IPv4 is so last century

A scary beast that lives in the Fens.

Fenrir is the latest addition to the Mythic Beasts family. It’s a virtual machine in our Cambridge data centre which is running our blog. What’s interesting about it, is that it has no IPv4 connectivity.

eth0 Link encap:Ethernet HWaddr 52:54:00:39:67:12
     inet6 addr: 2a00:1098:0:82:1000:0:39:6712/64 Scope:Global
     inet6 addr: fe80::5054:ff:fe39:6712/64 Scope:Link
     UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

It is fronted by our Reverse Proxy service – any connection over IPv4 or IPv6 arrives at one of our proxy servers and is forwarded on over IPv6 to fenrir which generates and serves the page. If it needs to make an outbound connection to another server (e.g. to embed our Tweets) it uses our NAT64 service which proxies the traffic for it.

All of our standard management services are running: graphing, SMS monitoring, nightly backups, security patches, and the firewall configuration is simpler because we only need to write a v6 configuration. In addition, we don’t have to devote an expensive IPv4 address to the VM, slightly reducing our marketing budget.

For any of our own services, IPv6 only is the new default. Our staff members have to make a justification if they want to use one of our IPv4 addresses for a service we’re building. We now also need to see how many addresses we can reclaim from existing servers by moving to IPv6 + Proxy.