VNC + VPN + ZA-P = Poor Performance?

[A J]

Hi Seb,

Thanks for the feedback on the performance issue being irrelevant of the 
VPN.  That's one less path to look into.

Here's an interesting wrinkle:  I fired up the browser access method, by 
going to http://machine_name:580x, and performance was fine, even with ZA 
active.  So, something is up with the VNC Viewer for Windows and ZA.

One work around I have found is to disable ZA, fire up VNC, and then 
re-enable ZA.  Most of the time that seems to be ok.  Sometimes I lose the 
VPN connection when I do this, but not always.

Thanks,
Al


>From: Seb Wills <saw27 "at" mrao.cam.ac.uk>
>Reply-To: vnc-list "at" uk.research.att.com
>To: <vnc-list "at" uk.research.att.com>
>Subject: Re: VNC + VPN + ZA-P = Poor Performance?
>Date: Thu, 8 Nov 2001 11:22:06 +0000 (GMT)
>
>Hi Al,
>
>I have exactly the same problem (VNC performance drops massively if
>ZoneAlarm is enabled on the windows machine running the VNC client -- in
>my case no VPN involved). It's the same with Windows 98 and Windows 2000.
>I haven't been able to find a solution, other than disabling ZoneAlarm
>whenever I want to use VNC, which obviously is not ideal.
>
>Do let me know if you get to the bottom of it!
>
>seb
>
>On Wed, 7 Nov 2001, Al Jacoutot wrote:
>
> > Hi,
> >
> > I searched through the archives, but haven't found anything addressing 
>this
> > issue in particular.
> >
> > First, my setup:
> > -- Cable modem into the house.
> > -- Linksys BEFSR41 Firewall/Router/NAT/4-Port-Switch
> > -- Win98 PC running ZoneAlarm-Pro (abbreviated ZA below) SW Firewall
> > -- VNC Viewer ver 3.3.3
> > -- Cisco VPN 3000 Client SW running on this PC.
> >
> > If I run all of the above on my home PC, I can access the office.  
>Telnet
> > and Browser sessions to the office network run fun.   However, if I open 
>a
> > VNC Viewer into any VNC Server (one on a Win 2K machine, one on a Red 
>Hat
> > 7.1 server), the performance is horrendous.  It takes 30 second for the
> > initial screen to load; 10-30 second for subsequent screen updates.
> > Interestingly, the mouse follows along almost at speed.
> >
> > If I turn off ZA, VNC Viewer performance is great.   Initial screen load 
>is
> > 1 second or better.   Interactive response time is virtually 
>instantaneous.
> >
> > Under ZA, I have the VPN IP address, the office IP range, and my local 
>PC
> > loopback IP all declared.   Initially I had to declare the VPN IP and my
> > loopback IP just to get the link to run.   Adding the office IP range 
>added
> > no performance benefit.
> >
> > If I set the resolution down to 8 bit (vs the 24 bit setting on the 
>server)
> > things get a little better, but still nowhere near the performance level
> > when ZA is turned off.
> >
> > Given that telnet and web sessions work fine regardless of whether ZA is 
>on
> > or not, it seems like it's an issue between ZA and VNC only.
> >
> > Has anyone experienced this?  Any suggestions to remedy the situation?
> >
> > (I have submitted the same question to ZoneLabs, but I got a form letter
> > reply.  I'll have to try again with them.)
> >
> > Thanks,
> > AJ
> >
> >
> >
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