[CentOS] IPv6 broken on Linode

Alice Wonder
Thu, 16 Feb 2017 11:35:49 -0000

On 02/16/2017 03:28 AM, James Hogarth wrote:
> On 16 February 2017 at 10:42, Alice Wonder <alice at domblogger.net>
wrote:
>> On 02/16/2017 02:32 AM, James Hogarth wrote:
>>>
>>> On 16 February 2017 at 10:17, Alice Wonder <alice at
domblogger.net> wrote:
>>>>
>>>> On 02/16/2017 02:03 AM, James Hogarth wrote:
>>>>>
>>>>>
>>>>> On 16 February 2017 at 09:09, Alice Wonder <alice at
domblogger.net> wrote:
>>>>>>
>>>>>>
>>>>>> On 02/16/2017 12:54 AM, Tony Mountifield wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> In article <4cbb9dc4-f063-3434-b7a1-d4d0e6581b5e
at domblogger.net>,
>>>>>>> Alice Wonder <alice at domblogger.net> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
https://forum.linode.com/viewtopic.php?f=19&t=14570&p=72785
>>>>>>>>
>>>>>>>> I can not figure out what I need to do.
>>>>>>>>
>>>>>>>> Apparently according to linode support, the VM
is trying to grab an
>>>>>>>> IPv6
>>>>>>>> address with some privacy stuff enabled by
default causing it to not
>>>>>>>> grab the IPv6 address that is assigned to me.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Does the accepted answer at the following link give
you any useful
>>>>>>> hints?
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
http://superuser.com/questions/243669/how-to-avoid-exposing-my-mac-address-when-using-ipv6
>>>>>>>
>>>>>>> Cheers
>>>>>>> Tony
>>>>>>>
>>>>>>
>>>>>> Not really - I tried
>>>>>>
>>>>>> net.ipv6.conf.all.use_tempaddr = 0
>>>>>>
>>>>>> and it still fails to grab the proper IPv6
>>>>>>
>>>>>> -=-
>>>>>>
>>>>>> Just in case, I did ask Linode support to verify that
my hardware
>>>>>> address
>>>>>> is
>>>>>> what it is suppose to be. Still waiting to hear on
that.
>>>>>>
>>>>>> _______________________________________________
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> it still is key=value  ... it uses the ifcfg- files (via
the rh
>>>>> plugin) and they are all key=value
>>>>>
>>>>> It would be helpful if you could paste the journal output
(journalctl
>>>>> -u NetworkManager) from the time period of attempting to
get an
>>>>> address ...
>>>>>
>>>>> also the nmcli conn sh <connection_name> information
for the interface
>>>>> along with your ifcfg- files
>>>>
>>>>
>>>>
>>>> ifcfg-lo is the only one that exists on any of the servers -
including
>>>> the
>>>> VMs that grab the correct IPv6 address.
>>>>
>>>> from /sbin/ifconfig -a :
>>>>
>>>
>>> For a start stop using ifconfig ... it's broken at this point
on
>>> linux, especially on multi ip and ipv6 scenarios
>>>
>>> Use `ip -6 addr sh` for ipv6 specfic stuff, or just ip addr sh to
see
>>> all IP address stuff regardless of family
>>>
>>>> eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu
1500
>>>>         inet 178.79.185.217  netmask 255.255.255.0  broadcast
>>>> 178.79.185.255
>>>>         inet6 fe80::a8ad:d312:4ef4:7272  prefixlen 64  scopeid
0x20
>>>>         inet6 2a01:7e00::825f:e564:ad53:72fc  prefixlen 64
scopeid
>>>> 0x0<global>
>>>>         ether f2:3c:91:18:8a:7e  txqueuelen 1000  (Ethernet)
>>>>         RX packets 9903  bytes 1088621 (1.0 MiB)
>>>>         RX errors 0  dropped 0  overruns 0  frame 0
>>>>         TX packets 7786  bytes 1087223 (1.0 MiB)
>>>>         TX errors 0  dropped 0 overruns 0  carrier 0
collisions 0
>>>>
>>>> That hardware address - the 18:8a:7e corresponds with what the
IPv6
>>>> address
>>>> is suppose to be. But that's not the address it is
grabbing, despite the
>>>> fact that net.ipv6.conf.all.use_tempaddr = 0 is set.
>>>>
>>>> I'm seriously wondering if the real issue is a
mis-configured dhcp server
>>>> in
>>>> their London facility because nothing makes sense.
>>>>
>>>> journalctl -u NetworkManager
>>>>
>>>> reports no journal entries found.
>>>>
>>>
>>> So are you not using NetworkManager then? there should be some logs
...
>>>
>>>
>>>> I think the problem must be on their end.
>>>>
>>>> It all was working fine until they migrated the VM because of a
hardware
>>>> issue, and I suspect now all the hardware address privacy stuff
being the
>>>> issue is barking up the wrong tree because all the reading I
have done
>>>> seems
>>>> to indicate that with
>>>>
>>>> net.ipv6.conf.all.use_tempaddr = 0
>>>>
>>>> that a fake temporary hardware address would not be sent to
their dhcp
>>>> server when obtaining the address, but the real one, that
should be
>>>> fetching
>>>> my assigned address.
>>>
>>>
>>> Only if the kernel is doing SLAAC ... if other things (eg NM) are
>>> handling it directly they may act differently ... but then from the
>>> lack of logs is NM actually handling this?
>>>
>>> Does systemctl status NetworkManager show it running and does nmcli
>>> show anything?
>>>
>>
>> systemctl status NetworkManager
>> ? NetworkManager.service - Network Manager
>>    Loaded: loaded (/usr/lib/systemd/system/NetworkManager.service;
enabled;
>> vendor preset: enabled)
>>    Active: active (running) since Thu 2017-02-16 08:19:34 UTC; 2h 19min
ago
>>
>> * more stuff *
>>
>> nmcli
>> eth0: connected to Wired connection 1
>>         "Red Hat Virtio network device"
>>         ethernet (virtio_net), F2:3C:91:18:8A:7E, hw, mtu 1500
>>         ip4 default, ip6 default
>>         inet4 178.79.185.217/24
>>         route4 178.79.187.246/32
>>         inet6 2a01:7e00::825f:e564:ad53:72fc/64
>>         inet6 fe80::a8ad:d312:4ef4:7272/64
>>         route6 2a01:7e00::/64
>>
>> * more stuff for other interfaces *
>>
>> -=-
>>
>> The output of
>>
>> sysctl -a | grep net.ipv6 :
>>
>> https://librelamp.com/sysctl.txt
>>
>> It looks from that like it should not be hiding the real MAC address.
>>
>
>
> do nmcli conn show "Wired connection 1"
>
> the entries of interest are:
>
> ipv6.ip6-privacy
> ipv6.addr-gen-mode
>
> man nm-settings to get what they mean
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>

ipv6.ip6-privacy:                       -1 (unknown)
ipv6.addr-gen-mode:                     stable-privacy