USB external disk write permission. What have I done wrong?

[Karl Larsen]

Rashkae wrote:
> Derek Broughton wrote:
>   
>> Karl Larsen wrote:
>>
>>     
>>>     Well I KNOW you can chown from the /dev/ address because I did it on
>>> MY USB hard drive. Worked fine and did not stop automount. Where do you
>>> get your info that it is risky to use /dev/???
>>>       
>> On a single user system, it probably isn't that risky.  You either have
>> access to a device, or you don't and then you want to change either
>> permissions or ownership.  But as a general principle, somebody went to
>> some trouble to decide what the ownership of every device should be, and
>> when you change that, you risk preventing other users from accessing the
>> device.
>>
>> On top of that, changing permissions or ownership of /dev nodes with chown,
>> chgrp and chmod is purely temporary - those settings are made by udev, so
>> unless you change the relevant udev rule, they get reset when you reboot.
>>     
>
> chaning ownership on /dev devices will also give users write permission
> on the raw device.. This is generally bad, since there is little reason
> why a user should write directly to the device.  You need to do so as
> root to format or otherwise do low level service to the device, but in a
> sane world, normal processes should not have permission to modify a file
> system device outside of the file system layer.  Especially when said
> file system might be mounted!
>
> And where I get my info?  (yes I know Derek, this is Karl, sorry I'm
> replying in your reply).  My gods man, you got some balls asking me that
> on this list.
>
>
>   
    The real point to all this is when you get to the point of adding 
the file system. To get mkfs.ext3 to work you must use the /dev/ address 
AND unmount the USB connection. Then run mkfs. While there you can do 
all the other stuff.

Karl


-- 

	Karl F. Larsen, AKA K5DI
	Linux User
	#450462   http://counter.li.org.
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