The roadwarrior carol sets up a connection to gateway moon. The authentication is based on X.509 certificates. Upon the successful establishment of the IPsec tunnel, leftfirewall=yes automatically inserts ip6tables-based firewall rules that let pass the tunneled traffic. In order to test both the IPv6 ESP tunnel and the firewall rules, carol sends an IPv6 ICMP request to the client alice behind the gateway moon using the ping6 command.