I'm exploring switching my ISP provider to CenturyLink. I test my firewall with ShieldsUP! Unfortunately, the heavy majority of "stealth" ports using my current provider display as "closed" using CenturyLink. Does anyone have experience with CenturyLink/ShieldsUP! and CenturyLink's modem settings? I hope it's appropriate posting this question here. It's perhaps not technically a Linux question but I am using Linux and iptables.