ping -c 3 www.vit.ac.in
ping -q www.vit.ac.in
ping -s 512 -c 5 www.vit.ac.in
ping -W 5 -c 5 www.vit.ac.in
ping -V

IFCONFIG: MAC,IP,INTERFACES,NETWORK SETTING
ifconfig
ifconfig -a
ifconfig -v lo

NETSTAT:
listening port: -l
tcp port: -t
udp port:-u
listening conn:-l
statistics of all proto:-s
kernel ip routing:-r
kernel interface:-i
service with pid:

nslookup www.google.com
arp -v


UDP CHAT CLIENT

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

public class UDPChatClient {
    public static void main(String args[]) throws Exception
    {
        BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));

        InetAddress IPAddress = InetAddress.getByName("localhost");

        String msg = "";
        while(true)
        {
            byte[] sendData = new byte[1024];
            byte[] receiveData = new byte[1024];
            DatagramSocket clientSocket = new DatagramSocket();
            System.out.printf("Send a Message: ");
            msg = inFromUser.readLine();
            if (msg.equals("bye"))
            {
                System.out.printf("Exiting Chat!");
                clientSocket.close();
                break;
            }
            sendData = msg.getBytes();

            DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 6789);
            clientSocket.send(sendPacket);

            DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
            clientSocket.receive(receivePacket);

            String reply = new String(receivePacket.getData());
            System.out.println("Reply: " + reply);
            clientSocket.close();
        }
    }
}



UDP CHAT SERVER

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

public class UDPChatServer {
    public static void main(String args[]) throws Exception
    {
        DatagramSocket serverSocket = new DatagramSocket(6789);


        BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
        String reply;
        while(true)
        {
            byte[] receiveData = new byte[1024];
            byte[] sendData = new byte[1024];
            DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
            serverSocket.receive(receivePacket);
            String msg = new String(receivePacket.getData());
            System.out.println("Message Received: " + msg);

            InetAddress IPAddress = receivePacket.getAddress();
            int port = receivePacket.getPort();

            System.out.printf("Enter reply: ");
            reply = inFromUser.readLine();
            if (reply.equals("bye"))
            {
                System.out.printf("Exiting Chat!");
                serverSocket.close();
                break;
            }
            sendData = reply.getBytes();
            DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, port);
            serverSocket.send(sendPacket);
        }

    }
}




TCP CHAT Server

import java.io.*;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.*;
public class GossipServer
{
  public static void main(String[] args) throws Exception
  {
      ServerSocket sersock = new ServerSocket(3000);
      Socket sock = sersock.accept( );
                              // reading from keyboard (keyRead object)
      BufferedReader keyRead = new BufferedReader(new InputStreamReader(System.in));
                      // sending to client (pwrite object)
      OutputStream ostream = sock.getOutputStream();
      PrintWriter pwrite = new PrintWriter(ostream, true);

                              // receiving from server ( receiveRead  object)
      InputStream istream = sock.getInputStream();
      BufferedReader receiveRead = new BufferedReader(new InputStreamReader(istream));

      String receiveMessage, sendMessage;
      while(true)
      {
        if((receiveMessage = receiveRead.readLine()) != null)
        {
           System.out.println(receiveMessage);
        }
        sendMessage = keyRead.readLine();
        pwrite.println(sendMessage);
        pwrite.flush();
      }
    }
}


TCP CHAT CLIENT

import java.io.*;
import java.net.*;
public class GossipClient
{
  public static void main(String[] args) throws Exception
  {
     Socket sock = new Socket("127.0.0.1", 3000);
                               // reading from keyboard (keyRead object)
     BufferedReader keyRead = new BufferedReader(new InputStreamReader(System.in));
                              // sending to client (pwrite object)
     OutputStream ostream = sock.getOutputStream();
     PrintWriter pwrite = new PrintWriter(ostream, true);

                              // receiving from server ( receiveRead  object)
     InputStream istream = sock.getInputStream();
     BufferedReader receiveRead = new BufferedReader(new InputStreamReader(istream));

     System.out.println("Start the chitchat, type and press Enter key");

     String receiveMessage, sendMessage;
     while(true)
     {
        sendMessage = keyRead.readLine();  // keyboard reading
        pwrite.println(sendMessage);       // sending to server
        pwrite.flush();                    // flush the data
        if((receiveMessage = receiveRead.readLine()) != null) //receive from server
        {
            System.out.println(receiveMessage); // displaying at DOS prompt
        }
      }
    }
}





Q2 Write a Java program to run the basic networking commands.

import java.net.*;
import java.util.*;
import java.io.*;
public class command
{
        public static void main(String args[])
        throws Exception
        {
                BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
                System.out.println("enter command:");
                String s=br.readLine();
                Process p=Runtime.getRuntime().exec(s);
                p.waitFor();
                BufferedReader reader=new BufferedReader(new InputStreamReader(p.getInputStream()));
                String line=reader.readLine();
                while(line!=null)
                {
                        System.out.println(line);
                        line=reader.readLine();0
                }
                System.out.println("done!");

}
}


Q3 Write a program to display the name of the computer and its IP address that you are currently working on

import java.net.*;
import java.io.*;
public class cm
{
public static void main(String args[])
{
try
{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the url which you want to find ip address and host name");
String str=br.readLine();
InetAddress add=InetAddress.getByName(str);
System.out.println("Local Host Information");
System.out.println("Host Name:"+add.getHostName());
System.out.println("IP address:"+add.getHostAddress());
}
catch(Exception e)
{
System.out.println(e);
}
}



Q4 Write a program to print the IP address of  “www.google.com” all IP addresses of  “www.microsoft.com”.




import java.net.*;
import java.io.*;
public class ip
{
public static void main(String args[])
throws UnknownHostException {
        System.out.println(InetAddress.getByName("www.google.com"));
        InetAddress[] inetAddresses=InetAddress.getAllByName("www.microsoft.com");
        for(InetAddress ipAddress:inetAddresses)
        {
                System.out.println(ipAddress);
        }
}
}



Q5 Write a program to print all Network Interfaces of “localhost”.

import java.net.*;
import java.util.*;
import java.io.*;
public class ni
{
public static void main(String args[]) throws UnknownHostException,SocketException
{

    Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
if(interfaces==null)
{
System.out.println("No network interfaces found");
}
else
{
for(NetworkInterface netIf:Collections.list(interfaces))
{
System.out.println("Display Name:" + netIf.getDisplayName());
System.out.println("Name : " + netIf.getName());
System.out.println();
}
}
}
}


