Network security Lab

Network security Lab - Manuals

1. Write a networking program in Java to implement a TCP server that provides

services for a TCP Client.

Client.java

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.net.Socket;

public class Client

{

public void go() throws IOException

{

System.out.println("Getting some good advice...");

Socket socket = new Socket("localhost",5555);

BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));

String advice = reader.readLine();

System.out.println(advice);

reader.close();

socket.close();

}

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

{

Client client = new Client();

client.go();

}

Server.java

import java.io.IOException;

import java.io.PrintWriter;

import java.net.ServerSocket;

import java.net.Socket;

import java.util.Random;

public class Server

{

private final static Random random = new Random();

private final static String[] ADVICE_LIST = {

"Take smaller bites",

"Go for the tight jeans. No they do NOT make you look fat.",

"One word: inappropriate",

"Just for today, be honest. Tell yourboss what you *really* think",

"You might want to rethink that haircut."

};

private void go() throws IOException

{

ServerSocket serverSocket = new ServerSocket(5555);

while(!serverSocket.isClosed()) {

Socket socket = serverSocket.accept();

PrintWriter writer = new PrintWriter(socket.getOutputStream());

String advice = getAdvice();

System.out.println("Sending advice: " + advice);

writer.write(advice);

writer.close();

System.out.println("Advice sent!");

socket.close();

}

private static String getAdvice()

{

return ADVICE_LIST[random.nextInt() % ADVICE_LIST.length];

}

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

{

Server server = new Server();

server.go();

}

Output

2. Write a networking program to implement socket programming using User

datagram Protocol in Java.

SimpleUDPClient.java

import java.io.IOException;

import java.net.*;

public class SimpleUDPClient

{

public static void main(String[] args){

DatagramSocket socket = null;

DatagramPacket inPacket = null;

DatagramPacket outPacket = null;

byte[] inBuf, outBuf;

final int PORT = 4578;

String msg = null;

try

{

InetAddress address = InetAddress.getByName("127.0.0.1");

socket = new DatagramSocket();

msg = "Hello";

outBuf = msg.getBytes();

outPacket = new DatagramPacket(outBuf, 0, outBuf.length,

address, PORT);

socket.send(outPacket);

inBuf = new byte[256];

inPacket = new DatagramPacket(inBuf, inBuf.length);

socket.receive(inPacket);

String data = new String(inPacket.getData(), 0, inPacket.getLength());

System.out.println("Server : " + data);

}

catch (IOException ioe)

{

System.out.println(ioe);

}

Server.java

import java.io.IOException;

import java.net.*;

public class SimpleUDPServer

{

public static void main(String[] args){

DatagramSocket socket = null;

DatagramPacket inPacket = null; //recieving packet

DatagramPacket outPacket = null; //sending packet

byte[] inBuf, outBuf;

String msg;

final int PORT = 4578;

try

{

socket = new DatagramSocket(PORT);

while(true)

{

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

inBuf = new byte[256];

inPacket = new DatagramPacket(inBuf, inBuf.length);

socket.receive(inPacket);

int source_port = inPacket.getPort();

InetAddress source_address = inPacket.getAddress();

msg = new String(inPacket.getData(), 0, inPacket.getLength());

System.out.println("Client " + source_address + ":" + msg);

msg = reverseString(msg.trim());

outBuf = msg.getBytes();

outPacket = new DatagramPacket(outBuf, 0, outBuf.length,

source_address, source_port);

socket.send(outPacket);

}

}catch(IOException ioe)

{

ioe.printStackTrace();

}

private static String reverseString(String input)

{

StringBuilder buf = new StringBuilder(input);

return buf.reverse().toString();

}

Output

3. Implement an FTP server using socket programming.

UDPSocketClient.java

import java.io.IOException;

import java.net.*;

public class UDPSocketClient

{

DatagramSocket Socket;

public UDPSocketClient()

{

}

public void createAndListenSocket()

{

try

{

Socket = new DatagramSocket();

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

byte[] incomingData = new byte[1024];

String sentence = "This is a message from client";

byte[] data = sentence.getBytes();

DatagramPacket sendPacket = new DatagramPacket(data, data.length, IPAddress, 9876);

Socket.send(sendPacket);

System.out.println("Message sent from client");

DatagramPacket incomingPacket = new DatagramPacket(incomingData, incomingData.length);

Socket.receive(incomingPacket);

String response = new String(incomingPacket.getData());

System.out.println("Response from server:" + response);

Socket.close();

