[plug] X over a Modem

[Peter Wright]

On Wed, Jun 21, 2000 at 03:55:28PM +0800, Kenworthy Family wrote:
> Brad Campbell wrote:
[ snip ]
> > learn. Now I need to do some homework on X over ssh. Does anyone
> > know if there is a compression protocol for X? Maybe to speed
> > it up a little over a slow 33.6k link? I guess if both modems
> > have compression enabled it removes the need for this anyway..
> 
> Try using VNC instead - its faster and somewhat more secure, and can
> also be run thru an ssh tunnel for good security.

I'd certainly echo Bill and recommend you try VNC if you haven't. It
may not be suitable for what you're trying to do, but it's a good
thing to keep in mind for the many situations where X is not
appropriate.

[ snip ]
> not the session traffic.  The speed advantage over X is mostly due
> to smart caching of X commands - they suggest that thru ssh may be
> faster as most encryption programs also perform a degree of traffic
> compression (not sure if that is the case or not for common ssh
> implementations - someone else may have experience there).

Or alternately :), you could use a program that has been specifically
written for compressing X traffic, dxpc.

http://www2.linuxjournal.com/lj-issues/issue53/2374.html

A snippet from that article:

| DXPC stands for Differential X Protocol Compression. It is a small
| client/server program that runs on both sides of a low bandwidth link
| (e.g., 28.8K modem PPP link), and is designed to exploit ``features''
| in the X protocol to speed up the remote display of applications
| across the link. It is capable of compressing the X messages as much
| as 10:1. However, not all messages receive such great performance.
| Some messages are not compressed at all. On the average, you can
| expect as much as 4:1 compression. This sweet little jewel was
| originally written by Brian Pane and further developed by Zachary
| Vonler.

Homepage is at http://www.vigor.nu/dxpc/

I haven't use it myself for a couple of years I think, but when I
_did_ use it (over a 28.8k link), the speed difference was truly
astounding. Remote X suddenly became quite usable. :)

I'm sure using a ssh tunnel (for either X or VNC) probably provides
reasonable compression too, but I doubt it could approach something
that was specifically written for the purpose of compressing the X
protocol.

Maybe you could even tunnel a dxpc link through ssh if you wanted to
go really over the top... *grin*

[ snip ]
> > Brad....
>
> BillK

Hope that proves useful.

Pete.
-- 
http://cygnus.uwa.edu.au/~pete/

--
hundred-and-one symptoms of being an internet addict:
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