Q6 Implement the simple version of “nslookup” utility

import java.net.*;
import java.io.*;
import java.util.*;
public class nslook
{
public static void main(String args[]) throws Exception
{
    BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
    System.out.println("Enter the hostname");
    String cmd=br.readLine();
    Process p=Runtime.getRuntime().exec("nslookup "+cmd);
    p.waitFor();
    BufferedReader reader=new BufferedReader(new InputStreamReader(p.getInputStream()));
    String line=reader.readLine();
    while(line!=null)
    {
        System.out.println(line);
        line=reader.readLine();
    }
    System.out.println("Done");
}
}


Q7 Write a program to download the contents associated with a HTTP URL and save it in a file.



import java.io.*;
    import java.net.*;
    public class GetJavaUrl
    {
      public static void main(String[] args)
         {
           URL u;
           InputStream is=null;
           DataInputStream dis;
           String s;
           try
           {
             u=new URL("ftp://10.30.2.53");
             is=u.openStream();
             dis = new DataInputStream(new BufferedInputStream(is));
             while((s=dis.readLine())!=null)
              {
                System.out.println(s);
              }
            }
           catch(MalformedURLException mue)
            {
              System.out.println("404: Error NOT FOUND");
              mue.printStackTrace();
              System.exit(1);
            }
           catch(IOException ioe)
            {
              System.out.println("404: Error NOT FOUND");
              ioe.printStackTrace();
              System.exit(1);
            }
          finally
            {
               try
                   {
                     is.close();
                   }
               catch(IOException ioe)
                   {
                   }
            }
        }

}




cyclesheet2


Q1 Write a program to list all ports hosting a TCP server in a specified host and identify available servers in well-known ports?


import java.net.Socket;
import java.net.*;

public class A {
public static void main(String[] args) throws Exception{
    try {
        for(int i=0;i<1024;i++)
        {
            Socket s=new Socket("localhost",i);
            System.out.println(i);
        }
    }
    catch(Exception e)
    {
        System.out.println(e);
    }
}
}



Q2 Implement echo server and client in java using TCP sockets.

server

import java.io.*;

import java.net.*;



public class EchoServer

{

public static void main(String args[]) throws Exception

{

try

{

int Port;

BufferedReader Buf =new BufferedReader(new

InputStreamReader(System.in));

System.out.print(" Enter the Port Address : " );

Port=Integer.parseInt(Buf.readLine());

ServerSocket sok =new ServerSocket(Port);

System.out.println(" Server is Ready To Receive a Message. ");

System.out.println(" Waiting ..... ");

Socket so=sok.accept();

if(so.isConnected()==true)

            System.out.println(" Client Socket is Connected Succecfully. ");

InputStream in=so.getInputStream();

OutputStream ou=so.getOutputStream();

PrintWriter pr=new PrintWriter(ou);

BufferedReader buf=new BufferedReader(new

InputStreamReader(in));

String str=buf.readLine();

System.out.println(" Message Received From Client : " + str);

System.out.println(" This Message is Forwarded To Client. ");

pr.println(str);

pr.flush();

}

 catch(Exception e)

  {

  System.out.println(" Error : " + e.getMessage());

  }

}

}



client

import java.io.*;

import java.net.*;



public class EchoClient

{

public static void main(String args[]) throws Exception

{

try {

int Port;

BufferedReader Buf =new BufferedReader(new

InputStreamReader(System.in));

System.out.print(" Enter the Port Address : " );

Port=Integer.parseInt(Buf.readLine());

Socket sok=new Socket("localhost",Port);

if(sok.isConnected()==true)

            System.out.println(" Server Socket is Connected Succecfully. ");

InputStream in=sok.getInputStream();

OutputStream ou=sok.getOutputStream();

PrintWriter pr=new PrintWriter(ou);

BufferedReader buf1=new BufferedReader(new

InputStreamReader(System.in));


BufferedReader buf2=new BufferedReader(new

InputStreamReader(in));

String str1,str2;

System.out.print(" Enter the Message : ");

str1=buf1.readLine();

pr.println(str1);

pr.flush();

System.out.println(" Message Send Successfully. ");

str2=buf2.readLine();

System.out.println(" Message From Server : " + str2);

     }

  catch(Exception e)

  {

   System.out.println(" Error : " + e.getMessage());

  }

}

}


Q3 Implement date server and client in java using TCP sockets


client

import java.io.*;

import java.net.*;



class DateClient

{

    public static void main(String args[]) throws Exception

    {

        Socket soc=new Socket(InetAddress.getLocalHost(),5217);

        BufferedReader in=new BufferedReader(new InputStreamReader( soc.getInputStream() ) );

   System.out.println(in.readLine());

    }

}



server

import java.net.*;

import java.io.*;

import java.util.*;



class DateServer

{

    public static void main(String args[]) throws Exception

    {

        ServerSocket s=new ServerSocket(5217);
        while(true)

        {

            System.out.println("Waiting For Connection ...");

            Socket soc=s.accept();

            DataOutputStream out=new DataOutputStream(soc.getOutputStream());

            out.writeBytes("Server Date" + (new Date()).toString() + "\n");

            out.close();

            soc.close();

        }



    }

}


Q4,Q6
Implement a chat server and client in java using TCP sockets.
Write a program to implement a simple message transfer from client to server process using TCP/IP.


SERVER

import java.io.*;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.*;
public class GossipServer
{
  public static void main(String[] args) throws Exception
  {
      ServerSocket sersock = new ServerSocket(3000);
      System.out.println("Server  ready for chatting");
      Socket sock = sersock.accept( );
                              // reading from keyboard (keyRead object)
      BufferedReader keyRead = new BufferedReader(new InputStreamReader(System.in));
                      // sending to client (pwrite object)
      OutputStream ostream = sock.getOutputStream();
      PrintWriter pwrite = new PrintWriter(ostream, true);

                              // receiving from server ( receiveRead  object)
      InputStream istream = sock.getInputStream();
      BufferedReader receiveRead = new BufferedReader(new InputStreamReader(istream));

      String receiveMessage, sendMessage;
      while(true)
      {
        if((receiveMessage = receiveRead.readLine()) != null)
        {
           System.out.println(receiveMessage);
        }
        sendMessage = keyRead.readLine();
        pwrite.println(sendMessage);
        pwrite.flush();
      }
    }
}


CLINET

import java.io.*;
import java.net.*;
public class GossipClient
{
  public static void main(String[] args) throws Exception
  {
     Socket sock = new Socket("127.0.0.1", 3000);
                               // reading from keyboard (keyRead object)
     BufferedReader keyRead = new BufferedReader(new InputStreamReader(System.in));
                              // sending to client (pwrite object)
     OutputStream ostream = sock.getOutputStream();
     PrintWriter pwrite = new PrintWriter(ostream, true);

