X-Forwarded-Host

The originating host of a client request.

Fastly reads this header from requests and writes it into requests. It is defined by an external standard.

For VCL services, Fastly will add or append X-Forwarded-Host headers on incoming requests over TLS, as follows:

The client Host header – if the request protocol is TLS.
The Host header from the edge – if the origin has a TLS configuration and shielding is enabled.
Even if client connection is TLS, unless the origin connection is over TLS, nothing will be added or appended at the shield.

Examples

Shielding	Request Protocol	Origin Protocol	Client Header	X-Forwarded-Host	Note
No	TLS	TLS	No	example.global.ssl.fastly.net	Added at edge
No	No TLS	TLS	No	null
No	TLS	TLS	Yes	Host1, example.global.ssl.fastly.net	Appended
No	No TLS	TLS	Yes	Host1	Pass-through
No	TLS	No TLS	No	example.global.ssl.fastly.net	Added at edge
No	No TLS	No TLS	No	null
No	TLS	No TLS	Yes	Host1, example.global.ssl.fastly.net	Appended
No	No TLS	No TLS	Yes	Host1	Pass-through
Yes	TLS	TLS	No	example.global.ssl.fastly.net, example.global.ssl.fastly.net	Added at edge and shield
Yes	No TLS	TLS	No	example.global.ssl.fastly.net	Added at shield
Yes	TLS	TLS	Yes	Host1, example.global.ssl.fastly.net, example.global.ssl.fastly.net	Added at edge and shield
Yes	No TLS	TLS	Yes	Host1, example.global.ssl.fastly.net	Added at shield
Yes	TLS	No TLS	No	example.global.ssl.fastly.net	Added at edge
Yes	No TLS	No TLS	No	null
Yes	TLS	No TLS	Yes	Host1, example.global.ssl.fastly.net	Added at edge
Yes	No TLS	No TLS	Yes	Host1	Pass-through

To set a single value for this header, add the following to vcl_miss and vcl_pass:

set bereq.http.X-Forwarded-Host = req.http.host;