Re: PTY DOS vulnerability?

From: Helge Hafting (
Date: Tue Jul 01 2003 - 14:53:23 EST

On Tue, Jul 01, 2003 at 06:57:49AM -0500, Jesse Pollard wrote:
> One problem is that ptys are not just "used by the user". Every terminal
> window opened uses a pty. As does a network connection.
> As does "expect" - which is less visible to the user since it is intended
> to be invisible.
> The real question is "how many PTYs should a single user have?"
> Which then prompts the question "How many concurrent users should there be?"
> second, just providing a user limit doesn't prevent a denial of service..
> Just have more connections than ptys and you are in the same situation.

Isn't this something a improved sshd could do? I.e. if the
connection using up the last (or one of the last) pty's logs
in as non-root - just kill it.

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