A connection between the subnets behind the gateways moon and sun is set up. The authentication is based on X.509 certificates. With ah=sha256-sha384 gateway moon proposes the use of AH. Gateway sun selects HMAC_SHA2_256_128 for integrity protection with its ah=sha256 configuration.

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.