Two subnets, one with PXE clients

Osmany osmany at
Fri Mar 5 14:08:50 UTC 2010

On Wed, 2010-03-03 at 16:59 +0000, Simon Hobson wrote:
> Osmany wrote:
> >Now the PXE Client boots perfectly with the IP it's meant
> >to have, but now I have another problem. Once the PXE client loads, it
> >begins configuring itself to load the OS and obviously does a
> >DHCPDISCOVER once again because it is no longer a PXE Client but I find
> >that the dhcp server assigns an IP from the subnet which I
> >don't want it to have those IPs because the LTSP server does not have
> >any of those IP's.
> Well of course, that's exactly how you've configured it !
> Once the client boots it's OS, it's not a PXE client, doesn't match 
> the PXE class, and so is only allowed an IP from the 
> subnet. If you want certain clients to continue getting a 
> address after boot, then you'll need to add a class 
> that matches them, and add the appropriate allow/deny statements.
> Eg :
> class "LTSPClients" {
>    match if ...
> }
> shared-network ... {
>    subnet netmask {
>      ...
>      pool{
>        ...
>        allow unknown-clients;
>        deny members of "PXEClients";
>        deny members of "LTSPClients";
>      }
>    }
>    subnet netmask {
>      pool{
>        ...
>        allow members of "PXEClients";
>        allow members of "LTSPClients";
>      }
>    }
> }
> The next issue you may find, at least if you boot Windows clients, is 
> that if the client supplies a Client-ID then it will be considered a 
> different client and would still be given a different IP. This is a 
> well known 'problem', and I believe there is finally a means of 
> getting round it without patching the source in the latest version 
> 4.2.0a ?
Well right now I am having trouble setting up the ltsp client so that it can send the vendor-class-identifier
to the dhcp3-server. I was thinking since the ltsp client is actually a
common client and the only thing that differs is that it boots from the
network, I thought about configuring the dhcp client in the
dhclient.conf file but with no positive outcome. I've included the line:
send vendor-class-identifier = "ltsp";
But as I said, I had no positive results. I also tried to configure the
udhcpc on the client but it seems to be that this version does not
support the vendor-class-identifier option, and I think this service is
actually the one that communicates with the dhcp server since all that
the client displays when it tries to bootup is that the udhcpc receives
the wrong IP because it does not send vendor-class-id. I don't know if
this is actually something that should be posted in this mailing list
but I would like some help getting through this.

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