Of course it did - you cant listen on just any old IP address, it has to be one that is assigned to your PC. 127.0.0.1 is the default loopback address so always refers to your PC and as such is always available to listen on (unless something else is already listening on the port you specify). So what Quiver has done is add entries to his HOSTS file (C:\Windows\System32\Drivers\etc\hosts) so that bad websites that might appear in popups etc are redirected to 127.0.0.1. Which is why I used 127.0.0.1 in my example code, because that is the specific IP he is trying to listen on.