Helps find out what ports are blocked by your router/firewall or ISP. Useful in testing which ports are blocked, in-use or open. Can be used with Cable or DSL connections so users can host their own photo server,website, FTP and mail server, etc. Many times the ISP or local router or firewall will block ports making self-hosting impossible. Port Detective helps determine exactly what ports are open or blocked making is easier to troubleshoot.