openssh PTY allocation

Chris Adams cmadams at
Thu Jul 28 00:16:17 EST 2011

Once upon a time, Damien Miller <djm at> said:
> The problem is a bug in ScreenOS, it refuses pty-req channel requests
> when the tty modes blob exceeds 256 bytes in length. If you want a
> workaround that preserves the usability of the tty, then comment out
> a couple of less-important modes in ttymodes.h and recompile

I hate to say it, but is there any way to get a reasonable work-around
into upstream OpenSSH?  Unfortunately, there are a ton of ScreenOS
devices out there, and even if Juniper fixed the SSH bugs tomorrow, all
those devices won't be updated overnight (if ever).  This will be a
serious irritation for network admins as OS distributions update to
newer OpenSSH versions (where most users get their OpenSSH).

Ideally, it would be something easy to enable on the command line (e.g.
a short option, not "-o WorkAroundBrokenScreenOS=1").  I'd be willing to
work on a patch if there is some hope it might be accepted.
Chris Adams <cmadams at>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble.

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