Index

1. Linux Terminal Server Project

• started in 1999
  • thin clients on GNU/Linux
• take out cdrom, floppy, harddrive
• most applications and all file store held on servers
• clients are built from low power silent computers with typical specification
  • 1 GB RAM
  • 1 GHz processor
  • mini itx board, onboard fast Ethernet, (onboard graphics)
  • 24inch screen, keyboard, mouse
  • (maybe add higher quality pci graphics card)
  • roughly £500.00
• this is almost certainly an over specified machine and built with premium components
  • obviously another technique is to use old machines and remove the hard disk

2. Concept

• ease of configuration
  • one file /opt/ltsp/i386/etc/lts.conf which describes all client configurations
• includes, graphics, various kernel modules, mouse type, mouse buttons, server, ramdisk size, nfs server, extra config files if really necessary, sound

3. Resources

• by default everything a user runs, executes on the server
  • ideal in todays environment
  • multi core 64 bit server (Opteron Quad/Dual Core) with multiple processors
  • huge hard drive on server
  • protect server against physical attacks and networked attacks
• users sit at thin client and effectively log into server using say, KDM
  • someone unacquainted with LTSP will think they are logging in normally
• by default all applications run on the server
• Linux is very good at disk caching and code sharing
  • so good that the LTSP project estimates you need
  • 250MB ram for the first user and only 50MB ram for subsequent users
• so how many users can you support with 1GB ram?
  • what about 4GB ram?
• LTSP is used at a call center and the server is one high end Dell machine
  • it serves 170 members of staff who are typically running OpenOffice and FireFox
• ideal also for exhibitions which want to provide Internet access
  • configure the networking on the server and plug in 100 thin clients..

4. LTSP client initialisation

• the client is diskless, so it boots using either
  • network interface card boot ROM
    • the preferred method
  • floppy disk
  • CDROM
• all methods
  • first it runs the DHCP protocol to obtain the IP, netmask, gateway, tftp server addresses
  • second using TFTP/UDP/IP it downloads pxelinux.0
  • third it runs pxelinux.0 which downloads the linux kernel from the tftp server
  • fourth it runs the kernel and uses NFS to download the root filesystem
• note it uses pxelinux.0 as the linux kernel is too large to fit into base memory
• it configures itself from the root filesystem and starts an X server which connects to an XDM server which provides a graphical login screen
• the XDM server is where the application programs are run
  • normally this should be a powerful machine
  • ie multiprocessor quad core Opteron

5. Example /etc/lts.conf file

• this file is located at: /opt/ltsp/i386/etc/lts.conf on the NFS server

• [Default]
          SERVER             = 192.168.0.6
          XSERVER            = auto
          X_MOUSE_PROTOCOL    = "IMPS/2"
          X_MOUSE_DEVICE     = "/dev/psaux"
          X_MOUSE_RESOLUTION = 400
          X_MOUSE_BUTTONS    = 5
          X_ZAxisMapping     = "4 5"
          USE_XFS            = N
          SCREEN_01          = startx
          SCREEN_02          = shell
          X_COLOR_DEPTH      = 24
          SOUND              = Y
          LOCAL_DEVICE_01    = /dev/hdc:cdrom
          HOTPLUG            = Y

6. Background reading and listening

• please take a look at ltsp and try listening to linux-terminal-09-2005.ogg
• this ogg file is an edited version of a VoIP conference (the original had a huge non ltsp intro - waiting for someone to turn up..)

7. Film of LTSP client booting

• apologies for camera shake..
• boot
• login

8. Use of LTSP

• LTSP allows full X windows, so for example the KDE, GNOME desktop
• applications by default run on server
  • can run applications on client
• typically client side programs include
  • dvd player ( mplayer , xine )
  • VoIP applications ( kphone )
• small text editors ( vi )
• OpenOffice runs exceptionally well on the server
  • first instance takes 3 seconds to start
  • subsequent instances have an almost instant start up time
• firefox also behaves in this way - check out the movie
• over 50% of users are educational establishments
  • greater 100,000 users
• popular use is to keep a Windows 2003 server on the network
  • and provide users with kdesktop
  • users have access to both GNU/Linux and Windows
• use 30 boot floppy disks to convert a Windows lab into a GNU/Linux lab
  • provides schools, Universities with low risk experimentation with GNU/Linux
• LTSP is available in the Ubuntu distribution (Breezy Badger)
  • and Debian (Etch/Sarge)
  • LTSP is being placed into Fedora and should lead to Redhat
• IBM is using LTSP
  • internally committed to replacing Windows with GNU/Linux
• sites are using LTSP with 140..170 clients per server

9. LTSP overseas

• Mark Shuttleworth in South Africa has organised 80,000 LTSP clients in schools
• South Korea 1 Million LTSP clients
• Brazil
  • Telecentos project: 6000 Cyber cafés which have 20 terminals each
  • 120,000 thin clients
• massive financial saving

10. Tutorial

• give yourself a GNU/Linux account by clicking here
  • and follow the instructions carefully
• you will need to reply to an email using Windows to activate your GNU/Linux account
  • why is this necessary?

11. Remote access to GNU/Linux

• firstly open up a terminal usually found under Applications -> Accessories
• now type

• j203-01 $ ssh mcgreg.comp.glam.ac.uk
  Do you want to connect? yes
  mcgreg $ vnc4passwd
  Password:
  Verify:

• your terminal has now connected to the mcgreg GNU/Linux file server and you have command line access to your account on this machine
  • is the speed of this interaction acceptable?
  • why is this the case?
• now, using a browser and file manager, cut and paste this

• #!/bin/sh
  
  [ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
  
  
  vncconfig -iconic &
  "$VNCDESKTOP Desktop" &
  startkde &

• script and copy it onto your file .vnc/xstartup in your home directory
• now continue to use your terminal session

• mcgreg $ vnc4server
  Log file is /home/gaius/.vnc/mcgreg:12.log
  mcgreg $ exit

• write down the log file number (in the above case it was 12)
• now find the vncviewer application in the pull down menus and run it
  • connect to mcgreg.comp.glam.ac.uk:12 (notice that in this case :12 was appended as it was the vnc value)
• now use the vncviewer to open another browser to read these notes
  • is the speed acceptable, for this activity?
  • what is the vncclient doing (roughly)?
    

12. Remote access to GNU/Linux

• now shutdown your vncserver (you can always start it up again at a later time)
  • to do this use the terminal again (which is still logged into mcgreg )

• $ vncserver -kill :12

• and now log out from mcgreg

• $ exit

13. Another method of accessing GNU/Linux remotely

• in theory if you had root access you could now shutdown your X display
• you could then login using the plain text terminal and type:

• X -query mcgreg.comp.glam.ac.uk

• and now log in again and use this session to read the blackboard notes again
  • is the speed acceptable?
  • why?

Index

This document was produced using groff-1.19.