> For a long time, it was considered best-practice to blanket-block ICMP I agree with your point, but think this needs some clarification about who considered

> For a long time, it was considered best-practice to blanket-block ICMP I agree with your point, but think this needs some clarification about who considered it a best practice - among enterprise firewall admins and financial-industry compliance audits, perhaps. Large scale network operators have seen the problems associated with entirely blocking ICMP for at least a decade. (v4 has blackhole problems too) A lot of the hatred for ICMP came from simple things like easy endpoint discoverability. nmap blew that argument out of the water pretty quick.