No UDP/TCP IPv6 connectivity (only) to router using gif interface - maybe ARM related

[Zaphod Beeblebrox]

Whether you feel it right, or not, net.inet.ip.forwarding must be 1 for gif
to work (even for IPv6).


On Mon, Sep 2, 2013 at 2:42 AM, Martin Laabs <mailinglists at martinlaabs.de>wrote:

> Hi,
>
> I tried to set up my raspberry PI as an ipv6 router. As a tunnel broker I
> use sixxs. Now I observed an interesting behavior:
>
> Every host from my network can reach the ipv6 world. The ipv6 world can
> also reach every host in my network. However - the router itself is unable
> to make udp or tcp connection to the "world" and is also unable to accept
> connections form the "world"
> ICMP however works properly.
> I had a look to the tcpdump and when trying to connect i.e. to
> www.kame.net
> the rasperry router sends a syn packet and get a syn/ack packet back. The
> rest of the handshake is missing.
> I tried also some udp with netcat (nc -6 -u -l 5555 on the server and nc -6
> -u <server> 5555 on the client)
> This works great for internal (ethernet) traffic but when the data should
> go through the tunnel if fails.
>
> The last test is maybe the most significant to describe the bug:
>
> Start netcat to listen for UDP packages on an external host:
>
> <external host> nc -6 -u -l 5555
>
> Connect from the RPI-Router to that host
>
> <RPI> nc -6 -u 2001:4dd0:xxxx:xxxx::2 5555
>
> Now it is possible to send data from the RPI router to the external host
> but the opposite direction does not work. Tcpdump however shows that the
> udp package arrives but it is not "forwarded" to the application.
> So for me it seems to be a problem with the handling of the receiving data
> in the gif interface.
>
> This behavior is independent from net.inet6.ip6.forwarding or
> net.inet6.ip6.redirect status.
>
> The router system: FreeBSD raspberry-pi.xxx 10.0-CURRENT FreeBSD
> 10.0-CURRENT #2 r254984
>
> Best regards,
>  Martin Laabs
>
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