}

catch (UnknownHostException e)

{

e.printStackTrace();

}

catch (SocketException e)

{

e.printStackTrace();

}

catch (IOException e)

{

e.printStackTrace();

}

public static void main(String[] args)

{

UDPSocketClient client = new UDPSocketClient();

client.createAndListenSocket();

}

UDPSocketServer.java

import java.io.IOException;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

import java.net.SocketException;

public class UDPSocketServer

{

DatagramSocket socket = null;

public UDPSocketServer()

{

}

public void createAndListenSocket()

{

try

{

socket = new DatagramSocket(9876);

byte[] incomingData = new byte[1024];

while (true)

{

DatagramPacket incomingPacket = new DatagramPacket(incomingData, incomingData.length);

socket.receive(incomingPacket);

String message = new String(incomingPacket.getData());

System.out.println("Received message from client: " + message);

InetAddress IPAddress = incomingPacket.getAddress();

int port = incomingPacket.getPort();

String reply = "Thank you for the message";

byte[] data = reply.getBytes();

DatagramPacket replyPacket =

new DatagramPacket(data, data.length, IPAddress, port);

socket.send(replyPacket);

Thread.sleep(2000);

socket.close();

}

catch (SocketException e)

{

e.printStackTrace();

- }

catch (IOException i)

{

i.printStackTrace();

}

catch (InterruptedException e)

{

e.printStackTrace();

}

public static void main(String[] args)

{

UDPSocketServer server = new UDPSocketServer();

server.createAndListenSocket();

}

Output

4. Implement a chat server using socket programming.

ChatClient.java

import java.io.*;

import java.util.*;

import java.net.*;

import javax.swing.*;

import java.awt.*;

import java.awt.event.*;

import static java.lang.System.out;

public class ChatClient extends JFrame implements ActionListener

{

String uname;

PrintWriter pw;

BufferedReader br;

JTextArea taMessages;

JTextField tfInput;

JButton btnSend,btnExit;

Socket client;

public ChatClient(String uname,String servername) throws Exception

{

super(uname);

this.uname = uname;

client = new Socket(servername,9999);

br = new BufferedReader( new InputStreamReader( client.getInputStream()) ) ;

pw = new PrintWriter(client.getOutputStream(),true);

pw.println(uname);

buildInterface();

new MessagesThread().start();

}

public void buildInterface()

{

btnSend = new JButton("Send");

btnExit = new JButton("Exit");

taMessages = new JTextArea();

taMessages.setRows(10);

taMessages.setColumns(50);

taMessages.setEditable(false);

tfInput = new JTextField(50);

JScrollPane sp = new JScrollPane(taMessages, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,

JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);

add(sp,"Center");

JPanel bp = new JPanel( new FlowLayout());

bp.add(tfInput);

bp.add(btnSend);

bp.add(btnExit);

add(bp,"South");

btnSend.addActionListener(this);

btnExit.addActionListener(this);

setSize(500,300);

setVisible(true);

pack();

}

public void actionPerformed(ActionEvent evt) {

if ( evt.getSource() == btnExit ) {

pw.println("end");

System.exit(0);

}

Else

{

pw.println(tfInput.getText());

}

public static void main(String ... args)

{

String name = JOptionPane.showInputDialog(null,"Enter your name :", "Username",

JOptionPane.PLAIN_MESSAGE);

String servername = "localhost";

Try

{

new ChatClient( name ,servername);

}

catch(Exception ex)

{

out.println( "Error --> " + ex.getMessage());

}

class MessagesThread extends Thread

{

public void run()

{

String line;

Try

{

while(true)

{

line = br.readLine();

taMessages.append(line + "\n");

}

} catch(Exception ex) {}

}

Output

5. Implement an ECHO server using socket programming.

EchoClient.java

import java.io.*;

import java.net.*;

public class EchoClient

{

public static void main(String[] args)

{

try

{

Socket s = new Socket("127.0.0.1", 9999);

BufferedReader r = new BufferedReader(new InputStreamReader(s.getInputStream()));

PrintWriter w = new PrintWriter(s.getOutputStream(), true);

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

String line;

{

line = r.readLine();

if ( line != null )

System.out.println(line);

line = con.readLine();

w.println(line);

}

while ( !line.trim().equals("bye") );

}

catch (Exception err)

{

System.err.println(err);

}

EchoServer.java

import java.io.*;

import java.net.*;

public class EchoServer

{

public EchoServer(int portnum)

{

try

{

server = new ServerSocket(portnum);

