How to find the ip address of a client machine from a web application?

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title></title>
<meta name="GENERATOR" content="Microsoft Visual Studio .NET 7.1">
<meta name="vs_targetSchema" content="http://schemas.
microsoft.com/intellisense/ie5">
<script id="clientEventHandlersJS" language="javascript">
<!--

function Button1_onclick() {
var locator = new ActiveXObject
"WbemScripting.SWbemLocator");
var service = locator.ConnectServer(".");
var properties = service.ExecQuery("SELECT * FROM Win32_NetworkAdapterConfiguration");
var e = new Enumerator (properties);
document.write("<table border=1>");
dispHeading();
for (;!e.atEnd();e.moveNext ())
{
var p = e.item ();
document.write("<tr>");
document.write("<td>" + p.Caption + "</td>");
document.write("<td>" + p.IPFilterSecurityEnabled + "</td>");
document.write("<td>" + p.IPPortSecurityEnabled + "</td>");
document.write("<td>" + p.IPXAddress + "</td>");
document.write("<td>" + p.IPXEnabled + "</td>");
document.write("<td>" + p.IPXNetworkNumber + "</td>");
document.write("<td>" + p.MACAddress + "</td>");
document.write("<td>" + p.WINSPrimaryServer + "</td>");
document.write("<td>" + p.WINSSecondaryServer + "</td>");
document.write("</tr>");
}
document.write("</table>");
}

function dispHeading()
{
document.write("<thead>");
document.write("<td>Caption</td>");
document.write("<td>IPFilterSecurityEnab...
document.write("<td>IPPortSecurityEnable...
document.write("<td>IPXAddress</td>");
document.write("<td>IPXEnabled</td>");
document.write("<td>IPXNetworkNumber</td...
document.write("<td>MACAddress</td>");
document.write("<td>WINSPrimaryServer</t...
document.write("<td>WINSSecondaryServer<...
document.write("</thead>");
}

//-->
</script>
</head>
<body>
<INPUT id="Button1" type="button" value="Button"
name="Button1" language="javascript" onclick="return Button1_onclick()">
</body>
</html>