Difference between revisions of "X2Go"

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[[Category:Networking]]
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[[Category:Remote desktop]]
== Description ==
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[[ja:X2Go]]
 +
[[zh-hans:X2Go]]
 +
[http://wiki.x2go.org X2Go] enables you to access a graphical desktop of a computer over the network. The protocol is tunneled through the [[Secure Shell]] protocol, so it is encrypted.
 +
{{Note|X2Go isn't compatible with all desktop environments. You can check [http://wiki.x2go.org/doku.php/doc:de-compat X2Go desktop environment compatibility] first, especially if you want to shadow your current desktop.}}
  
With x2go you can access your desktop using another computer -- that means both LAN and internet connections. The transmission is done using the ssh protocol, so it is encrypted. By using the free nx libraries from NoMachine, a very acceptable performance in both speed and responsiveness is achieved. Even an ISDN connection runs smoothly.
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== Installation ==
  
This makes it is possible to connect your laptop to any computer with the environment, applications, and performance of the remote desktop. It is also possible to have a bunch of computers connected to a single server (terminal-server, thin-client).
+
Two parts are available in [[official repositories]]. They can be [[Pacman|installed]] with the following packages:
 +
* {{Pkg|x2goserver}} - X2Go server
 +
* {{Pkg|x2goclient}} - X2Go client based on Qt4
  
Clients are available for Linux (Qt4), Windows, and Mac.  The latter two can be downloaded directly as binary from the x2go homepage.
+
== Server configuration ==
  
== x2go and Arch Linux ==
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=== Configure Secure Shell daemon ===
  
Arch Linux x2go packages are available in the AUR. Currently the server and clients are available. The LDAP based usermanagement suite is not yet finished, nor are tools that make x2go more convenient for use in schools and thin client environments.
+
X2Go uses [[Secure Shell]] in order to work, so you need to configure sshd daemon to allow X11 forwarding and then start it first. Follow the instructions at [[Secure Shell#X11 forwarding]] and [[Secure Shell#Daemon management]].
  
== Installation and configuration ==
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If you are using other than POSIX (C) locale, you may want to add the following line to [[Secure_Shell#Server_usage|configuration file]]
 +
# Allow client to pass locale environment variables
 +
AcceptEnv LANG LC_*
 +
 
 +
=== Load fuse kernel module ===
  
=== Configuring the Server ===
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In order for the server to be able to access files on the client computer you should load a {{ic|fuse}} [[kernel module]].
'''Install the x2goserver package:'''<br>
 
Install x2goserver from AUR (manually, with use of yaourt or other tools).
 
  
'''Install the ssh-daemon:'''<br>
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=== Setup SQLite database ===
  pacman -S openssh
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Run the following command on the server to initialize the SQLite database (which is required in order for the x2go server to work):
/etc/rc.d/sshd start
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  # x2godbadmin --createdb
  
To have sshd started at boot time, you have to put it into the daemeons line in
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=== Start X2Go server daemon ===
/etc/rc.conf, e.g.
 
  
DAEMONS=(... network ... sshd ...)
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Now all you need to do is [[start]] {{ic|x2goserver.service}}.
  
'''Load the fuse module:'''<br>
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== Desktop Shadowing ==
This makes it possible for the server to access files on the client computer.
 
  
modeprobe fuse
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To gain access to the "local desktop" (as opposed to a unique session/desktop environment) you need to install {{Aur|x2godesktopsharing}} from the [[AUR]]. Then, launch {{ic|x2godesktopsharing}}.
  
To have this module loaded at boot time, you also have to put it into the MODULES line in /etc/rc.conf, e.g.
+
Note, you do not need x2godesktopsharing to access "local desktop" of user "foo" by user "foo". x2godesktopsharing is for accessing "foo"'s desktop by "foo2" user. Just choose "Connection to local desktop" in "session type" in x2goclient.
  
