Connecting Sockets thru Proxy

[Gopal Shah]

Hi All,
I am trying to make socket connections thru a local firewall, for which I am setting the proxy host and port num.
I tried the method described in the following link
Getting through a Proxy with Sockets
But somehow I was unsuccessful to do so. Using the URLConnection approach it works i.e. when I do the

 
    System.setProperty("http.proxyHost", "myHost");
    System.setProperty("http.proxyPort", "8080");

or its equivalent mentioned in link above.
But for sockets it doesn't work, although I am trying to connect to the http port only. I even tried reading the source code of URL and its related classes -> URLConnection, etc. but it looks like URLConnection doesn't use the socket abstraction (Socket class in Java) and instead uses native methods to connect thru OS level sockets. Correct me if I am wrong in my understanding.
In Java API doc, its written

An application, by changing the socket factory that creates the socket implementation, can configure itself to create sockets appropriate to the local firewall.

Will this method work ? If yes how do we write custom socket factory ?
Thanks and regards,
Gopal

[Marlene Miller]

I have a guess as to why Socket(host, port) fails with Connection refused. Does this make sense?
----
This is how I see the problem:
This works:
URL u = new URL(http://java.sun.com);
URLConnection uc = u.openConnection();

But this does not work:
InetAddress addr = new InetAddress(http://java.sun.com);
Socket s = new (addr, 80);
This is the exception:
java.net.ConnectException: Connection refused: connect
----
When I do this:
URL u = new URL(host);
URLConnection uc = u.openConnection();
System.out.println(uc.getClass());
I get this:
class sun.net.www.protocol.http.HttpURLConnection
----
Here is my explanation. Does this make sense?
sun.net.www.protocol.http.HttpURLConnection is a subclass of the abstract class URLConnection. Sun must implement the abstract method URLConnection.connect().
I am guessing, when Sun implements connect(), Sun is calling Socket(host, port) with host and port of the proxy server. Sun is negotiating with the proxy server using the HTTP protocol.
[ March 03, 2004: Message edited by: Marlene Miller ]