restricted shell

[Mikkel L. Ellertson]

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On 10/16/2011 08:06 AM, Don Quixote de la Mancha wrote:
> 
> Chroot is great for securing certain kinds of things, but if the
> intended user is an administrator, he won't be able to administer any
> of the files outside of his chroot jail.
> 
> I'm pretty sure bash doesn't provide a facility like this, but there
> should be a different shell that does.
> 
> A simple hack that would work for any shell would be to remove the
> "others execute" permission from all of your executable programs,
> other than the commands you want him to be able to use.  You will also
> need to place him in his own group.
> 
> chmod o-x
> 
> will do it.
> 
> But some daemons run as unpriveliged users, either their own username
> or as "nobody".  You will need these daemons to be in a group that can
> run the commands.
> 
> Wholesale alteration of executable permissions could break your system
> in a big way, though.  The permissions might get reset by software
> updates.  It's probably best to keep looking for a shell that does
> what you really need.
> 
You may want to look at the -r option of bash, or bash invoked as
rbash. Unfortunately, there are ways to get around the restrictions
of rbash, or most other restricted shells.

Mikkel
- -- 
  Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!
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