The roadwarriors carol and dave set up a connection each to gateway moon.
Both carol and dave request a virtual IP via the IKE Mode Config protocol
by using the leftsourceip=%modeconfig parameter. By setting the option modeconfig=push
on both the roadwarriors and the gateway, the Mode Config server moon will actively push
the configuration down to carol and dave.
leftfirewall=yes automatically inserts iptables-based firewall rules that let pass the
tunneled traffic. In order to test the tunnels, carol and dave then ping the client
alice behind the gateway moon. The source IP addresses of the two pings will
be the virtual IPs carol1 and dave1, respectively.