Selecting fixed or dynamic address based on vendor-class-identifier

[Sten Carlsen]

My take on this would be to test this:

class "pxeclient" {
    match if substring (option vendor-class-identifier, 0, 9) =
"PXEClient";
  }

  host boottest {
    hardware ethernet 02:13:10:07:11:58;
    fixed-address 192.168.255.12;
  }


shared-network all{
    subnet 192.168.254.0 netmask 255.255.255.0 {
    pool {
      allow members of "pxeclient";
      range 192.168.254.100 192.168.254.109;
    }
  }

    subnet 192.168.255.0 netmask 255.255.255.0 {
      deny members of "pxeclient";   }
}

The uncertain point here is that in a shared network there is really
nothing to tell which subnet the host belongs to, no DHCP-Relays etc.
This should work if a class has higher preference than a host statement.

I don't know the answer to that, I would have to test it.

On 21/10/13 17.06, Anders Blomdell wrote:
> I would like the ISC dhcpd server to hand out either a dynamic ip
> address or
> a fixed address based on the vendor-class-identifier (I want a dynamic
> address
> from one subnet during pxeboots and a [possibly] fixed address from
> another
> subnet otherwise). I have been able to do it by running two instances
> of the
> dhcp server on the interface, but not by using shared-network.
>
> The working configuration consists of /tmp/254.conf:
>
>   class "pxeclient" {
>     match if substring (option vendor-class-identifier, 0, 9) =
> "PXEClient";
>   }
>
>   subnet 192.168.254.0 netmask 255.255.255.0 {
>     pool {
>       allow members of "pxeclient";
>       range 192.168.254.100 192.168.254.109;
>     }
>   }
>
> and /tmp/255.conf:
>
>   host boottest {
>     hardware ethernet 02:13:10:07:11:58;
>     fixed-address 192.168.255.12;
>     if substring(option vendor-class-identifier, 0, 9) = "PXEClient" {
>       ignore booting;
>     }
>   }
>   subnet 192.168.255.0 netmask 255.255.255.0 {
>   }
>
> when running both of them with:
>   /usr/sbin/dhcpd -d -cf /tmp/254.conf -lf /tmp/254.lease --no-pid
>   /usr/sbin/dhcpd -d -cf /tmp/255.conf -lf /tmp/255.lease --no-pid
>
> I get the following expected result:
>
>   # PXE-booting
>   DHCPDISCOVER from 02:13:10:07:11:58 via eth0
>   DHCPOFFER on 192.168.254.100 to 02:13:10:07:11:58 via eth0
>   # Ordinary boot
>   DHCPDISCOVER from 02:13:10:07:11:58 via eth0
>   DHCPOFFER on 192.168.255.12 to 02:13:10:07:11:58 via eth0
>
> But I'm not able to achieve it with just one instance of dhcpd,
> the reason seems to be that the 'ignore booting' will be active
> for both subnets when the machine is PXE-booting and hence it will
> not get an address from the pool.
>
> Anybody that has a good idea on how to solve this?
>
> Regards
>
> Anders
>

-- 
Best regards

Sten Carlsen

No improvements come from shouting:

       "MALE BOVINE MANURE!!!" 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.isc.org/pipermail/dhcp-users/attachments/20131021/165f7912/attachment.html>