The 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 Forwarded header.
| Header type | Request header |
|---|---|
| Forbidden header name | no |
Syntax
X-Forwarded-Proto: <protocol>
Directives
- <protocol>
- The forwarded protocol (http or https).
Examples
X-Forwarded-Proto: https
Other non-standard forms:
# Microsoft Front-End-Https: on X-Forwarded-Protocol: https X-Forwarded-Ssl: on X-Url-Scheme: https
Specifications
Not part of any current specification. The standardized version of this header is Forwarded.