@wallabybob:
@dhatz:
pfSense's CP "Allowed IP Addresses" feature will work with most websites, but it probably won't work very well with google.com (which the original poster asked for) due to Google NS constantly changing the IPs to which the www.google.com resolves.
Fair enough, but I suspect Google won't be issuing new Captive Portal voucher codes for a (private?) captive portal.
LOL, true, however I mentioned it because the issue of constantly changing IPs comes up with other Google websites, like Google Analytics, which people might want to use in a CP context.