[1] RFC 6520 - Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS) Heartbeat Extension (2015-03-08 14:25:23 +09:00 版) http://tools.ietf.org/html/rfc6520

[2] Transport Layer Security (TLS) Parameters (2015-02-27 12:03:35 +09:00 版) http://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#heartbeat-message-types

[3] Transport Layer Security (TLS) Parameters (2015-02-27 12:03:35 +09:00 版) http://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#heartbeat-modes