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JasonYeung's avatar
JasonYeung
Brass Contributor
Nov 16, 2023
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Domain fronting in Azure Front Door question

I recently received an email from Microsoft that mentions domain fronting will stop before Jan. 8, 2024. I checked what uses Front Door in our Azure tenant and it's a couple of our websites (App Serv...
  • _AndreG's avatar
    Nov 17, 2023
    I am not sure I can fully explain it to you. However, most likely, if you don't know what it is, but you feel you understand your current Front Door setup, you are not using it. I have seen these emails as well and technically they provide you the option to test this out, for instance on an acceptance domain. You would have to create a support ticket for it:

    https://azure.microsoft.com/en-us/updates/blocking-domain-fronting-behavior-on-azure-front-door-azure-front-door-classic-and-azure-cdn-standard-from-microsoft-classic/

    Some more technical details about domain fronting can be found, for instance, on wikipedia:
    https://en.wikipedia.org/wiki/Domain_fronting

    But in reality, if you have a setup like:

    http://www.mydomain.com (Frondoor) -> myapp.azurewebsites.net (App Service)
    (having custom domains, like app1.mydomain.com setup on the app service makes no difference for this scenario)

    you should have nothing to worry about.

    Only if you are doing some scenario, and I don't really understand what scenario that would, besides avoiding censorship, where you use http://www.mydomain.com in the url, but force something else (like the wikipedia example of 'Host: http://www.youtube.com') in the host header, you are more than likely fine.

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