That's also a questionable "feature". Such a text box
should not send
anything before you confirm it.
Perhaps as part of the firewall installation step, the user could be
given a list of sites that their PC may "call home" to - including
official repos - and let them opt-in or opt-out accordingly. If we
block, say, *.mozilla.com at the firewall level, there's no chance
that firefox will call home before the user has a chance to set their
preferences.
Of course, we'd need an obvious way to let them opt-in later, after
they've set their preferences, else "why doesn't google work?" and
"why can't I yum update?" will become FAQs.