'''Initialize the SQL database (and start the SQL server):'''
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== Client configuration ==
  
You can choose to use either Postgres or SQLite database, the latter does not need a running server.
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Make sure you can open an SSH session from the client to the server:
 +
$ ssh ''username@host''
  
Initialize SQLite db:
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Then run X2Go client itself:
  x2godbadmin --createdb
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  $ x2goclient
  
Start the x2goserver:
+
You can now create several sessions, which then appear on the right side and can be selected by a mouse click. Each entry consists of your username, hostname, IP, and port for SSH connection. Furthermore you can define several speed profiles (coming from modem up to LAN) and the desktop environment you want to start remotely.
/etc/rc.d/x2goserver start
 
  
If you want to have this services started at boot time, include them in the DAEMONS line in /etc/rc.conf
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=== Common mistakes ===
  
DAEMONS=(... network ... sshd ... x2goserver)
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Do not simply choose the defaults of KDE or Gnome, since the executables ''startkde'' and ''startgnome'' are usually not in the {{ic|$PATH}} when logging in using SSH. Use full paths to ''startkde'' or ''startgnome''. You can also start [[openbox]] or another window manager.
  
'''Check SSH daemon configuration to allow non-English session:'''
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You should be asked for your password for your user at the server now and after login you will see the X2Go logo for a short time, and the desktop.
  
If you are using other than POSIX (C) locale, you may want to add the following line to /etc/ssh/sshd_config:
+
=== Exchange data between client and server (desktop) ===
  
# Allow client to pass locale environment variables
+
On the X2Go client (e.g. laptop) local directories could be shared. The server will use [[fuse]] and [[SSHFS]] to access this directory and mount it to a subdirectory media of your home directory on the server. This enables you to have access to laptop data on your server or to exchange files. It is also possible to mount these shares automatically at each session start.
AcceptEnv LANG LC_*
+
 
 +
=== To leave a session temporarily ===
 +
 
 +
Another special feature of X2Go is the possibility of suspending a session. This means you can leave a session on one client and reopen it even from another client at the same point. This can be used to to start a session in the LAN and to reopen it later on a laptop. The session data are stored and administered in a [[SQLite]] database on the server in the meanwhile. The state of the sessions is protocolled by a process named ''x2gocleansessions''.
 +
 
 +
== Troubleshooting ==
 +
 
 +
=== No selection screen in x2goclient ===
  
Then, restart the daemon (as root):
+
A regression in {{Pkg|iproute2}} causes ''ss'' to show no result when specifying the {{ic|-u}} flag, as done in {{ic|/usr/bin/x2golistdesktops}}. [https://marc.info/?l=linux-netdev&m=143018447007958&w=2]
/etc/rc.d/sshd restart
 
  
== Configuration of the Client ==
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See [http://bugs.x2go.org/cgi-bin/bugreport.cgi?bug=799], [https://bbs.archlinux.org/viewtopic.php?pid=1541035] for more information.
  
'''Install the client:'''<br>
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=== Sessions do not logoff correctly ===
X2goclient is available in AUR. It is a Qt GUI app, although you can also check-out the command line options by running
 
  
x2goclient --help
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Due to [http://bugs.x2go.org/cgi-bin/bugreport.cgi?bug=914 this bug] the X2Go sessions might not logoff correctly. The script that initiates the session spits out many log lines that might confuse X2go. A simple workarround is to create a custom session script and redirect the log output either to a file or to {{ic|/dev/null}} and then point your X2Go-client to this custom script.
  
'''Double check ssh'''<br>
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Here is a sample script for an XFCE session:
Convince yourself that you can open a ssh-session from the client to
 
the server (host).
 
  
ssh YourUsername_onServer@yourhost_or_ip
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  #!/bin/sh
 +
  #
 +
  #xfce4-session spits out quite a bit of text during logout, which I guess
 +
  #confuses x2go so we would get a black screen and session hang.
 +
  #adding redirect to a logfile like "~/logfile" or "/dev/null" nicely solved it
 +
  # see http://bugs.x2go.org/cgi-bin/bugreport.cgi?bug=914
 +
  /usr/bin/xfce4-session > /dev/null
  
Within the local network this should not be a problem. The way you
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=== Shared folders do not mount (Windows Clients) ===
connect from beyond your network, lets say the internet, to your
 
comuter at home is a question of how your network is build up. This
 
would go beyond the scope of this article. Therefore here only a few
 
items:
 
* A port has to be opened at the router resp. gateway which forwards requests to your server, and there especially to the sshd-port (which normally is 22). To prevent a big part of the portscan attacks it is probably better to have 222 as publicly reachable port.
 