                              // receiving from server ( receiveRead  object)
     InputStream istream = sock.getInputStream();
     BufferedReader receiveRead = new BufferedReader(new InputStreamReader(istream));

     System.out.println("Start the chitchat, type and press Enter key");

     String receiveMessage, sendMessage;
     while(true)
     {
        sendMessage = keyRead.readLine();  // keyboard reading
        pwrite.println(sendMessage);       // sending to server
        pwrite.flush();                    // flush the data
        if((receiveMessage = receiveRead.readLine()) != null) //receive from server
        {
            System.out.println(receiveMessage); // displaying at DOS prompt
        }
      }
    }
}



Q7 Implement a TCP based server program to authenticate the client’s User Name and Password. The validity of the client must be sent as the reply message to the client and display it on the standard output.

CLIENT

import java.io.*;
import java.net.*;
class TCPClientAuth {

    public static void main(String argv[]) throws Exception
    {
        String username;
        String password;
    String auth;

        BufferedReader inFromUser =
          new BufferedReader(new InputStreamReader(System.in));

        Socket clientSocket = new Socket("localhost", 6789);

        DataOutputStream outToServer =
          new DataOutputStream(clientSocket.getOutputStream());

                BufferedReader inFromServer =
          new BufferedReader(new
          InputStreamReader(clientSocket.getInputStream()));

    System.out.print("Username :");
        username = inFromUser.readLine();

    System.out.print("Password :");
    password = inFromUser.readLine();


        outToServer.writeBytes(username + '\n' + password + '\n' );

        auth = inFromServer.readLine();

        System.out.println("FROM SERVER: " + auth);

        clientSocket.close();

    }
}

SERVER


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

class TCPServerAuth {

  public static void main(String argv[]) throws Exception
    {
      String username;
      String password;
      String auth;

      ServerSocket welcomeSocket = new ServerSocket(6789);

      while(true) {

            Socket connectionSocket = welcomeSocket.accept();

           BufferedReader inFromClient =
              new BufferedReader(new
              InputStreamReader(connectionSocket.getInputStream()));



           DataOutputStream  outToClient =
             new DataOutputStream(connectionSocket.getOutputStream());

           username = inFromClient.readLine();
       password = inFromClient.readLine();


           if (username.equals("Admin")){
        if (password.equals("root")){
            auth = "Login Successful!";
        }else{
            auth = "Wrong Password";
        }
       }else{
        auth = "Wrong Username";
       }

           outToClient.writeBytes(auth);
       connectionSocket.close();
        }
    }
}

************************************************

CYCLESHEET 2

Q8.Find the physical address of a host when its logical address is known (ARP protocol) using TCP/IP.

CLIENT:
import java.io.*;
import java.util.*;
import java.net.*;

public class q8client
{
public static void main(String[] args)
{
try
{
Socket s = new Socket("localhost",5555);
BufferedReader b = new BufferedReader(new InputStreamReader(System.in));
DataOutputStream dout = new DataOutputStream(s.getOutputStream());
DataInputStream din = new DataInputStream(s.getInputStream());
System.out.println("Enter the logical address: ");
String str = b.readLine();
dout.writeBytes(str + "\n");
String str1 = din.readLine();
System.out.println("Physical Address of str: " + str1);
s.close();
}
catch (Exception e)
{
}
}}

SERVER:

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

public class q8server
{
public static void main(String[] args)
{
try
{
ServerSocket ss = new ServerSocket(5555);
Socket s = ss.accept();
BufferedReader b = new BufferedReader(new InputStreamReader(System.in));
DataOutputStream dout = new DataOutputStream(s.getOutputStream());
DataInputStream din = new DataInputStream(s.getInputStream());
String str = din.readLine();
String logical[] = {"172.16.27.34","195.24.54.204"};
String physical[] = {"8E:AE:08:AA","0A:78:6C:AD"};
for(int i=0;i<logical.length;i++)
{
if (str.equals(logical[i]))
{
dout.writeBytes(physical[i] + "\n");
break;
}
}
s.close();
}
catch (Exception e)
{
}
}
}


OUTPUT:


=====================================================





Q9.Find the logical address of a host when its physical address is known (RARP protocol) using TCP/IP.

CLIENT:
import java.io.*;
import java.net.*;
class TCPLogClient {

    public static void main(String argv[]) throws Exception
    {
        String logicAdd;
        String phyAdd;

        BufferedReader inFromUser =
          new BufferedReader(new InputStreamReader(System.in));

        Socket clientSocket = new Socket("localhost", 6789);

        DataOutputStream outToServer =
          new DataOutputStream(clientSocket.getOutputStream());

                BufferedReader inFromServer =
          new BufferedReader(new
          InputStreamReader(clientSocket.getInputStream()));

    System.out.println("Enter Physical address of host");
        phyAdd = inFromUser.readLine();

        outToServer.writeBytes(phyAdd + '\n');

        logicAdd = inFromServer.readLine();

        System.out.println("FROM SERVER: Logical Address " + logicAdd);

        clientSocket.close();

    }
}

SERVER:
import java.io.*;
import java.net.*;

class TCPLogServer {

  public static void main(String argv[]) throws Exception
    {
      String phyAdd;


      ServerSocket welcomeSocket = new ServerSocket(6789);

      while(true) {

            Socket connectionSocket = welcomeSocket.accept();

           BufferedReader inFromClient =
              new BufferedReader(new
              InputStreamReader(connectionSocket.getInputStream()));


          String logical[] = {"172.16.27.34","195.24.54.204", "10.10.137.1"};
      String physical[] = {"8E:AE:08:AA","0A:78:6C:AD", "d4:6d:50:84:db:c8"};

           DataOutputStream  outToClient =
             new DataOutputStream(connectionSocket.getOutputStream());

           phyAdd = inFromClient.readLine();
    for(int i = 0; i < physical.length; i++)
    {
        if (phyAdd.equals(physical[i]))
        {
            outToClient.writeBytes(logical[i] + "\n");
            connectionSocket.close();
        }
    }


