HP-UX IPFilter Version 16 Administrator's Guide

Sending ICMPv6 Responses
IPFilter supports the return-icmpv6-as-dest and return-icmpv6 keywords for IPv6.
These keywords are equivalent to the IPv4 keywords return-icmp-as-dest and
return-icmp. The primary use for these keywords is to send an ICMPv6 message with type
destination unreachable and code port unreachable in response to UDP packets sent
to a blocked port. For example:
block return-icmp-as-dest(port-unr) in quick proto udp from any to 2001:db8::2 port = 53
See “return-icmp-as-dest: Responding to Blocked UDP Packets” (page 32) for guidelines and
more information about sending ICMP responses.
40 Configuring and Loading IPv6 Filter Rules