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List:       suse-linux-uk-schools
Subject:    Linux Server & Windows PC configuration
From:       "Martin Dart" <mjdart () brookes ! ac ! uk>
Date:       2000-10-26 12:38:46
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Hello all - I thought I might share our recent configuration with you in
response to Huw Harpers earlier mailing.

Our department has recently implemented a SuSE 6.4 server, running 28 Win 98
(previously Win95) clients. Because of the 'inquisitive' nature of our
students, we wanted each workstation to rewrite its hard disk after every
boot, ensuring a clean environment for the next user, and preventing any
junk files from using up hard disk space, and also to prevent any hacking
software from being sneakily installed on the network. The whole thing works
like this...

The SuSE server is configured to run DHCP. Each workstation has a PXE
compliant NIC (we use 3COM 3C905C cards) that broadcast their MAC address at
boot. The Server has a list of reservations in its DHCP set-up that reserves
a single IP address for a specific MAC address (each workstation therefore
keeps its own IP address after multiple boots).

Once the server has assigned the correct IP addresses to the NICs (the
reserved list stops other client machines chatting to the DHCP server and
stealing the available IP addresses!), then the server initiates a TFTP
(Trivial File Transfer Protocol) session that downloads a small DOS-like
program called BpBatch to the workstation.

BpBatch does a quick check to see if the image file on the workstation
differs from the master copy held on the server. If the server copy is
newer, BpBatch initiates a download of the new image to the workstation,
then the client machine will boot off this nice fresh copy of Windows. If
the two image files match, then the really clever bit kicks in! - In the
event of matching image files, the workstation restores the C:\ partition of
its hard disk from a hidden partition on its own drive (this hidden
partition contains a copy of the current server-based image file). BpBatch
sets up this hidden partition the first time it loads (based on a text file
you can edit), and once it is all set up and running, this makes booting the
machine much faster, as each machine does not always have to download a copy
of the master image file from the server at every boot. It is worth noting
though that when this does need to happen (after you update the Windows
images file from a workstation), booting time is very slow, and can only be
done 5 workstations at a time, during a 'quiet' time of the day. But, the
image file only needs updating  if you must install new software to all
machines in one go, which if you plan as far ahead as possible, is not very
often!

As a rough guide, when we used a Win95 set-up with Office 2000 and a few
other small-ish programs installed, each machine took around 3 minutes to
completely re-write its own hard disk, and boot the clean copy of Windows.
Now we have 'upgraded' to Win98, it is around 4 minutes. I did try WinME a
few weeks ago, but judging by the huge increase in the size of the C:\
drive, I didn't even bother to try re-imaging it - I think it would have
taken it well past the 5/6 minute stage (too long to expect users to put up
with I think!).

The reaction from our students and staff has been very good - they like the
reliability and robustness of the system. A student could literally fdisk
the C:\ drive, and a simple off/on of the power has the whole system back up
in 4 minutes - much quicker than a re-install would take!

Oh - when the time comes to update the Windows set-up, just configure a
workstation the way you want, then run a supplementary little program called
MrZip (which uses a small text file called ZipWin to tell it what to save
and to where). The image is then saved back to your directory on the server
in about 15/20 minutes. A nice touch is that you can create a history of
image files on your server, so you can restore the whole network to a
previous state at any time you want.

We also map 2 permanent network drives from the workstation onto the server,
and into these drives we install any software (Office/Delphi/Encarta 2000
etc.) This saves disk space on the workstation (making the images faster to
load/boot), and means we can back up to tape the entire installed software
paths (nice in case of disaster of hacking). We have not noticed any
horrible slow down of the software running it remotely this way.

Sorry this is getting a bit long. The process of this set-up took me some
time to get to grips with, and that was only then because I had the help of
a Linux expert here at work!  But the set-up works so well I can heartily
recommend anyone trying it. A good starting place for further info is this
web page: http://www.bpbatch.org/ . Any number of Linux books or web pages
will help you with the set-up of DHCP or TFTP (a good explanation and sample
set-up files are here: http://www.bpbatch.org/docs/linux.html ). The guide
to BpBatch is here: http://cui.unige.ch/info/pc/remote-boot/howto.html , and
the program can be downloaded from:
http://cui.unige.ch/info/pc/remote-boot/soft/ . A really useful support
forum exists at: http://www.bpbatch.org/forum/.

Good luck to all!

Martin Dart
Senior Computing Officer
School of Computing & Mathematical Sciences
Oxford Brookes University
Gipsy Lane
Headington, OXFORD
Tel (01865) 483667
Mobile 0797 927 1628


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