Getting DHCP Server to ignore range of MAC addresses

[BladeRunner 0]

Our Windows 2000 AD domain uses a DHCP server.

This is fine, any Windows box on the network is automatically configured with an IP address etc.

However, we have some Linux boxes that are running DHCP - these are so that we can attach set-top boxes to the network.

The set-top boxes all have a MAC address starting the same way.

The problem at the moment is that when one of these set-top boxes is added to the network there is a 50-50 change the Windows DHCP server will assign an IP address before the Linux box (which is configured to look for certain MAC ranges) gets there.

Is there a way to configure the DHCP server on Win2k Server to ignore a whole range of MAC addresses?

For example if MAC address starts FF then do not assign IP address, then the Linux box can do as it needs.

 

Ta

[clutch 1]

You can't just assign static IPs to the Linux boxes, or reserve an IP range for their specific MAC addresses? I guess I am missing what you want to do.

[BladeRunner 0]

OK.

Basically speaking.

Windows 2000 AD domain.

This makes up some 85-90% of the network - Windows 2000 servers with Windows 2000 Professional & Windows XP Professional workstations.

Each Windows box logs onto the network, the Windows DHCP server happily assigns an IP address to them, they are happy.

The other 10-15% of the network is made up of Linux boxes and set-top boxes.

Each of the developers has their own range of development MAC addresses and also their own range of IP addresses.

Each of them run a DHCP server on their Linux boxes.

So, a set-top box is attached, the Linux box is only distributing IP addresses for a certain list of MAC addresses -all is peachy (mainly because usually the set-top boxes are attached directly to the Linux boxes).

 

Now they have the need to plug in the odd set-top box somewhere else on the network.

It has it's own manually specified MAC address (from that developers range) and what we want to happen is that developers Linux box hands over an IP address from that developers range.

However, before the Linux boxes have any time to hand over an address the Win2k Servers have responded quicker and already given out the address.

 

I guess the only way forward here is to configure the Windows DHCP server to do all the dishing out of IP addresses to all boxes, be they Windows or Linux.

Is that possible to do?

 

Create a new scope which gives out IP addresses to certain MAC addresses?

It isn't exactly reservation as such.

Example:

 

Developer1

IP Address range 10.171.254.1 - 10.171.254.254

MAC Address range 00:02:02:FF:FF ;(x

 

Developer2

IP Address range 10.171.253.1 - 10.171.253.254

MAC address range 00:02:02:FF:FE ;(x

 

Would that be possible?

[clutch 1]

OK, I get what you're driving at now. Unfortunately, the only way I can think of at the moment would be to reserve the IPs of your regular workstations in a specific address range, and assign that to the 2K DHCP servers. I know that isn't what you're looking for, and that would be a pretty bad idea from an administration angle. I just don't see any option enabling MAC filtering right now. Do any of the Linux boxes allow for this? Are the Linux boxes already using this sort of filtering mechanism? Also, what's to prevent some developer A's Linux box from assigning an IP to developer B's set-top box when he's roving the network? If the Linux boxes can perform this kind of filtering, maybe they can take the place of the 2K DHCP servers.

[BladeRunner 0]

It would appear that the Linux DHCP servers can indeed do this.

They are acting purely on a list of known MAC addresses and simply don't get involved with any MAC address that doesn't concern them.

So in the above example only Developer1's DHCP server will respond to one of Developer1's set-top boxes - well with the exception of the Windows servers of course as they are busy answering anything - but Developer2's DHCP server will not attempt to assign an IP address to a device using a MAC address from Developer1's pool.

 

I was hoping that maybe the Windows DHCP server could do the same (as a rule the Windows servers can do more or less the same as the Linux boxes, however the features are usually hidden away).

Oh well, back to the drawing board I feel.