The pf.conf man page specifically mentions "icmp6" as a protocol: "This
rule applies only to packets of this protocol. Common proto-cols are
icmp(4), icmp6(4), tcp(4), and udp(4). For a list of all the protocol
name to number mappings used by pfctl(8), see the file /etc/protocols."
/etc/protocols does not, however, contain "icmp6" so any mention of it in
pf.conf will cause pfctl to fail to load the rules. A trivial diff to add
an alias for "icmp6" is included below. FreeBSD and NetBSD HEAD contain
the same change with slight differences in whitespace.
--- protocols 2005-01-01 14:04:40.587355664 -0600
+++ protocols-icmp6 2005-01-01 14:44:31.057948896 -0600
@@ -66,7 +66,7 @@
mobile 55 MOBILE # IP Mobility
tlsp 56 TLSP # Transport Layer Security Protocol
skip 57 SKIP # SKIP
-ipv6-icmp 58 IPV6-ICMP # ICMP for IPv6
+ipv6-icmp 58 IPV6-ICMP icmp6 # ICMP for IPv6
ipv6-nonxt 59 IPV6-NONXT # no next header for ipv6
ipv6-opts 60 IPV6-OPTS # destination options for ipv6
# 61 # any host internal protocol