A connection between the subnets behind the gateways <b>moon</b> and <b>sun</b> is set up. The authentication is based on <b>X.509 certificates</b>. The proprietary IKEv1 fragmentation protocol prevents the IP fragmentation of the IKEv1 messages carrying the large X.509 certificates. <p/> Upon the successful establishment of the IPsec tunnel, <b>leftfirewall=yes</b> automatically inserts iptables-based firewall rules that let pass the tunneled traffic. In order to test both tunnel and firewall, client <b>alice</b> behind gateway <b>moon</b> pings client <b>bob</b> located behind gateway <b>sun</b>.