client took a host assigned ip

anthony acqant at
Mon Feb 26 14:35:10 UTC 2007


It happened again this morning.

My host entry

host dhcp33 {
         hardware ethernet 00:0a:95:9c:28:b0;

my logs
dhcpd: DHCPDISCOVER from 00:15:c5:c2:59:f6 via
  dhcpd: DHCPREQUEST for ( from 00:15:c5:c2:59:f6 
via lease unavailable.
  dhcpd: DHCPNAK on to 00:15:c5:c2:59:f6 via
dhcpd: DHCPOFFER on to 00:15:c5:c2:59:f6 (hr-cdecresc) via

And yet the pc still used it.

Simon Hobson wrote:
> anthony wrote:
>> I have a mac os client that for some reason requested an ip that was not
>> in dhcp range but rather was a host assigned ip.
>> The logs show the dhcp server never offered the ip to that mac os.
>> How do I ensure not no clients get host assigned ip's.
> It is sufficient (with the ISC server) to not include the address in 
> a range or a fixed-address statement, it will then NOT be offered to 
> any client.
> The server will not however NACK an address that a client might 
> request if the address is a valid address for the subnet - eg in the 
> example config you give, would be considered valid (and 
> not NACKed) but would NOT be offered to a client. So if you have 
> another dhcp server on the subnet then it is quite easy for the other 
> server to hand out addresses you did not intend to be used.
> Another explanation is that a client has moved from another network 
> and is requesting the address it last had.
>> Do I need to   make a pool of host assigned ip's and deny the clients
>> like this?
>>         pool {
>>                  failover peer "dhcp-failover";
>>                  range;
>>                  range;
>>                  option domain-name-servers;
>>                  deny dynamic bootp clients;
>>          }
>>          pool {
>>                  range;
>>                  deny all clients;
>>          }
>> host procurve2wp {
>>          hardware ethernet 00:08:83:FF:FA:80;
>>          fixed-address;
>> }
> No, there is no need for that.

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