Making folders accesible only by password

English Applications
21

On 2013-05-02, Jim Henderson <hendersj@no-mx.forums.opensuse.org> wrote:
> A separate partition for your daughter’s home directory isn’t necessary
> (indeed, nobody sets up a separate partition for each user - traditional
> partition tables can’t handle enough entries for some systems).

IMO, Jim’s solution is the only sensible one. I think an extra partition can be useful in a multiple user setup to have
shared directories accessible via symbolic links created within each respective /home/user/.

22

Actually I only said about a separate partition so *** NOBODY *** logged in on my account could see as long as they didn’t have the root password and that would apply to my daughter as well, even the Windows partition can’t be mounted without the root’s password and that’s something nobody will ever know =]

BTW, what encryption openSUSE uses? Name; type; how secure it is comparing it to others?

23

On 2013-05-02 18:46, Jim Henderson wrote:
> On Wed, 01 May 2013 17:36:02 +0000, amarildojr wrote:
>
>> Actually I thought of a much simpler method: Make a hidden folder. She’s
>> 9yo and I doubt that she will be ever able to find a simple hidden
>> folder.
>
> Never underestimate the ingenuity of children.
>
> Security by obscurity is no security at all.

Yep to both :slight_smile:

> A separate partition for your daughter’s home directory isn’t necessary
> (indeed, nobody sets up a separate partition for each user - traditional
> partition tables can’t handle enough entries for some systems).

I think the limit was about 127 partitions, or perhaps more. The limit
is arbitrary by the kernel, the disk themselves do not have limits on
the number of logical partitions as they are a linked list. Of course,
you need the space :slight_smile:

There was a time when the kernel changed from hda, hdb… devices for
IDE disk to the sda, sdb types when there was a limit of 15 partitions
only, because of the available minor device numbers. I was one of the
people complaining of this, and finally a SUSE developer designed a
kernel modification that was accepted and is in use now, which gives
more or less unlimited logical partition numbers.

I digress, I think - but it is already written O:-)

Oh, I forget: GPT partition tables do have a physical number limit.

> A separate login would suffice - that uses the file permissions system
> and helps ensure separation of content, restricted to each user. That’s
> what it’s there for - there’s no need to go looking for an overly
> complicated and convoluted solution.

Yes, you are absolutely right - but I understood reading it that the
kids knew the root password, which is why I suggested encryption. And of
course, they can reboot the machine with a live Linux system and read
anything they wish: filesytem permissions are only enforced as long as
the machine is physically protected.

–
Cheers / Saludos,

Carlos E. R.
(from 12.1 x86_64 “Asparagus” at Telcontar)

24

On Thu, 02 May 2013 18:56:02 +0000, amarildojr wrote:

> Actually I only said about a separate partition so *** NOBODY *** logged
> in on my account could see as long as they didn’t have the root password
> and that would apply to my daughter as well, even the Windows partition
> can’t be mounted without the root’s password and that’s something nobody
> will ever know =]

You don’t need a separate partition to accomplish that. A partition
isn’t necessarily a barrier for encryption. encfs, for example, is a
FUSE-based filesystem that works at the file and directory level.

> BTW, what encryption openSUSE uses? Name; type; how secure it is
> comparing it to others?

That’s like asking “what filesystem does openSUSE use?” - it depends on
what you configure.

But you’re looking at encryption solutions and overlooking the single
most obvious solution - rather than try to limit permissions using
encryption, consider using the built-in permissions system to accomplish
this. That’s what the permissions system is for.

Jim

–
Jim Henderson
openSUSE Forums Administrator
Forum Use Terms & Conditions at http://tinyurl.com/openSUSE-T-C

25

On Thu, 02 May 2013 20:38:06 +0000, Carlos E. R. wrote:

> I think the limit was about 127 partitions, or perhaps more. The limit
> is arbitrary by the kernel, the disk themselves do not have limits on
> the number of logical partitions as they are a linked list. Of course,
> you need the space :slight_smile:

Traditional partition tables support 4 partitions; if you made all of
them extended partitions, that tops out at 16 (but I don’t think you can
actually do that, I think you have to have at least one primary
partition).

> There was a time when the kernel changed from hda, hdb… devices for
> IDE disk to the sda, sdb types when there was a limit of 15 partitions
> only, because of the available minor device numbers. I was one of the
> people complaining of this, and finally a SUSE developer designed a
> kernel modification that was accepted and is in use now, which gives
> more or less unlimited logical partition numbers.
>
> I digress, I think - but it is already written O:-)
>
> Oh, I forget: GPT partition tables do have a physical number limit.

