An IPv6 ESP transport connection between the hosts moon and sun is successfully set up.
The authentication is based on X.509 certificates. Upon the successful establishment of
the IPsec SA, leftfirewall=yes automatically inserts ip6tables-based firewall
rules that let pass the protected traffic. In order to test both the transport connection
and the firewall rules, moon sends an IPv6 ICMP request to sun using the ping6 command.