X11vnc

x11vnc is a virtual network client that allows you to log into a computer and see the desktop screen from a remote location (remote dekstop). This requires running x11vnc as a server on the server computer, then connecting to the x11vnc server using a host with a remote desktop client (I use Chicken of the VNC).

Installing

Prerequisites

Mac

To install x11vnc on a Mac, you will need a jpeg library, which I was able to download from Fink.

Linux

You can use a package management software like aptitude or yum to install x11vnc. This should resolve dependencies.

Configuring

For the Mac, my configure line looked like:

#!/bin/sh
#
# run configure
# make
# make install

./configure \
 --prefix=/path/to/x11vnc \
 --with-jpeg=/sw

Then run make and make install.

Once the installation is done, add the bin/ directory to your $PATH variable, and open a new shell. Typing "which x11vnc" should print /path/to/x11vnc/bin/x11vnc.

Starting

When you first run x11vnc, you will see a bunch of loud warnings about not setting a password. Follow the instructions given to set a password. This is a password used to access your desktop - without it, anyone who connects to your server can control the screen.

Once you have set your password, create a script for starting x11vnc. Mine looks like this:

#!/bin/sh

sudo x11vnc -usepw -display :0 -ncache 10 -forever

Tunneling

This is where things get a little more tricky. Since remote desktop shares such valuable information, it is important to take necessary security mesures. One such measure is tunneling the remote desktop connection through an [SSH]] tunnel, encrypting all remote desktop traffic. This can be done as described on the [SSH]] page, using the command (run from the client computer):

ssh -f -N -L 5900:localhost:5900 server_username@server.com

One of the problems with tunneling the connection through an SSH tunnel is that it's very slow. The reason for this is, SSH is encrypting all outgoing traffic and decrypting all incoming traffic - a time-consuming and slow process. This makes the response time and graphics quality of remote desktop windows very poor.

SSH can be tweaked, however, to use a faster (albeit less secure) cipher called Arcfour (see wikipedia:RC4 for details). This is done by using the -c flag for the SSH command:

ssh -c arcfour -f -N -L 5900:localhost:5900 server_username@server.com

If you run the command man ssh you can see all of the different options you have for the -c flag. Arcfour is almost assured to be the fastest, unless your machine is unusual.