I was looking at this earlier, and I saw something that said GPT is
limited to 128 partitions.

Jim

–
Jim Henderson
openSUSE Forums Administrator
Forum Use Terms & Conditions at http://tinyurl.com/openSUSE-T-C

26

On 2013-05-02 22:46, Jim Henderson wrote:
> On Thu, 02 May 2013 20:38:06 +0000, Carlos E. R. wrote:
>
>> I think the limit was about 127 partitions, or perhaps more. The limit
>> is arbitrary by the kernel, the disk themselves do not have limits on
>> the number of logical partitions as they are a linked list. Of course,
>> you need the space :slight_smile:
>
> Traditional partition tables support 4 partitions; if you made all of
> them extended partitions, that tops out at 16 (but I don’t think you can
> actually do that, I think you have to have at least one primary
> partition).

No, believe me, there is no limit (for logical partitions). The 16 limit
was for scsi devices on old kernels; as I said, a SUSE kernel dev
changed this and there is no limit now.

You can have just one extended partition (no other primaries), and
inside as many logical as you want. I once did 22 this way:


http://susepaste.org/51338135

That graph of a speed test of a hd.

This person made 204 partitions:


http://lists.opensuse.org/opensuse/2010-01/msg00417.html

I don’t have a link handy to the document that explains how this is
done, bypassing the major/minor number limit. It was a SUSE dev who did it.

–
Cheers / Saludos,

Carlos E. R.
(from 12.1 x86_64 “Asparagus” at Telcontar)

27

You do realize we’re talking about a 9-yo Brazilian child that doesn’t speak the language that the system is installed and she barely knows how to turn the monitor on, right? She WON’T figure out how to unhide folders, she doesn’t even know that exists :smiley:

That’s not security, I just don’t want her to see some folders =) When someone doesn’t have the keys to the Lamborghini that means the car won’t be driven :wink:

28

On Thu, 02 May 2013 22:26:02 +0000, amarildojr wrote:

> You do realize we’re talking about a 9-yo Brazilian child that doesn’t
> speak the language that the system is installed and she barely knows how
> to turn the monitor on, right? She WON’T figure out how to unhide
> folders,
> she doesn’t even know that exists :smiley:

I learned when my kid was 9 never to underestimate him.

> That’s not security, I just don’t want her to see some folders =) When
> someone doesn’t have the keys to the Lamborghini that means the car
> won’t be driven :wink:

A separate account solves that problem and is how the system is designed
to be used.

Jim

–
Jim Henderson
openSUSE Forums Administrator
Forum Use Terms & Conditions at http://tinyurl.com/openSUSE-T-C

29

On Thu, 02 May 2013 21:38:06 +0000, Carlos E. R. wrote:

> I don’t have a link handy to the document that explains how this is
> done,
> bypassing the major/minor number limit. It was a SUSE dev who did it.

Maybe it was a limitation of fdisk, but I hadn’t heard of this being done
before.

Learn something new every day.

Jim

–
Jim Henderson
openSUSE Forums Administrator
Forum Use Terms & Conditions at http://tinyurl.com/openSUSE-T-C

30

Good, I got your point like 10 posts ago =)
I don’t underestimate her, it’s just that it’s impossible that she will learn** by** **herself **how to do this particular operation. In comparison you could install a system your son doesn’t know yet in Chinese or some language he doesn’t know, and ask him to do something that would require him to learn new things. I suppose your son knows way more about computers than my daughter so I’m still correct that she will not learn how to unhide folders, unless you prove me wrong :wink:

31

On 2013-05-03 01:38, Jim Henderson wrote:

> On Thu, 02 May 2013 21:38:06 +0000, Carlos E. R. wrote:
>
>> I don’t have a link handy to the document that explains how this is
>> done,
>> bypassing the major/minor number limit. It was a SUSE dev who did it.
>
> Maybe it was a limitation of fdisk, but I hadn’t heard of this being done
> before.

Just try it, fdisk did manage :slight_smile:

Enterprise people were limited to 15 partitions; home users were not.
I’ll explain :wink:

It was not a limitation of the disks nor of the software: it was a
kernel limitation. Actually, a limitation of the bits available for
devices defined in /dev, the major/minor numbers (one byte for each,
IIRC). See “/usr/src/linux/Documentation/devices.txt”:


8 block       SCSI disk devices (0-15)
0 = /dev/sda          First SCSI disk whole disk
16 = /dev/sdb          Second SCSI disk whole disk
32 = /dev/sdc          Third SCSI disk whole disk

See? There are only 16 minor numbers for the device sda, from 0 to 15. 0
was the complete disk, and the rest the partitions, 14 available in
fact. The limit is arbitrary, because simply using a bigger integer size
would increase the available devices (this was discussed but rejected).
The hardware had no such limitations.

