启用SSL后，设置ssl_ciphers来改变openssl默认的加密算法。Swoole底层默认使用EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH
ssl_ciphers
openssl
EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH
$server->set(array( 'ssl_ciphers' => 'ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP', ));