Re: multihomed server with ipv6

[Martinx - ジェームズ <thiagocmartinsc@gmail.com>]

On 12 December 2014 at 12:07,  <lists@onemanifest.net> wrote:
> Hi all,
>
>
> I’m trying to setup a multi-homed server with dual stack networking.
>
> I’ve setup static adressing for both NICs for ipv4 and ipv6 like this:
>
>   # The primary LAN network interface
>   allow-hotplug eth0
>   iface eth0 inet static
>     address 192.168.1.xx
>     netmask 255.255.255.0
>     network 192.168.1.0
>     broadcast 192.168.1.255
>     gateway 192.168.1.1
>     # dns-* options are implemented by the resolvconf package, if installed
>     dns-nameservers 192.168.1.1
>     dns-search somedomain.tld
>
>   iface eth0 inet6 static
>     address 2001:xxxx:xxxx:3::20
>     netmask 64
>     gateway 2001:xxxx:xxxx:3::1
>     dns-nameservers 2001:xxxx:xxxx:3::1
>     dns-search somedomain.tld
>
>
>   # The secondary DMZ network interface
>   allow-hotplug eth1
>   iface eth1 inet static
>     address 192.168.0.xx
>     netmask 255.255.255.0
>     network 192.168.0.0
>     broadcast 192.168.0.255
>     gateway 192.168.0.1
>     # dns-* options are implemented by the resolvconf package, if installed
>     dns-nameservers 192.168.0.1
>     dns-search somedomain.tld
>
>   iface eth1 inet6 static
>     address 2001:xxxx:xxxx:2::20
>     netmask 64
>     gateway 2001:xxxx:xxxx:2::1
>     dns-nameservers 2001:xxxx:xxxx:2::1
>     dns-search somedomain.tld
>
> The NICs are configured fine, but only _one_ ipv6 gets assigned. After a reboot either
> eth0 or eth1 gets it’s ipv6 assigned, never both. I can add the missing ip manually with
>
>   ip -6 addr add 2001:xxxx:xxxx:2::20/64 dev eth1
>
> But I can’t get it to be assigned automatically. What am I doing wrong here? I’ve been googling for multi homed servers, but can’t find anything on this issue.
>
> Also, I noticed that if I ping6 a host is subnet A from a NIC in subnet B, the servers ip6 in subnet A is used as source ip, even if an ipv6 in subnet B is available on that NIC. Does this mean that the return traffic is routed over subnet A in stead of B? This is not desirable since I’d like the traffic between both subnets to be fire-walled by the router.
>
>
> Thanks

Hi!

 You need to read this:
http://lartc.org/howto/lartc.rpdb.multiple-links.html    ;-)

 Also, AFAIK, `ifupdown` doesn't handle multi-gateways, with load
balance and etc, so, you'll need to configure it using "up ip ...",
or, via /etc/rc.local (i.e., don't use "gateway" entry on
/etc/network/interfaces on this case).

 I have a similar setup working here (multi-wan), I can share the
confs if you want.

Best!
Thiago