If you're running Windows 2000, ME, 98, XP, NT, a double-monitor icon appears in your system tray, and your TCP/IP protocol stack is initialized, double-click the icon, click the Properties button in the Local Area Connection Status box, then choose the Internet Protocol (TCP/IP) selection and click the Properties button in the Local Area Connection box and read the IP address from the General tab. If you're running Linux, type ifconfig in a command window.
Make visible what, without you, might perhaps never have been seen. - Robert Bresson
I'll add to what Michael said. You can also type ipconfig at a dos/command prompt to get it in textual form under win98/2k/XP. Under linux you can do the ifconfig as he mentioned, but if you know which device (eth0,eth1,eth2) your connection is on, you can specifically query it by typing "ifconfig eth0" for example for the eth0 device. I have my code actually parse the text response from that to see if my linux box is on a dhcp enabled network. If it's not, my program assigns the box a default network address. I do that so a user can direct connect using a crossover cable from a laptop.. Its really cool. Just reread your post. Is your computer even visible to the outside world beyond your lan? Better check on that, as many lans are set up to restrict access in to mostly servers and such, and not user's machines. Also, if you are trying to get your IP inside the Lan from some remote machine outside the lan, you are going to have to set up a remote RMIregistry on a server that can be accessed from the web. I haven't done that, but I think Michael has. Check out his big loooong post. I believe he describes how to do that there. HTH Chris