Re: ipv6 connexion fail - ipv4 OK

[Daniel <tech@tootai.net>]

Hi

Le 30/08/2021 à 19:59, Roman Mamedov a écrit :
> On Mon, 30 Aug 2021 19:44:21 +0200
> Daniel <tech@tootai.net> wrote:
>
>>> Do you get WG working at all, between some other two hosts (not involving this
>>> particular server for now)?
>> Yes. Clients are shown on both sides as connected, trafic seems to go
>> out on each side but other one as received near to nothing.
> I mean not just "shown as connected", but have you got actual traffic working
> between any two hosts. Even just forgetting this server for a while. So that
> you can rule out some general issue and concentrate on just the particular
> machine setup.

I went a step further. Server has a /64 on eth0, his address being .1/64 
Interface I gave to wireguard is called wigserver and get .a2/64 as 
address when up. Now I start the client which is a .24/64 while tcpdump 
-ni any udp and port 38194 is running on the server. Output is

19:28:45.790295 eth0  In  IP6 2001:db8:16e:10::24.50012 > 
2001:db8:c2c:7c50::a2.38194: UDP, length 148
19:28:45.790629 eth0  Out IP6 2001:db8:c2c:7c50::a2.38194 > 
2001:db8:16e:10::24.50012: UDP, length 92
19:29:06.572059 eth0  Out IP6 2001:db8:c2c:7c50::1.38194 > 
2001:db8:16e:10::24.50012: UDP, length 148
19:29:11.947969 eth0  Out IP6 2001:db8:c2c:7c50::1.38194 > 
2001:db8:16e:10::24.50012: UDP, length 148
19:29:17.324065 eth0  Out IP6 2001:db8:c2c:7c50::1.38194 > 
2001:db8:16e:10::24.50012: UDP, length 148

As you can see, the original request is going to the right IP which 
respond with the right source IP (line 1 and 2) From here, all packets 
are going out with the IP of eth0 not the one from wigserver which is 
.a2/64. The client has "allowed ips = 10.99.98.0/27, ::/0"

Remember, no FW involved. Before this test I bring up interfaces without 
wireguard configuration and did server/client test like nc -lu IP PORT 
on the server while on the client I used nc -u IP PORT Everything worked 
well. I also started the client while server was not running and got the 
ICMP6 respons "unreachable port" sended to the client. I also tried to 
tell to the client to connect to the .1/64 insteed of the .a2/64, didn't 
work

If someone had an idea on what's going on here, would be helpful ;)

-- 
Daniel