Question

How would I get a users IP address?

InetAddress ip;
try {

 ip = InetAddress.getLocalHost();
 System.out.println("Current IP address : " + ip.getHostAddress());

} catch (UnknownHostException e) {

e.printStackTrace();

 }

That returns: 127.0.0.1

I know that is not my IP. It is my local IP address. How do I get a users IP using java..?

Answer 1

The shortest method is:

try {
InetAddress thisIp =InetAddress.getLocalHost();
System.out.println("IP:"+thisIp.getHostAddress());
}
catch(Exception e) {
e.printStackTrace();
}

However getLocalHost docs say:

If there is a security manager, its checkConnect method is called with
the local host name and -1 as its arguments to see if the operation is
allowed. If the operation is not allowed, an InetAddress representing
the loopback address is returned.

and in some cases InetAddress.getLocalHost() doesn’t consult your interfaces, it simply returns constant 127.0.0.1 (for IPv4))

I think NetworkInterface.getNetworkInterfaces is what you need to enumerate all the possibilities. Here’s an example which doesn’t show virtual addresses, but works for “main” interfaces:

import java.net.*;
import java.util.*;

public class Test
{
    public static void main(String[] args)
        throws Exception // Just for simplicity
    {
        for (Enumeration<NetworkInterface> ifaces = 
               NetworkInterface.getNetworkInterfaces();
             ifaces.hasMoreElements(); )
        {
            NetworkInterface iface = ifaces.nextElement();
            System.out.println(iface.getName() + ":");
            for (Enumeration<InetAddress> addresses =
                   iface.getInetAddresses();
                 addresses.hasMoreElements(); )
            {
                InetAddress address = addresses.nextElement();
                System.out.println("  " + address);
            }
        }
    }
}

Alternatively:

Try using this (First output should be IP after PC name):

    InetAddress[] localaddr;

    String computername = null;

    try {
        computername = InetAddress.getLocalHost().getHostName();//get pc name
    } catch (UnknownHostException ex) {
        ex.printStackTrace();
    }

    System.out.println(computername);

    try {
        localaddr = InetAddress.getAllByName(computername);
        for (int i = 0; i < localaddr.length; i++) {
            System.out.println("\n" + localaddr[i].getHostAddress());
        }
    } catch (UnknownHostException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

References:

• IP Address not obtained in java
• http://www.roseindia.net/java/java-get-example/get-ip-address.shtml