I've started to set up a server at my house, where I eventually want to run it headless, and I can just VNC in from my other Desktop. I installed Ubuntu 10.10, setup remote desktop on the server, and from there was able to do any work remotely. That was nice. I turn the computer off at night, and the next day when I was going to work on it, I cannot VNC in anymore. One day passed, and now every time I try to use VNC it comes up with "Failed to connect to server" I also set a static IP address on the server too, so I know the address isn't changing every so often. 

I did it earlier, so I know I have it set up correctly, but when I restarted the computer, did some magical firewall get setup without my knowledge?

Solution:

The setup was done almost immediately after a fresh installation of 8.04 desktop on our office internal network.

Objective:

To have vncserver setup with gdm on the host so that a remote vnc connection to it will be greeted with a gdm login screen for the user to login.

Clarification of terms used:

Host - refers to the PC you are trying to install vncserver on.
Remote - the PC that is going to connect to the host

1. Get required packages installed

On the host, run

Code:
sudo apt-get install vnc4server xinetdBeing a server guy, I prefer to ssh into the host and do all the work, so I also 

Code:
sudo apt-get install openssh-serverThis way I can directly test the vnc by using vncclient on my remote desktop to the host.
Of course if you have only a host PC, then you may also need a vncclient to test it.

2. Enable XDMCP

This is the part that is responsible for bring up the gdm login.

Code:
sudo vi /etc/gdm/gdm.confUncomment this line

Code:
RemoteGreeter=/usr/lib/gdm/gdmloginEnable xdmcp, look for [xdmcp] and change Enable to true.

Code:
[xdmcp]
Enable=trueRestart gdm,

Code:
sudo /etc/init.d/gdm restart3. Setup xinetd
Create a new service file for xinetd

Code:
sudo vi /etc/xinetd.d/Xvnc(vi is of course one of many editors you can use)

Paste the following into the file and save:

Code:
service Xvnc
{
        type = UNLISTED
        disable = no
        socket_type = stream
        protocol = tcp
        wait = no
        user = nobody
        only_from = localhost
        server = /usr/bin/Xvnc
        server_args = -inetd -query localhost -geometry 1024x768  -depth 16 -cc 3 -once -SecurityTypes=none -extension XFIXES
        port = 5901
}

Code:
sudo  /etc/init.d/xinetd restart

4. Connect from remote

Because I added only_from = localhost in /etc/xinetd.d/Xvnc above, I will need to ssh tunnel and forward my remote port (see term clarification above, as this is actually my local PC that I working from) to the host (this is the 'remote' where vncserver is being installed). If you do not need this step (why not?), just remove the line.

I use putty on Windows so just go to 

Connections >SSH >Tunnels
Source Port: 5901
Destination: localhost:5901
Add

Then establish a normal ssh connection to the host or use my existing ssh connection.

I use UltraVNC, so this is what I do:

Open Viewer
VNC Server: localhost:5901
Connect

5. Done

The vnc viewer should open up and a gdm login screen presented (with a Debian logo).
Enter your username and password. That's it.

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