Strange permissions on mounted dvd

Nils Kassube kassube at
Wed Dec 24 07:55:35 UTC 2008

Derek Broughton wrote:
> Jonas Norlander wrote:
> > 2008/12/20 Jonas Norlander <jonorland at>:
> >> $ ls -l /media/
> >> lrwxrwxrwx  1 root       root          6 2008-11-20 19:06 cdrom ->
> >> cdrom0 dr--r--r-- 30 4294967295 4294967295 3024 2008-08-02 11:17
> >> cdrom0
> >>
> >> See that strange owner and group id on the mountpoint?
> >>
> >> $ LANG=C ls -l /media/cdrom0/
> >> ls: cannot access /media/cdrom0/20 Golden Love Songs Vol.1 (2007) -
> >> Easy Listening: Permission denied
> >> ls: cannot access /media/cdrom0/A Tribute To Abba (metal):
> >> Permission denied <snip>
> C'mon, Jonas - do you really expect us to HELP you listen to Abba? 
> Friends don't let friends do Abba :-)


> I _have_ seen things like this before.  Mostly they happen when
> somebody copies filesystems from one machine to another, but they can
> also happen if a user/group has been deleted.
> Check that he actually has a group "cdrom".  If not, it's easy - just
> create "cdrom" as group 30 (not that I really think it should be owned
> by cdrom - mine has root - but I'm sure it would work).
> if that doesn't work, look in /etc/udev/rules.d for anything to do with
> cdrom.  This is where the symlink from cdrom to cdrom0 and the
> permissions should all be being set.

The problem seems to be wrong permissions on the DVD media, not from udev. 
I have checked the commercial DVDs I have and a home made one (made with 
DeVeDe). They all have the same UID/GID 4294967295/4294967295 which is 
just the highest available 32 bit unsigned integer (2^32-1). As there is 
no user known with that UID/GID, ls just shows the number. But all my 
DVDs had permissions dr-xr-xr-x not dr--r--r--. As root doesn't care 
about the missing x bit for directories, the "sudo ls" command was 
successful. Now the question is what type of DVD is it? Is it a 
commercial one or home made? If it is home made, what program was used to 
create it?


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