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 IPv4 addresses. Upon the successful establishment of the IPsec tunnels,
automatically inserted iptables-based firewall rules 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>.
