> On Mar 17, 2015, at 21:52, German <gentger...@gmail.com> wrote:
> 
> On Tue, 17 Mar 2015 20:39:46 +0200
> Matti Nykyri <matti.nyk...@iki.fi> wrote:
> 
>>> On Mar 17, 2015, at 19:33, German <gentger...@gmail.com> wrote:
>>> 
>>> On Tue, 17 Mar 2015 19:16:42 +0200
>>> Matti Nykyri <matti.nyk...@iki.fi> wrote:
>>> 
>>>>>> On Mar 17, 2015, at 18:11, German <gentger...@gmail.com> wrote:
>>>>>> 
>>>>>> Don't hit your head to a brick wall. A small strace to the login process 
>>>>>> reveals that login set things as you tell it to in /etc/login.defs
>>>>>> 
>>>>>> In this file change the line:
>>>>>> TTYPERM 0600
>>>>>> To:
>>>>>> TTYPERM 0620
>>>>>> 
>>>>>> And your problem is fixed.
>>>>> 
>>>>> Sorry, this didn't fix it
>>>> 
>>>> Yes. Sorry. The mode was wrong:
>>>> 
>>>> TTYPERM 660
>>>> 
>>>> Will fix it, if your screen is setgid tty and ttyX is gid tty. If not then:
>>>> 
>>>> TTYPERM 666
>>>> 
>>>> Will fix it, but also your tty will be world readable. If you don't 
>>>> consider that too big security risk, then just go
>>> 
>>> Neither 660 nor 666 fixed it. Sorry :(
>> 
>> If you have:
>> 
>> TTYPERM 0666
>> 
>> And logout and login. What mode and ownership do you have in you tty 
>> (/dev/ttyX)?
> 
> Ok, Matti, 0666 worked, now I can run screen as a user. Thanks. Do you think 
> I have to try to run it 0660? Will it be less security risk?

Well 0666 = 666. The reason it now worked is because you logged out and then 
back in. This is becaus login program only reads the /etc/login.defs-file when 
you login.

With mode 0666 every user on your computer can read everything (every 
character) you have in your screen (so not much privacy). If you set:

TTYGROUP utmp
TTYPERM 0660

And have:

-rwxr-sr-x root utmp /usr/bin/screen

Everything will also work and you have more privacy.

When /bin/login us run it changes ownership of the tty to the user who logs in. 
Su -l does not do this. That is why the screen doesn't work. ConsoleKit is the 
program that is responsible for many of these permission changes. Do you have 
that installed?

-- 
-Matti




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