* To prevent you from having the need to keep your public IP address in mind (especially if this changes dynamically) it is advisable to use a dynamic DNS-Service (DynDNS, DynIP). Many routers are preconfigured to be reachable under a name rather than an IP address.
 
  
'''Enough preliminaries! Now to the x2goclient. Run it:'''<br>
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The ssh-daemon used by the X2go windows client uses depreceated ssh-dss keys by default and because Arch does not accept them your shared folders will not mount. Check out this [http://bugs.x2go.org/cgi-bin/bugreport.cgi?bug=1009 bug report] for more information.
x2goclient
 
This opens the client application. You can now create several sessions, which then appear on the right side and can be selected by a mouseclick. Each entry consists of your username on the server, hostname and IP and the port for ssh-connection. Furthermore you can define several speed profiles (coming from modem up to LAN) and the desktop environment you want to start remotely.
 
  
'''Common mistakes:'''<br>
+
This can be solved on the windows side by generating different type of key:
Do not simply choose the defaults of KDE or Gnome, since the executables startkde or startgnome are usually not in the PATH when logging in using ssh. Use full paths to startkde or
 
startgnome. You can also start openbox or another window manager.
 
  
You should be asked for your password for your user at the server now and after login you will see the x2go logo for a short time, and -- voila -- the desktop.
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  C:\Program Files (x86)\x2goclient\ssh-keygen -b 2048 -t rsa
  
'''Exchange data between client and server(desktop)'''<br>
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And simply replace {{ic|c:\Users\User\.x2go\etc\ssh_host_dsa_key}} and {{ic|c:\Users\User\.x2go\etc\ssh_host_dsa_key.pub}} with the newly generated key files.
On the x2goclient (e.g. laptop) local directories could be shared. The server will use fuse and sshfs to access this directory and mount it to a subdirectory media
 
of your home directory on the server. This enables you to have access to laptop data on your server or to exchange files. It is also possible to mount these shares
 
automatically at each session start.
 
  
'''To leave a session temorarily'''<br>
+
Other workarrounds from [http://bugs.x2go.org/cgi-bin/bugreport.cgi?bug=1009] might help, too.
Another special feature of x2go is the possibility of suspending a session. This means you can leave a session on one client and reopen
 
it  even from another client  at the same point. This can be used to to start a session in the LAN and to reopen it later on a laptop.
 
The session data are stored and administrated in a potges databse on the server in the meanwhile. The state of the sessions is protocolled
 
by a process named x2gocleansessions.
 
  
== Various ==
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=== Workaround for failing compositing window manager for remote session ===
  
'''Workaround for failing compositing window manager for remote session'''
+
{{style}}
  
This is useful for situations, when the computer running x2gserver is used also for local sessions with e.g. compiz as the window manager. For remote connections with x2goclient, compiz fails to load and metacity should be used instead. The following is for GNOME, but could be modified for other desktop environments. (Getting compiz ready is not part of this how-to.)
+
This is useful for situations, when the computer running x2goserver is used also for local sessions with e.g. compiz as the window manager. For remote connections with x2goclient, compiz fails to load and metacity should be used instead. The following is for GNOME, but could be modified for other desktop environments. (Getting compiz ready is not part of this how-to.)
  
