Forum administrators have long used IPs to identified ban evaders and users misusing alternate accounts. Unfortunately, users have become increasingly adept at using proxy services. Banning proxies is not a good solution, because there are many legitimate reasons to use proxies--e.g., ad blocking. Looking into the future, we are going to have to rely on something other than IPs to attempt to identify proxy abusers. Is it possible to create an addon that attempts to associate users not based on IPs, but based on sessions? E.g., X cookie on Ymachine was seen active on the site during a 1-hour period, and was associated with Z users. It wouldn't be firm evidence, as different users may share computers, but this is similarly true of IPs. The data would also be perishable, as cookies change over time, but the same is true of IPs, most of which are dynamic. Is it possible? Is it legal?