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Kerberos authentication won’t impact this in any way. You can embed it as you normally would.
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Is it possible to display a Microsoft Sway doc nicely from a Confluence page using Iframe for Confluence? I have whitelisted https://sway.office.com/* .
Your whitelist entry is correct, but you need to embed the embed code, not the base url (because MS blocks that). See their docs at:
https://support.microsoft.com/en-us/office/share-your-sway-1cf853b8-ef7e-46b0-b704-003e58d28998
We are not sure what the “Get embed code” produces, but you can either rip the URL out of there and place it in the iframe macro, or take the whole thing and put it in the Secure HTML macro that we include.