DHCP on router and BOOTP on server. Is it possible?

Dmitry Shumilin sdv.brest at gmail.com
Tue Aug 4 07:27:29 UTC 2009

Thanks for quick answer.
All these ways are very smart, but not acceptable in my case.
1. I can't change router's configuration
2. There can be absolutely random PCs on network with random MAC addresses.
3. I can't turn off existing DHCP on router.

But, i got some idea.
Maybe it's possible to configure DHCP client in way, so it will accept only
requests containing netboot part OR we can configure DHCP client for accept
only requests from specified IP or MAC (maybe by configuring DHCP client or
using firewall in init environment if this is possible).
Remember, that DHCP client is running on init environment. I can change
initrd configs and re-assemble it.

Thanks in advance.

2009/8/4 Glenn Satchell <Glenn.Satchell at uniq.com.au>

> >Date: Mon, 3 Aug 2009 22:43:30 +0300
> >Subject: DHCP on router and BOOTP on server. Is it possible?
> >From: äÍÉÔÒÉÊ ûÕÍÉÌÉÎ <sdv.brest at gmail.com>
> >To: dhcp-users at lists.isc.org
> >X-BeenThere: dhcp-users at lists.isc.org
> >
> > Hi, ISC DHCP users!
> >
> > In short, my target is to add ability of booting thin clients from
> netboot
> > server (server with running on it TFTP, NFS, DHCP) without making changes
> or
> > disabling DHCP server running on router.
> >
> > Is it possible to configure DHCP server in way, so DHCP server will be
> > responsible for providing ONLY data regarding network boot and getting
> all
> > other data (IP address, netmask, gateway, etc) from DHCP running on
> router
> > and providing all data together to client.
> Depends on how configurable your router's dhcp server is. For example,
> in ISC dhcp you can specify thgat the tftp server is another system.
> But generally there is no way, without re-writing the code, that one
> dhcp server can aggregate information from two different sources to
> return a dhcp response.
> > Maybe there are some other ways of adding netboot ability to my network
> > without changing currently running DHCP server?
> Essentially you need a way to identify netboot requests, and respond to
> that, but ignore other dhcp requests. There are a few ways to do this
> with ISC dhcp. So you need to see if there is some option, or a known
> MAC address prefix you can filter against, or are they all on one
> subnet, for example?
> Likewise on the router, it needs to ignore these clients and respond to
> all other requests. This is the key to whether it is achievable,
> otherwise your netboot clients will get two responses, and they get to
> choose which one they use. The response from ISC dhcp will allow them
> to boot, the other probably not.
> So defining a class to match your thin clients only is needed. Are they
> all the same brand? If so then you might be able to use a common MAC
> address prefix, eg:
> class "netboot-clients" {
>        match if (substring(hardware, 1, 3) = aa:bb:cc);
> }
> subnet ( ... ) {
>        pool {
>                range ...
>                allow members of "netboot-clients";
>        }
> }
> Note no quotes around the mac address prefix as we are doing a binary
> comparison.
> > I got work netboot before with ISC DHCP server WITHOUT router’s DHCP and
> now
> > I need to make it work together with router’s DHCP.
> In the end it's probably going to be easier to just pick one dhcp
> server or the other and go with that. Is there some political or
> business reason why you can't have a dhcp server not running on the
> router? Let me guess, the network guys run the dhcp service, and you've
> just been given responsibility for all these new thin clients? :)
> > Thanks in advance.
> HTH.
> regards,
> -glenn
> --
> Glenn Satchell     mailto:glenn.satchell at uniq.com.au | I telephoned the
> Uniq Advances Pty Ltd         http://www.uniq.com.au | swine flu info
> PO Box 70 Paddington NSW Australia 2021              | line and all I got
> tel:0409-458-580  tel:02-9380-6360  fax:02-9380-6416 | was crackling.
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