If you have worked a lot in the enterprise with scsi disks, as I
understand, then you would be limited to that number for many years, so
it is understandable that you thought the limit was there.

On the other hand, home users saw different limits: we used IDE disks
which had a different bit distribution:


3 block       First MFM, RLL and IDE hard disk/CD-ROM interface
0 = /dev/hda          Master: whole disk (or CD-ROM)
64 = /dev/hdb          Slave: whole disk (or CD-ROM)

See? Fewer disk names, but more partitions for each (63). Again, an
arbitrary limit.

Now, look at this paragraph hidden in the same doc:


Fourth, remember that Linux now has extensive support for dynamic
allocation of device numbering and can use sysfs and udev to handle the
naming needs. There are still some exceptions in the serial and boot
device area. Before asking for a device number make sure you actually
need one.

....

259 block    Block Extended Major
Used dynamically to hold additional partition minor
numbers and allow large numbers of partitions per device

I don’t have currently that number of partitions, so I can not see for
myself what numbers are actually used.

Learn something new every day.

We all do :slight_smile:

I happen to know about this because I was very interested in the issue.
When the disk drivers were replaced so that names were changed from hd*
to sd* (libata implementation) people like me that were using more than
15 partitions could simply not update our systems and we had to wait.
Many developers argued that nobody used more than 15 partitions, but
many of us were (with IDE disks). Specially beta-testers with many
operating systems in few disks (even one).

Enterprise users, on the other hand, were not affected, they had the
same number of partitions as before.

Fortunately, we managed to convince enough people, and in particular a
SUSE developer did the job, Tejun Heo. See:


Kernel Log: Coming in 2.6.28 - Part 1: ATA support and block layer

> http://www.heise-online.co.uk/open/Kernel-Log-Coming-in-2-6-28-Part-1-ATA-support-and-block-layer--/news/111743

"(...) A number of small block layer patches by Libata developer Tejun
Heo further removes the limitation of a maximum of 15 hard drive
partitions on data media driven via Libata."

http://lwn.net/Articles/303270/
http://lwn.net/Articles/290141/

Date: Wed, 31 Dec 2008 12:56:34 +0100 (CET)
From: Carlos E. R. <>
To: OS-en <opensuse at opensuse.org>
Subject: Re: [opensuse] Are multiple partitions back yet?

> This last article is very interesting; it is from last July, thoug. What
> it does is use dynamic minor limits, asigned on the fly, considering that
> the udev system assigns nodes on the fly anyway: meaning basically
> unlimited number of partitions. The article says it is unclear wether this
> will be adopted by al distros, anyway (the change of names from hdX to sdX
> hurted many), but considering who made the patches and who he works for,
> we'll see them in 11.2 :-D

This was finally implemented in 11.2, not that long ago. :slight_smile:

–
Cheers / Saludos,

Carlos E. R.
(from 12.1 x86_64 “Asparagus” at Telcontar)

32

On 2013-05-03 02:46, amarildojr wrote:
> I suppose your son knows way more about
> computers than my daughter so I’m still correct that she will not learn
> how to unhide folders, unless you prove me wrong :wink:

I did a flight simulator when I was 15, on a TI-57 calculator >:-)

–
Cheers / Saludos,

Carlos E. R.
(from 12.1 x86_64 “Asparagus” at Telcontar)

33

Using a software that was written in your language, right? =]

34

On 5/2/2013 7:46 PM, amarildojr wrote:
>
> hendersj;2553339 Wrote:
>> I learned when my kid was 9 never to underestimate him.
>>
>> –
>> Jim Henderson
>> openSUSE Forums Administrator
>> Forum Use Terms & Conditions at ‘openSUSE Forums FAQ’
>> (http://tinyurl.com/openSUSE-T-C)
>
> Good, I got your point like 10 posts ago =)
> I don’t underestimate her, it’s just that it’s impossible that she will
> learn* by* *herself *how to do this particular operation. In comparison
> you could install a system your son doesn’t know yet in Chinese or some
> language he doesn’t know, and ask him to do something that would require
> him to learn new things. I suppose your son knows way more about
> computers than my daughter so I’m still correct that she will not learn
> how to unhide folders, unless you prove me wrong :wink:
>
>

Do you not have Google in Brazil? Typing “show hidden files” into http://translate.google.com, gives the translation “mostrar
arquivos ocultos”. I do not know Portuguese, so maybe it’s not a good translation. You be the judge. One can have Google
translate each menu item. Is your daughter of normal intelligence? Do any of her friends have access to a computer? Does her
school have computers? As long as you have internet service in Brazil, do not think that information can be hidden from your
daughter. Maybe hidden files will work today and maybe even tomorrow. But, someday they will not. Change your password and give
your daughter her own account.

