openssl s_client -connect localhost:5556 -debug -msg -state -tls1_2 -CAfile x509-ca.pem -cert x509-client.pem -key x509-client-key.pem -verify 0 openssl s_server -accept 5556 -debug -msg -state -tls1_2 -www -CAfile x509-ca.pem -cert x509-server.pem -key x509-server-key.pem -verify 0
openssl s_client -connect localhost:5556 -mtu 1500 -debug -msg -state -dtls1_2 -CAfile x509-ca.pem -cert x509-client.pem -key x509-client-key.pem -verify 0 openssl s_server -accept 5556 -mtu 1500 -debug -msg -state -dtls1_2 -CAfile x509-ca.pem -cert x509-server.pem -key x509-server-key.pem -verify 0
NOTE: This is mainly of use to test the handshake. There doesn't appear to be an 'echo server' option with DTLS, but it will print to stdout anything you send it, and lines you type into stdin (at the server) will be sent to the client.