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Date:      Fri, 14 Jul 2000 01:35:25 +0100
From:      Tony Finch <dot@dotat.at>
To:        jim@reptiles.org
Cc:        hackers@freebsd.org
Subject:   Re: patch for openssh to work with pty-redir
Message-ID:  <E13CtRt-0006Ga-00@chiark.greenend.org.uk>
In-Reply-To: <20000713182202.C677@reptiles.org>

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Jim Mercer <jim@reptiles.org> wrote:
>
>i was using pty-redir (from netbsd) and ssh to do VPN (ppp over ssh).
>under 3.x release, with the ports/ssh, this worked fine.
>however, starting with when openssh became part of the system, it stopped
>working.
>when i did a "pty-redir ssh remhost /usr/sbin/pppd"
>the openssh would complain:
>"Pseudo-terminal will not be allocated because stdin is not a terminal."
>
>i managed to get it working with the stock openssh using the following patch.
>(yes, it is a quick and ugly hack)

Hmm, I was confused for a while there by your reversed patch, but I know
where we are now :-)

I had a similar problem with user-ppp over ssh talking to an sshd on
OpenBSD.  The problem turned out to be that if sshd gives you a pty then
stdin and stdout are the same bidirectional descriptor (so ppp works)
but if that isn't the case then sshd uses two pipes in a unidirectional
fashion. FreeBSD's sshd (since March in -CURRENT and April in 4.x) has
a tweaked includes.h that doesn't #define USE_PIPES, so stdin is always
bidirectional and ppp over ssh works. If your sshd is compiled in this
way then you shouldn't need pty-redir either (although I can't find
the source to check that it does what I think it does).

Thanks to Brian "ppp over ssh over httptunnel" Somers for the explanation!

Tony.
-- 
f.a.n.finch    fanf@covalent.net    dot@dotat.at
404 the crinkley caress of crenulated crevice clips


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