On 09.07.2008, sulekhasweety@gmail.com wrote:
>
> Dear all,
>
> this is what i have read in the book ubuntu linux unleashed,
>
> if you have a desire to severly restrict what a user can do, you can
> provide him with a restricted shell. to run a restricted bash shell,
> you would use the -r option
>
> ex:- bash -r
>
> then try to do something that you could do as a regular user, such as
> ls -a,
>
> you will then see
>
> bash: ls: no such file or directory
>
>
> now my question is suppose i have my shell restricted, how to make it
> back un restricted ?

You can't. But you can search for a program, which can execute other
programs. If you can't find out the rest, then you don't deserve
unrestricted shell.

--
Secunia non olet.
Stanislaw Klekot

sulekhasweety@gmail.com wrote:
> Dear all,
>
> this is what i have read in the book ubuntu linux unleashed,
>
> if you have a desire to severly restrict what a user can do, you can
> provide him with a restricted shell. to run a restricted bash shell,
> you would use the -r option

You may also want to consider creating a bash with an AppArmor
profile. That will allow you to customize what a user can and
cannot do. AppArmor is not hard to use... but there is a learning
curve.

>
> ex:- bash -r
>
> then try to do something that you could do as a regular user, such as
> ls -a,
>
> you will then see
>
> bash: ls: no such file or directory

That's not a "restriction", that's just not having a PATH
properly setup in the restricted shell.

However, you will find a restricted shell to be pretty
primitive... takes a bit of work to design things to
work in the confines of a restricted shell environment.
Knife cuts both ways... in some ways... I find the
restricted shell to NOT be the answer to anything.

>
>
> now my question is suppose i have my shell restricted, how to make it
> back un restricted ?

Exit that shell and executed a non-restricted shell