X-Forwarded-Proto (XFP) header is a de-facto standard header for identifying the protocol (HTTP or HTTPS) that a client used to connect to your proxy or load balancer. Your server access logs contain the protocol used between the server and the load balancer, but not the protocol used between the client and the load balancer. To determine the protocol used between the client and the load balancer, the
X-Forwarded-Proto request header can be used.
A standardized version of this header is the HTTP
|Header type||Request header|
|Forbidden header name||no|