We used to evade the filter at school by entering IP addresses instead of normal URLs. (This also seems to work to evade the IWF.) Is there an easy way to block

We used to evade the filter at school by entering IP addresses instead of normal URLs. (This also seems to work to evade the IWF.) Is there an easy way to block IP addresses based on a reverse-lookup match against .xxx? Regardless, I could see this being used as an excuse to shunt porn sites to .xxx, even if doing so wouldn't actually solve anything.