Coldfusion 2021 on Linux behind a firewall

No, there's not a single page listing all domains, that I know of. But yes, there are pages listing at least one other domain you'll want to open:

• adobe.io

Or for those who prefer to limit to specific subdomains:

• coldfusion.adobe.io
• cfactivation.adobe.com

These come from this page on cf kicense activation . One can also find reference to the domain used on the settings page of the "Licensing and Activation" page of the cf admin, introduced in cf2021. Beware that url may redirect to another, whose domain you should open. 

Note there's also provision there to configure cf to use a proxy (instead of your opening firewall holes). That may be easier than maintaining such a whitelist, if supported in your environment. See the "settings" tab on that page (and as discussed in the cf docs and in that link above). 

While we're on the topic, there are also the same concerns regarding downloading cf updates, and the specific subdomains used for that add:

• www.adobe.com
• cfdownload.adobe.com

And the first of these, too, is offered on the cf admin page updates page ("package management" since cf2021, "server updates" before then), which also offers a settings page for configuring proxy info, and which also has a docs page and a much older Adobe blog post on updates (still mostly relevant) discussing things further. 

It would be nice to have a single page listing all domains (and even urls, and those which they may redirect to), as well as ports, that one may need to consider opening in a firewall (and their purposes). Again, none exists that I know of.

You should open a feature request at tracker.adobe.com. That's how things like this get Adobe's attention, as they may not see this post. If you do open one, please share the link here so interested folks can add their votes. 

Let us know if the above gets you going and is sufficient and the complete list you confirm you need.