What is FreeNX

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.

It's Open Source, secure (SSH based), fast and versatile! License: GPL

Note: Running FreeNX as server on Ubuntu with the free "NX Client for Windows" from NoMachine on a Windows workstation is working fine, except resuming sessions.

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.

Installation Prerequisites

Before installing FreeNX server make sure you have SSH set up and is working. You can find the SSH Howto here: https://help.ubuntu.com/community/SSHHowto

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.

FreeNX is not included in Ubuntu, so we'll add it from the FreeNX Team PPA. This step will be in the installation instructions for your Ubuntu distribution of choice below.

For the paranoid: there is an added security risk involved in using the default keys. If you keep the default keys then everybody will be able to connect to your SSH server as the NX user which is added to your system during the installation. This opens an additional (and unnecessary) opportunity to attack your computer. You could avoid it by using custom SSH keys, as explained later.


Installing the FreeNX server on Ubuntu Karmic (9.10) and higher

Install FreeNX server on Karmic (9.10), Lucid (10.04), Maverick (10.10), and Natty (11.04)

  1. Open your terminal

    Applications->Accessories->Terminal
  2. Add the FreeNX PPA

    sudo apt-add-repository ppa:freenx-team
    • NOTE: If you do not have apt-add-repository installed add the following

        sudo apt-get install python-software-properties
  3. As of March 2013, there are no packages built for Quantal( but the Precise packages seem to work ), Maverick or Natty ( but the packages for Lucid seem to work). There are packages for Precise so skip this step. Update the sources list as follows:

    Ubuntu Natty (11.04):

    sudo sed -i 's/natty/lucid/g' /etc/apt/sources.list.d/freenx-team-ppa-natty.list

    Ubuntu Maverick (10.10):

    sudo sed -i 's/maverick/lucid/g' /etc/apt/sources.list.d/freenx-team-ppa-maverick.list

    Ubuntu Quantal (12.10):

    sudo sed -i 's/quantal/precise/g' /etc/apt/sources.list.d/freenx-team-ppa-quantal.list

    Ubuntu Raring (13.04):

    sudo sed -i 's/raring/precise/g' /etc/apt/sources.list.d/freenx-team-ppa-raring.list
  4. Update Apt

    sudo apt-get update
  5. Install FreeNX

    sudo apt-get install freenx-server
  6. Get the nxsetup script

    As of July 2011, the FreeNX PPA package is missing the nxsetup script. The script can be downloaded from here by issuing:

    wget https://bugs.launchpad.net/freenx-server/+bug/576359/+attachment/1378450/+files/nxsetup.tar.gz

    Unpack the nxsetup script:

    tar -xvf nxsetup.tar.gz

    Copy the setup script to /usr/lib/nx:

    sudo cp nxsetup /usr/lib/nx/nxsetup
  7. Run nxsetup:

    sudo /usr/lib/nx/nxsetup --install 


Installing the FreeNX server on older Ubuntu Versions

These instructions are for Ubuntu versions prior to Ubuntu Karmic (9.10).

FreeNX is not included in Ubuntu, so we'll add it from the FreeNX Team PPA.

Add this repository using the Third-Party Sources Tab in Software Sources. When it asks, Reload the information about available software. Now you can see and install the freenx package in Synaptic Package Manager.

You must edit the configuration files and install by hand:

  1. Add this PPA to it's own list file

    sudo bash -c "echo 'deb http://ppa.launchpad.net/freenx-team/ppa/ubuntu VERSION main
    deb-src http://ppa.launchpad.net/freenx-team/ppa/ubuntu VERSION main' >> /etc/apt/sources.list.d/freenx.list"

    where VERSION can be: dapper, hardy, intrepid or jaunty. More information can be found at FreeNX Team PPA.

  2. Add the public key of FreeNX PPA run:

    sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com F3A662B57D580D3A2E98E5152A8E3034D018A4CE
  3. Then Update Apt

    sudo apt-get update
  4. After you add the repository, then install the freenx package (using Aptitude to install extra needed packages).

    sudo aptitude install freenx
  5. Now use nxsetup to install necessary files and create the special user "nx"

    sudo /usr/lib/nx/nxsetup --install 


Installing the NX Client

The official NX client is not in the Ubuntu repositories.

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

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! [Note: If you are behind a firewall you may need to enable SSL encryption under the Advanced configuration tab - JeremySchroeder]


Installing QTNX (Opensource client)

sudo apt-get install qtnx

Miscellany

NX Server Free Edition

NX Server Free Edition provided by NoMachine is not related to FreeNX. NXSFE has a limit of 2 sessions per server. FreeNX doesn't have this limit.

Neatx

Neatx is a similar system to FreeNX, produced by Google.

It's Open Source, secure (SSH based), but does have some feature drawbacks compared to FreeNX. License: GPL2

x2go

x2go is another similar system to FreeNX, labelled as an "Open source terminal server project". The Ubuntu version is offered as a PPA similar to FreeNX, and is noted as having several features including remote audio, printing, and shared directories. x2go is also known for the ease in which it can be set up.

