summary [was: vnc and security]

Jeff Walker jwalker "at"
Tue, 19 Jun 2001 16:09:08 +0000

> -----Original Message-----
> From: W. Brian Blevins [mailto:brian.blevins "at"]
> Sent: Tuesday, June 19, 2001 8:05 AM
> To: jwalker "at"; ATT Email List
> Subject: Re: summary [was: vnc and security]
> Jeff,
> > Date: Mon, 18 Jun 2001 12:05:41 -0600
> > From: Jeff Walker <jwalker "at">
> > Subject: summary [was: vnc and security]
> > 
> > First of all, thanks for the help, I didn't really find an 
> acceptable
> > solution, but here is what I found.
> > 
> > - -Seems like the Tridia version of the viewer seemed to 
> have a problem taking
> > the "-encodings" flag, but the AT&T version did fine.
> What exactly was the problem with the Tridia viewer?  I have tested it
> extensively, including reviewing server logs to get an idea 
> of the level
> of compression afforded cersus CPU time used.  I'm not aware of any
> problem with the "-encodings" parameter.

Looks like the problem with the Tridia viewer was me.  I tried it again and
didn't have any trouble, so I don't know what the problem was.  Sorry for
the false error report.

> > - -Looks like over ssh, zlib was the best encoding to use 
> (kinda strange,
> > since I had ssh compression on [low compression])
> To my knowledge, the AT&T viewers and servers do not support 
> zlib.  If you
> specified zlib to an AT&T vncviewer, I would guess it would 
> be ignored,
> resulting the vncviewer default encoding, hextile.
> If you specified zlib to a Tridia viewer when connecting to 
> an AT&T server,
> you probably got some type of unknown encoding error in the 
> server logs,
> because the Tridia vncviewer would have sent the zlib 
> encoding request to
> the AT&T server, which would not have been able to support 
> it.  In this
> case you may have gotten the VNC server or protocol default 
> encoding, which
> is *raw*.

Indeed that was with the Tridia viewer, which is the one I use.  What I did
was use the "connection options..." dialog to change the encoding on the
fly.  (sorry for the lack of clarity)

> A thorough review of the server logs should indicate precisely which
> encodings are rejected and which one is actually used for 
> each connection.
> In addition, the Unix based servers have some interesting 
> compression and
> CPU time statistics output to the log file when each 
> connection closes.

I'm seeing some strange things when I connect by hand to the server.  I
believe I am using the same viewer, but when I connect by hand, I get
"ignoring unknown encoding type", but I am specifying hextile, and that is
what I get.  Strange.  Usually, I use a dos batch program to run the viewer
(the same viewer) with a "config" option and I pass it settings saved from a
previous run.

I guess part of the problem might just be that I don't know what type of
server I am using.  I know that I patched it to fix a problem that someone
on the list gave me, to fix a problem when the mouse cursor moves via an X
app, the vnc was moving it back.  So I am reluctant to use a vanilla server,
but I may experiment with that when I have more time.

> Thanks for the feedback!

Thank you.

> -- 
> Brian
> --------------------------------------------------------------
> --------------
> TridiaVNC, the cross-platform, open source, remote control solution.
>   and

Jeff Walker                   MatchLogic, Inc.
jwalker "at"        7233 Church Ranch Blvd.
Voice 1 (303) 222-2105        Westminster, CO  80021
Fax   1 (303) 222-2001
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