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Old 10-14-2008, 10:42 PM   #1
Registered: Nov 2001
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How to make DHCP answer only to select mac address?

I have a network with 100 hosts, I want DHCPD to simple ignore 10 of them. How do I do that using software?
Old 10-14-2008, 11:09 PM   #2
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you can:
1. block the mac address of the 10 with an iptables rule like:

iptables -A INPUT -m mac --mac-source 00:aa:cc:bb:nn:dd -j DROP

2. in your DHCP server configuration (assuming to be /etc/dhcpd.conf), you can
define the mac address to ip definition, and don't define an IP range to be offerred:

host OKPC01 {
hardware ethernet 00:16:3e:0b:f2:29;
Old 10-15-2008, 01:16 AM   #3
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Original Poster
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Option 2 is best for me because I have two dhcp/LTSP servers and some hosts need to get IP settings from one server and some other hosts from the other server. Why you ask. Because it is a thin client network so every thin client has to get ip settings from the same dhcp/LTSP everytime they boot. Otherwise crazy things might happen.

But in this network I also have lots of normal desktop clients that also need IP settings from a dhcp server.

1 - Can I use this...

host OKPC01 {
hardware ethernet 00:16:3e:0b:f2:29;
...and also especify a range for normal clients?

2 - If 1 is possible. I'd specify this range in one of the DHCP servers. What happens if a normal desktop client asks for Ip settings from a DHCP server and it's rejected. Would the desktop client try again to find another DHCP server in the network or would it just bail?
Old 10-15-2008, 01:37 AM   #4
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For the record, using iptables won't work if the daemon uses raw sockets (like dhcpd does).

So iptables wasn't really an option for this in the first place.


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