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?
- 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
- 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
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
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
- 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
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
Index
1. Linux Terminal Server Project
2. Concept
3. Resources
4. LTSP client initialisation
5. Example /etc/lts.conf file
6. Background reading and listening
7. Film of LTSP client booting
8. Use of LTSP
9. LTSP overseas
10. Tutorial
11. Remote access to GNU/Linux
12. Remote access to GNU/Linux
13. Another method of accessing GNU/Linux remotely
Index
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