*BSD News Article 93870


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From: j@uriah.heep.sax.de (J Wunsch)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Restricted Shell?
Date: 18 Apr 1997 19:28:39 GMT
Organization: Private BSD site, Dresden
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whuff@airnet.net (Walter Huff) wrote:

> I need to provide a user restricted access to a FreeBSD machine which
> I administer.

Using a ``restricted'' shell for this of work kind is the worst abuse
you could do.  You don't need to give your users a restricted shell
then at all.  If they are stupid, they won't notice the difference
anyway, and if they are clever, they probably won't take more than 15
minutes to circumvent the ``restrictions''.

The restricted shells have been invented to make script systems a
little less risky.  As soon as someone gets an interactive prompt on
it, your bets are off.  I consider them a big security hole, for
giving the admin a warm feeling where he should get a cold shudder.

If you really need to give somebody restricted shell access, consider
the (hard) work of setting up a chroot environment.  Still, he can
abuse the network connections (if there are any), but it's way safer
than what any restricted shell could offer you.

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)