Getting the 'external' IP address in Java

Question

I'm not too sure how to go about getting the external IP address of the machine as a computer outside of a network would see it.

My following IPAddress class only gets the local IP address of the machine.

public class IPAddress {      private InetAddress thisIp;      private String thisIpAddress;      private void setIpAdd() {         try {             InetAddress thisIp = InetAddress.getLocalHost();             thisIpAddress = thisIp.getHostAddress().toString();         } catch (Exception e) {         }     }      protected String getIpAddress() {         setIpAdd();         return thisIpAddress;     } } 

Answer 1

I am not sure if you can grab that IP from code that runs on the local machine.

You can however build code that runs on a website, say in JSP, and then use something that returns the IP of where the request came from:

request.getRemoteAddr()

Or simply use already-existing services that do this, then parse the answer from the service to find out the IP.

Use a webservice like AWS and others

import java.net.*; import java.io.*;  URL whatismyip = new URL("http://checkip.amazonaws.com"); BufferedReader in = new BufferedReader(new InputStreamReader(                 whatismyip.openStream()));  String ip = in.readLine(); //you get the IP as a String System.out.println(ip);