        }
    }
}

=======================================


10.Implement Domain Name System (DNS) using TCP/IP

SERVER:
import java.io.*;
import java.net.*;
class TCPLoServer {
 public static void main(String argv[]) throws Exception
    {
      String D;
       ServerSocket welcomeSocket = new ServerSocket(6789);
    while(true) {
   Socket connectionSocket = welcomeSocket.accept();
BufferedReader inFromClient =
              new BufferedReader(new
              InputStreamReader(connectionSocket.getInputStream()));
String hostaddr[] = {"172.16.27.34","195.24.54.204", "10.10.137.1"};
      String DNS[] = {"www.google.com","www.facebook.com", "www.vit.ac.in"};
           DataOutputStream  outToClient =
             new DataOutputStream(connectionSocket.getOutputStream());
   D = inFromClient.readLine();
for(int i = 0; i < hostaddr.length; i++)
    {
        if (D.equals(hostaddr[i]))
        {
            outToClient.writeBytes(DNS[i] + "\n");
            connectionSocket.close();
        }
    }


        }
    }
}



CLIENT:
import java.io.*;
import java.net.*;
class TCPLoClient {

    public static void main(String argv[]) throws Exception
    {
        String hostaddr;
        String DNS;

        BufferedReader inFromUser =
          new BufferedReader(new InputStreamReader(System.in));

        Socket clientSocket = new Socket("localhost", 6789);

        DataOutputStream outToServer =
          new DataOutputStream(clientSocket.getOutputStream());

                BufferedReader inFromServer =
          new BufferedReader(new
          InputStreamReader(clientSocket.getInputStream()));

    System.out.println("Enter IP address of host");
        DNS = inFromUser.readLine();

        outToServer.writeBytes(DNS + '\n');

       hostaddr = inFromServer.readLine();

        System.out.println("FROM SERVER: Logical Address " + hostaddr);

        clientSocket.close();

    }
}



*************************************************

11.Implement a TCP/IP based Server program in Java to compute the factorial of a number (can contain arbitrary number of digits). Write a client program to test the working of the same.

CLIENT:
import java.io.*;
import java.net.*;
class client {
 public static void main(String argv[]) throws Exception
 {
  String sentence;
  String modifiedSentence;
  BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
  Socket clientSocket = new Socket("localhost", 2222);
  DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream());
  BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
  System.out.println("Enter a number - ");
  sentence = inFromUser.readLine();
  outToServer.writeBytes(sentence + '\n');
  modifiedSentence = inFromServer.readLine();
  System.out.println ("Factorial: " + modifiedSentence );
  clientSocket.close();
 }
}
SREVER:

import java.io.*;
import java.net.*;
class serv {
 public static void main(String argv[]) throws Exception
 {
  String clientSentence;
  String capitalizedSentence;
  ServerSocket welcomeSocket = new ServerSocket(2222);
   Socket connectionSocket = welcomeSocket.accept();
   BufferedReader inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
   DataOutputStream outToClient = new DataOutputStream (connectionSocket.getOutputStream());
   clientSentence = inFromClient.readLine();
   int num = Integer.parseInt(clientSentence);
   int fact=1;
   for(int i=1;i<=num;i++)
    fact=fact*i;
   System.out.println("Factorial : "+fact);
   capitalizedSentence = String.valueOf(fact);
   //capitalizedSentence = clientSentence.toUpperCase() + '\n';
   outToClient.writeBytes(capitalizedSentence);
 }
}

******************************************************

Ques12.Find the class of the IP address using TCP/IP.
import java.io.*;
import java.net.*;

class TCPIpclassServer {

  public static void main(String argv[]) throws Exception
    {
      String ip;
    int fbyte;
    String ipclass = "Invalid";


      ServerSocket welcomeSocket = new ServerSocket(6789);

      while(true) {

            Socket connectionSocket = welcomeSocket.accept();

           BufferedReader inFromClient =
              new BufferedReader(new
              InputStreamReader(connectionSocket.getInputStream()));


           DataOutputStream  outToClient =
             new DataOutputStream(connectionSocket.getOutputStream());

           ip = inFromClient.readLine();
       int index;
           index = ip.indexOf(".");
           ip = ip.substring(0, index);


       fbyte = Integer.parseInt(ip);
    if (fbyte >= 0 && fbyte <= 127)
        ipclass = "Class A";
    else if (fbyte >= 128 && fbyte <= 191)
        ipclass = "Class B";
    else if (fbyte >= 192 && fbyte <= 223)
        ipclass = "Class C";
    else if (fbyte >= 224 && fbyte <= 239)
        ipclass = "Class D";
    else if (fbyte >= 240 && fbyte <= 255)
        ipclass = "Class E";

    outToClient.writeBytes(ipclass + "\n");
    connectionSocket.close();

        }
    }
}

//client

import java.io.*;
import java.net.*;
class TCPIpclassClient {

    public static void main(String argv[]) throws Exception
    {
        String ip;
    String ipclass;

        BufferedReader inFromUser =
          new BufferedReader(new InputStreamReader(System.in));

        Socket clientSocket = new Socket("localhost", 6789);

        DataOutputStream outToServer =
          new DataOutputStream(clientSocket.getOutputStream());

                BufferedReader inFromServer =
          new BufferedReader(new
          InputStreamReader(clientSocket.getInputStream()));

    System.out.println("Enter an IP address: ");
        ip = inFromUser.readLine();

        outToServer.writeBytes(ip + '\n');

        ipclass = inFromServer.readLine();

        System.out.println("FROM SERVER: Class for IP: "+ ip + " is : " + ipclass);

        clientSocket.close();

    }
}

*************************************************


CYCLESHEET 3


1.Implement echo server and client in java using UDP sockets.

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

public class EServer
{
 public static void main(String[] args) throws IOException
 {

  ServerSocket S = new ServerSocket(3000);

  while(true)
  {
   Socket Client = S.accept();

   InputStream in = Client.getInputStream();

   DataInputStream Dis = new DataInputStream(in);

   System.out.println(Dis.readUTF());

   Client = new Socket("localhost",4000);

  BufferedReader buff = new BufferedReader(new InputStreamReader (System.in));

   String Str = buff.readLine();

   OutputStream out = Client.getOutputStream();

   DataOutputStream Dos = new DataOutputStream(out);

   Str = "Server Says :: " + Str;

   Dos.writeUTF(Str);

   Client.close();

  }

 }

}



//client
import java.io.*;
import java.net.*;
import java.util.*;

public class EClient
{
 public static void main(String[] args) throws IOException
 {
  Socket C = new Socket("localhost",3000);
  BufferedReader buff = new BufferedReader(new InputStreamReader (System.in));
  String Str = buff.readLine();

  OutputStream out = C.getOutputStream();

  DataOutputStream Dos = new DataOutputStream(out);

  Dos.writeUTF("Client Say :: " + Str);
  Dos.flush();

  ServerSocket S = new ServerSocket(4000);
  Socket Client = S.accept();
  InputStream in = Client.getInputStream();
  DataInputStream Dis = new DataInputStream(in);
  System.out.println(Dis.readUTF());
  Client.close();
 }
}

OUTPUT:


***************************************************



2.Write a program to implement a text based message transfer from client to server process using UDP.

