Control TLS server_name when Host remapping

1 posts, 0 answers
  1. Jason
    Jason avatar
    1 posts
    Member since:
    Jul 2016

    Posted 14 Jul Link to this post


    Using Fiddler v4.6.2.30081 on Windows 10 x64 I am using the Composer's Raw tab to make a request:

    GET HTTP/1.1

    Am I also using Fiddler Host Remapping to use a different origin for, eg:


    When Fiddler makes the request, the TLS handshake to sends the SNI server name value of "" and then sends the HTTP request with Host value "".

    Many web servers consider it a protocol violation if the HTTP Host request header value does not match the SNI server name used during the TLS handshake. In my scenario, the origin is running such a web server and the response is a HTTP 403 Forbidden with a HTML response body describing the mismatch between the HTTP Host and TLS SNI hostnames. Other web servers respond with a HTTP 400 Bad Request. I do not control this origin.

    I need Fiddler to use the value from the Host request header, "", as the SNI server name during the TLS handshake to the origin. How can I instruct Fiddler to override the SNI server name? That is, a Fiddler equivalent to the `-servername` argument that `openssl s_client` accepts.



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