Adding IPv6 to Ubuntu systems

To bind IPv6 IPs to your Ubuntu server, edit your /etc/network/interfaces file and add the following lines to the bottom.

#IPV6 configuration
iface eth1 inet6 static
pre-up modprobe ipv6
address 2607:f0d0:2001:0000:0000:0000:0000:0010
netmask 64
gateway 2607:f0d0:2001:0000:0000:0000:0000:0001

The first line tells the system which interface to use IPv6 on.
The second line tells the system to load the module for IPv6.
The third line gives the IPv6 address.
The fourth line defines the netmask for the IPv6 subnet.
The fifth line defines the default gateway for the IPv6 subnet.

After this has been performed you will need to restart networking:

/etc/init.d/networking restart

Verifying IPv6 connectivity

Verify IPv6 IP is bound

root@server:~# ip -6 address show eth1
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 2607:f0d0:2001::/64 scope global
       valid_lft forever preferred_lft forever
    inet6 fe80::230:48ff:fe7e:330a/64 scope link
       valid_lft forever preferred_lft forever

IPv6 Neighbor Cache

root@server:~# ip -6 neighbor show dev eth1
2607:f0d0:2001::1 lladdr 00:1b:0d:e6:57:c0 router REACHABLE

If the neighbor cache shows a fe80 entry only then your gateway is either not set, the IP is not bound to the correct interface, the IP is not bound correctly to the public interface, or your software firewall is blocking IPv6 ICMP.

IPv6 Default Gateway

root@server:~# ip -6 route show dev eth1
2607:f0d0:2001::/64  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295
fe80::/64  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295
default via 2607:f0d0:2001::1  metric 1024  mtu 1500 advmss 1440 hoplimit 4294967295

If you do not have the default gateway listed, yet you can ping6 your default gateway then you may add it manually:

root@server:~# ip -6 route add default via 2607:f0d0:2001::1

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