Wrong address assigned --- bottom bits of MAC address ignored ?

Sten Carlsen stenc at s-carlsen.dk
Thu Feb 28 12:15:51 UTC 2013


On 28/02/13 13:00, gary mazzaferro wrote:
> Hi Sten,
>
> Thank you for the reply and the explanation...
>
> I do understand host statements are global. Placing them under the
> subnets was for documentation than anything else.
>
> The explanation doesn't address the issue I'm experiencing, IP address
> for 172.31.1.16 is already provisioned for mac address
> 90:e2:ba:0c:0d:51 and in my reading of the documentation, the server
> should not be offering to the incoming request using mac address
> 90:e2:ba:0c:0d:50.
Well, this is probably another misunderstanding, if I understand you
correctly. Putting a fixed address into a host statement does NOT
reserve it for any purpose. The server will happily hand it out to any
who may ask IF it is in the pool/range of the subnet the discover
arrives at.
My guess is that your eth1 has an address in the 172.31.1.x range - this
would mean that it will get an address in that range (or no addresss at
all) whatever you put in the host statement.

Again I will warn against putting host statements in the subnets, in
this case it will mean that the following options will be given even
when the address is:

Feb 27 18:07:54 DCAPXEserver dhcpd: DHCPACK on 172.31.1.16 to
90:e2:ba:0c:0d:50 (hd-node4) via eth1

  option domain-name "wbu.mydomain.com";
  option domain-name-servers 10.96.191.251,10.119.248.254;
  option routers 10.96.164.1;
  default-lease-time 3456000;
  max-lease-time 34560000;

