OCSP stapling: ssl_stapling_verify directive. OCSP response verification is now switched off by default to simplify configuration, and the ssl_stapling_verify allows to switch it on. Note that for stapling OCSP response verification isn't something required as it will be done by a client anyway. But doing verification on a server allows to mitigate some attack vectors, most notably stop an attacker from presenting some specially crafted data to all site clients.