[lfs-support] Regeneration of udev net rules

Geoff Swan gswan3 at bigpond.net.au
Fri Jun 5 01:50:07 PDT 2015



On 2015-06-05 4:26 PM, Geoff Swan wrote:
>
> On 2015-06-05 6:16 AM, Bruce Dubbs wrote:
>> Geoff Swan wrote:
>>>
>>> On 2015-06-04 1:48 PM, Bruce Dubbs wrote:
>>>> Geoff Swan wrote:
>>>>>
>>>>> On 2015-06-03 6:53 AM, Paul Rogers wrote:
>>>>>>> However, when I move this OS drive to another similar server, the
>>>>>>> network devices fail to start because the definitions in the udev
>>>>>>> rule
>>>>>>> file are stilll bound to the MAC addresses of the previous hardware.
>>>>>>>
>>>>>>> The question is, is there a mechanism to allow the system to
>>>>>>> regenerate
>>>>>>> the rules file and bind the names to the new hardware devices
>>>>>>> automatically?
>>>>>>>
>>>>>>> Perhaps if the file was emptied before the OS drive being moved
>>>>>>> then it
>>>>>>> would be generated for the new hardware?
>>>>>> Yep, that'll do it.  Just delete the file.  It'll make a new one,
>>>>>> though
>>>>>> the order it finds them on that first boot.  Note, however, if you
>>>>>> need
>>>>>> a particular NIC/plug to have a particular name, eth?, you can just
>>>>>> edit
>>>>>> the MAC address.
>>>>> No, deleting the file just causes the interface initialisation to
>>>>> fail.
>>>>> It did not rebuild the 70-persistent-net-rules file.
>>>>> I am looking for a way to have this file generated or updated
>>>>> according
>>>>> the the interfaces currently in the hardware that the OS drive is
>>>>> plugged in to. It could be moved between several machines.
>>>> What you need to do is (as root):
>>>>
>>>> rm /etc/udev/rules.d/70-persistent-net.rules
>>>> bash /lib/udev/init-net-rules.sh
>>>>
>>>>    -- Bruce
>>>>
>>> Thanks Bruce.
>>> I guess there is no automatic mechanism for when the box has not KB or
>>> monitor attached, which was what I was hoping for.
>>> Even if I remove the rules file before moving the OS drive, it does not
>>> appear to rebuild the rules file automaticaaly when started on a
>>> different box.
>>> I guess I could exec the init-net-rules.sh script at startup if the
>>> rules file is not present to have it build it automatically.
>> Generally you need to make several changes when moving from one box to
>> another.  Things like hostname, static ip addresses, etc are the most
>> obvious.  You probably do not want a dhcp ip address on a headless box
>> because you need to know the ip address for ssh.
>>
>> Just update the net rules at the same time.
>>
>> Note that the init-net-rules.sh script will not generate rules in a
>> virtual box.  There is generally no guarantee that the MAC address
>> will be the same for different instances.
>>
>>   -- Bruce
>>
>>
> I put together a quick init boot script to check to see if the rules
> file existed and if not ran the script to create it.
> However it appears to have come up with its own set of names;
> KERNEL=="enp*", NAME="enp7s0f0", instead of the expected eth* names.
>
>
After a bit of searching I found this.
http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/

Looks like udev has changed again, and naming using 'eth' names is
discouraged.




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