I wanted to assign Unique Local Addresses (ULA) to a couple of machines inside my LAN alongside the link-local ones and the globally routable ones. I am currently running dual stack.
I also wanted to keep them short, like fd69:6666::.

One machine is running Debian Jessie (kernel 3.16.0-4-amd64) and the other one Linux Mint 17.2 (kernel 3.16.0-38-generic x86_64).

After following this guide: Set Up An IPv6 LAN with Linux.
I ended up with the following configuration:


allow-hotplug eth0
iface eth0 inet static

auto eth0
iface eth0 inet6 static
address fd69:6666:: #fd69:7777:: on the other machine.
netmask 64


interface eth0
    AdvSendAdvert on;
    prefix fd69:6666::/64 { #fd69:7777:: on the other machine.
        AdvOnLink on;
        AdvAutonomous on;

Problem is that I end up having both machines with the fd69:6666 prefix and nothing else! IPv6 connectivity stops working. What am I doing wrong?


Try using fd69::6666 instead. Using fd69:6666:: only sets the network part of the address.
Remember to change the netmask too!
This should be the result:


auto eth0
iface eth0 inet6 static
address fd69::6666
netmask 64
| improve this answer | |
  • Remarkably enough, radvd is not really needed. Perhaps because i didn't add the autoconf 0 clause? – ppparadox Nov 13 '15 at 15:52
  • The Debian machine now lost its global IPv6 address. How can this be? – ppparadox Nov 13 '15 at 16:11
  • I would stick to 64 bit netmask. – Archemar Nov 13 '15 at 16:13
  • Why? Is it related to the debian machine losing its global address? – ppparadox Nov 13 '15 at 16:18
  • For some reason now echo 1 > /proc/sys/net/ipv6/conf/eth0/autoconf is needed (plus waiting a few minutes). Add to sysctl.conf as needed. – ppparadox Nov 13 '15 at 16:52

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.