The roadwarrior <b>alice</b> sitting behind the NAT router <b>moon</b> sets up a tunnel to
the peer <b>bob</b> hiding behind the NAT router <b>sun</b>. UDP encapsulation is used to
traverse the NAT routers.
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Upon the successful establishment of the IPsec tunnel, the updown script automatically
inserts iptables-based firewall rules that let pass the tunneled traffic.
In order to test the double NAT-ed IPsec tunnel <b>alice</b> pings <b>bob</b>.