 
Create /usr/local/share/applications/gnome-wm-test.desktop:
 
Create /usr/local/share/applications/gnome-wm-test.desktop:
Line 135: Line 132:
 
  $ gconftool-2 --type string --set /desktop/gnome/session/required_components/windowmanager "gnome-wm-test"
 
  $ gconftool-2 --type string --set /desktop/gnome/session/required_components/windowmanager "gnome-wm-test"
  
== Future ==
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=== /bin/bash: No such file or directory when connect (or what ever shell you use) ===
 
 
At the moment the package consists mainly of the x2goserver and the x2goclient. It is planned to add in near future:  
 
* LDAP-Integration. This allow the administration of users, sessions and logins using LDAP. This is an interesting feature for schols or companys. For this purpose there are control programs which integrate themselves into the KDE Control Center.
 
* The option to use x2goclient as a login screen for thin clients.
 
* The possibility to use locale devices (CD, floppy, USB-stick) remotely and transparently.
 
 
 
Questions and problems? You could contact me also directly.
 
[[Special:Emailuser/Gerbra|GerBra]]
 
 
 
(Many thanks to Stefan Husmann for translation from archlinux.de wiki)
 
 
 
== Links ==
 
  
[http://wiki.archlinux.de/?title=Bild:X2go-1.png Screenshot KDE-Session]
+
In you ssh configuration, if you chroot a user, this user need to have his own /bin directory inside his chrooted directory. If not, you will not be able to connect.
  
[http://wiki.archlinux.de/?title=Bild:X2go-2.png Screenshot configuration dialog]
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== See also ==
  
[http://x2go.berlios.de Project page]
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* [http://wiki.archlinux.de/?title=Bild:X2go-1.png Screenshot KDE-Session]
 +
* [http://wiki.archlinux.de/?title=Bild:X2go-2.png Screenshot configuration dialog]

Latest revision as of 16:04, 14 April 2018

X2Go enables you to access a graphical desktop of a computer over the network. The protocol is tunneled through the Secure Shell protocol, so it is encrypted.

Note: X2Go isn't compatible with all desktop environments. You can check X2Go desktop environment compatibility first, especially if you want to shadow your current desktop.

Installation

Two parts are available in official repositories. They can be installed with the following packages:

Server configuration

Configure Secure Shell daemon

X2Go uses Secure Shell in order to work, so you need to configure sshd daemon to allow X11 forwarding and then start it first. Follow the instructions at Secure Shell#X11 forwarding and Secure Shell#Daemon management.

If you are using other than POSIX (C) locale, you may want to add the following line to configuration file

# Allow client to pass locale environment variables
AcceptEnv LANG LC_*

Load fuse kernel module

In order for the server to be able to access files on the client computer you should load a fuse kernel module.

Setup SQLite database

Run the following command on the server to initialize the SQLite database (which is required in order for the x2go server to work):

# x2godbadmin --createdb

Start X2Go server daemon

Now all you need to do is start x2goserver.service.

Desktop Shadowing

To gain access to the "local desktop" (as opposed to a unique session/desktop environment) you need to install x2godesktopsharingAUR from the AUR. Then, launch x2godesktopsharing.

Note, you do not need x2godesktopsharing to access "local desktop" of user "foo" by user "foo". x2godesktopsharing is for accessing "foo"'s desktop by "foo2" user. Just choose "Connection to local desktop" in "session type" in x2goclient.

Client configuration

Make sure you can open an SSH session from the client to the server:

$ ssh username@host

Then run X2Go client itself:

$ x2goclient

You can now create several sessions, which then appear on the right side and can be selected by a mouse click. Each entry consists of your username, hostname, IP, and port for SSH connection. Furthermore you can define several speed profiles (coming from modem up to LAN) and the desktop environment you want to start remotely.

Common mistakes

Do not simply choose the defaults of KDE or Gnome, since the executables startkde and startgnome are usually not in the $PATH when logging in using SSH. Use full paths to startkde or startgnome. You can also start openbox or another window manager.

You should be asked for your password for your user at the server now and after login you will see the X2Go logo for a short time, and the desktop.

