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Date:      Sat, 16 Nov 2002 10:23:19 +0100
From:      Pawel Jakub Dawidek <nick@garage.freebsd.pl>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        freebsd-hackers@freebsd.org
Subject:   Re: tty/pty devices not safe in jail?
Message-ID:  <20021116092319.GR590@garage.freebsd.pl>
In-Reply-To: <200211132001.gADK188f001694@apollo.backplane.com>
References:  <98485.1037216817@critter.freebsd.dk> <200211132001.gADK188f001694@apollo.backplane.com>

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On Wed, Nov 13, 2002 at 12:01:08PM -0800, Matthew Dillon wrote:
+>     Would people be interested if I added such a feature?  Limit the
+>     highest allocatable pty to 90% when operating within a jail?  e.g.
+>     if you have 256 ptys both jail and normal tend to allocate ptys=20
+>     from the bottom up, but the jail would not be allowed to allocate
+>     past pty #227.  This way if a jail eats all the ptys the sysadmin
+>     can still ssh in.

First of all, there is no such limit in main system (not jailed),
so there is always chance to DoS Your machine in this way if You
have not-jailed users. So this isn't a complete solution.
But if there are no free ptys, I log in via:

	% ssh -vC <IP> /bin/sh

--=20
Pawel Jakub Dawidek
UNIX Systems Administrator
http://garage.freebsd.pl
Am I Evil? Yes, I Am.

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