Allow ICMP echo for IPV6 Broker

Hi,

Trying to setup IPV6 tunnel through a broker and they require the ability to ping my IPV4 address and the Airport Extreme is refusing ICMP echo. Is there any way at all to turn this on? I am very surprised there is no firewall feature of any sort. Sort of makes the IPV6 tunneling features useless if I cant provide some basic firewalling.

Thanks,
Steve