// Telnet Client

import java.net.*;
import java.io.*;

class TelnetClient
{
    publicstaticvoid main(String args[]) throws Exception
    {
        Socket soc=new Socket("127.0.0.1",5217);
        String LoginName;
        String Password;
        String Command;
        
        
        DataInputStream din=new DataInputStream(soc.getInputStream());        
        DataOutputStream dout=new DataOutputStream(soc.getOutputStream());
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

        System.out.println("Welcome to Telnet Client");
        System.out.println("Your Credential Please...");
        System.out.print("Login Name :");

        LoginName=br.readLine();
        
        System.out.print("Password :");
        Password=br.readLine();
        
        dout.writeUTF(LoginName);
        dout.writeUTF(Password);

        if (din.readUTF().equals("ALLOWED"))
        {
            do
            {
            System.out.print("< Telnet Prompt >");
            Command=br.readLine();            
            dout.writeUTF(Command);
            if(!Command.equals("quit"))
            {
                System.out.println(din.readUTF());        
            }                
            }while(!Command.equals("quit"));
        }
        soc.close();        
    }
}

// Telnet server

import java.net.*;
import java.io.*;
import java.lang.*;
import java.io.*;
import java.util.*;

class TelnetServer
{
    publicstaticvoid main(String args[]) throws Exception
    {
        ServerSocket Soc=new ServerSocket(5217);
        while(true)
        {
            Socket CSoc=Soc.accept();
            AcceptTelnetClient ob=new AcceptTelnetClient(CSoc);
        }
    }
}

class AcceptTelnetClient extends Thread
{
    Socket ClientSocket;
    DataInputStream din;
    DataOutputStream dout;
    String LoginName;
    String Password;

    AcceptTelnetClient(Socket CSoc) throws Exception
    {
        ClientSocket=CSoc;
        System.out.println("Client Connected ...");
        DataInputStream din=new DataInputStream(ClientSocket.getInputStream());
        DataOutputStream dout=new DataOutputStream(ClientSocket.getOutputStream());
        
        System.out.println("Waiting for UserName And Password");
        
        LoginName=din.readUTF();
        Password=din.readUTF();
            
        start();        
    }
    publicvoid run()
    {
        try
        {    
        DataInputStream din=new DataInputStream(ClientSocket.getInputStream());
        DataOutputStream dout=new DataOutputStream(ClientSocket.getOutputStream());

        BufferedReader brFin=new BufferedReader(new FileReader("Passwords.txt"));

        String LoginInfo=new String("");
        boolean allow=false;
        
        while((LoginInfo=brFin.readLine())!=null)
        {
            StringTokenizer st=new StringTokenizer(LoginInfo);
            if(LoginName.equals(st.nextToken()) && Password.equals(st.nextToken()))
            {
                dout.writeUTF("ALLOWED");
                allow=true;
                break;
            }
        }
        
        brFin.close();

        if (allow==false)
        {
            dout.writeUTF("NOT_ALLOWED");            
        }
        
    

        while(allow)
        {
            String strCommand;
            strCommand=din.readUTF();
            if(strCommand.equals("quit"))
            {
                allow=false;
            }
            else
            {
                Runtime rt=Runtime.getRuntime();
            
                Process p=rt.exec("TelnetServer.bat " + strCommand);
                
                String stdout=new String("");
                String st;
                DataInputStream dstdin=new DataInputStream(p.getInputStream());
                while((st=dstdin.readLine())!=null)
                {
                    stdout=stdout +st + "\n";
                }
                dstdin.close();
                dout.writeUTF(stdout);                        
            }                        
        }
        ClientSocket.close();
        }
        catch(Exception ex)
        {
            ex.printStackTrace();
        }
    } 
}