FreeNX on PowerPC

There are no precompiled binaries of FreeNX on this platform (Launchpad PPA doesn't provide support), so FreeNX have to be compiled from source. Sources can be found at the FreeNX Team PPA.

These steps will build FreeNX from source (you need to add the deb-src repository):

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

    mkdir freenxSource; cd freenxSource
  2. Build the freenx packages and install related packages.

    sudo apt-get build-dep nx freenx
    apt-get -b source nx freenx
    This will download the source 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 /etc/init.d/freenx-server stop

(Replace stop by start for starting it again)

Configuring SSH port

By default, nxserver uses port 22 for communicating over SSH. On some machines or networks, port 22 may be blocked; some Internet providers block port 22, for instance. Port 22 is also a common target of people trying to crack into a network. To make the SSH server listen on port 8888, you can do the following:

Edit the file /etc/ssh/sshd_config

gksudo gedit /etc/ssh/sshd_config

Find

Port 22

and change it to

Port 8888

You then need to restart SSHD. Try

/etc/init.d/ssh restart

FreeNX should detect the SSHD port, but otherwise: Edit the file /etc/nxserver/node.conf

gksudo gedit /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

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

Using custom SSH keys

After installation, FreeNX will use a set of default ssh keys for authentication. This is a security risk, especially on any internet-facing machines, and the default keys should be replaced with your own custom keys.

To change the default keys to your own custom keys - on the machine hosting the freenx-server, run the command:

sudo dpkg-reconfigure freenx-server

This will launch a dialogue that will guide you through the generation of custom keys. On the first page hit 'OK' and on the second page select 'Create new custom keys'

a key file called client.id_dsa.key will be created in: /var/lib/nxserver/home/.ssh/

Now, we need to transfer the key to the client machine so that it can be imported in the FreeNX client application. First copy the key to your home directory on the server machine:

sudo cp /var/lib/nxserver/home/.ssh/client.id_dsa.key ~/

Next, copy client.id_dsa.key to your client machine. Ideally you should copy the file securely, for example by running the following command from the client computer:

scp user@freenx-server:~/client.id_dsa.key ~/

which will securely copy the client.id_dsa.key file from the freenx-server computer to your home directory on the client.

If your client is a Windows machine, just copy the key with your preferred method.

In the nx client software you can now import this key.

After you have tested that authentication is working using your custom keys you should then remove the client.id_dsa.key file from your home directories on both the server and client machines.


Using Custom SSH keys on Lucid

Summary: When finished, a custom key should have been created, and you should be able log into the remote machine with a valid userid id and password that belongs to the server and client.

Objective:

Custom Keys.

User ID and Password.

Authentication method: PASSDB. (PASSDB: Uses an internal user database.)

Adding the PPA repos

deb http://ppa.launchpad.net/freenx-team/ppa/ubuntu lucid main

deb-src http://ppa.launchpad.net/freenx-team/ppa/ubuntu lucid main

You can add them from Menu > System > Administration > Software Sources

Click the Other Software Tab > Click Add and paste each line separately.

From the terminal:

sudo vi /etc/apt/sources.list.d/freenx
i (insert) > paste
esc > :wq

Update sources and install freenx

sudo aptitude update
sudo apt-get install freenx

Check for, and or Download and Install nxsetup

ls -l /usr/lib/nx/nxsetup

Get NXSETUP

Unpack it:

In Nautilus,navigate to where you downloaded nxsetup > right click on the file to get the context menu, and then select Extract Here

At the terminal:

$tar -xvzf nxsetup.tar.gz

Install it:

chmod 755 nxsetup
sudo cp nxsetup /usr/lib/nx/
sudo chown root:root /usr/lib/nx/nxsetup

sudo /usr/lib/nx/nxsetup --install

I told it to Y for custom keys, but it did not happen.

Enabling the PASSDB database

Now, since i opted to use 'PASSDB' as the authentication method, the following also has to be done:

Be sure that the /etc/nxserver/node.conf file contains the following line:

ENABLE_PASSDB_AUTHENTICATION="1"

Adding the User ID and Password to the database:

Add yourself to the nxserver database. Suppose your username is jra:

sudo nxserver --adduser jra
NX> 100 NXSERVER - Version 3.2.0-74-SVN OS (GPL, using backend: 3.3.0)
NX> 1000 NXNODE - Version 3.2.0-74-SVN OS (GPL, using backend: 3.3.0)
NX> 716 Public key added to: /home/jawara/.ssh/authorized_keys2
NX> 1001 Bye.
NX> 999 Bye

Assign a password for jra:

sudo nxserver --passwd jra
NX> 100 NXSERVER - Version 3.2.0-74-SVN OS (GPL, using backend: 3.3.0)
New password: 
Password changed.
NX> 999 Bye

Adding SSH permissions for the users.

Add nx and jra user ids to sshd_config:

I did it under the Authentication section.

sudo vi /etc/ssh/sshd_config
i (insert)
AllowUsers nx jra

Save the file.

esc > :wq

Restart the SSH service.

