[AusNOG] Telstra Mobile NAT64 Gateway dropping UDP?

[Russell Langton]

Hi Matthew,

As others have said, get that Ipv6 enabled asap ;)

Telstra is currently in shutdown mode for non-critical staff until next
week.

I'll reach out to you next week and we work together to see whats going on.

-Russell at Telstra.



On Wed, 5 Jan 2022, 6:33 pm Andras Toth, <diosbejgli at gmail.com> wrote:

> Hi Matthew,
>
> As long as you use a DNS hostname instead of an IPv4 literal address,
> things should work fine for both local apps or tethered/hotspot access
> because Telstra's DNS servers can do DNS64. Locally on the iPhone you can
> use a literal IPv4 too because iOS will do local address translation
> (CLAT), but it can't translate IPv4 literals to IPv6 for connections via
> the hotspot.
>
> I don't have any problems with UDP on Telstra IPv6-only connection, I just
> tried and I can send and receive UDP packets via the Telstra NAT64 gateway
> when visiting https://h2o.examp1e.net/ in a browser that supports QUIC
> (because that uses UDP) and since that hostname does not have an IPv6
> address, Telstra converts it to IPv6 via DNS64. You can see from the packet
> capture below that both src and dst addresses are Telstra (one is mine,
> other side is the DNS64 gateway).
>
> 18:25:12.424022 IP6 (flowlabel 0xd0300, hlim 64, next-header UDP (17)
> payload length: 1238) 2001:8004:c81:6820:f5b6:b0a:c39c:7cf.58910 >
> 2001:8004:11d0:4e2a::84e2:18c.443: [udp sum ok] UDP, length 1230
> 18:25:12.666177 IP6 (hlim 45, next-header UDP (17) payload length: 1288)
> 2001:8004:11d0:4e2a::84e2:18c.443 >
> 2001:8004:c81:6820:f5b6:b0a:c39c:7cf.58910: [udp sum ok] UDP, length 1280
> 18:25:12.667703 IP6 (flowlabel 0xd0300, hlim 64, next-header UDP (17)
> payload length: 1238) 2001:8004:c81:6820:f5b6:b0a:c39c:7cf.58910 >
> 2001:8004:11d0:4e2a::84e2:18c.443: [udp sum ok] UDP, length 1230
> 18:25:12.668868 IP6 (hlim 45, next-header UDP (17) payload length: 1288)
> 2001:8004:11d0:4e2a::84e2:18c.443 >
> 2001:8004:c81:6820:f5b6:b0a:c39c:7cf.58910: [udp sum ok] UDP, length 1280
>
> I would suggest trying to replicate the issue and gathering a packet
> capture to see what packets go through and what gets lost. It might be MTU
> related issues if too large packets can't go through but I can send 1410
> bytes packets via the cellular connection successfully.
>
> Regards,
> Andras
>
>
> On Tue, Jan 4, 2022 at 9:34 PM Matthew H <Matthew at marrold.co.uk> wrote:
>
>> Hi,
>>
>> The app works fine on other IPv6 only networks with NAT64 in place which
>> appears to satisfy Apple's requirements.
>>
>> We are looking into adding proxies with IPv6 support, however it's likely
>> to take some time and it would be good if we can find a fix / workaround in
>> the meantime
>>
>> Thanks
>>
>> On Tue, Jan 4, 2022 at 10:10 AM Troy <troy at troykelly.com> wrote:
>>
>>> Apologies for a non answer, but any app (at least with Apple) is
>>> required to support IPv6 only networks.
>>>
>>> https://developer.apple.com/support/ipv6/
>>>
>>> Rather than work on a 6 to 4 fix, why not put some energy into
>>> supporting IPv6?
>>>
>>> *Regards, Troy*
>>> Brevity is the elixir of life.
>>> Father Hector McGrath, Pixie 2020
>>>
>>>
>>>
>>>
>>> -------- Original Message --------
>>> On 4 Jan 2022, 9:03 pm, Matthew H < Matthew at marrold.co.uk> wrote:
>>>
>>>
>>> Hi,
>>>
>>> We are developing a WebRTC mobile app that sets up a media session via
>>> Web Socket and then sends the media via RTP over UDP. It's working on most
>>> networks but we've had users report issues with the app when their iPhone
>>> is connected to the Telstra Mobile network.
>>>
>>> Unfortunately our network only supports IPv4, and after examining the
>>> available logs it appears their iPhone only gets an IPv6 address. The Web
>>> Socket communication is able to reach us so I assume a NAT64 gateway is in
>>> use, but we don't see any RTP / UDP arrive at our network edge.
>>>
>>> We found a couple of posts that suggest users have had similar issues
>>> with UDP being dropped:
>>>
>>>
>>> https://crowdsupport.telstra.com.au/t5/network-roaming/unable-to-stream-video-over-udp-on-ipv6-only-connection/td-p/933472
>>>
>>> https://crowdsupport.telstra.com.au/t5/network-roaming/ios-and-ipv6/td-p/931449
>>>
>>> https://crowdsupport.telstra.com.au/t5/apple-ios/nordvpn-won-t-connect-on-4g-ios/td-p/932511
>>>
>>> Is anyone aware of Telstra's NAT64 gateway dropping UDP?
>>>
>>> Thanks
>>> Matthew
>>>
>>> _______________________________________________
>> AusNOG mailing list
>> AusNOG at lists.ausnog.net
>> http://lists.ausnog.net/mailman/listinfo/ausnog
>>
> _______________________________________________
> AusNOG mailing list
> AusNOG at lists.ausnog.net
> http://lists.ausnog.net/mailman/listinfo/ausnog
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ausnog.net/pipermail/ausnog/attachments/20220105/e12ad2d9/attachment-0001.htm>