AbyssGuard can detect Open Proxies that are mostly used by hackers and bots in order to cover their tracks.
A Proxy is a Server standing between your website and the real visitor, so you can only see the Proxy's identity but not the one of the person behind it. Not all proxies are bad but the Open ones can be used by anyone therefore they are heavily abused from offenders to hide their tracks and real identity.
AbyssGuard has double detection layer system that will attempt to detect if the visitor is using proxy and whether or not it's Open to anyone.
The false positives here are almost impossible as the Open Proxyes are usually servers not used by real visitors to browse the Internet. Also no traffic is lost as no legitimate real visitor will ever try to access your website through an Open Proxy. Plus they can always use their real IP address.
It is more common for legitimate users to try and stay anonymous through the TOR Project. AbyssGuard provides TOR Project Detection too.
In order for the Open Proxy Detection to work you have to enable the Open Proxy Detection option in your Settings.