Exchange data between client and server (desktop)

On the X2Go client (e.g. laptop) local directories could be shared. The server will use fuse and SSHFS to access this directory and mount it to a subdirectory media of your home directory on the server. This enables you to have access to laptop data on your server or to exchange files. It is also possible to mount these shares automatically at each session start.

To leave a session temporarily

Another special feature of X2Go is the possibility of suspending a session. This means you can leave a session on one client and reopen it even from another client at the same point. This can be used to to start a session in the LAN and to reopen it later on a laptop. The session data are stored and administered in a SQLite database on the server in the meanwhile. The state of the sessions is protocolled by a process named x2gocleansessions.

Troubleshooting

No selection screen in x2goclient

A regression in iproute2 causes ss to show no result when specifying the -u flag, as done in /usr/bin/x2golistdesktops. [1]

See [2], [3] for more information.

Sessions do not logoff correctly

Due to this bug the X2Go sessions might not logoff correctly. The script that initiates the session spits out many log lines that might confuse X2go. A simple workarround is to create a custom session script and redirect the log output either to a file or to /dev/null and then point your X2Go-client to this custom script.

Here is a sample script for an XFCE session:

 #!/bin/sh
 #
 #xfce4-session spits out quite a bit of text during logout, which I guess
 #confuses x2go so we would get a black screen and session hang.
 #adding redirect to a logfile like "~/logfile" or "/dev/null" nicely solved it
 # see http://bugs.x2go.org/cgi-bin/bugreport.cgi?bug=914
 /usr/bin/xfce4-session > /dev/null

Shared folders do not mount (Windows Clients)

The ssh-daemon used by the X2go windows client uses depreceated ssh-dss keys by default and because Arch does not accept them your shared folders will not mount. Check out this bug report for more information.

This can be solved on the windows side by generating different type of key:

 C:\Program Files (x86)\x2goclient\ssh-keygen -b 2048 -t rsa

And simply replace c:\Users\User\.x2go\etc\ssh_host_dsa_key and c:\Users\User\.x2go\etc\ssh_host_dsa_key.pub with the newly generated key files.

Other workarrounds from [4] might help, too.

Workaround for failing compositing window manager for remote session

Tango-edit-clear.pngThis article or section needs language, wiki syntax or style improvements.Tango-edit-clear.png

Reason: please use the first argument of the template to provide a brief explanation. (Discuss in Talk:X2Go#)

This is useful for situations, when the computer running x2goserver is used also for local sessions with e.g. compiz as the window manager. For remote connections with x2goclient, compiz fails to load and metacity should be used instead. The following is for GNOME, but could be modified for other desktop environments. (Getting compiz ready is not part of this how-to.)

Create /usr/local/share/applications/gnome-wm-test.desktop:

[Desktop Entry]
Type=Application
Encoding=UTF-8
Name=gnome-wm-test
Exec=/usr/local/bin/gnome-wm-test.sh
NoDisplay=true

Create script /usr/local/bin/gnome-wm-test.sh:

#!/bin/sh
# Script for choosing compiz when possible, otherwise metacity
# Proper way to use this script is to set the key to mk-gnome-wm
# /desktop/gnome/session/required_components/windowmanager
xdpyinfo 2> /dev/null | grep -q "^ *Composite$" 2> /dev/null
IS_X_COMPOSITED=$?
if [ $IS_X_COMPOSITED -eq 0 ] ; then
    gtk-window-decorator &
    WM="compiz ccp --indirect-rendering --sm-client-id $DESKTOP_AUTOSTART_ID"
else
    WM="metacity --sm-client-id=$DESKTOP_AUTOSTART_ID"
fi
exec bash -c "$WM"

Modify the following gconf key to start the session with gnome-wm-test window manager:

$ gconftool-2 --type string --set /desktop/gnome/session/required_components/windowmanager "gnome-wm-test"

/bin/bash: No such file or directory when connect (or what ever shell you use)

In you ssh configuration, if you chroot a user, this user need to have his own /bin directory inside his chrooted directory. If not, you will not be able to connect.

See also