$sudo service sshd restart
* Restarting OpenBSD Secure Shell server
sshd [ OK ]

Generate the custom keys.

sudo /usr/lib/nx/nxkeygen

Backing up existing client key to /var/lib/nxserver/home/.ssh/client.id_dsa.key.20101117-131539 Unique key generated; your users must install

  • /var/lib/nxserver/home/.ssh/client.id_dsa.key

on their computers.

The key file, client.id_dsa.key, will be in: /var/lib/nxserver/home/.ssh/

Now, we need to securely transfer /var/lib/nxserver/hone/.ssh/client.id_dsa.key to the client machine so that it can be imported into nxclient.

Now securely transfer the file from the freenx-server, to home directory on your client machine.

scp source destination

sudo scp /var/lib/nxserver/home/.ssh/client.id_dsa.key jra@Ip.Address.Or.Hostname:''

For safety, do delete the ~/client.id_dsa.key from your client machine when finished.

Download and Install the nxclient.

From website: Get NXClient

or in your terminal with wget,

wget http://64.34.161.181/download/3.4.0/Linux/nxclient_3.4.0-7_i386.deb

Install with GDebi from the Nautilus context menu, if installed, or in the terminal with,

sudo dpkg -i nxclient_3.4.0-7_i386.deb

From your menu Open the NX Connection Wizard.

Enter a Session Name,

Enter Hostname (or IP Address),

Enter Port number or keep the default,

Select your Type of connection I chose LAN, and select Next.

Next:

Select the Desktop System you want to use (Gnome or KDE),

Set the Desktop Size (1024x768),

Do not check the disable encryption box if you want SSL encryption.

Select Next when finished.

Next:

Now, choose if you want to Create shortcut on desktop.

Select Show the Advanced Configuration dialog box.

Click Finish.

Importing the custom key file client.id_dsa.key.

In the advanced dialog window under the General Tab, you should see the items you have already entered, and to the right of Remember my password there is a Key... button.

Click the Key button, a window will popup initially displaying the Default Key

Now, Click the Import button, navigate to the directory where you saved the client.id_dsa.key file you copied from the server, and select it to open and import the key. You show now see the custom keys which should be different from the initial default key.

Click Save > Save > Ok.

You should now be presented with a login prompt, displaying your,

Login: User ID

Password: Blank

Session: session name

Just enter the password you added too the nxserver database, Click Login, the nxclient will make's the connection, and once there are no errors, you should be on your remote machine.


If your client is a Windows machine, just copy the key with your preferred method.

In the nx client software you can now import this key.

After you have tested that authentication is working using your custom keys you should then remove the client.id_dsa.key file from your home directories on both the server and client machines.


Troubleshooting

  • Problem: Everything is installed as described above, but I still get errors at installing nxsetup --install

  • Solution: The issue is due custom SSH server configuration. Check /etc/ssh/sshd_config to see if this line exists "AllowUsers nx" and is set to authorized_keys2 "AuthorizedKeysFile %h/.ssh/authorized_keys2", if commented, just uncomment them. after that run this command in a terminal

    sudo /etc/init.d/ssh restart
  • Problem: At the client, the !M logo window appears, but after a few seconds that window just closes, even without showing any error message.

  • Solution: The issue is due custom VNC configuration. In the server, access your home directory and run these commands,

    sudo rm .Xauthority*
    touch .Xauthority
    chmod 600 .Xauthority
  • Problem: What can I do if I get the error "Could not yet establish the connection to the remote proxy"?

  • Solution: This commonly happens when the Advanced tab configuration option "Disable encryption of all traffic" has been selected, but the appropriate firewall ports have not been opened. Open the necessary firewall ports, or uncheck the option to re-enable encryption over SSH. NoMachine knowledge base article

  • Problem: NX Client connects and displays the desktop but the screen does not refresh.

  • Solution: Set Disable Direct Draw for screen rendering in the client's advanced configuration tab.

  • Problem: NX Client authenticates user NX and tries to authenticate normal user but then fails with:
    Permission denied (publickey).
    NX> 280 Exiting on signal: 15.

  • Solution: Set authentication = SU in /etc/nxserver/node.conf. All other authentication methods set to "0". Automated Solution and workaround credit: this thread

  • Problem: NX session started from Linux client cannot be resumed on Windows client (http://mail.kde.org/pipermail/freenx-knx/2011-January/009152.html)

  • Solution: Apply the patch posted on https://bugs.launchpad.net/freenx-server/+bug/589723/comments/25 to /usr/lib/nx/nxserver. Then restart the nxserver with sudo nxserver --restart.

References

You can also have a look at the article about installing the NX packages provided by NoMachine company

Desktop integration wanted

For those who want to have freenx supported in krfb, krdc, log into bugs.kde.org, and add a comment and vote for the following bugs (wishlist) :

  • 187310 : nxserver support in krfb

  • 149482 :nx support in krdc (client), it seems that work is already in progress, and there only a few problems left.

The same should be done on gnome side, for vino and vinagre.

NXLaunch is another solution and could possibly be integrated in other Remote Desktop clients.


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FreeNX (last edited 2014-02-23 21:09:48 by tgp1994)