Menus for non-Linux users
Jerry Feldman
gaf at blu.org
Mon Sep 9 13:06:48 EDT 2002
I'm not looking to restrict him from commands, just to save him from
learning Linux.
Actually, he was supposed to be setting up a Linux server for hosting the
web pages and the mailing list, but he never got around to it.
On 9 Sep 2002 at 12:54, Derek D. Martin wrote:
> I don't know of any such thing, but I do want to issue a word of
> caution:
>
> Be aware that if your user is clueful, it's virtually impossible to
> write a restricted shell that actually restricts the user to only
> those commands. (I suspect that the reason you want such a thing is
> because your user is NOT clueful, but I'll continue my thoughts under
> the assumption that I'm wrong.)
>
> For a restricted shell to be successful, you must not allow the user
> access to any commands that can be used to get a shell. So for
> example, most editors are out. You must also not allow the user to be
> able to modify their environment, so now the rest of your editors are
> out, and you also need to make their home directory read-only. A
> partial discussion as to why this is the case is here:
>
> http://www.pizzashack.org/rssh/security.html
>
> The attack that I describe here is far from the only one. A user
> might also be able to modify their environment by changing the PATH
> variable, potentially causing an arbitrary program to be run, in the
> event that some program they can run is not specified by full path, or
> is a script which contains commands that are not fully specified. Etc.
>
> - --
> Derek Martin ddm at pizzashack.org
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Jerry Feldman <gaf at blu.org>
Associate Director
Boston Linux and Unix user group
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