Subject: Re: xon/xoff, dtr/dsr, cts/rts... help!
To: Johnny Billquist <bqt@update.uu.se>
From: Greg A. Woods <woods@weird.com>
List: current-users
Date: 11/01/2002 16:04:56
[ On Friday, November 1, 2002 at 17:14:37 (+0100), Johnny Billquist wrote: ]
> Subject: Re: xon/xoff, dtr/dsr, cts/rts... help! 
>
> I hope it helps. Obviously, you could have quite a lot of characters
> queued up in ssh and the tcp/ip stack, so that while the xoff sill stop
> any more output from the source, the buffers could hold several thousand
> bytes still pouring out to your terminal. Buffered networks, along with
> delays, really play havoc with xon/xoff. To work properly, it should
> probably be handled locally...

That's exactly why you need to use a full implementation of the SSHv2
protocol when you want terminal flow control to work properly.  The
original design of the SSHv1 protocol had no ability to support terminal
session flow control at all.  SSHv2 on the other hand can properly
handle flow control and interrupts (in much the same way as 'rsh'
normally does) by passing protocol level messages back and forth as
necessary out-of-band from the data channel.  With SSH-3.2, for example
(I haven't really tested OpenSSH) you should get near instantaneous
response from XON and XOFF with data streaming from a remote host (as
good as with any other local application), and an interrupt sent while
output is stopped should also properly flush any output buffered "in the
network".

-- 
								Greg A. Woods

+1 416 218-0098;            <g.a.woods@ieee.org>;           <woods@robohack.ca>
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