[K12OSN] Single NIC Setup

["Terrell Prudé, Jr."]

Mark Cockrell wrote:

> Hello all,
>    I'm a total newbie (read idiot) when it comes to Linux, so don't be 
> afraid to treat me like one- I can handle it.  I've got a Windows NT 
> domain running at the moment, and I want to deploy some LTSP clients 
> throughout the network.  Since I want to have the clients spread out 
> throughout the network, the default K12LTSP setup in which the server 
> acts as a router for a lab situation isn't appropriate.  Can someone 
> tell me how configure my server with just one NIC and my clients to 
> get their IP address from my existing MS DHCP server and then boot 
> from the Linux server?  I await great wisdom.
>

Welcome, Mark, to the world of software freedom!  You will not regret 
it, for many reasons.

No "great" wisdom here, but as it turns out, this is exactly how I run 
all of my K12LTSP deployments.  In my case, I use a cisco router as the 
DHCP server, and it works very, very well.  I've not played with the 
Microsoft DHCP server for netbooting, but I would advise you to consider 
going with something considerably more standards-compliant...say, ISC 
DHCPD or a cisco router.  Windows DHCP servers are notoriously difficult 
to get anything netbooting, including LTSP clients.

That said, here's how you set up the K12LTSP server.  Make sure there's 
a Gig-E card in your server.  No, Fast Ethernet isn't good enough; trust 
us, you *will* need Gigabit Ethernet.  If your motherboard includes a 
Gig-E integrated NIC, that is also supported by the Linux kernel (most 
are), you're all set.  Make sure that your NIC is *not* hooked up to the 
school LAN at this point.  It has to do with DHCP; just trust us and do 
it for now; we'll get to that.  Install K12LTSP, plugging in whatever IP 
address you've assigned in your IP range; your Gig-E card will be seen 
as eth0.  Note that this presumes that you don't have any other NICs in 
the box, or if you've got those integrated FastEthernet NICs, that 
you've disabled 'em in the BIOS.

After you install K12LTSP (you still haven't hooked up to the LAN yet, 
be patient), then you've got just a bit more work to do.  Remember that 
K12LTSP has a built-in DHCP server in it (ISC DHCPD, to be precise), and 
we need to disable it or else you'll hose your entire LAN.  Here we go.  
Fire up a terminal session, su to root, and do this:

    [root at takhisis microman]# /sbin/service dhcpd stop

This will stop the DHCP "daemon", which is the original name for what 
Windows people call a "service".  On any UNIX or UNIX-like system, 
they're known as daemons.  That's why, BTW, there's that "d" at the end 
of "dhcpd".

OK, great, we've stopped dhcpd, but that's only until the next reboot!  
Not good.  So, we'll tell GNU/Linux to not start it at boot-time, 
either!  Heh heh...

    [root at takhisis microman]# chkconfig --level 2345 dhcpd off
   
*NOW*, you can hook up your K12LTSP server to the LAN.

There is one last thing to do on the K12LTSP server.  You've got to 
tweak /opt/ltsp/i386/etc/lts.conf to reflect your actual subnet.  This 
is because the default assumes 192.168.0.*/24.  In my case, I run 
subnets of 10.0.0.0/9, specifically /20's, so 192.168.0.*/24 ain't gonna 
work for me.  You may also need to tweak /etc/hosts to change all the 
192.168.0's to whatever your IP subnet is.  KEdit's "Find & Replace" 
function comes in very handy here.

That ought to do it for the K12LTSP server.

At this point, you get to set your Windows DHCP scope to hand out the 
proper parameters.  Take a look through the archives of this list, 
because I recall someone posting the specific tweaks that they had to do 
in Windows to make it work.  Of course, you *could* simply switch from 
using the Windows DHCP service to the ISC DHCPD built into K12LTSP!  
:-)  Seriously, that might be a better solution, since you'll be running 
a single-NIC K12LTSP server, thus everyone on the LAN can see that server.

Hope this helps,

--TP

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