I am watching my ip6table and observing an icmp packet arriving and getting dropped at the rate of 1 per second. I am trying to find out what that message is about. I tried using tcpdump (it is definitely not an echo since I explicitly allowed that):
tcpdump 'icmp[icmptype] != icmp-echo' 0 packets captured 0 packets received by filter 0 packets dropped by kernel
As can be seen, I am seeing nothing. I have also tried logging it with iptables without any success. Any ideas?