Re: I need help configuring IPv6

Le 24/02/2022 à 08:45, Nathan Van Ymeren a écrit :
>>>>>
>>>>> The relevant portion of /etc/network/interfaces is:
>>>>>
>>>>> iface eno1 inet6 static
>>>>>       address 2604:xxxx:xxxx:xxxx::2/64
>>>>>       gateway 2604:xxxx:xxxx:xxxx::1
>>>>>
>>>>> As far as I can tell from reading the debian wiki and whatever else,
>>>>> it should work like this

Yes.

>>>>> but even ping6'ing the gateway gives "ping6:
>>>>> connect: Network is unreachable".


>>> It seems that the missing piece of the puzzle was this:  You can't
>>> just add a default route (apparently).

You can as long as the router's address is in the interface prefix.

>>>  You have to first add the
>>> route to a specific interface.  It's not clear to me if this is
>>> universally true,

It is not.

>>> or just a consequence of something specific to my
>>> setup (the server in question has multiple NICs).

I see only one interface eno1 in the routing table below.

>>> # ip -6 route add blah:blah::1 dev eno1
>>> # ip -6 route add default via blah:blah::1
>>>
>>> where blah:blah::1/64 is the address my datacenter gave me for the v6
>>> gateway router.

That should not be necessary.

> I suppose v6 addresses aren’t really private.  The server is on 2604:5800:0:1f::2 and the gateway I was given is 2604:5800:0:1f::1
> 
> # route -A inet6

The output of "ip -6 route" is more compact and readable.

> Kernel IPv6 routing table
> Destination                    Next Hop                   Flag Met Ref Use If
> localhost/128                  [::]                       U    256 2     0 lo
> 2604:5800:0:1f::1/128          [::]                       U    1024 1     0 eno1
> 2604:5800:0:1f::2/128          [::]                       U    256 2     0 eno1
> fe80::/64                      [::]                       U    256 1     0 eno1
> [::]/0                         2604:5800:0:1f::1          UG   1024 21     0 eno1
> localhost/128                  [::]                       Un   0   27     0 lo
> 2604:5800:0:1f::2/128          [::]                       Un   0   10     0 eno1
> fe80::/128                     [::]                       Un   0   3     0 eno1
> fe80::28c:faff:fe0e:b01c/128   [::]                       Un   0   7     0 eno1
> ff00::/8                       [::]                       U    256 5     0 eno1
> [::]/0                         [::]                       !n   -1  1     0 lo

The direct route for 2604:5800:0:1f::/64 which shoud have been created 
by the quoted portion of /etc/network/interfaces is missing.