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Re: limiting access



On Sun, Aug 20, 2000 at 01:34:04AM -0800, Ethan Benson wrote:
> On Sun, Aug 20, 2000 at 02:11:00AM -0700, kmself@ix.netcom.com wrote:
> > 
> > As suggested, the restricted shell.  Invoked with rbash or bash -r.
> > 
> > This doesn't allow changes to $PATH, users can't cd, and a number of
> > other restrictions exist.  You *have* to either point users to a system
> > directory with commands they can use, or create a commands directory for
> 
> but you can't really include /bin or /usr/bin without allowing the
> user to trivially break out of the restricted shell:
> 
> if /bin is in the $PATH then they need to only run `exec bash' to get
> a real shell without restrictions.  if /usr/bin is in the path they
> can run chsh -s /bin/bash and logout and relogin to get a real shell
> (or passwd -s /bin/bash) 
> 
> really you have to only have ~/bin in thier PATH and create
> appropriate symlinks or shell wrappers to the real binaries.

If it wasn't apparent, this was the sort of configuration I was
advocating.  An alternative would be to have some sort of an "rbash/bin"
directory someplace which all restricted users could be pointed at.
You'd want to avoid including, for obvious reasons, /bin, /usr/bin, or
administrative commands.

-- 
Karsten M. Self <kmself@ix.netcom.com>     http://www.netcom.com/~kmself
 Evangelist, Opensales, Inc.                    http://www.opensales.org
  What part of "Gestalt" don't you understand?   Debian GNU/Linux rocks!
   http://gestalt-system.sourceforge.net/    K5: http://www.kuro5hin.org
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