[bradleyland]

Using a software filter to "cure" a porn addiction is like hiding drugs from a heroin addict. It's ineffective, because the addict will just find another way to get their fix, and it doesn't address the underlying problem.

Treatment of addiction is relatively uniform, regardless of the object of addiction. The best advice for your friend would be to seek assistance that isn't technical. There are groups like AA for pornography addiction. Getting past the social stigma will be difficult, but once he's past it, I'd imagine things will get a lot easier.