IPv6 address not stable, when querying via --wds-get-current-settings (from same CID)

[Martin Maurer]

Am 26.09.2023 um 10:29 schrieb Aleksander Morgado:
>>> I am doing multiple --wds-get-current-settings (around 1 second
>>> between each request).
>>>
>>> IPv6 address changes on each request, all other entries remain stable.
>>>
>>> (4 numbers equal, the other 4 number change)
>>>
>>> Even when "/64" (half of the 128 bit number) shall it change all the time???
>> I've also noticed this.  It's always been like that on all my QMI
>> qmodems.
>>
>> The network allocates a /64.  The rest is invented by the modem.  I
>> definitely agree that the modem firmware should have ensured that the
>> address it generates is stable.  But it doesn't.  And we just have to
>> live with that.
>>
>> My best advice is to ignore the addresses generated by the modem and
>> create your own stable ones instead, using the assigned /64 prefix of
>> course.
>>
>> Note that stable-privacy works fine on any IP interface, even the
>> non-ethernet ones, if you want something stable and automagic.
>>
>> The gateway addresses are pointless and can be completely ignored.
>> There's no neighbour discovery. between host and modem.
>>
> Just one additional comment; if you run SLAAC on the modem network
> interface, it will happen exactly the same. The modem itself will send
> the SLAAC Router Advertisement with the prefix that was previously
> negotiated with the network (the modem itself did SLAAC with the
> network earlier when the PDN was connected). This applies to all
> Qualcomm based modems.
>
> You should just take the assigned /64 prefix and build your own stable
> addresses.

Hello Bjørn, hello Aleksander,

many thanks for your answers!

May I ask a followup question:

When I do a "get_current_settings", I get the IPv6 address and the IPv6 
gateway address, as below:

get_current_settings_ready internet.v6.telekom Couldn't get IPv4 
address: Field 'IPv4 Address' was not found in the message 
(value_ipv6_address_address=[10753, 1433, 2313, 53274, 61731, 34358, 
42385, 54212], value_ipv6_address_prefix_length=64) 
2A01:599:909:D01A:F123:8636:A591:D3C4/64 
(value_ipv6_gateway_address_address=[10753, 1433, 2313, 53274, 30064, 
27635, 18861, 56880], value_ipv6_gateway_address_prefix_lengt=64) 
2A01:599:909:D01A:7570:6BF3:49AD:DE30 Getting current settings done

Till now I used these for

sudo ip link set dev wwan0 down

-> ok sudo ip -6 addr add 2A01:599:909:D01A:F123:8636:A591:D3C4/64 dev wwan0

-> ok

sudo ip -6 route add default via 2A01:599:909:D01A:7570:6BF3:49AD:DE30 
dev wwan0 -> RTNETLINK answers: No route to host sudo ip link set mtu 
1500 dev wwan0 -> ok

sudo ip link set dev wwan0 up

-> ok

According to above message, Bjørn told, I can ignore the gateway 
address, so I can simply skip the command with the error?

Is it correct, how I set the IPv6 /64 bit address? Or do I somehow need 
to reduce the number to a shorter length due to /64?

Or not use the /64 because my (single) local IPv6 address must be 128 
bits in size?

Yesterday I already tried a lot of variants, but ping was not yet 
successful, when doing it like

$ sudo ping -I wwan0 2001:4ca0:0:103::81bb:fe09

ping: connect: Network is unreachable

$

Is there something more needed? I have not yet setup DNS...

I using a second network interface (eth0) to connect via putty. I hope 
this does not influence the tests via wwan0...

Best regards,

Martin
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