External content in iFrame macro

[My Atlassian]

I am using the iFrame macro, as per the desription it says that it can include "external" content but whenever I try to include a site external to confluence what I get is a "Page cannot be found" message in the iFrame. Any internal Confluence links given works fine. 

[Mallmann]

Hello there,

Can you give an exemplo of page that you're trying to include? Can you try to include the Atlassian home page just like the example here?

Also, make sure that you can reach the address from your Confluence server. A curl or a ping might answer this.

Eduardo

[Nicolas Casel]

Thanks @Eduardo Mallmann .

Even with the Atlassian website url, it displays an empty box.

I presume I need to set a parameter in the Confluence General Configuration, however which one?