VNC Access to the GSI LinuxFarm

VNC (short for Virtual Network Computing) is a protocol to forward X (i. e. your Linux desktop and GUI applications) from one box to another. Originally developed by AT&T there are many different implementations available for all common operating systems. Additional informations can be found at Wikipedia (english) for example.

Brief howto

  • Start vncserver on the target box.
    • Choose appropriate settings for resolution an color depth to assure a fair operating speed, e.g. vncserver -depth 16 -geometry 1024x768.
    • You'll have to set a password on first start. This password is independent from your other UNIX or windows passwords. It will be stored in the file ~/.vnc/passwd and can later be altered using vncpasswd.
    • The server will tell you the display ID to connect to (hostname:display_number, e.g. lxi007:2).
  • Start a VNC client on the other box.
    • In the LinuxFarm there's the KDE app krdc available (Internet MOVED TO... Remote Desktop Connection in the KDE menu).
    • The native client vncviewer may not be installed on all linux hosts at GSI.
    • You'll be asked for the server's display ID and the connection password.
  • If you don't need the VNC server anymore you can stop it on the target box with the command line: vncserver -kill :display_number

Advanced hints

  • The applications to start inside the VNC session are defined in ~/.vnc/xstartup. This file will be created automatically after the first usage of vncserver. It must be executable by the owner, otherwise it will be ignored during the startup.
  • VNC sessions do not start KDE by default. If you want to export a complete KDE desktop you'll have to change the corresponding entry in ~/.vnc/xstartup. A quite sparse version of this file contains only two lines like:
    startkde &

    Many KDE themes eg. Oxygen and QtCurve don't work well with VNC and produce display errors.
    • You can change the theme to Plastique (at System SettingsApplication AppearanceStyle) together with the Plastik window frames (at System SettingsWorkspace AppearanceWindow Decorations).
    • Alternatively use the recommended X2go.
  • Changes in ~/.vnc/xstartup require a server restart.
  • For troubleshooting take a look at the log entries first. They are located in the directory ~/.vnc with file names like {servername}:{displaynumber}.log, e.g. lxi006:9.log.
  • VNC sessions can of course be tunneled over SSH, see SSH Usage The port to forward will normally be 5900 + display_number.
. -- ChristopherHuhn, StefanHaller - Jun 2006...Aug 2008

This topic: Linux > LXadmin > ItMeetings > HpcMeeting > LinuxProtokoll060105 > VncConnection
Topic revision: 2016-01-21, KatharinaMader
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