//server
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class Server
{

    private static Socket socket;

    public static void main(String[] args)
    {
        try
        {

            int port = 25000;
            ServerSocket serverSocket = new ServerSocket(port);
            System.out.println("Server Started and listening to the port 25000");

            //Server is running always. This is done using this while(true) loop
            while(true)
            {
                //Reading the message from the client
                socket = serverSocket.accept();
                InputStream is = socket.getInputStream();
                InputStreamReader isr = new InputStreamReader(is);
                BufferedReader br = new BufferedReader(isr);
                String number = br.readLine();
                System.out.println("Message received from client is "+number);

                //Multiplying the number by 2 and forming the return message
                String returnMessage;
                try
                {
                    int numberInIntFormat = Integer.parseInt(number);
                    int returnValue = numberInIntFormat*2;
                    returnMessage = String.valueOf(returnValue) + "\n";
                }
                catch(NumberFormatException e)
                {
                    //Input was not a number. Sending proper message back to client.
                    returnMessage = "Please send a proper number\n";
                }

                //Sending the response back to the client.
                OutputStream os = socket.getOutputStream();
                OutputStreamWriter osw = new OutputStreamWriter(os);
                BufferedWriter bw = new BufferedWriter(osw);
                bw.write(returnMessage);
                System.out.println("Message sent to the client is "+returnMessage);
                bw.flush();
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            try
            {
                socket.close();
            }
            catch(Exception e){}
        }
    }
}








//client

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.InetAddress;
import java.net.Socket;

public class Client
{

    private static Socket socket;

    public static void main(String args[])
    {
        try
        {
            String host = "localhost";
            int port = 25000;
            InetAddress address = InetAddress.getByName(host);
            socket = new Socket(address, port);

            //Send the message to the server
            OutputStream os = socket.getOutputStream();
            OutputStreamWriter osw = new OutputStreamWriter(os);
            BufferedWriter bw = new BufferedWriter(osw);

            String number = "2";

            String sendMessage = number + "\n";
            bw.write(sendMessage);
            bw.flush();
            System.out.println("Message sent to the server : "+sendMessage);

            //Get the return message from the server
            InputStream is = socket.getInputStream();
            InputStreamReader isr = new InputStreamReader(is);
            BufferedReader br = new BufferedReader(isr);
            String message = br.readLine();
            System.out.println("Message received from the server : " +message);
        }
        catch (Exception exception)
        {
            exception.printStackTrace();
        }
        finally
        {
            //Closing the socket
            try
            {
                socket.close();
            }
            catch(Exception e)
            {
                e.printStackTrace();
            }
        }
    }
}

OUTPUT:






**********************************************





3.Implement a chat server and client in java using UDP sockets.

//server
import java.io.*;
import java.net.*;

public class UDPChatServer {
    public static void main(String args[]) throws Exception
    {
        DatagramSocket serverSocket = new DatagramSocket(6789);

        BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
        String reply;
        while(true)
        {
            byte[] receiveData = new byte[1024];
            byte[] sendData = new byte[1024];
            DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
            serverSocket.receive(receivePacket);

            String msg = new String(receivePacket.getData());
            System.out.println("Message Received: " + msg);

            InetAddress IPAddress = receivePacket.getAddress();
            int port = receivePacket.getPort();

            System.out.printf("Enter reply: ");
            reply = inFromUser.readLine();
            if (reply.equals("bye"))
            {
                System.out.printf("Exiting Chat!");
                serverSocket.close();
                break;
            }
            sendData = reply.getBytes();
            DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, port);
            serverSocket.send(sendPacket);
        }

    }
}










//client
import java.io.*;
import java.net.*;

public class UDPChatClient {
    public static void main(String args[]) throws Exception
    {
        BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));

        InetAddress IPAddress = InetAddress.getByName("localhost");

        String msg = "";
        while(true)
        {
            byte[] sendData = new byte[1024];
            byte[] receiveData = new byte[1024];
            DatagramSocket clientSocket = new DatagramSocket();
            System.out.printf("Send a Message: ");
            msg = inFromUser.readLine();
            if (msg.equals("bye"))
            {
                System.out.printf("Exiting Chat!");
                clientSocket.close();
                break;
            }
            sendData = msg.getBytes();

            DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 6789);
            clientSocket.send(sendPacket);

            DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
            clientSocket.receive(receivePacket);

            String reply = new String(receivePacket.getData());
            System.out.println("Reply: " + reply);
            clientSocket.close();
        }
    }
}


****************************************



4. Implement a DNS server and client in java using UDP sockets.

//server
import java.io.*;
import java.net.*;
import java.util.*;
class Serverdns12
{

            public static void main(String args[])
            {
            try
            {
                        DatagramSocket server=new DatagramSocket(1309);
                        while(true)
                        {
                                    byte[] sendbyte=new byte[1024];
                                    byte[] receivebyte=new byte[1024];
                                    DatagramPacket receiver=new DatagramPacket(receivebyte,receivebyte.length);
                                    server.receive(receiver);
                                    String str=new String(receiver.getData());
                                    String s=str.trim();
                                    //System.out.println(s);
                                    InetAddress addr=receiver.getAddress();
                                    int port=receiver.getPort();
                                    String ip[]={"165.165.80.80","165.165.79.1"};
                                    String name[]={"www.aptitudeguru.com","www.downloadcyclone.blogspot.com"};
                                    for(int i=0;i<ip.length;i++)
                                    {
                                                if(s.equals(ip[i]))
                                                {
                                                            sendbyte=name[i].getBytes();
                                                            DatagramPacket sender=new DatagramPacket(sendbyte,sendbyte.length,addr,port);
                                                            server.send(sender);
                                                            break;
                                                }
                                                else if(s.equals(name[i]))
                                                {
                                                            sendbyte=ip[i].getBytes();
                                                            DatagramPacket sender=new DatagramPacket(sendbyte,sendbyte.length,addr,port);
                                                            server.send(sender);
                                                            break;
                                                }
                                    }
                                    break;
                        }
            }
            catch(Exception e)
            {
                        System.out.println(e);
            }
            }
}




