UTL_HTTP giving a nasty ORA-24247: network access denied

I got a question today from a colleague.

He had the following code:

declare
l_response varchar2(4000);
begin
l_response := UTL_HTTP.REQUEST(‘http://www.google.com’);
end;

Executing this worked fine but incorporating it in a package function gave back an ORA-24247: network access denied by access control list (ACL).

I didn’t hear about ACLs before but listen to the [...]