The roadwarriors <b>carol</b> and <b>dave</b> set up a connection each 
to gateway <b>moon</b>. The roadwarriors' authentication is based on
<ib>Pre-Shared Keys</b> (PSK) whereas the gateway uses an <b>RSA signature</b>
(RSASIG) certified by an X.509 certificate.
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>.