Make DHCPd Ignore/Deny giving an IP.

[Eric J]

I had been searching for a few hours looking for the answer to my
question. "How can I prevent DHCPd from giving a MAC address an IP?"
I actually saw quite a few people out there looking for the same
thing, with no answer. So, I wanted to post an answer. I have found
two solutions, because in my situation, I didn't want to flat out deny
an adapter an IP.

My setup, I have a LAN and Internet, I have connected them to each
other, but when I do this, my internet computers would pick up a LAN
IP from DHCP.

First, if you want to make DHCPd flat out Deny an IP to an adapter,
add this to your dhcpd.conf

host bob {
hardware ethernet 00:21:A1:B1:71:41;
deny booting;
}

If this dhcpd is the first to respond, your computer will not get an
IP. Access Denied.

Now, what I wanted... I just wanted my LAN DHCPd to ignore an adapter
so it would find an IP, but somewhere else.

First, add this line towards the top of dhcpd.conf:

not authoritative;

Then furthur down, add:

host bob {
hardware ethernet 00:21:A1:B1:71:41;
next-server 24.26.163.32;
}

Not authoritative tells dhcpd that it is not the final word in DHCP, I
think this is the line that ignores requests when needed. Next-server
tells the client to look towards this address for another dhcp server.

To get an address for next-server, in Windows, open winipcfg(9x) or
ipconfig /all (WinNT/2k/XP) and look for DHCP server. You should be
connected to the internet, before performing this.

SUMMARY
All I did was read the MAN page for dhcpd.conf, all the answers were
there. I just wanted to post this because I have seen other people
out there looking for nearly the same thing, maybe they will find
this. Maybe if you have furthur questions you can email me.