//client

import java.io.*;
import java.net.*;
import java.util.*;
class Clientdns12
{
            public static void main(String args[])
            {
            try
            {
                        DatagramSocket client=new DatagramSocket();
                        InetAddress addr=InetAddress.getByName("127.0.0.1");

                        byte[] sendbyte=new byte[1024];
                        byte[] receivebyte=new byte[1024];

                        BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
                        System.out.println("Enter the DOMAIN NAME or IP adress:");
                        String str=in.readLine();
                        sendbyte=str.getBytes();
                        DatagramPacket sender=new DatagramPacket(sendbyte,sendbyte.length,addr,1309);
                        client.send(sender);
                        DatagramPacket receiver=new DatagramPacket(receivebyte,receivebyte.length);
                        client.receive(receiver);
                        String s=new String(receiver.getData());
                        System.out.println("IP address or DOMAIN NAME: "+s.trim());
                        client.close();
            }
            catch(Exception e)
            {
                        System.out.println(e);
            }
            }
}

***************************





5. Find the logical address of a host when its physical address is known (RARP protocol) using UDP.

//SERVER
import java.io.*;
import java.net.*;

public class UDPRARPServer {
    public static void main(String args[]) throws Exception
    {
        DatagramSocket serverSocket = new DatagramSocket(6789);
        byte[] receiveData = new byte[1024];
        byte[] sendData = new byte[1024];

        String logical[] = {"172.16.27.34","195.24.54.204", "10.10.137.1"};
        String physical[] = {"8E:AE:08:AA","0A:78:6C:AD", "d4:6d:50:84:db:c8"};
        String reply = "";

        while(true)
        {
            DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
            serverSocket.receive(receivePacket);

            String phyaddr = new String(receivePacket.getData());
            System.out.println("Physical Address received: " + phyaddr);
            phyaddr = phyaddr.trim();
            InetAddress IPAddress = receivePacket.getAddress();
            int port = receivePacket.getPort();

            for(int i = 0; i < physical.length; i++)
            {
                if (phyaddr.equals(physical[i]))
                {
                    reply = logical[i];
                    sendData = reply.getBytes();
                    DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, port);
                    serverSocket.send(sendPacket);
                }
            }

        }
    }
}










//CLIENT
import java.io.*;
import java.net.*;

public class UDPRARPClient {
    public static void main(String args[]) throws Exception
    {
        BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
        DatagramSocket clientSocket = new DatagramSocket();
        InetAddress IPAddress = InetAddress.getByName("localhost");
        byte[] sendData = new byte[1024];
        byte[] receiveData = new byte[1024];

        System.out.printf("Enter Physical address: ");
        String phyaddr = inFromUser.readLine();
        sendData = phyaddr.getBytes();

        DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 6789);
        clientSocket.send(sendPacket);

        DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
        clientSocket.receive(receivePacket);

        String logaddr = new String(receivePacket.getData());
        System.out.println("Logical Address:" + logaddr);
        clientSocket.close();
    }
}


********************************


6.Find the physical address of a host when its logical address is known (ARP protocol) using UDP.

//server
import java.io.*;
import java.net.*;
import java.util.*;
class Serverarp12
{
            public static void main(String args[])
            {
            try
            {
                        DatagramSocket server=new DatagramSocket(1309);
                        while(true)
                        {
                                    byte[] sendbyte=new byte[1024];
                                    byte[] receivebyte=new byte[1024];
                                    DatagramPacket receiver=new DatagramPacket(receivebyte,receivebyte.length);
                                    server.receive(receiver);
                                    String str=new String(receiver.getData());
                                    String s=str.trim();
                                    //System.out.println(s);
                                    InetAddress addr=receiver.getAddress();
                                    int port=receiver.getPort();
                                    String ip[]={"165.165.80.80","165.165.79.1"};
                                    String mac[]={"6A:08:AA:C2","8A:BC:E3:FA"};
                                    for(int i=0;i<ip.length;i++)
                                    {
                                                if(s.equals(ip[i]))
                                                {
                                                            sendbyte=mac[i].getBytes();
                                                            DatagramPacket sender=new DatagramPacket(sendbyte,sendbyte.length,addr,port);
                                                            server.send(sender);
                                                            break;
                                                }
                                    }
                                    break;


                        }
            }
            catch(Exception e)
            {
                        System.out.println(e);
            }
            }
}













//client
import java.io.*;
import java.net.*;
import java.util.*;
class Clientarp12
{
            public static void main(String args[])
            {
            try
            {
                        DatagramSocket client=new DatagramSocket();
                        InetAddress addr=InetAddress.getByName("127.0.0.1");

                        byte[] sendbyte=new byte[1024];
                        byte[] receivebyte=new byte[1024];
                        BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
                        System.out.println("Enter the logical address (IP):");
                        String str=in.readLine();
                        sendbyte=str.getBytes();
                        DatagramPacket sender=new DatagramPacket(sendbyte,sendbyte.length,addr,1309);
                        client.send(sender);
                        DatagramPacket receiver=new DatagramPacket(receivebyte,receivebyte.length);
                        client.receive(receiver);
                        String s=new String(receiver.getData());
                        System.out.println("The Physical Address is(MAC): "+s.trim());
                        client.close();
            }
            catch(Exception e)
            {
                        System.out.println(e);
            }
            }
}



*********************************


7.Implement Client - Server communication to access Date using UDP in Java.


//server
import java.io.*;
import java.net.*;
import java.util.*;

public class UDPDateServer {
    public static void main(String args[]) throws Exception
    {
        DatagramSocket serverSocket = new DatagramSocket(6789);
        byte[] receiveData = new byte[1024];
        byte[] sendData = new byte[1024];
        String GetDate = "";
        while(true)
        {
            DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
            serverSocket.receive(receivePacket);

            String msg = new String(receivePacket.getData());
            System.out.println("Message: " + msg);

            InetAddress IPAddress = receivePacket.getAddress();
            int port = receivePacket.getPort();
            msg = msg.trim();
            if (msg.equals("date"))
            {
                Date d = new Date();
                GetDate = d.toString();
            }

            sendData = GetDate.getBytes();
            DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, port);
            serverSocket.send(sendPacket);
        }
    }
}













//client

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


public class UDPDateClient {
    public static void main(String args[]) throws Exception
    {
        BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
        DatagramSocket clientSocket = new DatagramSocket();
        InetAddress IPAddress = InetAddress.getByName("localhost");
        byte[] sendData = new byte[1024];
        byte[] receiveData = new byte[1024];

        System.out.printf("Enter Request: ");
        String msg = inFromUser.readLine();
        sendData = msg.getBytes();

        DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 6789);
        clientSocket.send(sendPacket);

        DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
        clientSocket.receive(receivePacket);

        String reply = new String(receivePacket.getData());
        System.out.println("FROM SERVER:" + reply);
        clientSocket.close();
    }
}




7 USING UDP

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

public class Clientnew {

public static void main(String[] args) throws Exception{

    System.out.println("Server Time >>>>");

    DatagramSocket cs=new DatagramSocket();

    InetAddress ip=InetAddress.getByName("localhost");

    byte[] rd=new byte[100];
    byte[] sd=new byte[100];

    DatagramPacket sp=new DatagramPacket(sd,sd.length,ip,1234);

    DatagramPacket rp=new DatagramPacket(rd,rd.length);

    cs.send(sp);

    cs.receive(rp);

    String time=new String(rp.getData());

    System.out.println(time);

    cs.close();

}

}



==============================

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

public class Server {

public static void main(String[] args) throws Exception{

DatagramSocket ss=new DatagramSocket(1234);

while(true){

System.out.println("Server is up....");

byte[] rd=new byte[100];
byte[] sd=new byte[100];

DatagramPacket rp=new DatagramPacket(rd,rd.length);

ss.receive(rp);

InetAddress ip= rp.getAddress();

int port=rp.getPort();

Date d=new Date();   // getting system time

String time= d + "";  // converting it to String

sd=time.getBytes();   // converting that String to byte

DatagramPacket sp=new DatagramPacket(sd,sd.length,ip,port);

ss.send(sp);

rp=null;

System.out.println("Done !! ");

}

}

}
1. Write a Java program to display the server’s date and time details at the client end.

Server:

import java.io.*;
import java.net.*;
import java.util.Date;
class server1 {
  public static void main(String argv[]) throws Exception
    {
      String capitalizedSentence;
      ServerSocket welcomeSocket = new ServerSocket(6789);
      while(true) {
            Socket connectionSocket = welcomeSocket.accept();
DataOutputStream  outToClient = new DataOutputStream(connectionSocket.getOutputStream());
           capitalizedSentence = new Date().toString() + '\n';
           outToClient.writeBytes(capitalizedSentence);
        }
    }
}


Client:

import java.io.*;
import java.net.*;
class client1 {
    public static void main(String argv[]) throws Exception
    {
   String modifiedSentence;
   Socket clientSocket = new Socket("localhost", 6789);
BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        modifiedSentence = inFromServer.readLine();
        System.out.println("FROM SERVER: " + modifiedSentence);
        clientSocket.close();
    }
}


2. Write a Java program to display the client’s address at the server end.

Server:

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

class server1 {
  public static void main(String argv[]) throws Exception
    {
      ServerSocket welcomeSocket = new ServerSocket(6789);
      while(true) {
            Socket connectionSocket = welcomeSocket.accept();
            BufferedReader inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
System.out.println("Address Received from client : "+ inFromClient.readLine());
        }
    }
}


Client:

import java.io.*;
import java.net.*;
class client1 {
    public static void main(String argv[]) throws Exception
    {
   Socket clientSocket = new Socket("localhost", 6789);
DataOutputStream outToServer =  new DataOutputStream(clientSocket.getOutputStream());
        outToServer.writeBytes(InetAddress.getLocalHost().getHostAddress() + '\n');
        clientSocket.close();

    }
}



3. Write a Java program to implement an echo UDP server.
4. Write a Java program to develop a simple Chat application.


5. The message entered in the client is sent to the server and the server encodes the message and
returns it to the client. Encoding is done by replacing a character by the character next to it i.e. a as b,
b as c ...z as a. This process is done using the TCP/IP protocol. Write a Java program for the above

server:

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

class server1 {

    public static void main(String argv[]) throws Exception {
        String clientSentence;
        ServerSocket welcomeSocket = new ServerSocket(6789);
        while (true) {
            Socket connectionSocket = welcomeSocket.accept();
            BufferedReader inFromClient
                    = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
            DataOutputStream outToClient
                    = new DataOutputStream(connectionSocket.getOutputStream());
            clientSentence = inFromClient.readLine();
            System.out.println("Received from client : " + clientSentence);
            String a = clientSentence.toLowerCase();
            String b = "";//abc
            String x = "abcdefghijklmnopqrstuvwxyz";
//code to encode
            for (int i = 0; i < a.length(); i++) {
                if (a.charAt(i) == 'z') {
                    b += 'a';
                } else {
                    for (int j = 0; j < x.length(); j++) {
                        if (x.charAt(j) == a.charAt(i)) {
                            b += x.charAt(j + 1);
                            break;
                        }
                    }
                }
            }
            outToClient.writeBytes(b+"\n");
        }
    }
}

client:

import java.io.*;
import java.net.*;
class client1 {
    public static void main(String argv[]) throws Exception {
        String sentence;
        String modifiedSentence;
        BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
        Socket clientSocket = new Socket("localhost", 6789);
        DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream());
        BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        sentence = inFromUser.readLine();
        outToServer.writeBytes(sentence + '\n');

        modifiedSentence = inFromServer.readLine();

        System.out.println("FROM SERVER: " + modifiedSentence);

        clientSocket.close();

    }
}

6. 5th pro with udp


7. Write a Java program to display the name and address of the computer that we are currently
working on.

import java.net.InetAddress;
public class pro1 {
  public static void main(String []args) throws Exception{
      InetAddress a=InetAddress.getLocalHost();
      System.out.println(a);
  }
}

LAB:
1. Write a Java program to display the server’s date and time details at the client end.


server:

import java.util.*;
import java.net.*;
import java.io.*;
public class datetime
{
public static void main(String args[])throws Exception
{
ServerSocket listener=new ServerSocket(9090);
while(true)
{
Socket socket=listener.accept();
PrintWriter out=new PrintWriter(socket.getOutputStream(),true);
out.println(new Date().toString());
socket.close();
listener.close();
}
}
}

client:

import java.util.*;
import java.net.*;
import java.io.*;
public class dateclient
{
public static void main(String args[])throws Exception
{
Socket s=new Socket("127.0.0.1",9090);
BufferedReader input=new BufferedReader(new InputStreamReader(s.getInputStream()));
String answer=input.readLine();
System.out.println("date+time:::\t"+answer);
System.exit(0);
}
}


output:













2. Write a Java program to display the client’s address at the server end.

Server:

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

class server1 {
  public static void main(String argv[]) throws Exception
    {
      ServerSocket welcomeSocket = new ServerSocket(6789);
      while(true) {
            Socket connectionSocket = welcomeSocket.accept();
            BufferedReader inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
System.out.println("Address Received from client : "+ inFromClient.readLine());
        }
    }
}


