*/
private void performHandshake(SimpleHttpServerConnection conn) throws IOException {
Header challenge = createChallenge();
ResponseWriter out = conn.getWriter();
out.println("HTTP/1.1 407 Proxy Authentication Required");
out.print(challenge.toExternalForm());
out.print(new Header("Proxy-Connection", "Keep-Alive").toExternalForm());
out.print(new Header("Content-Length", "0").toExternalForm());
out.println();
out.flush();
conn.connectionKeepAlive();