Re: little bit off topic CLAT-Daemon for 464xlat for "Linux" (not android)

[Bjørn Mork <bjorn mork no>]

Tore Anderson <tore fud no> writes:
> * Bjørn Mork
>
> > bjorn nemi:~$ mmcli -b 0
> > Bearer '/org/freedesktop/ModemManager1/Bearer/0'
> >   -------------------------
> >   Status             |   connected: 'yes'
> >                      |   suspended: 'no'
> >                      |   interface: 'wwan0'
> >                      |  IP timeout: '20'
> >   -------------------------
> >   Properties         |         apn: 'telenor.ipv6'
> >                      |     roaming: 'allowed'
> >                      |     IP type: 'ipv6'
> >                      |        user: 'none'
> >                      |    password: 'none'
> >                      |      number: 'none'
> >                      | Rm protocol: 'unknown'
> >   -------------------------
> >   IPv4 configuration |   method: 'unknown'
> >   -------------------------
> >   IPv6 configuration |   method: 'static'
> >                    |  address: '2a02:2121:1:8d03:1071:2644:9af8:1353'
> >                    |   prefix: '64'
> >                    |  gateway: '2a02:2121:1:8d03:b8aa:bdb9:24af:f588'
> >                    |      DNS: '2001:4600:4:fff::54', '2001:4600:4:1fff::54'
> >
> >
> > bjorn nemi:~$ ifconfig wwan0
> > wwan0     Link encap:Ethernet  HWaddr f6:6f:09:a5:cc:39  
> >           inet6 addr: fe80::f46f:9ff:fea5:cc39/64 Scope:Link
> >           inet6 addr: 2a02:2121:1:8d03:f46f:9ff:fea5:cc39/64 Scope:Global
> >           UP BROADCAST RUNNING NOARP MULTICAST  MTU:1500  Metric:1
> >           RX packets:15750 errors:0 dropped:0 overruns:0 frame:0
> >           TX packets:10439 errors:0 dropped:0 overruns:0 carrier:0
> >           collisions:0 txqueuelen:1000 
> >           RX bytes:17693802 (16.8 MiB)  TX bytes:2424185 (2.3 MiB)
>
> Hmm, interesting. Is there some support for IPv6 on mobile broadband in
> NM nowadays?

I believe Dan just added such support. But I don't use NM at the
moment.  I do:

 mmcli -m 0 --simple-connect=apn=telenor.ipv6,ip-type=ipv6
 ip link set wwan0 up

relying on RAs from the modem to configure the address.

> On my Fedora 20, there is no «IPv6» tab in
> nm-connetion-editor for mobile broadband connection profiles like there
> is for e.g. WiFi. Also I find it curious that ModemManager knows
> anything about Layer 3, as I thought that would be NetworkManager's job.
> Hmmm! I'll have to fiddle around more with this I think...
>
> > bjorn nemi:~$ ip -6 route
> > 2a02:2121:1:8d03::c1a7 dev clat  metric 1024 
> > 2a02:2121:1:8d03::/64 dev wwan0  proto kernel  metric 256 
>
> Also this I find interesting. I first tried setting up TAYGA on my
> desktop connected to an Ethernet segment with routing looking pretty
> much like yours, but I ran into a problem - my CPE would do ICMPv6 NS
> for the ::c1a7 address, not getting any NA responses because that
> address isn't found anywhere on the Ethernet link.

ND proxy?  Or maybe adding the address to both interfaces will work?

> Is the fact that it works for you on Ethernet some artifact of the
> Ethernet implementation in the WWAN module being bastardised in some way
> causing it to blindly forward everything in the /64 to the fake MAC
> address f6:6f:09:a5:cc:39, or did you manage make the Linux IPv6 stack
> respond to NS for the ::c1a7 address, or convince the WWAN module to
> send packets to ::c1a7 to f6:6f:09:a5:cc:39 in some other way?
>
> If it's blindly forwarding everything to your computer, does that mean
> that bridging wwan0 with e.g. wlan0 (to make a wireless hotspot, say)
> won't work?

Yes, this is blind forwarding. Note the NOARP flag on the interface. The
modem connection is MBIM, so there aren't any L2 headers to play with.
All the ethernet stuff is just faked by the driver.

And this does mean that L2 bridging is meaningless.  But there is
nothing preventing you from playing routing tricks.  Instead of
bridging, you could for example just move the /64 route from the wwan0
interface to some other interface.



Bjørn