import java.net.ServerSocket;
import java.net.Socket;

public class VPNServer {
    public static void main(String[] args) {
        try {
            ServerSocket serverSocket = new ServerSocket(1234);
            System.out.println("VPN server started on port 1234");
            
            while (true) {
                Socket clientSocket = serverSocket.accept();
                VPNClientHandler clientHandler = new VPNClientHandler(clientSocket);
                clientHandler.start();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

public class VPNClientHandler extends Thread {
    private Socket clientSocket;

    public VPNClientHandler(Socket socket) {
        this.clientSocket = socket;
    }

    public void run() {
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
            PrintWriter writer = new PrintWriter(clientSocket.getOutputStream(), true);
            
            String request = reader.readLine();
            System.out.println("Received request from client: " + request);
            
            // Process client request and generate response
            String response = processRequest(request);
            
            writer.println(response);
            System.out.println("Sent response to client: " + response);
            
            reader.close();
            writer.close();
            clientSocket.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    private String processRequest(String request) {
        // Add your logic to process the client request here
        // This is just a placeholder logic
        return "Hello, client! This is the VPN server.";
    }
}