A connection between the subnets behind the gateways moon and sun is set up. The authentication is based on X.509 certificates with signatures consisting of RSA-encrypted SHA-3 hashes.
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 both tunnel and firewall, client alice behind gateway moon pings client bob located behind gateway sun.