Linux.Desktop.Hacks [Electronic resources] نسخه متنی

Hack 30. Access Windows and Mac OS X from Linux

No need to move to another computer; just sit
put and access them all.

Although you don't need to go
far to hear someone extolling the
benefits of Linux and free software, many people still need to use
other operating systems, such as Microsoft Windows and Apple Mac OS
X. Aside from personal choice, other reasons to use non-Linux
operating systems include running applications that are available
only on a particular OS, an employer mandating that you use a
particular platform, or even a need to test software and services
across different platforms. For some, the solution is a huge desk set
up to accommodate three computers with three monitors and three
keyboards/mice; however, there is a better way.

This hack uses a piece of software called Virtual Network
Computer (VNC). This useful little tool allows you to essentially
redirect your monitor output to another computer on a network, and
accept keyboard and mouse input from the remote computer. With this
software you can run the VNC server on a Windows machine
and view the Windows desktop on your Linux machine. Likewise, you can
run the VNC server on your Linux machine and view your Linux desktop
on a Windows-based desktop. VNC is available for most Unix-based
OSes, such as Linux, FreeBSD, Solaris, etc., as well as Microsoft
Windows and Mac OS X. VNC gives you the ability to pull together
these disparate operating systems on a single desktop.

4.10.1. Configure a Linux VNC Server

VNC comes in a few different guises, but most attention is focused on
the RealVNC and TightVNC variants. Of the two versions, TightVNC
appears to be the better performer and you can get it from
http://www.tightvnc.com/downloadl. A
number of different packages are available for the supported
platforms, and you need both the server (to provide a VNC resource to
connect to) and the viewer (to connect to another VNC resource). You
should be able to install a recent version of TightVNC using your
distributions package manager.

If you run a Mac and want to access your Mac OS X desktop from your
Linux machine, you need the OSXvnc package from http://www.redstonesoftware.com/vncl as
RealVNC and TightVNC do not natively support Mac OS X. A VNC client
for Mac OS X is also available within the Fink packaging system at
http://fink.sourceforge.net.

To run a VNC server on Linux you must launch the server and give it a
special display number to connect to. This usually starts at
1 and increases by one for each new server
created. As an example, if you run a VNC server on a machine with the
address 192.168.0.2, you would access the first
VNC resource as 192.168.0.2:1. To run the server,
specify the screen resolution and color depth with the
-geometry and -depth
command-line options:

foo@bar:~$ vncserver -geometry 1024x768 -depth 24

These settings are parameters for your virtual screen, not the real
settings of the machine you are running the server on. This means the
physical screen might be displaying an image at 1280x1024 in 8-bit
color, but you can view it remotely at 1024x768 in 24-bit color. Of
course, the machine you are viewing the image on must support your
choices.

You can specify a nonstandard resolutionfor instance, 990x745. Doing this allows you to maximize the size of the remote image on your desktop without obscuring your local desktop's toolbars and panels.

When you first run the server, you are prompted for a password. This
password is used to ensure that clients are who they say they are,
and the password is stored and remains the same each time you use the
VNC server (you can change the password later with
vncpasswd if you need to). When the password is
successfully entered, the server indicates which display number it
has been given.

While the server is running, all applications that are used appear on
the VNC display as well as the normal screen on the computer (if a
monitor is attached). You can also route applications to display only
on the VNC server by using the DISPLAY environment
variable and specifying the hostname and display number:

foo@bar:~$ mozilla -display 192.168.0.2:1 &

To stop the VNC server, you need to use the -kill
option and the display number assigned earlier when you started the
server:

foo@bar:~$ vncserver -kill :1

4.10.2. Connect to a VNC Server

To connect to the VNC
server from a Linux machine, you can use the
vncviewer tool that is included with the VNC
software. This simple little program is used like this:

foo@bar:~$ vncviewer 192.168.0.2:1

In this command, you specify the IP address, a colon
(:), and then the display number to connect to.
When you run the command, you are prompted for the VNC server
password and then the VNC desktop is displayed.

4.10.3. Configure a Windows VNC Server

Installing the Windows VNC
server is a
fairly painless process. Once installed, it can be configured as a
Windows Service so that it is always running (like a daemon in
Linux). The benefit of running the server as a service is that you
will still be able to access the server when the machine is locked or
the user has logged out.

Download the Windows installer from the TightVNC web site. It is a
typical Windows installer that offers no surprises.

To use the VNC server as a service, tick each box that refers to the
VNC Server System Service in the VNC installation routine. When you
have done this, the Server Options dialog box will appear, and you
must configure at least the Authentication tab to run the server. In
this tab, you should select the VNC 3.3 Authentication option and use
the Set Password field to define the password for the server. You
should never disable authentication unless you are 100% sure the host
network is secure.

To start and stop your server, use the standard Windows Services
configuration tool to start and stop the service.

4.10.4. Configure a Mac OS X VNC Server

The official VNC distribution
does not include support
for Mac OS X; however, a VNC server is freely available from Redstone
Software (http://www.redstonesoftware.com/vncl),
called OSXvnc. This software is available as a Mac OS X disk image
file (.dmg). Download the software and then
double-click it in the Finder. A window will pop up with the program
inside it; drag the program to the desktop. Now if you double-click
the icon on the desktop, the VNC Settings dialog will appear. For a
quick and easy VNC connection, the defaults are fine, and you can
just click the Start Server button to begin the connection.

4.10.5. View Your Desktop in a Web Browser

One intriguing feature of
the VNC server is that it includes a small
web server that exports the VNC desktop to a browser using a special
Java applet. To access your VNC server, connect to port
5801 with a Java-enabled web browser. This port
number is appended to the hostname/IP address in the same way as a
normal web resource:

http://foo.com:5801

This port number actually maps to the VNC display you are running. If
you are running display number 1, use port
5801; display number 2 is port
5802, etc.

Some distributions, notably Debian, package the Java applet separately from the VNC server package.

When you are running any server on the Internet, you should take
steps to ensure that it is protected with a firewall. A firewall
keeps all unwanted traffic away from your server. If you are running
a firewall already, you should ensure that ports 5800-5805 are
available for use. If you want to be extra secure, only open port
5801 for use and make sure you always run off desktop number 1.
Another option is to encrypt your VNC connection with an SSH tunnel
[Hack #32] .