[Zzed]

I have written a similar unpublished hack to this for VB2. There are a list of about 40 common ports used by proxies. I have discovered that using the HTTP_FORWARDED family of variables is not a very effective way of proxy detection because it actually tends to mistake certain ISP addresses as proxies. The port scan itself is not completely fool proof either. But it is able to catch a good number of proxies. I have set up my board to redirect all unregistered people who are using a proxy to register.com. There is no need to IP ban proxies since almost all of them have a very short lifetime.

You should be able to create something with a few hours worth of effort.