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Message-ID: <20030501153113.91224.qmail@web20809.mail.yahoo.com>
Date: Thu, 1 May 2003 08:31:13 -0700 (PDT)
From: Brian Genisio <briangenisio AT yahoo DOT com>
Reply-To: brian AT genisio DOT org
Subject: Re: SSH tunneling buffers...
To: cygwin AT cygwin DOT com
In-Reply-To: <Pine.GSO.4.44.0305011122070.25128-100000@slinky.cs.nyu.edu>
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--- Igor Pechtchanski <pechtcha AT cs DOT nyu DOT edu> wrote:
> On Thu, 1 May 2003, Brian Genisio wrote:
> 
> > Hi all...
> >
> > I am using SSH to tunnel (Using LocalForwarding ports) from one application
> to
> > another.  The system exists of a controller software in Linux (where the
> SSH
> > server resides), and the actual software in Cygwin.
> >
> > Cygwin connects to the Linux SSH server and sets up a port forward.  The
> Linux
> > app sends a small amount of data (about 12 bytes) 30 times per second.
> >
> > The problem is that the Cygwin/SSH side of the tunnel is buffering the data
> > before it sends it to the Cygwin app.  The result is the data is received
> in
> > bursts, and the control is not fluid.
> >
> > I have tried this system in a Linux to Linux situation, and the buffering
> did
> > not happen.  Also, I have tried sending data from Cygwin to Linux, and the
> > buffering does not happen.  It only happens when data is being sent from
> Linux
> > to Cygwin.
> >
> > I have also tried switching between LocalForward and RemoteForward, and it
> is
> > the dirction that matters, not the type of port forwarding.
> >
> > Both sides sets the TCP_NODELAY flag before it starts sending, and I know
> the
> > SSH code does the same...
> >
> > Any ideas?
> > Brian
> 
> Brian,
> 
> Does "ssh -vvv" show anything that could be related to this?
> 	Igor

Yeah, -vvv tells us that the TCP_NODELAY is being set.

Brian

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