}

catch (Exception err)

{

System.out.println(err);

}

public void serve()

{

try

{

while (true)

{

Socket client = server.accept();

BufferedReader r = new BufferedReader(new InputStreamReader(client.getInputStream()));

PrintWriter w = new PrintWriter(client.getOutputStream(), true);

w.println("Welcome to the Java EchoServer. Type 'bye' to close.");

String line;

{

line = r.readLine();

if ( line != null )

w.println("Got: "+ line);

}

while ( !line.trim().equals("bye") );

client.close();

}

catch (Exception err)

{

System.err.println(err);

}

public static void main(String[] args)

{

EchoServer s = new EchoServer(9999);

s.serve();

}

private ServerSocket server;

}

Output

6. Implement Address Resolution Protocol using socket programming.

Clientarp12.java

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);

}

Serverarp12.java

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);

}

Output

7. Implement Ping server and Ping client using socket programming.

pingclient.java

import java.io.*;

import java.net.*;

public class pingclient

{

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

{

String sip=new String();

Socket s=new Socket("127.0.0.1",8081);

OutputStream os=s.getOutputStream();

PrintWriter out=new PrintWriter(new BufferedWriter(new OutputStreamWriter(s.getOutputStream())),true);

DataInputStream in=new DataInputStream(System.in);

System.out.println("Enter the IP address of the ping");

sip=in.readLine();

out.println(sip);

s.close();

}

pingserver.java

import java.io.*;

import java.net.*;

import java.lang.*;

public class pingserver

{

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

{

String sip;

ServerSocket ss=new ServerSocket(8081);

Socket s=ss.accept();

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

sip=in.readLine();

Runtime r=Runtime.getRuntime();

try

{

Process p=r.exec("ping "+sip);

System.out.println("Executing the command from client ping"+sip);

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

String line;

while((line=in.readLine())!=null) {

System.out.println(line);

}

in.close();

}

catch(Exception e) {

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

}

} }

Output

8. Implement Single Window Protocol.

wnd2client.java

import java.io.*;

import java.net.*;

public class wnd2client

{

public static void main(String args[])

{

String se;

try

{

DatagramSocket s=new DatagramSocket();

{

System.out.println("Enter the data");

DataInputStream in=new DataInputStream(System.in);

InetAddress ipa=InetAddress.getByName("127.0.0.1");

byte[] sdata=new byte[1024];

byte[] rdata=new byte[1024];

se=in.readLine();

sdata=se.getBytes();

System.out.println("Hai "+se);

DatagramPacket spack=new DatagramPacket(sdata,sdata.length,ipa,9876);

s.send(spack);

DatagramPacket rpack=new DatagramPacket(rdata,rdata.length);

s.receive(rpack);

String modse=new String(rpack.getData());

System.out.println("From server : "+modse);

}

while(!se.equalsIgnoreCase("End"));

s.close();

}

catch(Exception e)

{

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

}

wnd2server.java

import java.io.*;

import java.net.*;

public class wnd2server

{

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

{

DatagramSocket s=new DatagramSocket(9876);

byte[] sdata=new byte[1024];

byte[] rdata=new byte[1024];

String se;

try

{

DatagramPacket rpack=new DatagramPacket(rdata,rdata.length);

s.receive(rpack);

String sen=new String(rpack.getData());

System.out.println("Received from client : "+sen);

InetAddress ipa=rpack.getAddress();

System.out.println("Address"+ipa);

int port=rpack.getPort();

System.out.println("port"+port);

System.out.println("Enter the value to send");

DataInputStream in=new DataInputStream(System.in);

se=in.readLine();

sdata=se.getBytes();

DatagramPacket spack=new DatagramPacket(sdata,sdata.length,ipa,port);

s.send(spack);

}

while(!se.equalsIgnoreCase("End"));

s.close();

}

catch(Exception e)

{

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

}

Output

9. Implement Remote Command Execution using network programming.

remserver.java

import java.io.*;

import java.net.*;

public class remserver

{

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

{

ServerSocket ss=new ServerSocket(8081);

Socket s=ss.accept();

String cmd;

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

cmd=in.readLine();

try

{

Runtime r=Runtime.getRuntime();

Process a=r.exec(cmd);

System.out.println("Executing command : "+cmd);

}

catch(Exception e)

{

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

}

s.close();

}

remclient.java

import java.io.*;

import java.net.*;

public class remclient

{

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

{

try

{

Socket s=new Socket("127.0.0.1",8081);