P.V.
“We’re all in this together, I’m pulling for you” Red Green

35

On 5/2/2013 5:26 PM, amarildojr wrote:
> That’s not security, I just don’t want her to see some folders =) When
> someone doesn’t have the keys to the Lamborghini that means the car
> won’t be driven

I’ve known a number of people that would have your Lamborghini going in 15 sec and chopped up for parts in less than an hour.

–
P.V.
“We’re all in this together, I’m pulling for you” Red Green

36

shortstorywritten* in English

scene1:-
Father:- Nay.nobody will open my file as long as they are hidden. Goes to to get a beer
Child:- Hey what is this stupid folder with a (.) before it(unhidden folder), look like garbage delete
Father:- >:(

scene2:-
Father:- Nay.nobody will open my file as long as they are hidden. Needs to move away from desk as door bell rang
Child:- My friend says “ctrl+H” un-hides folder. Let me try that out. Cool there are indeed some hidden folders on the system. Right clicks and moves to “Trash”
Father:- >:(

scene3:-
Father:- Nay.nobody will open my file as long as they are hidden. Needs to move …from desk
Child:- Let me play some games now that father is away. Deletes some folders and hidden folder is a sub folder
Father:- >:(

sceneN+1:-
Father:- Nay.nobody will open my file as long as they are hidden. …
Child:- Deletes hidden folder… infinite loop
Father:- >:(

…loop again

some people learn only by experience

37

Yes, of course, Google and Internet are available here and that translation is perfectly correct. BUT, she would NOT search for that, for some reasons:

  • She will be distracted playing games / wathcing videos
  • Why would she search for hidden files/folders? All she does is “Can I play that web game?” or “Can I play a Steam game?”. If anything strange happens she’ll call me, because she knows that she’s not supposed to do anything out of ordinary
  • She doesn’t know how to go to translate.google.com, she doesn’t even know that feature exists in fact.
  • She knows I’m the owner of the machine and I’d not let her use it for a period of time if she does anything wrong without asking for assistance.

Now, in the “does she have a normal intelligence” subject yes, she’s one of the best in her class, never misses a day (except when she’s sick) and gets some of the best scores on exams. Now let me explain why she doesn’t use *** MY *** computer at all. I didn’t want to talk about this here, but you leave me no choice. I know this has nothing to do with the forum but the situation is kind of pointing to a direction where I’m starting to suspect some of the users here either can’t read correctly (someone give me a heads up if I’m not expressing myself correctly on my posts) or they know more about my daughter than me. Anyway, let me explain:

Basically, Brazil is living a “dark sexual age”, where children of her age are starting to know and get stimulated about sex, that’s mainly because of our media showing sex scenes in the “Nobel hours” (the time where TV gets more audience, somewhere between 6PM and 11PM), couples getting almost naked and doing pretty much “soft porn”. Not that this is a problem in, maybe, the country you live or some other (families may take better care of their children there), the problem is most parents and media here don’t give a **** what their children are watching, resulting in uncontrolled children that are knowing adult things at the age where they were supposed to be out,playing with toys in the garden, and not thinking about boyfriends or having a fight because some kid is in love with another child. Note that controlled doesn’t mean robots, but making they know that there are some things out there that are for older people and can confuse their heads because they might not be prepared to learn about.
So, some children here in her age are behaving in a way that some prostitutes would be embarrassed, listening to “forbidden funk” (a type of funk where explicit sex/violence lyrics are sang), using drugs, smoking, having sex and etc <<– If you don’t believe, a 12-yo girl said to me: I have a classmate that she had sex with 5 guys, she says she loves it". Tell me how sane that is, and I’m talking about (in my perspective) 70% of young girls.
Funk, from Rio de Janeiro, was not much appreciated in the past, most lyrics talked about how drug dealers kill police or about sex. Now, Funk is everywhere, which is a SHAME since most of them are: “I’ll throw you in bed, take your clothes off and give you a night of pleasure. Now SEAT, SEAT you *****”.

