Server Variables

<table border="1">
<%
IEnumerator en = Request.ServerVariables.Keys.GetEnumerator();
en.MoveNext();
foreach( string key in Request.ServerVariables.Keys)
{
    if (Request.ServerVariables[key].Trim().Length > 0)
    {
        Response.Write( string.Format("<tr><td><b>{0}</b></td><td>{1}</td></tr>",
                        key, Request.ServerVariables[key]));
    }
}
%>
</table>

<table border="1">
<%
for each name in Request.ServerVariables
    if len(trim( Request.ServerVariables(name) )) > 0 then
        Response.write( "<tr><td><b>"&name&":</b></td><td>" )
        Response.write( Request.ServerVariables(name) )
        Response.write( "</td></tr>" )
    end if
next
%>
</table>

<h3>Client side IP geolocation using <a href="http://ipinfo.io">ipinfo.io</a></h3>

<hr/>
<div id="ip"></div>
<div id="address"></div>
<hr/>Full response: <pre id="details"></pre>

$.get("http://ipinfo.io", function (response) {
    $("#ip").html("IP: " + response.ip);
    $("#address").html("Location: " + response.city + ", " + response.region);
    $("#details").html(JSON.stringify(response, null, 4));
}, "jsonp");

In this asp based site simply iterating through ServerVariables reveals this information.
The aspx sample requires the IEnumerator workaround code as an error happens without it.