changed from
>     crw-rw---- 1 root root 180, 0 2006-11-04 23:13 /dev/usb/lp0
> to
>     crw-rw-rw- 1 root root 180, 0 2006-11-04 23:13 /dev/usb/lp0
> 
> Now I don't want the device to be read-/writeable by everyone; but running 
> cupsd and the backends with setuid (root) permissions instead doesn't work.
> 
> CUPS 1.1.x worked "out of the box" without changing any permissions, although 
> I can't see any obvious differences in file permissions between the two 
> installations.
> 
> My question: which binaries access printer devices directly and hence have to 
> run with setuid root, or is there another solution to this problem?
> Please note that I'm interested in all CUPS binaries that access printer 
> devices, not only USB devices, if there is more than one.

You can either chgrp the devices to the default CUPS Group setting
("lp") or chmod the USB backend to mode 700 so that it runs as root.

-- 
______________________________________________________________________
Michael Sweet, Easy Software Products           mike at easysw dot com
Internet Printing and Publishing Software        http://www.easysw.com