How to ignore a set of Mac addresses in dhcpd.conf?

Solution 1:

You can use something like:

class "ignored" {
        match if substring(hardware,1,4) = 00:02;

pool {
        deny members of "ignored";

Solution 2:

From this thread on the mailing list, another option to block specific hosts is:

class "black-hole" {
    match substring (hardware, 1, 6);
    # deny booting;
    ignore booting;
subclass "black-hole" <MAC-ADDRESS-TO_IGNORE>;

The thread also says that the difference between ignore and deny is that the later logs the request whereas the former does not.