how respond only to specific clients

Carl Karsten carl at
Fri Jun 16 05:28:28 UTC 2006

Glenn Satchell wrote:
>> Date: Fri, 16 Jun 2006 09:55:25 +0800
>> From: "Joey S. Eisma" <jeisma at>
>> To: dhcp-users at
>> Subject: how respond only to specific clients
>> hi!
>> i need to configure dhcp to respond and give ip address only to specific 
>> nic (mac addrs). if one nic requests for an address and is not on the 
>> list. ignore this nic. this nic (client) should look for another dhcp 
>> server.
>> anyone have sample configuration on this?
>> thanks!
>> joey
> All your hosts you want to supply dhcp to will need to be defined in a
> host statement. You'll need one of these for each known host.
> Something like this should do it:
> host foo1 { hardware ethernet; }
> host foo2 { .... }
> ...
> subnet netmask {
>   pool {
>     option routers;
>     option ...
>     ignore unknown-clients;
>     range;
>   }
> }
> Repeat for as many hosts and subnets as required.

Don't you need that whole thing wrapped in a group { .. } ?

Also, what is going to make it " look for another dhcp server." ?

I don't think what is being requested can be done, at least not reliably.  the 
"look for another dhcp server" sounds like "broad cast again and see if the 
other server responds quicker this time" and there isnt anything preventing that 
from happening the first time.

This is starting to sound familiar - isn't the solution to have the 'special' 
server listen on a different port, and have the special client just use that 
port.  Nno try this server then try that server - each client only talks to the 
server it should get an IP from.

Carl K

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