The classic better approach would be to drop part of the IP address entirely, so it's impossible to recreate the full value. For example, dropping the last oct

The classic better approach would be to drop part of the IP address entirely, so it's impossible to recreate the full value. For example, dropping the last octet (turning 123.4.5.6 into 123.4.5.0) means you can usually still do useful IP things (where in the world do our users come from, very roughly) while making it impossible to track unique users, or to definitively recognize real individuals. I've seen one octet masking used as standard, probably just because it's easy, but you could do any other similar change you like, optimising for more or less anonymity/granularity as required.