In resume, Brazil is going backwards on evolution, for much reasons: (and these are only regarding minors)

  • Parents are raising their children with no eye on the future at all. Children here are LOOSE and easily manipulated in any direction you want

  • Media is showing sex scenes at those hours I said above (see Balacobaco 05/12/2012 - Sexo entre Isabel e Norberto - YouTube or search for “sexo novela”](http://www.youtube.com/results?search_query=sexo+novela&oq=sexo+novela&gs_l=youtube.3...931.2186.0.2281.11.10.0.0.0.0.67.347.8.8.0...0.0...1ac.1.11.youtube.H9y6D9yzHOg) on youtube)

  • Radios are broadcasting songs with explicit sex lyrics (Funk from Rio, not the good old James Brown one)

  • Children of 16yo and bellow can: kill and form a theft group; and what happens to them: NOTHING. Children that commit that (usually poor and abandoned by their parents) go to a “prison for minors” where the Rio Mafias are dominating, meaning they do a “College of Crime”, or “Phd of crime” as called here. Then, after 9 months they’re free on the streets doing the same things over and over. Why only 9 months? Because who OWNS those prisons are the Mafia Bosses, if the Manager doesn’t obey he gets killed. The same applies to the agents in the buildings, they’re hostages of crime, if you may call that. Brazil is NOT a safe place, specially on Rio, Sao Paulo and some most of the northeastern states where crime rates are high. Just to imagine: Brazil deaths by guns in 2012 were higher than war deaths in Irak, Pakistan, Colombia, Palestine and other, ALL TOGETHE, and this with a restrict gun-ownership where sometimes even police officers have to take their guns back at the station.

All above (and many more) is making a society of young deliberate children who are: making sex too young, drinking too young, using drugs too young and making our country stand as second worst on education in the world (A College degree here stands behind even of a High Scholl in US). Just look at my country and you’ll see no good coming from here, I could write thousand of pages on what isn’t good here, and about 2 lines about what is good.

So, that’s basically why my daughter doesn’t use PC’s or Cellphones too much, I don’t want her having conversations with her friends/classmates because I KNOW these kind of subjects would appear very soon, don’t tell me “No” beacuse I’m the one who lives here long enough to know how kids behave these days. So what do I do? Educate her to:

  • Ask me when she has questions about something strange, and not her friends
  • Behave like a decent human being and not copy what children do on TV
  • Study and play instead of using facebook or any social network (I don’t let her use facebook or etc, but I’m planning to allow that soon as long as I know her password)

This way, using PC’s at school or here, and only, she doesn’t have contact with all said above. I’m raising her this way and it’s been working flawlessly, she does what she wants but she KNOWS ***some ***of the dangers out there. Of course, this is ONLY regarding technology.
We live in the most “Civilized” state, Rio Grande do Sul, in an interior city, away from the big ones. I’ve never been robbed or mugged, nobody plays loud music at night, most people come from Italian families and we’re kind of like country people, except with technology LOL.

Sorry if it was too long, but I needed to pull this out of my chest.

Just letting you get to know her :smiley:

Reading a game package
Complaining about how hot it was that day
At the age of 7
“Exercising” at the park](https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-ash3/14768_474136065968758_302066421_n.jpg)
With Santa, on the age of 3

38

Just to blow your theories to nothing:

  • I install the system in English. She only speaks Portuguese and Italian.
  • Nobody except her and me uses this computer (the only one in our home)
  • She only uses it to: Play games / Watch videos / Do homework.

=)

EDIT: Better. Let me do that, one by one LOL

1 - I don’t drink
2 - Rare to find a person who uses Linux. Only techguys or some advanced users, although I only found 3 in my town using Linux.
3 - She doesn’t browse through folders. If she needs to she asks my help

Your loop won’t complete ATM hehehe

39

Just so people don’t think I live in the woods: (I tried to edit my big post)

http://www.naomaispelo.com.br/admin/uploads/gallery/galeria_379/farroupilha.jpg

http://images02.olx.com.br/ui/11/86/83/1310645415_228168383_1-Apartamento-a-Venda-Farroupilha-Centro-Centro.jpg

http://www.imofar.com.br/vista.imobi/fotos/iimofarim2698_17318.jpg

40

Sorry to break your bubble.English is only of the easiest languages to learn on the face of earth.

I mentioned only part of the story. There are 1000++ scenarios :sarcastic:

Are you really in Brazil. There are (Over 50,000,000 New GNU/Linux Users in Brazil!!!) according to [BIG News] Over 50,000,000 New GNU/Linux Users in Brazil!!! - comp.os.linux.advocacy](http://compgroups.net/comp.os.linux.advocacy/-big-news-over-50-000-000-new-gnu-linu/1762095)