IP address incorrectly assigned on boot

[jdow]

On 2012/02/03 16:52, Rick Stevens wrote:
> On 02/03/2012 02:39 PM, Geoffrey Leach wrote:
>> On 02/03/2012 01:54:34 PM, j.e.aneiros wrote:
>>> On Fri, Feb 3, 2012 at 4:01 PM, Geoffrey Leach<geoff at hughes.net>
>>> wrote:
>>>
>>>> A system on my local network (pvr) has its IP address in /etc/hosts
>>>>
>>>> geoff at pvr[1]->cat /etc/hosts
>>>> 127.0.0.1 localhost localhost.localdomain localhost4
>>>> localhost4.localdomain4
>>>>
>>>> 192.168.10.2 pvr.mtranch.com pvr
>>>> 192.168.10.3 mtranch.mtranch.com mtranch
>>>> 192.168.10.1 Netgear
>>>> 198.168.20.5 Homerun
>>>>
>>>> Netgear router accessed from pvr via wireless. It has the address
>>>> 192.168.10.2 reserved and assigned to pvr. Worked fine. Today
>>> after
>>>> booting up the latest kernel, (3.2.2-1.fc16.i686.PAE), the IP
>>> address
>>>> has changed to 192.168.10.5:
>>>>
>>>> geoff at pvr[2]->ifconfig wlan0
>>>> wlan0 Link encap:Ethernet HWaddr AE:5D:BA:91:67:2D
>>>> inet addr:192.168.10.5 Bcast:192.168.10.255
>>>> Mask:255.255.255.0
>>>> inet6 addr: fe80::ac5d:baff:fe91:672d/64 Scope:Link
>>>> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
>>>> RX packets:484 errors:0 dropped:0 overruns:0 frame:0
>>>> TX packets:462 errors:0 dropped:0 overruns:0 carrier:0
>>>> collisions:0 txqueuelen:1000
>>>>
>>>> you'll note that it is 192.168.10.5
>>>>
>>>> Not surprisingly, I can't ssh 192.168.10.2, but I can ssh
>>> 192.168.10.5
>>>>
>>>> Question: where is this (dynamic?) assignment taking place?
>>>>
>>>
>>> I think the machine is requesting the router a new IP and the router
>>> couldn't match the MAC of the request with the MAC associated to the
>>> reserved IP 192.168.10.2, so is giving a new IP in the range.
>>> Something
>>> change at the machine, did you check the MAC AE:5D:BA:91:67:2D
>>> against
>>> your
>>> rule in the router?
>>
>> Your suspicion was correct. I replaced the one in use with the one from
>> ifconfig. Unfortunately that did not fix the problem.
>>
>> I need a tutorial on assigning MAC addresses, as they are inconsistent
>> on the server and client. Is it correct that the MAC address is the
>> same as HWADDR in the ifcfg file? And why would the value change when
>> the hardware did not?
>
> They're supposed to be the same. The only way to be sure is to actually
> see what the driver assigned as the MAC address:
>
> $ cat /sys/class/net/wlan0/address
>
> What's returned by that is the MAC address as set up by the driver.
> That should match the value in the ifcfg file's HWADDR field.

There is also the little pesky detail that the computer remembers the address
that it last used and requests that of the DHCP server. Modulo the server
involved it will give the requested address regardless of whether it has a
formal assignment for that MAC to another address or not. You may have to
tell the computer to formally release the current DHCP assignment before
going off to request a new one.

{o.o}   Been bit by this one before. It's also painful to change a computer's
         name on a network in which the dhcpd updates the named. Absurdly short
         TTLs helps.