User privacy

Tue Feb 16 20:15:45 UTC 2021

Am Dienstag, den 16.02.2021, 19:33 +0000 schrieb Chris Green:
> On Tue, Feb 16, 2021 at 08:02:02PM +0100, Volker Wysk wrote:
> > Am Dienstag, den 16.02.2021, 12:21 -0500 schrieb Robert Heller:
> > > At Tue, 16 Feb 2021 17:37:21 +0100 "Ubuntu user technical support, not 
> > for general discussions" <ubuntu-users at lists.ubuntu.com> wrote: 
> > > > Content-Type: text/plain
> > > > 
> > > > Am Dienstag, den 16.02.2021, 15:54 +0000 schrieb Chris Green:
> > > > > On Tue, Feb 16, 2021 at 04:35:57PM +0100, Volker Wysk wrote:
> > > > > > Am Dienstag, den 16.02.2021, 23:23 +0800 schrieb Bret Busby:
> > > > > > > On 16/02/2021, Volker Wysk <post at volker-wysk.de> wrote:
> > > > > > > > Hi
> > > > > > > > 
> > > > > > > > Am Dienstag, den 16.02.2021, 14:18 +0000 schrieb Ian Bruntlett:
> > > > > > > > > Hi,
> > > > > > > > > 
> > > > > > > > > I'm sorting out an existing Lubuntu 18.04 laptop for a mother and
> > > > > > > > > daughter. At the moment when I run umask I get the result "0002" which I
> > > > > > > > > believe means that different users can read each other's files in their
> > > > > > > > > $HOME directories. They want to stop each other from reading their files.
> > > > > > > > > 
> > > > > > > > > Now I have a rough idea on how to arrange this. I believe a different
> > > > > > > > > umask value has to be specified however I don't know:-
> > > > > > > > > * What value of umask to use
> > > > > > > > > * Where to set that value so that it is set as the default on
> > > > > > > > > bootup/login.
> > > > > > > > 
> > > > > > > > You don't need to touch the umask. Just delete the permissions for "others"
> > > > > > > > on the home directories:
> > > > > > > > 
> > > > > > > > chmod o-rwx /home/HOMEDIR1
> > > > > > > > chmod o-rwx /home/HOMEDIR2
> > > > > > > > 
> > > > > > > > Bye,Volker
> > > > > > > > 
> > > > > > > 
> > > > > > > Is it "others" or "group"?
> > > > > > > 
> > > > > > > I preferred it when it was numbers; the 777 system, so, for example,
> > > > > > > chmod 007
> > > > > > 
> > > > > > It's "others". Each user should have its own private group with the same
> > > > > > name as the user name and only that user in it. So the group ownership or
> > > > > > permissions should not be a problem.
> > > > > > 
> > > > > It always seems to be a rather strange default set-up to configure
> > > > > every new user to have a group of their own.  It makes the whole idea
> > > > > of groups in permissions rather redundant!
> > > > 
> > > > Not at all. You still can create groups, if you want to share something, or
> > > > want to grant access rights to something to specific users. You just don't
> > > > share anything by default. Its more secure this way.
> > > > 
> > > > > It *may* be a good idea to configure things so that, by default, files
> > > > > don't have group read permission (i.e. umask 002, I *think*) but one
> > > > > often *does* want to share files for reading and that requires that
> > > > > users belong to some common groups.  They can then set group read
> > > > > permission on files they want to share.
> > > > 
> > > > Yes, just add a group named "users" with all the users in it. Then they can
> > > > set the group ownership to "users" for files they want to share between all
> > > > users. But they must do so explicitly, and I think this is a good thing. 
> > > > 
> > > > Come to think of it, this also means those users will also have to do
> > > > something with their home directory group membership, when they want to
> > > > share something inside their home directory. If it has been configured to
> > > > exclude "others", as I've advised above...
> > > 
> > > chmod go+x ~
> > > 
> > > (note: not r!)
> > > 
> > > Execute on a directory allows directory traversal, but not read access.
> > 
> > That's right. You need to know the name of the file or directory inside ~,
> > and then you can access it, when its permissions allow it. You could, for
> > instance, create a directory ~/shared, with world read- and lookup (x)
> > rights. 
> > 
> > The problem is, you also can guess names inside the ~, such as .bashrc or
> > bin/... When those don't deny read rights to "others", they can be read...
> > 
> More to the point, does it *matter* if others can read what's there?
> 
> Everyone in the world is welcome to the contents of my .bashrc file,
> I'd love them to be able to learn any morsels of information they can
> find there.
> 
> Default should be *ALLOW* access, hide the bits you think should be
> hidden.  In a work situation I'd have thought nothing should be
> hidden, what part of your work should be hidden from your colleagues? 

I don't mean to say that the .bashrc file is particularly sensitive. It's
just an example of an easily guessable filename. 

I say, the default should be to DISALLOW access, maybe except for in a work
situation. 

It won't hurt to hide the contents of your .bashrc by default, will it? If
it actually will, then make it readable.

Bye,
Volker
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