Ubuntu – Configure static IPv6 on Ubuntu

ifconfigipv6pingUbuntu

I'm trying to configure IPv6 on a dedicated Ubuntu server. My provider gave me a "/64" (whatever that is – I'm still confused) of IPv6 addresses.

However, when I try to use them, I can't ping anything. What do I do? 🙁

# ping6 ipv6.google.com
    PING ipv6.google.com(vx-in-x63.1e100.net) 56 data bytes
    From fe80::219:d1ff:fefb:42d8 icmp_seq=1 Destination unreachable: Address unreachable
    From fe80::219:d1ff:fefb:42d8 icmp_seq=2 Destination unreachable: Address unreachable
    From fe80::219:d1ff:fefb:42d8 icmp_seq=3 Destination unreachable: Address unreachable

     --- ipv6.google.com ping statistics ---
    3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2014ms

# tracepath6 ipv6.google.com
    1?: [LOCALHOST]                        0.025ms pmtu 1500
    1:  fe80::219:d1ff:fefb:42d8%eth0                       2000.022ms !H
    Resume: pmtu 1500

# cat /etc/network/interfaces
    # The loopback network interface
    auto lo
    iface lo inet loopback

    # The primary network interface
    auto eth0
    iface eth0 inet static

    address 64.***.***.***
    netmask 255.255.255.248
    gateway 64.***.***.***

    iface eth0 inet6 static
    pre-up modprobe ipv6
    address 2607:F878:1:***::1
    netmask 64
    gateway 2607:F878:1:***(same as address)::1

# ifconfig
    eth0      Link encap:Ethernet  HWaddr 00:19:d1:fb:42:d8
         inet addr:64.***.***.***  Bcast:64.***.***.***  Mask:255.255.255.248
         inet6 addr: fe80::219:d1ff:fefb:42d8/64 Scope:Link
         inet6 addr: 2607:f878:1:***::1/64 Scope:Global
         UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
         RX packets:52451 errors:0 dropped:0 overruns:0 frame:0
         TX packets:39729 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:1000
         RX bytes:6817761 (6.8 MB)  TX bytes:6153835 (6.1 MB)
         Interrupt:41 Base address:0xc000

    lo        Link encap:Local Loopback
         inet addr:127.0.0.1  Mask:255.0.0.0
         inet6 addr: ::1/128 Scope:Host
         UP LOOPBACK RUNNING  MTU:16436  Metric:1
         RX packets:166 errors:0 dropped:0 overruns:0 frame:0
         TX packets:166 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:0
         RX bytes:31714 (31.7 KB)  TX bytes:31714 (31.7 KB)

Best Answer

Default Gateways work a bit differently on IPv6.

What I suggest you do is fire up tcpdump and watch it for Router Advertisements (you might want to analyse the capture in WireShark - much easier). This is how your IPv6 host knows how to get out to the internet. Also watch for Neighbor Solicitation as this is the replacement for ARP.

If you see these requests coming in, but not going back out, then your internal firewall is blocking IPv6 traffic. If you see them going out (requests), but not back in, then you need to make sure that your prefix length is correct (that's the /64 part. Although I've seen a lot of /64s being passed out that are actually a /48).

Big Important Bold Bit

ICMP is absolutally critical for IPv6 functionality. In IPv4 it can be blocked without huge impact, but in IPv6, the whole network relies on ICMP for all its functionality. Don't block it.

In reference to

My provider gave me a "/64" (whatever that is - I'm still confused) of IPv6 addresses

That's your Prefix Length, previously known as your Subnet Mask that's used for CIDR. The lower the number, the more IP addresses you have. For IPv6, /64 and /48 are very common and should give you more IP addresses than you will ever need in your entire life.

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