[44net] Is this a worry ?

< IP 0.0.0.0.5678 > 255.255.255.255.5678: UDP, length 106 > Hello, They say a little knowledge is dangerous ! At the moment at my tunl0 ( remote location ) I am getting groups of five of the above line every minute in my recently installed gateway. I have tried without success to stop it appearing using iptables with < -A INPUT -p udp -i tunl0 --sport 5678 -j DROP >. It shows as dropped when I monitor iptables but still appears when using tcpdump at the same time. It can be stopped by removing my ipencap entry but that stops my ampr-ripd reception was well. Is this just something I have to accept or is there a solution ? Regards, Ian..