I have access to four computers: 1 Ubuntu Server desktop (Version 10.04) 1 Mac Mini (Snow Leopard) 1 Windows desktop (Windows 7) 1 Windows laptop (Windows Vista) The first three will always be on the home network. My goal is to SSH from the laptop into the server and be able, through VNC (or another remote desktop software), to control the windows and mac computers. The goal of this would be a slightly heightened network security over using VNC to directly access the mac or windows desktop. I have successfully used SSH to connect to the server, but have not been able to successfully implement the remote desktop connection. I would appreciate help doing so. Here's what I've done so far: As per instructions here: http://www.stuartellis.eu/articles/vnc-on-linux/ I installed the following: vnc4server – the main VNC server software vnc-java – enables access from Web browsers with Java support xvnc4viewer – a basic VNC viewer I then set up a password using the vncpasswd command. To attempt to connect to the mac, I followed directions I found in a thread at superuser. com and went to "System PreferencesSharing" and enabled "Screen Sharing". Subsequently, I tried entering the following commands into Ubuntu: vncviewer mac_ip_address::5904 vncviewer mac_ip_address:0 vncviewer mac_ip_address:1 They all returned the following: VNC Viewer Free Edition 4.1.1 for X - built Apr 9 2010 18:41:55 Copyright (C) 2002-2005 RealVNC Ltd. See http ://www .realvnc. com for information on VNC. vncviewer: unable to open display "" I'm sure I'm missing something important, but I'm not sure what it is. Do I need to have a GUI installed, or did that come with the vnc packages I installed?