Reindex.remote.whitelist wildcard details

I don't understand quite well how does the reindex.remote.whitelist works when it comes to wildcards.

Is there a way to whitelist *:* ? (my cluster is living on a private network)

Is something like 10.*:* is valid ?

Since it takes restarts to reload the config, I really wan't to have the right configuration on the first take!

Per the docs;

(e.g. otherhost:9200, another:9200, 127.0.10.*:9200, localhost:* )

So yes, you can use wildcards where you want.