Mimicing ip addresses to the server

Question

I'm trying to set the user agent property to other than Java/1.4.2_02, and also mimic different ip addresses. In another words i am trying that I could send the request with variety of different setting of user-agent and ip address. I have this piece of code that works fine for the user-agent. But how can I send request to the server mimicing different ip addresses. Any ideas?thanks
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import javax.swing.text.html.HTMLDocument;
public class teste {
private static HttpURLConnection conn = null;
private static URL url = null;
private static HTMLDocument html = new HTMLDocument();
public static void main(String args[]) {
BufferedReader in = null;
String str = "";
try {
url = new URL("http://www.google.com/search?hl=de&ie=ISO-8859-1&q=test");
} catch(MalformedURLException e) {
System.out.println(e);
System.exit(-1);
try {
conn = (HttpURLConnection) url.openConnection();
conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.7.2) Gecko/20040803");
conn.connect();
in = new BufferedReader(new InputStreamReader(url.openStream()));
} catch(IOException e) {
System.out.println(e);
System.exit(-1);
}

Answer 1

I would suggest you try 1.4.2_08 as many bugs have been fixed since 1.4.2_02
A better choice would be 1.5.0_04.
You can creta emltiple addresses using multiple loop back interfaces. How this is setup is OS dependant and I only know how to do this for Solaris.
However, this kind of testing is unlikely to make any difference unless you need to test network based secuirty features.
BTW: When a reply is sent, it goes to the address which openned the connection. If you use dummy addresses how will you be able to get any of the replies?
My suggestion, don't worry about many different hosts, just run many clients on the same machine.