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[http://freenx.berlios.de FreeNX] is a system that allows you to access your desktop from another machine over the internet. You can use this to login graphically to your desktop from a remote location. One example of its use would be to have a FreeNX server set up on your home computer, and graphically logging in to the home computer from your work computer, using a FreeNX client. This page will describe how to set up a FreeNX server and a client on Ubuntu systems, for the above example usage. See FreeNxIntegration for how FreeNX can be incorporated into Ubuntu.

Terminology

The Server is the computer you want to connect to. This is the computer where the FreeNX server will need to be installed. The name of the Ubuntu package providing the server is "freenx". For the example used here, the home computer is the server.

The Client is the computer from which you want to be able to access the Server. The name of the Ubuntu package providing the client is "nxclient". For the example used here, the work computer is the client.

Installing the FreeNX server

We will be installing the FreeNX server on the Server machine, i.e., the machine that you want to access remotely. In the stated example, this is your computer that is at home. For Ubuntu 5.10 and 6.06, there are prebuilt packages available. Several mirrors can be found at: http://seveas.ubuntulinux.nl/. After you add the repository, refresh your package information and then install the freenx package.

During installation you will be given the option to select NoMachine keys, or custom keys. It is easier to select NoMachine keys. There is absolutely NO added security risk involved in using the default keys. Read an [http://en.wikipedia.org/wiki/Secure_Sockets_Layer SSL] primer if you want to know the details about why this is the case

Defining a non-default ssh port

By default, the nxserver uses port 22 for communicating over SSH. On some machines or networks, port 22 may be blocked. For example, my evil ISP blocks port 22. So I have the sshd (daemon) listening on port 8888. If port 22 is blocked on the machine that acts as the freenx server, then you can change the default port by doing the following:

Edit the file /etc/ssh/sshd_config

Find

Port 22

and change it to

Port 8888

Edit the file /etc/nxserver/node.conf

Find

# The port number where local 'sshd' is listening.
#SSHD_PORT=22

and change it to:

# The port number where local 'sshd' is listening.
SSHD_PORT=8888

(Here, "8888" is the port that sshd is listening on)

That is, change the port number to the one that sshd is listening to, and uncomment the line.

Installing the NX Client

You should be able to access your Ubuntu box from any Windows or Linux box using the free client from [http://nomachine.com NoMachine's website]. You can also embed your NX Server in a webpage by installing the Nomachine Web Companion and the Apache webserver.

This section covers installation of the NX client on a Ubuntu machine. For the example covered in this article, the client is the work computer. The repository for the client is the same as for the server. Several mirrors can be found at http://seveas.ubuntulinux.nl/. After you add a mirror to your sources, refresh your package list and install the nxclient package.

Now you can execute the installed client using the following command:

/usr/NX/bin/nxclient &

Or by looking it up in the menu

This will start the NX client in a GUI, and step you through getting connected to the FreeNX server, and you will be on your way!

Miscellany

FreeNX on PowerPC

There are no precompiled binaries of FreeNX on this platform, so FreeNX have to be compiled from source. Sources for breezy can be found in this repository:

deb-src http://seveas.ubuntulinux.nl/ breezy-seveas freenx

These steps will build FreeNX from source:

1. Create a directory to hold the FreeNX source, and cd into it.

   mkdir freenxSource; cd freenxSource

2. Build the freenx pacakges and install related packages.

   sudo apt-get build-dep nx freenx
   apt-get -b source nx freenx

   This will download the souce tarballs and build the freenx packages (*.deb) in the current directory.

3. Install the FreeNX packages.

   sudo dpkg -i *.deb

4. If dpkg complains about missing packages, let apt fix it

   sudo apt-get -f install
   sudo dpkg -i *.deb

How to start/stop FreeNX

The FreeNX server is not a service but uses ssh. The following command will stop the FreeNX program from accepting connections.

sudo nxserver --stop

(Replace --stop by --start for starting it again)

Troubleshooting

• If you encounter problems with icons when loggin multiple times with the same user in a gnome session, run gnome-settings-daemon. Let it run at every login (gnome->preferences->sessions).

Using custom SSH keys

This is NOT supported by the FreeNX developers - only do this if you have no other option

1. Generate the DSA private-public key pair.

    ssh-keygen -t dsa

   By default this key is places in ~/.ssh/id-dsa. You can leave the passphrase empty, this will not pose a security risk.

2. Install the public key in the FreeNX serving machine. The key should be placed in the file authorized_keys2 in the .ssh dir of the user named nx.

   cat ~/.ssh/id_dsa.pub | sudo -u nx tee -a ~nx/.ssh/authorized_keys2

3. Install the private key in the NX client software. When creating a session, press the button labeled "Key" and select your new key in the window that pops up.

References

• [http://en.wikipedia.org/wiki/FreeNX FreeNX on Wikipedia]

• [http://mirror.ubuntulinux.nl FreeNX repository]

CategoryDocumentation