ISC dhcpd can do interesting stuff, but ... / 2010-09-27

ISC dhcpd can do interesting stuff, but some options can be quite obscure. Today we suddenly got flooded by alcatel telephones doing DHCP requests in the wrong VLAN. Probably having to do something with moving phones between buildings with different voice vlans. I don't want them to use up dynamic IPs in a production network so I searched a bit and found DHCP for specific range of mac addresses? - Networking. Simple bit of config:

    if binary-to-ascii (16, 8, "-", substring (hardware, 0, 4)) = "1-0-80-9f" {
        deny booting;
    }

Which will deny those 00:80:9f addresses. The first 1 is for hardware class ethernet.