Basic point is DON'T put fixed address statements in the range you give
the server to hand out, there will not be any reservations made. Sorry I
missed this at first reading.
>
> cheers,
> gary
>
> On Wed, Feb 27, 2013 at 7:36 PM, Sten Carlsen <stenc at s-carlsen.dk> wrote:
>> It seems that you think the host statement can have a limited scope, limited
>> to a subnet. That is not correct, host statements are global wherever they
>> are placed. The bad thing about putting them into subnets is that they will
>> inherit options from the subnet even if they get addresses from another
>> subnet.
>>
>> The server will hand out an address corresponding to the subnet it sees the
>> discover coming from, it will use the fixed address only if it matches the
>> subnet the discover comes from, else it will use an address from the
>> subnet's pool.
>>
>>
>>
>> On 28/02/13 2:36, gary mazzaferro wrote:
>>
>> Hi,
>>
>> Maybe someone can help me..
>>
>> I have an intel card with 4 ports.. with incremental  mac addresses.
>>
>> I'm trying to to use the dhcp server 4.2.3.P2 to assign two subnets
>> based on mac addresses, The server is assigning the first address it
>> finds close to the mac address.  Not sure if my config file is bad..
>>
>> 90:e2:ba:0c:0d:50 should be 10.96.165.16
>> 90:e2:ba:0c:0d:51 should be 172.31.1.16
>>
>> 90:e2:ba:0c:0d:50 sees and offer of 172.31.1.16
>>
>> Feb 27 18:07:53 DCAPXEserver dhcpd: DHCPDISCOVER from 90:e2:ba:0c:0d:50 via
>> eth1
>> Feb 27 18:07:54 DCAPXEserver dhcpd: DHCPOFFER on 172.31.1.16 to
>> 90:e2:ba:0c:0d:50 (hd-node4) via eth1
>> Feb 27 18:07:54 DCAPXEserver dhcpd: DHCPREQUEST for 172.31.1.16
>> (172.31.1.10) from 90:e2:ba:0c:0d:50 (hd-node4) via eth1
>> Feb 27 18:07:54 DCAPXEserver dhcpd: DHCPACK on 172.31.1.16 to
>> 90:e2:ba:0c:0d:50 (hd-node4) via eth1
>>
>> Can some one please help me ?
>>
>> lease file:
>> # The format of this file is documented in the dhcpd.leases(5) manual page.
>> # This lease file was written by isc-dhcp-4.2.3-P2
>>
>> server-duid "\000\001\000\001\030\224\215R\000\014)\375\317\242";
>>
>> lease 172.31.1.16 {
>>   starts 4 2013/02/28 01:07:54;
>>   ends 2 2013/04/09 01:07:54;
>>   cltt 4 2013/02/28 01:07:54;
>>   binding state active;
>>   next binding state free;
>>   rewind binding state free;
>>   hardware ethernet 90:e2:ba:0c:0d:50;
>>   client-hostname "hd-node4";
>> }
>>
>> option domain-name-servers 172.31.1.10;
>> default-lease-time 3456000;
>> ddns-update-style none;
>> authoratative ;
>> subnet 172.31.1.0 netmask 255.255.255.0 {
>>   option domain-name "dca.wbu.mydomain.com";
>>   option domain-name-servers 172.31.1.10;
>>   option routers 172.31.1.1;
>>   default-lease-time 3456000;
>>   max-lease-time 34560000;
>>   range 172.31.1.11 172.31.1.30;
>>   host hd-namenode-data1 {
>>     option host-name "hd-namenode";
>>     hardware ethernet 00:0c:29:c6:82:be;
>>     filename "vmunix.hd-namenode";
>>     fixed-address 172.31.1.11;
>>   }
>>   host pikespeak1 {
>>     hardware ethernet 00:00:c0:5d:bd:95;
>>     filename "vmunix.pikepeak";
>>     server-name "pikespeak1";
>>   }
>>   host node1-data1 {
>>     option host-name "hd-node1";
>>     hardware ethernet 00:0c:29:c1:6e:35;
>>     filename "vmunix.stargo";
>>     fixed-address 172.31.1.13;
>>   }
>>   host node2-data1 {
>>     option host-name "hd-node2";
>>     hardware ethernet 00:0c:29:b8:af:f3;
>>     filename "vmunix.stargo";
>>     fixed-address 172.31.1.14;
>>   }
>>   host node3-data1 {
>>     option host-name "hd-node3";
>>     hardware ethernet 00:0c:29:04:65:ee;
>>     filename "vmunix.stargo";
>>     fixed-address 172.31.1.15;
>>   }
>>   host node4-data1-stargo {
>>     option host-name "hd-node4";
>>     hardware ethernet 90:e2:ba:0c:0d:51;
>>     filename "vmunix.stargo";
>>     fixed-address 172.31.1.16;
>>   }
>> }
>> subnet 10.96.165.0 netmask 255.255.255.0 {
>>   option domain-name "wbu.mydomain.com
>> ";
>>   option domain-name-servers 10.96.191.251,10.119.248.254;
>>   option routers 10.96.164.1;
>>   default-lease-time 3456000;
>>   max-lease-time 34560000;
>>   range 10.96.165.11 10.96.165.44;
>>   host hd-namenode-mgt {
>>     option host-name "hd-namenode";
>>     hardware ethernet 00:0c:29:c6:82:b4;
>>     filename "vmunix.hd-namenode";
>>     fixed-address 10.96.165.11;
>>   }
>>   host hd-node1-mgt {
>>     option host-name "hd-node1";
>>     hardware ethernet 00:0c:29:c1:6e:2b;
>>     filename "vmunix.hd-node1";
>>     fixed-address 10.96.165.13;
>>   }
>>   host hd-node2-mgt {
>>     option host-name "hd-node2";
>>     hardware ethernet 00:0c:29:b8:af:9e;
>>     filename "vmunix.hd-node2";
>>     fixed-address 10.96.165.14;
>>   }
>>   host hd-node3-mgt {
>>     option host-name "hd-node3";
>>     hardware ethernet 00:0c:29:04:65:e4;
>>     filename "vmunix.hd-node3";
>>     fixed-address 10.96.165.15;
>>   }
>>   host hd-node4-mgt-stargo {
>>     option host-name "hd-node4";
>>     hardware ethernet 90:e2:ba:0c:0d:50;
>>     filename "vmunix.hd-node4";
>>     fixed-address 10.96.165.16;
>>   }
>> }
>> _______________________________________________
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>>
>>
>> --
>> Best regards
>>
>> Sten Carlsen
>>
>> No improvements come from shouting:
>>        "MALE BOVINE MANURE!!!"
>>
>>
>> _______________________________________________
>> dhcp-users mailing list
>> dhcp-users at lists.isc.org
>> https://lists.isc.org/mailman/listinfo/dhcp-users
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-- 
Best regards

Sten Carlsen

No improvements come from shouting:
       "MALE BOVINE MANURE!!!"

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