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What’s my IPv6 address?

If you would like IPv6 connectivity to any dedicated host or virtual machine, here’s how to find your address and configure your host. You will get a /64 for every host you have with us, and a /48 on request.

Virtual machines – Your routing is already set up, email us and we will tell you what the range you have is.

Dedicated servers – Your routing is already set up; your IPv6 range can be found from your IPv4 address – whatever the x is in decimal on the left, you need to convert to hex on the right:

IPv4 address IPv6 prefix
89.16.161.x 2001:41c8:0010:00xx::0/64
89.16.176.x 2001:41c8:0010:01xx::0/64
89.16.177.x 2001:41c8:0010:02xx::0/64
89.16.178.x (0-63) 2001:41c8:0010:03xx::0/64
89.16.178.x (64-127) 2001:41c8:0010:04xx::0/64
89.16.178.x (128-191) 2001:41c8:0010:05xx::0/64
89.16.178.x (192-255)   2001:41c8:0010:06xx::0/64
89.16.179.x (0-63) 2001:41c8:0010:07xx::/64
89.16.179.x (64-127) 2001:41c8:0010:08xx::/64
89.16.179.x (128-191) 2001:41c8:0010:09xx::/64
89.16.179.x (192-255) 2001:41c8:0010:0axx::/64
46.43.34.x (0-63) 2001:41c8:0010:0bxx::/64
46.43.34.x (64-127) 2001:41c8:0010:0cxx::/64
46.43.34.x (128-191) 2001:41c8:0010:0dxx::/64
46.43.34.x (192-255) 2001:41c8:0010:0exx::/64

e.g. so would have a corresponding IPv6 range of
2001:41c8:0010:02*7b*::0/64 .

Other ranges (private VLANs, older hosts) may not be automatically set up, so you will need to ask .

Wherever you are on our network, your gateway address will always be the link-local address fe80::1 .

You should see the content DNS example file for worked examples of how to specify IPv6 addresses in your DNS configuration files.

Setup on Debian or Ubuntu

While there are many possible setups and many distributions, we will document the most common requirement, i.e. a single IPv6 address on a Debian or Ubuntu host.

Add a clause to your /etc/network/interfaces file as follows, replacing the xxxxs with your real address as gleaned from the paragraph above. You can also use a different address from ::10 if you like, but on some networks Bytemark have claimed several lower-numbered addresses.

iface eth0 inet6 static
	address 2001:41c8:xxxx:xxxx::10
	netmask 64
	gateway fe80::1
	pre-up [ \! -f /proc/modules ] || /sbin/modprobe ipv6
	pre-up echo 0 > /proc/sys/net/ipv6/conf/eth0/autoconf

Finally run ifdown eth0 && ifup eth0 (preferably from the console shell) to activate your IPv6 configuration. This will momentarily break your IPv4 configuration too, so if you’re not confident of tracking down your own typos etc. please do this within office hours so you can give us a call if you need to!

Setup on CentOS or Fedora

You need to edit your /etc/sysconfig/network file and add:


if it’s not there already.

Then edit /etc/sysconfig/network-scripts/ifcfg-eth0, and, replacing the xxxxs according to your machine’s proper address (see the top of the page),


Finally you should be able to bring up the interface by restarting networking:

 service network restart

IPv6 testing

After setting up your IPv6, you should be able to ping your local gateway, and Google’s IPv6 service. Try these commands:

ping6 -c 5 -I eth0 fe80::1
ping6 -c 5

IPv6 reverse DNS

We will set these up for you in our Network Organizer email us to let us know what you want.

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