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Message-ID: <20021029220638.10157.qmail@web20804.mail.yahoo.com>
Date: Tue, 29 Oct 2002 14:06:37 -0800 (PST)
From: Brian Genisio <briangenisio AT yahoo DOT com>
Reply-To: brian AT genisio DOT org
Subject: SSH Tunneling and TCP_NODELAY
To: cygwin AT cygwin DOT com
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Content-Type: text/plain; charset=us-ascii

Hi all,

I am using SSH port forwarding on a linux sshd from the Cygwin ssh.  Both sides
have version OpenSSH 3.4p1.  There is no problem with my tunneling, as I have
been using many (about 10) port forwards (server and local) for quite some time
now.

A new application has been introduced to my mix that uses the network to send
control messages at about 30 times per second.  These messages are small (4-12
bytes), but sent at a frequent rate.

If port forwarding is NOT used, the control stream is working well.  BUT, if I
send the control string through the SSH tunnel, it gets sent as bursts... for
example, the receiving application wukk get no data for 5 frames, and the 6th
frame will get all 6 frames.

This makes for a jerky control of the software.  My control program has
TCP_NODELAY set in it's ouput socket which is why it works properly.  I
_thought_ that openssh starting at version 3.1 had TCP_NODELAY set on it's
forwarded ports (my debug outputs tell me so).  None the less, the bursting
(which I believe is a cacheing at some point) still happens.

My question:

Is there something about the Cygwin version of SSH where TCP_NODELAY doesnt
work properly, or it is a stub function?  Can anyone think of a reason this is
happening?

Thanks,
Brian

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