SSH Tunneling and TCP_NODELAY

From: Brian (briang@NOSPAM.OasisAdvancedEngineering.com)
Date: 10/30/02 

From: Brian <briang@NOSPAM.OasisAdvancedEngineering.com>
Date: Wed, 30 Oct 2002 09:02:28 -0500

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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