the ssl session. If the session is still open, when
L<SSL_clear(3)|SSL_clear(3)> or L<SSL_free(3)|SSL_free(3)> is called,
it is considered bad and removed according to RFC2246.
-The actual condition for a correctly closed session is SSL_SENT_SHUTDOWN.
+The actual condition for a correctly closed session is SSL_SENT_SHUTDOWN
+(according to the TLS RFC, it is acceptable to only send the "close notify"
+alert but to not wait for the peer's answer, when the underlying connection
+is closed).
SSL_set_shutdown() can be used to set this state without sending a
close alert to the peer (see L<SSL_shutdown(3)|SSL_shutdown(3)>).