nRF2840: IPv6 over BLE to IPv4 internet via NAT64

[BoKarolis]

Hello,

I am really new to the field, I apologise, if things I am saying do not make sense, explanations and corrections appreciated :) I am trying to reach IPv4 internet from my PCA10056 nRF52840 node which is running IoT icmp example with adapted headers from PCA10040 nRF52832 so the buttons and LED's work. It is connected via BLE to my border router Raspberry Pi 3B, running Debian Stretch.

I can ping the nodes local "fe80" and "2001" addresses from the router. The node can ping local bt0 IPv6 address, tcp server/client setup works as well. As my ISP does not provide IPv6, I am using Tayga to communicate to IPv4 internet via IPv6. I have tried pinging Google's IPv4 address using NAT64 prefix from my Raspberry Pi and it works, although when I am trying to do the same with from the node, I get an error in tcpdump destination unreachable, beyond scope <prefix::808:808>.

I was thinking, that the bt0 interface cannot access anything beyond bt0, hence the ethernet interface is unreachable. My question is, would a bridge between the bt0 and ethernet interface help to solve my problem? If so, I would appreciate any tutorials or explanations how to successfully do that. Or would a tunnel broker such as hurricane electric be a better idea to just bypass all the IPv4 translation?

tayga.conf:

tun-device nat64
ipv4-addr 192.168.255.1
prefix 2001:db8:1:ffff::/96
dynamic-pool 192.168.255.0/24
data-dir /var/db/tayga

My ifconfig:

bt0: flags=4177<UP,POINTOPOINT,RUNNING,MULTICAST>  mtu 1280
        inet6 2001:db8::1  prefixlen 64  scopeid 0x0<global>
        inet6 fe80::4343:a1ff:fe12:1fac  prefixlen 64  scopeid 0x20<link>
        unspec 41-43-A1-FF-FE-12-1F-AC-00-00-00-00-00-00-00-00  txqueuelen 1  (UNSPEC)
        RX packets 12  bytes 496 (496.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 37  bytes 2187 (2.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

enxb827eb0ab32d: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.5.129  netmask 255.255.255.0  broadcast 192.168.5.255
        inet6 2001:db8:1::1  prefixlen 64  scopeid 0x0<global>
        inet6 fe80::ba27:ebff:fe0a:b32d  prefixlen 64  scopeid 0x20<link>
        ether b8:27:eb:0a:b3:2d  txqueuelen 1000  (Ethernet)
        RX packets 4281  bytes 4697929 (4.4 MiB)
        RX errors 0  dropped 4  overruns 0  frame 0
        TX packets 2934  bytes 341453 (333.4 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1  (Local Loopback)
        RX packets 270  bytes 19420 (18.9 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 270  bytes 19420 (18.9 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

nat64: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>  mtu 1500
        inet 192.168.5.129  netmask 255.255.255.255  destination 192.168.5.129
        inet6 fe80::e95a:684b:91f5:e2ca  prefixlen 64  scopeid 0x20<link>
        inet6 2001:db8:1::1  prefixlen 128  scopeid 0x0<global>
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 500  (UNSPEC)
        RX packets 6  bytes 564 (564.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 20  bytes 1544 (1.5 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

route -n -A inet6:

Destination                    Next Hop                   Flag Met Ref Use If    
2001:db8::/64                  ::                         U    256 0     0 bt0
2001:db8:1::1/128              ::                         U    256 0     0 nat64
2001:db8:1::/64                ::                         U    256 0     0 wlan0
2001:db8:1::/64                ::                         U    256 0     0 enxb827eb0ab32d
2001:db8:1:ffff::/96           ::                         U    1024 1    11 nat64
fe80::/64                      ::                         U    256 0     0 wlan0
fe80::/64                      ::                         U    256 0     0 enxb827eb0ab32d
fe80::/64                      ::                         U    256 0     0 nat64
fe80::/64                      ::                         U    256 1    23 bt0
::/0                           ::                         !n   -1  1   212 lo
::1/128                        ::                         Un   0   5     8 lo
2001:db8::/128                 ::                         Un   0   1     0 lo
2001:db8::1/128                ::                         Un   0   1     0 lo
2001:db8:1::/128               ::                         Un   0   1     0 lo
2001:db8:1::/128               ::                         Un   0   1     0 lo
2001:db8:1::1/128              ::                         Un   0   3     6 lo
2001:db8:1::1/128              ::                         Un   0   1     0 lo
2001:db8:1::1/128              ::                         Un   0   2     3 lo
fe80::/128                     ::                         Un   0   1     0 lo
fe80::/128                     ::                         Un   0   1     0 lo
fe80::/128                     ::                         Un   0   1     0 lo
fe80::/128                     ::                         Un   0   1     0 lo
fe80::4343:a1ff:fe12:1fac/128  ::                         Un   0   2     5 lo
fe80::ba27:ebff:fe0a:b32d/128  ::                         Un   0   1     0 lo
fe80::ba27:ebff:fe5f:e678/128  ::                         Un   0   1     0 lo
fe80::e95a:684b:91f5:e2ca/128  ::                         Un   0   1     0 lo
ff00::/8                       ::                         U    256 2    12 wlan0
ff00::/8                       ::                         U    256 3   233 enxb827eb0ab32d
ff00::/8                       ::                         U    256 1     3 nat64
ff00::/8                       ::                         U    256 3    13 bt0
::/0                           ::                         !n   -1  1   212 lo

I appreciate the help,

Karolis

[Petter Myhre]

Are you able to ping Google's IPv6 address from the RPi?

[BoKarolis]

Hi, thank you for the reply, as I said, my ISP does not provide IPv6 addresses, hence I cannot. I am not trying to reach IPv6 internet, I am sure that will be not possible without a tunnel broker. I just need for my node to access IPv4. As the providers will at some point switch to IPv6, I need the nodes to be on IPv6

[Petter Myhre]

Ok. I'm not too familiar with Tayga, but I'm pretty sure you need a IPv4 tunnel if you want your IPv6 packets from the nodes to reach a IPv6 network. Doesn't sound like that is what Tayga is doing.

[BoKarolis]

I must have not made myself clear, my aim is to reach IPv4 network, not IPv6.

[Petter Myhre]

I'm sorry, I don't understand. How would the nodes benefit from reaching a IPv4 network? They only support IPv6. If you don't have IPv6 connectivity, you need to send the IPv6 packets through a IPv4 tunnel to a server that "unpacks" the IPv6 packets relays them to the IPv6 network.