Walter,
I created a page and put it on the external web server. I am using the UserHostAddress method.

However, I am getting a different IP address than whatismyip.org gives. I know the whatismyip.org address is the one I want, and I can't figure out what is going on.

>If you have control over that external web server...
>
>getip.aspx:
>

>< %@ Page language="c#"  % >< %
>    Response.ContentType = "text/plain";
>    Response.Write( Request.UserHostAddress.ToString() );
>% >
>

>
>getip.cs (command line example program)
>

>using System;
>using System.IO;
>using System.Net;
>
>public class GetIpApp
>{
>	static void Main()
>	{
>		WebClient client = new WebClient();
>		
>		try {
>			string strMyIp = client.DownloadString( "http://localhost/getip.aspx" );
>			Console.WriteLine( "IP Address is: {0}", strMyIp );
>		}
>		catch( Exception ex ) { Console.WriteLine( ex.ToString() ); }
>	}
>}
>

>
>If you were to try this on your own PC (as I've written) you'd get 127.0.0.1 as the IP address but on a remote server the firewall's IP would come back.
>
>If you don't have the ability to put a page of some sorts on the remote server, you're stuck. There is no way your client PC can get this information, short of doing a traceroute and guessing.