RA messages
ra_dns bool 1 Announce DNS configuration in
RA messages (RFC8106)
+ra_pref64 string Announce PREF64 option
+ [IPv6 prefix] for NAT64 prefix (RFC8781)
ndproxy_routing bool 1 Learn routes from NDP
ndproxy_slave bool 0 NDProxy external slave
prefix_filter string ::/0 Only advertise on-link prefixes within