Re: [K12OSN] Dual boot to LTSP?

Steve Wright (paua@quicksilver.net.nz)
Thu, 11 Jul 2002 09:16:18 +1200 

Michael Thomas wrote:

> We have an existing Windows 98 lab used for training.  However, we 
> want to be able to use the existing lab to train teachers on Linux / 
> LTSP applications.  Of course, setting up a dual boot Windows/Linux 
> machine is fairly easy, but the LTSP lab model has generated some 
> questions:


If you are using an existing windows box for your LTSP server, be aware 
they *can* be quite a different animal.
The main difference will be RAM.  If you have around 256MB RAM on the 
LTSP server, you will be able to boot 2-4 clients
no worries.  Many windows boxes have only 128MB RAM, and if this is true 
for your situation, the server, and consequently the
desktops will struggle.

>
> 1.  Can the machines be set up to boot off of the LTSP server over the 
> LAN without affecting the Windows setup on the HD?  I would assume 
> this is the case since the standard k12LTSP setup bypasses the local 
> HD by the use of a boot rom image on a floppy.  Would the use of a 
> boot rom floppy when desiring Linux be the easiest way to do this? Or 
> is there better way?


There is always a better way. 8-)   No, the etherboot floppy will be 
fine.  You will need to be certain you have the correct
etherboot image for each machine.   Audit each machine *first* to find 
out what type of network cards you have installed, and then
download the required images from the rom-o-matic site, dd the images to 
the floppies, making sure you have labeled the floppy disks
correctly.  Of course, if all your clients are identical, then your job 
here is very easy.

>
> 2.  These Windows machines already received their IPs via a 
> centralized DHCP server.  Assuming that we want to leave these 
> machines plugged in to the existing LAN, how do we configure the 
> workstations to get their DHCP numbers?  Not from the LTSP server, but 
> from the LAN DHCP server, right?  If so, do we turn off DHCP services 
> on the LTSP server?  How then does the workstation know to pull the 
> kernel, apps, etc. via TFTP from the LTSP server?  What other sorts of 
> changes need to be made to the LTSP server? Workstations?


Ok, this is the hard part, or the easy part.  The easy way is to simply 
UNPLUG the network so the LAB is isolated from your
test LTSP system.  If you want network access, then plug the school 
network back into the 'other' NIC on the LTSP server.

The hard way is ..  8-o

1.)  Allocate your IP addresses:   A small dynamic range for your LTSP 
clients, and a fixed IP for your server.
    If 192.168.0.254 is already allocated, try to steal it, especially 
if it's just a printer or something.  Changing the IP address
    of an LTSP server is a LONG HARD ROAD.  We did it, and it wasn't 
funny.  Mind you, we didn't know what we were
    doing, and basically grepped the entire HDD for the server IP 
address to change.

2.)  Tell your existing (windows?)  DHCP server to NOT REPLY to DHCP 
clients who have the vendor-identifier-string
    "etherboot*" and "linux*".

If you don't do this, windows' DHCPd will offer a perfectly valid IP 
address to your booting client, which of course will be
perfectly useless to a booting Linux diskless client.


3.)  Modify the LTSP servers' /etc/dhcpd.conf to specifically NOT REPLY 
to booting windows clients OR YOU WILL TAKE
    THE WHOLE SCHOOL NETWORK DOWN.  How do I know ?  I'm not saying..   :-[

4.)  Modify the LTSP servers' /etc/dhcpd.conf to allocate your new IP 
address range to your booting clients.


My resources were `man dhcpd.conf`   `man dhcpd-options`  and hundreds 
of hours of trailblazing, mind-bending, and so-on.

But, here, you may have my /etc/dhcpd.conf  
 http://linuxathome.ath.cx/testing/dhcpd.conf
This is NOT production-ready but it will give you lots of info on how 
it's done.  This conf file is currently
modified to boot everything, including win-clients.

>
> These are general questions, I know.  I looked through the discussion 
> archives and could not find an answer to this scenario, 


Yeah, I know.  8-)  I meant to write a HOWTO on this, but er..  it never 
got done.

There will something I have missed.   Please feel free to post to the 
list again, and we'll pitch in.



Have fun with networking.

regards,
Steve




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