Rob,
Do you have a firewall that drops by default?
On my machine, I have to allow 520/udp from 44.0.0.1 to 520/udp at 244.0.0.9. I also have to allow IPENCAP. I now use a dynamic rule so only IPs in the Portal can send IPENCAP packets.
I recall my requiring to added these iptables rules around that time. It had to so with kmod-ipip and netfilter/iptables. They were not FILTERED as they are now.
- Lynwood KB3VWG
I had to put back the -r option that I had cleaned up from my start script as it still does not work with the multicast socked on Debian Linux with kernel 3.16. I remember it failed after some kernel update and it apparenty is still broken.