how to enable headers in ispconfig? Missing Headers Content-Security-Policy Content Security Policy is an effective measure to protect your site from XSS attacks. By whitelisting sources of approved content, you can prevent the browser from loading malicious assets. X-Frame-Options X-Frame-Options tells the browser whether you want to allow your site to be framed or not. By preventing a browser from framing your site you can defend against attacks like clickjacking. Recommended value "x-frame-options: SAMEORIGIN". X-XSS-Protection X-XSS-Protection sets the configuration for the cross-site scripting filter built into most browsers. Recommended value "X-XSS-Protection: 1; mode=block". X-Content-Type-Options X-Content-Type-Options stops a browser from trying to MIME-sniff the content type and forces it to stick with the declared content-type. The only valid value for this header is "X-Content-Type-Options: nosniff". Referrer-Policy Referrer Policy is a new header that allows a site to control how much information the browser includes with navigations away from a document and should be set by all sites.