Retaining information between DHCP requests

Bill Shirley Bill at
Thu Oct 9 16:37:39 UTC 2014

On 10/9/2014 12:17 PM, CLOSE Dave wrote:
> Simon Hobson wrote:
>>> The DISCOVER and REQUEST messages in the first exchange include a
>>> unique vendor-class-identifier starting with "anaconda". I can and
>>> do detect that string and provide the special nameserver response
>>> needed. But the subsequent REQUESTs do not include that string and
>>> dhcpd then provides the normal operation response. That confuses
>>> kickstart and the installation fails.
>> The first suggestion is to look at why Kickstart isn't behaving
>> properly - raise it as a bug report and see what happens.
> I may do that. But even if the report is accepted and fixed, the time
> frame doesn't help me. I need to install machines now.
>> Otherwise there are a few things I can think of.
>> 1) Do you actually *have* to use a static address ?
> Yes.
>> 2) Does the address used by kickstart have to be in the same range as
>> that used by the machine once it's running ?
> No. But once I add the entry to dhcpd.conf using "hardware ethernet",
> how do I then specify a different address for kickstart? Please recall
> that, in addition to an initial installation, I need to provide for a
> subsequent re-installation at any time, preferably without the need to
> edit dhcpd.conf at that time.
>> 3) Would reserved leases help ?
> Don't know.
>> 4) Are you providing any "per host" options ?
> No.
>> One thought is to use a separate pool for Kickstart. Use a class to
>> have Kickstart use this pool and the booted machine to use the main
>> pool. You can then apply options to the pools. If you *must* have
>> fixed addresses, then would reserved addresses do ? Create a "stub"
>> lease and add the "reserved" statement to it. That lease will then
>> only be used for the specific client. Without the reserved statement,
>> the addresses will still be effectively static if your set of
>> machines is smaller than the pool size - because the server will try
>> and issue the same address to each client even if it was long
>> expired.
> Basically, that's what I was trying to do using vendor-class-identifer,
> use a separate set of instructions for kickstart. I wasn't trying a
> different pool but that might be possible. Can you please enlighten me
> on how I can accomplish that?

Are you able to set up a separate subnet for kickstart boots? If so, I have an idea that may work for you.


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