For the last week I was without IPv6 connectivity on all of my client machines. Running traceroute6 from the tunnel-end-point worked fine, although i could not get any further than to the first hop from the clients. The IPv6 prefix is advertised over a IPv4-OpenVPN from the server running the tunnel. I dug really deep into it, turning off all netfilter rules to eliminate the packet filter from the possible troublemakers but all my packets were still dropped at the tunnel. Routing was set up correctly, I could reach all IPv6 sites from the tunnel itself.

After having spent almost half a day on this problem I remembered that I applied for a Hurricane Electric tunnel a month ago so I decided to remove the go6 client from the server. Setting up the new tunnel was quite easy, as i could just place it's configuration inside /etc/network/interfaces (applies to Debian):

auto ipv6-he iface ipv6-he inet6 v4tunnel address 2001:470:1f14:804::2 netmask 64 endpoint 216.66.84.46 local 193.170.104.5 ttl 255 up    ip -6 route add default dev ipv6-he metric 2 up    ip -6 addr add 2001:470:1f15:804::dead/64 dev br0 down  ip -6 addr del 2001:470:1f15:804::dead/64 dev br0 down  ip -6 route del default dev ipv6-he metric 2

This gave me a 64 prefix to advertise to my clients on interface br0, a bridge consisting of a physical interface and the OpenVPN tap device. I created the file /etc/radvd.conf:

interface br0 { AdvSendAdvert on; AdvLinkMTU 1280; AdvDefaultPreference low; prefix 2001:470:1f15:804::/64 { AdvOnLink on; AdvAutonomous on; }; };

After starting radvd I got full IPv6 connectivity back, this time through Hurricane Electric. The update to the AAAA records for uni.fladi.at will take it's time to get distributed across DNS.