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From: Michal Kleczek <michal_wytnijto@kleczek.org>
Newsgroups: comp.lang.java.programmer
Subject: Re: java proxy server problem
Date: Mon, 27 May 2013 11:28:41 +0200
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On 2013-05-24 13:12, mcheung63@gmail.com wrote:
> Dear All
>     My proxy server just work in one level forward, That mean vncviewer->my proxy server->vnc server works.
> But for two levels forward, vncviewer->my proxy server->my proxy server > vncserver doesn't work, so why?
>
> public class SimpleProxyServer {
> 	public static void main(String[] args) throws IOException {
> 		try {
> 			String host = "210.5.164.14";
> 			int remoteport = 5999;
> 			int localport = 1234;

I assume your proxies are run on different hosts (so they can both bind 
to port 1234).
Your first proxy connects to port 5999 and the second listens on port 
1234. They both connect to the target server.

> 				// Start the client-to-server request thread running
> 				t.start();
>
> 				// Read the server's responses
> 				// and pass them back to the client.
> 				int bytesRead;
> 				try {
> 					while ((bytesRead = streamFromServer.read(reply)) != -1) {
> 						streamToClient.write(reply, 0, bytesRead);
> 						streamToClient.flush();
> 					}
> 				} catch (IOException e) {
> 				}

Here you are blocking accepting new connections.
Server-to-client relay should be done in a dedicated thread such as 
client-to-server.

--
Michal