[K12OSN] Re: K12OSN Digest, Vol 3, Issue 74

Dan Bo faengoy at yahoo.com
Mon May 17 15:00:20 UTC 2004

OK, from the Etherboot Website:
The first part is Etherboot contains code that when it
sends out a DHCPDISCOVER request, a tag containing a
Vendor Class Identifier of "Etherboot-x.y" is sent
out, where x.y is the version number, currently 5.0.
The 5 and the 0 are printable digits, not binary
values, i.e. byte values 53 and 48 respectively. This
allows the server to identify Etherboot clients and
ignore all others.

The second part is Etherboot can be conditionally
compiled to require a Vendor Encapsulated Option
containing a VCI of "Etherboot", otherwise it will
ignore the DHCPOFFER. The option is not compiled in by
default because it would cause Etherboot to not boot
in plain setups. The server we want to respond will
include this tag in DHCPOFFERs and while other servers
(e.g. Windows servers) may respond, they will be
This means that only the Etherboot clients will get
answers and that they will get it only from the DHCP
server requested.  There may very well be an answer
and a lease from another server, but is that really
As to school policy on such matters, I can't answer,
but we were talking about using different ports, which
I don't think would be viewed any differently than
this setup.
Do it on a test LAN first with a regular DHCP client
to check that it's not getting any answers before you
put it live,
From: "Terrell Prude', Jr."
<microman at cmosnetworks.com>
Subject: Re: [K12OSN] 2 DHCP Servers
To: "Support list for opensource software in schools."
	<k12osn at redhat.com>
Message-ID: <40A8A330.4010709 at cmosnetworks.com>
Content-Type: text/plain; charset=us-ascii;

But then we've got to make sure that the standalone
(Windows, Mac, whatever) don't respond to the K12LTSP
server's DHCP 
server. That's the bigger problem. The K12LTSP clients
may not respond 
to the pre-existing (Windows-based) DHCP server, but
the existing LAN 
workstations will happily respond to the K12LTSP
server's DHCP server, 
and that can cause major problems without involving
the IT staff of the 

Also, there may or may not be other issues of policy
preventing more 
than one DHCP server on the LAN. I know there is in my

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