misinformation concerning apple remote desktop

James Weatherall jnw "at" realvnc.com
Wed Sep 6 11:55:00 2006

Hi Alex,

I'm afraid that you are mistaken regarding the issues with Apple's Remote

> However, James also tells someone that 'Chicken of the VNC' 
> is irrelevant because it's a client and people are asking
> about the server. However, for whatever reason, more people
> report success connecting from various versions of Chicken
> to Apple's RDC implementation than any other setup.

The post to which I was responding involved connecting using a viewer
running on Windows XP to a server running Mac OS X - someone suggested
trying Chicken on the Mac, having misunderstood that the Mac was to be the
server, not the viewer.
> Now, for me the big stumbling block was errors like:
> ReadFromRFBServer: rdr::EndOfStream (vncviewer 3.3.7 on linux)
> or
> no matching security types (vncviewer 4.0b4 from fink)
> or
> unrecognized authType 30 (chicken on the mac)
> Now, all of these are because of a very un-mac-like 
> behaviour: when you change the preferences of the Apple
> Remote Desktop, you have to stop and restart the server
> for the changes to take effect. So these messages are the
> result of connecting to RDC without VNC being properly 
> enabled on the server side

These error messages all indicate that the server to which you are
connecting is not offering any authentication methods which the viewer can
use.  There is not, and never has been, a security type of 30, so the server
is definitely at fault in this instance.

>. If you stop and restart the server, authentication does in fact
> proceed. Then you might get:
>  main:        unknown message type (vncviewer 4.0b4 from fink)

This indicates that the server sent a message with a message-type code that
does not exist in the negotiated version of the RFB protocol.  This is a
fault in the server implementation.

> I didn't solve this one. Some hints indicated that you had to 
> run chicken, or had to run tight vnc, or what have you.
> I found that vncviewer
> 3.3.7worked (slowly), and that TightVNC, UltraVNC, and RealVNC
> 4.1.2 from windows all worked, as well as osx2x to just 
> control the mouse and keyboard of the Mac.

This goes back to the issue of the protocol version number.  Protocol
version numbers aren't just there as a curiosity.  The server's protocol
version tells the viewer how to communicate with it, and vice versa.
Apple's Remote Desktop has a bug and reports a non-existent protocol version
that causes modern viewers to assume that it implements the highest existing
protocol version, which in fact it doesn't.

VNC-compatible viewers will mostly work with ARD if they are based on our
legacy VNC 3 system (e.g. vncviewer 3.3.7, TightVNC), or if they explicitly
include workarounds for ARD (e.g. Chicken of the VNC, VNC Enterprise
Edition, etc), since they use RFB 3.3, which is what ARD is based on.
UltraVNC isn't VNC-compatible, but I'm told it may work with ARD in some

All VNC 4 series viewers support the "Always use protocol 3.3" option,
specifically to allow them to connect to broken servers such as ARD, and VNC
Enterprise and Personal Edition viewers will automatically degrade
gracefully to protocol 3.3 when they encounter servers that report bad
version numbers.

Alternatively, Mac OS X users can disable ARD and install VNC Server for Mac
OS X, of which a beta-release is currently available from


Wez @ RealVNC Ltd.