Did you every figure out how to ignore alerts for IPv6 ICMP and multicast? I have a similar setup with the same issues on the WAN side. My provider refuses to turn off IPv6 on the cable modem. I have "Allow IPv6" unchecked in System -> Advanced -> Networking. I also have "IPv6 over IPv4" tunneling unchecked.
I also don't understand why despite a firewall blocking everything unless allowed, we still see alerts for ICMP?
My setup differs in that although I am using Suricata with blocking turned on, I am not in Inline Mode, not Legacy Mode. I am only using Snort Personal rules with the pre-set "Balanced" IPS Policy set and nothing else, yet.
I see lots of things that I want to start messing with in System -> Advanced -> System Tunables to further turn off support... but I definitely don't fall into the pre-requisite "Advanced Users" category.
However, my end goal is not to just suppress alerts and therefore allow IPv6 packets, but to just drop all IPv6 packets and not log any pattern alerts or logs in any system.
If my provider or anyone wants to talk on IPv6 I want it to be a black hole of nothingness for them to waste their time on and not bug me about it.
I have an HP switch that I setup an access list to drop all IPv6 on my LAN side, but that doesn't stop the thousands of alerts in the Suricata logs on the WAN port. Just stops all of the alerts on the LAN side. This is working perfectly, because anyone that leaves IPv6 enabled on their device just drops at the switch so I never hear about it on pfSense.
Can I do something similar to this on the WAN side?
ipv6 access-list "drop-all-v6"
10 deny ipv6 ::/0 ::/0
vlan 444
name "YO_MAMA"
untagged 1-48
ip address 172.25.1.2 255.255.255.0
ipv6 access-group "drop-all-v6" vlan-in
exit