The roadwarrior carol and the gateway moon use the openssl plugin based on the OpenSSL library for all cryptographical and X.509 certificate functions whereas roadwarrior dave uses the default strongSwan cryptographical plugins aes des sha1 sha2 md5 gmp and x509.
The roadwarriors carol and dave set up a connection each to gateway moon. The authentication is based on X.509 certificates. Upon the successful establishment of the IPsec tunnels, leftfirewall=yes automatically inserts iptables-based firewall rules that let pass the tunneled traffic. In order to test both tunnel and firewall, both carol and dave ping the client alice behind the gateway moon.