I have used the example in the article, and while I can successfully do html include macro to show http://www.google.com, if I put it in the iframe in html macro, it shows nothing.
If I put /dashboard.action info the iframe, it does work, just not any external. Whitelist is turned off at this time.
If you are on 5.8.15+ of Confluence, this is likely due to a security fix implemented to prevent clickjacking.See Confluence pages in iFrame no longer display after upgrading to 5.8.15 for a workaround. Note, that following the workaround will make your Confluence instance vulnerable to clickjacking so we don't recommend implementing. Follow at your own risk.
Jennifer Bennett | Confluence Support
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