Apr 142014

In this blog I’ll try and explain what ipv6 is and how i setup the server to use it.

What is IPv6? IPv6 is pretty much the same as IPv4. IPv4 is what is primarily used on the internet today. The big difference is the size of the address. The address for IPv6 are 128 bits long vs 32 bits for IPv4. IPv6 also uses hex to express address where as IPv4 only uses numeric values so you will see numbers 0-9 and letters A-F in a IPv6 address.

Why do we need IPv6? Well simply put we are running out of IPv4 address. There are roughly 4.2 billion or 4,294,967,296 to be precise unique address for IPv4 where as IPv6 has 340,282,366,920,938,463,463,374,607,431,768,211,456 unique addresses, I’ll let you work out how many that is.

So what do IPv6 addresses look like? Ipv6 addresses look like this, 2001:0470:1f09:0d2b:0000:0000:0000:0300. IPv6 addresses can be shortened by removing all leading zeros so this address would become 2001:470:1f09:d2b::300. :: is used to shorten down IPv6 addresses. :: means that the space in between is filled by zeros and can only be used once in an address.

When using IPv6 the minimum allocation you are given is a /64 which would give you 18,446,744,073,709,551,616 unique IPv6 addresses, that’s way more than enough for the average person but some places will allow you to request a /48 which would give you 1,208,925,819,614,629,174,706,176 unique IPv6 addresses now compare that to the 1 IPv4 address most people get given.

Now onto setting up the server to use IPv6. As one of my server provider doesn’t offer native IPv6 yet i have to use a tunnel service, you can find a few different providers but i chose Hurricane Electric IPv6 Tunnel Broker as i heard good things about there support and their tunnel server is located very close to my server (average of 1-2ms away).

So first off sign-up for an account (its free). Time to create our first tunnel, click on “Create Regular Tunnel” it should then automatically select the closes tunnel server to use (you can override this if need be) now just input your IPv4 address where the tunnel will finish i.e. (make sure its the servers Public IPv4 address) then click “submit”. It will then create the tunnel and show you all the info you will need to setup on the server, at the bottom of the page their is a drop down box where you can get the config info for different operating systems.

As I want it to connect to the tunnel server automatically after reboots i need to manually add it to the config file (this is for CentOS 6.x)

Create or edit “/etc/sysconfig/network-scripts/ifcfg-sit1”


Obviously change “IPV6TUNNELIPV4” to the ip of the tunnel server, change “IPV6TUNNELIPV4LOCAL” to your servers IPv4 address and change “IPV6ADDR” to the “Client IPv6 address” you will find all the info on the details page of your tunnel.

Then i added the following to “/etc/sysconfig/network-scripts/ifcfg-eth0”

IPV6ADDR_SECONDARIES="2001:470:1f09:d2b::220/64 2001:470:1f09:d2b::200/64"

The “IPV6ADDR” is the main IPv6 address for the network adapter and “IPV6ADDR_SECONDARIES” is used to specify any extra address you want to use on the same server. If like me your using Webmin/Virtualmin it will automatically add new IPv6 address to the “IPV6ADDR_SECONDARIES” when you create them.

UPDATE – When i setup my new server i had to edit “/etc/sysconfig/network” and add the following


You could also setup the server to act as a router and give other devices on your network IPv6 address but a don’t need that here (but i have done that at home) just use google to find the extra info you need to add for it to act as a router.

Your server should now be accessible by IPv6, test by pinging a few different IPv6 enabled site and then remember to setup your firewall. Here’s a link to a quick example IPv6 Firewall For Linux google also has loads of others.

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