Connect HTTP Proxy with Authorization with Fiddler

Question

I would like to connect to a HTTP Proxy with Fiddler Core.

I'm using the oSession['X-OverrideGateway'] = "HOSTNAME:PORT" code to do it.

Now authentication is needed for the proxy. I see in other question a solution. It says:

oSession.oRequest["Proxy-Authorization"] = "Basic sOMeBASE64eNCODEdSTRING=";

Where the hash at the end is the Base64 coding of the 'username:password'

My question about this workaround:

It results a HTTP_PROXY_AUTHORIZATION HTTP header to my requests. Not just from fiddler to the proxy, but also from the proxy to the web.

Shouldn't it be removed by the proxy?

Is there a workaround with Fiddler so I can connect a HTTP Proxy with credentials without HTTP headers?

I would like to use Fiddler Core.

UPDATE:

As I can see the image

I only have to provide the Proxy-Authorization header if a Proxy Authentication header was in a response with a status code. It seams ok. But in fiddler core how can I reach the previous response? If I just simply save into a field variable it won't work, since the order of the traffic is not

Request, Response, Request, Response, etc.

But mor like

Request, Response (407), Request, Request, etc.

In the 2nd example on the 3rd Request we shouldn't send the Proxy Authorization header but we will, since the last Response was a 407.

Any ideas?

Answer 1

HTTP_PROXY_AUTHORIZATION header is required for proxy to work.

Please refer to the HTTP RFC section 4.4 https://www.rfc-editor.org/rfc/rfc7235#section-4.4

As it mentions, if there are multiple proxies in a chain, your proxy server may forward the headers ahead.

The difference you see with Fiddler Core and Proxifier could be due difference in their configuration.