openssh PTY allocation
morty at frakir.org
Sun Jul 24 13:16:59 EST 2011
On Sun, Jul 24, 2011 at 11:24:45AM +1000, Darren Tucker wrote:
> Damien already added a config option ("RequestTTY") but there hasn't
> been a release since then (this problem didn't become apparent until
> after the 5.8 release when people used it with the problem devices).
> Specifies whether to request a pseudo-tty for the session. The
> argument may be one of: ``no'' (never request a TTY), ``yes''
> (always request a TTY when standard input is a TTY), ``force''
> (always request a TTY) or ``auto'' (request a TTY when opening a
> login session). This option mirrors the -t and -T flags for
That sounds great. It is indeed one of the two features I asked for.
But I think we still need a second option, in the event that a TTY/PTY
is requested and fails, to decide what should happen. Something like
ExitOnTTYFailure yes|no|no-warn. That way, sites where a TTY/PTY
error is normal for many devices and not catastrophic for other
devices don't need to configure RequestTTY for each device. Instead,
we can just do a:
The above corresponds to the behavior for openssh and ssh.com's ssh1
for many years.
Similarly, sites where a TTY/PTY error is always a problem can just
Only sites with a mixture of devices, some that don't support PTYs and
some where PTY allocation failure is catastrophic, will need to do
per-device RequestTTY. I suspect that the last case will be very
rare. So most of us will be happy with global ExitOnTTYFailure
settings and RequestTTY auto.
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