The roadwarriors <b>carol</b> and <b>dave</b> set up a connection each 
to gateway <b>moon</b>. The authentication is based on distinct <b>pre-shared keys</b>
and <b>IPv4</b> addresses. Upon the successful establishment of the IPsec tunnels,
<b>leftfirewall=yes</b> automatically inserts iptables-based firewall rules that
let pass the tunneled traffic. In order to test both tunnel and firewall, both
<b>carol</b> and <b>dave</b> ping the client <b>alice</b> behind the gateway <b>moon</b>.
