I bilt a program so you can chat on network, but it only works over local network. In program you need to enter ip address and a port number. So I tried 192.168.1.2 and similar and it works. But now I wonted to chat over internet. So I went to see what my internet ip address is, and its 89.201.183.44. I entered that address but an exeption is raised saying that socket cant bind to that address. So I dont know how to host over internet. Over internet I found that my hostname is 89-201-183-44.dsl.optinet.hr. From here I found that my ip address is 89.201.183.44 (actualy thats my router ip address). In my program I tried GetHostName() and I get my computer name not 89-201-183-44.dsl.optinet.hr. Im using .NET 3.5

Your router uses Network Address Translation (look it up on Google or Wikipedia.) You need to tell the router, if it offers that facility (check your router's manual), to set up "forwarding" - so that the server software on your PC binds a socket to your local IP address of 192.168.1.2 but the client software (on another computer on the Internet) connects to 89.201.183.44 (by the way, this address is likely to be different every time you connect to the Internet) and your router forwards the packets to your computer.