This page scans your local host for open ports. It will make an HTTP request to every port on your machine, except a small list of ports that all browsers block.
If it finds a favicon, it indicates that there is a running local web application, which may or may not be vulnerable to CSRF attacks or other attacks like the Rails yaml attack.
If it times out, probably that port is vulnerable to some kind of attack, like the old form protocol attack.
If it errors, the port may be closed, or the process listening at the port may have detected invalid input and closed the connection. We could run a timing loop to determine if a connection was made or not, but for now the current page doesn't output any information for this case.
The scan will take about ten minutes.