Client:

import java.io.*;
import java.net.*;
class client1 {
    public static void main(String argv[]) throws Exception
    {
   Socket clientSocket = new Socket("localhost", 6789);
DataOutputStream outToServer =  new DataOutputStream(clientSocket.getOutputStream());
        outToServer.writeBytes(InetAddress.getLocalHost().getHostAddress() + '\n');
        clientSocket.close();

    }
}



4) Write a Java program to develop a simple Chat application



import java.io.*;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.*;
public class GossipServer
{
  public static void main(String[] args) throws Exception
  {
      ServerSocket sersock = new ServerSocket(3000);
      Socket sock = sersock.accept( );

      BufferedReader keyRead = new BufferedReader(new InputStreamReader(System.in));

      OutputStream ostream = sock.getOutputStream();
      PrintWriter pwrite = new PrintWriter(ostream, true);


      InputStream istream = sock.getInputStream();
      BufferedReader receiveRead = new BufferedReader(new InputStreamReader(istream));

      String receiveMessage, sendMessage;
      while(true)
      {
        if((receiveMessage = receiveRead.readLine()) != null)
        {
           System.out.println(receiveMessage);
        }
        sendMessage = keyRead.readLine();
        pwrite.println(sendMessage);
        pwrite.flush();
      }
    }
}


CHAT CLIENT

import java.io.*;
import java.net.*;
public class GossipClient
{
  public static void main(String[] args) throws Exception
  {
     Socket sock = new Socket("127.0.0.1", 3000);

     BufferedReader keyRead = new BufferedReader(new InputStreamReader(System.in));

     OutputStream ostream = sock.getOutputStream();
     PrintWriter pwrite = new PrintWriter(ostream, true);

     InputStream istream = sock.getInputStream();
     BufferedReader receiveRead = new BufferedReader(new InputStreamReader(istream));

     System.out.println("Start the chitchat, type and press Enter key");

     String receiveMessage, sendMessage;
     while(true)
     {
        sendMessage = keyRead.readLine();
        pwrite.println(sendMessage);
        pwrite.flush();
       if((receiveMessage = receiveRead.readLine()) != null)
        {
            System.out.println(receiveMessage);
        }
      }
    }
}



5). The message entered in the client is sent to the server and the server encodes the message and
returns it to the client. Encoding is done by replacing a character by the character next to it i.e. a as b,
b as c ...z as a. This process is done using the TCP/IP protocol. Write a Java program for the above

server:

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

class server1 {

    public static void main(String argv[]) throws Exception {
        String clientSentence;
        ServerSocket welcomeSocket = new ServerSocket(6789);
        while (true) {
            Socket connectionSocket = welcomeSocket.accept();
            BufferedReader inFromClient
                    = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
            DataOutputStream outToClient
                    = new DataOutputStream(connectionSocket.getOutputStream());
            clientSentence = inFromClient.readLine();
            System.out.println("Received from client : " + clientSentence);
            String a = clientSentence.toLowerCase();
            String b = "";//abc
            String x = "abcdefghijklmnopqrstuvwxyz";
            for (int i = 0; i < a.length(); i++) {
                if (a.charAt(i) == 'z') {
                    b += 'a';
                } else {
                    for (int j = 0; j < x.length(); j++) {
                        if (x.charAt(j) == a.charAt(i)) {
                            b += x.charAt(j + 1);
                            break;
                        }
                    }
                }
            }
            outToClient.writeBytes(b+"\n");
        }
    }
}

client:

import java.io.*;
import java.net.*;
class client1 {
    public static void main(String argv[]) throws Exception {
        String sentence;
        String modifiedSentence;
        BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
        Socket clientSocket = new Socket("localhost", 6789);
        DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream());
        BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        sentence = inFromUser.readLine();
        outToServer.writeBytes(sentence + '\n');

        modifiedSentence = inFromServer.readLine();

        System.out.println("FROM SERVER: " + modifiedSentence);

        clientSocket.close();

    }
}


7)Write a Java program to display the name and address of the computer that we are currently

working on.


import java.net.*;

import java.io.*;

import java.util.*;

public class cm

{

public static void main(String args[]) throws UnknownHostException

{

InetAddress add=InetAddress.getLocalHost();

System.out.println("Host Name:"+add.getHostName());

System.out.println("IP address:"+add.getHostAddress());

}

}



9. Using threading concepts, write a Java program to create a daemon process.

import java.util.*;
import java.io.*;
import java.net.*;
class daemon extends Thread
{
public daemon()
{
setDaemon(true);
}
public void run()
{
if(Thread.currentThread().isDaemon())
{
int count=0;
while(true)
{
System.out.println("hello "+count++);
try
{
sleep(1000);
}
catch(InterruptedException e){}
}
}
}
public static void main(String args[])
{
daemon d=new daemon();
d.start();
System.out.println("Main method started and goes on sleep");
try{
Thread.sleep(7500);
}
catch(InterruptedException e){}
System.out.println("Main Thread end");
}}





3. Write a Java program to implement an echo UDP server

import java.util.*;

public class ClientEcho
{
  public static void main( String args[] ) throws Exception
  {
    InetAddress add = InetAddress.getByName("snrao");

    DatagramSocket dsock = new DatagramSocket( );
    String message1 = "This is client calling";
    byte arr[] = message1.getBytes( );
    DatagramPacket dpack = new DatagramPacket(arr, arr.length, add, 7);
    dsock.send(dpack);                                   // send the packet
    Date sendTime = new Date();                          // note the time of sending the message

    dsock.receive(dpack);                                // receive the packet
    String message2 = new String(dpack.getData( ));
    Date receiveTime = new Date( );   // note the time of receiving the message
    System.out.println((receiveTime.getTime( ) - sendTime.getTime( )) + " milliseconds echo time for " + message2);
  }
}

import java.util.*;

public class ServerEcho
{
  public static void main( String args[]) throws Exception
  {
    DatagramSocket dsock = new DatagramSocket(7);
    byte arr1[] = new byte[150];
    DatagramPacket dpack = new DatagramPacket(arr1, arr1.length );

    while(true)
    {
      dsock.receive(dpack);

      byte arr2[] = dpack.getData();
      int packSize = dpack.getLength();
      String s2 = new String(arr2, 0, packSize);

      System.out.println( new Date( ) + "  " + dpack.getAddress( ) + " : " + dpack.getPort( ) + " "+ s2);
      dsock.send(dpack);
    }
  }
}