There are many situation when it would handy to know the IP address of a device where our app is running. Maybe you want to identify who is running your app? By IP address it is also possible to calculate the approximate location of a device. If you connect to Internet through a router, there are big chances that it implements "Network Address Translation" (NAT), to make it harder for remote machines to establish a direct connection to a machine within a local network. Recently I have come acro...