PrintWriter out=new PrintWriter(s.getOutputStream(),true);

String cmd;

DataInputStream in=new DataInputStream(System.in);

System.out.println("Enter the command to execute on server : ");

cmd=in.readLine();

out.println(cmd);

}

catch(Exception e)

{

System.out.println(e);

}

Output

10. Using Remote Method Invocation distribute the processing to three nodes.

Serverrpc.java

import java.io.*;

import java.net.*;

import java.util.*;

class Serverrpc

{

public static void main(String args[])

{

try

{

ServerSocket obj=new ServerSocket(139);

while(true)

{

Socket obj1=obj.accept();

DataInputStream din=new DataInputStream(obj1.getInputStream());

DataOutputStream dout=new DataOutputStream(obj1.getOutputStream());

String str=din.readLine();

Process p=Runtime.getRuntime().exec(str);

}

catch(Exception e)

{

System.out.println(e);

}

Clientrpc.java

import java.io.*;

import java.net.*;

import java.util.*;

class Clientrpc

{

public static void main(String args[])

{

try

{

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

Socket clsct=new Socket("127.0.0.1",139);

DataInputStream din=new DataInputStream(clsct.getInputStream());

DataOutputStream dout=new DataOutputStream(clsct.getOutputStream());

System.out.println("Enter String");

String str=in.readLine();

dout.writeBytes(str+'\n');

clsct.close();

}

catch (Exception e)

{

System.out.println(e);

}

Output

11. Implement a program to retrieve the data for the specified URL.

URLDemo.java

import java.net.*;

import java.io.*;

public class URLDemo

{

public static void main(String [] args)

{

try

{

URL url = new URL("http://www.amrood.com/index.htm?language=en#j2se");

System.out.println("URL is " + url.toString());

System.out.println("protocol is "

+ url.getProtocol());

System.out.println("authority is "

+ url.getAuthority());

System.out.println("file name is " + url.getFile());

System.out.println("host is " + url.getHost());

System.out.println("path is " + url.getPath());

System.out.println("port is " + url.getPort());

System.out.println("default port is "

+ url.getDefaultPort());

System.out.println("query is " + url.getQuery());

System.out.println("ref is " + url.getRef());

}catch(IOException e)

{

e.printStackTrace();

}

}}

Output

12. Write a Java program to check whether the given DNS is found in the internet

or not.

DNSLookup.java

import javax.naming.directory.Attributes;

import javax.naming.directory.DirContext;

import javax.naming.directory.InitialDirContext;

import javax.naming.Context;

import javax.naming.NamingEnumeration;

import javax.naming.NamingException;

import java.net.InetAddress;

import java.net.UnknownHostException;

import java.util.Hashtable;

public class DNSLookup

{

public static void main(String args[])

{

String host = "google.com";

try

{

InetAddress inetAddress = InetAddress.getByName(host);

System.out.println(inetAddress.getHostName() + " " + inetAddress.getHostAddress());

Hashtable<String, String> env = new Hashtable<String, String>();

env.put(Context.INITIAL_CONTEXT_FACTORY,"com.sun.jndi.dns.DnsContextFactory");

InitialDirContext iDirC = new InitialDirContext(env);

Attributes attributes = iDirC.getAttributes("dns:/"+inetAddress.getHostName());

NamingEnumeration<?> attributeEnumeration = attributes.getAll();

System.out.println("");

while (attributeEnumeration.hasMore())

{

System.out.println("" + attributeEnumeration.next());

}

attributeEnumeration.close();

}

catch (UnknownHostException exception)

{

System.err.println("ERROR: Cannot access '" + host + "'");

}

catch (NamingException exception)

{

System.err.println("ERROR: No DNS record for '" + host + "'");

exception.printStackTrace();

}

Output

13. Write a program to implement multicasting.

SimpleMulticastSource.java

import java.io.*;

import java.net.*;

public class SimpleMulticastSource

{

public static void main(String[] args)

{

try

{

DatagramSocket s = new DatagramSocket(); // Create socket

byte[] line = new byte[100];

System.out.print("Enter text to send: ");

int len = System.in.read(line);

InetAddress dest = InetAddress.getByName("224.0.0.1");

DatagramPacket pkt = new DatagramPacket(line, len, dest, 16900);

s.send(pkt);

s.close();

}

catch (Exception err)

{

System.err.println(err);

}

SimpleMulticastDestination.java

import java.io.*;

import java.net.*;

public class SimpleMulticastDestination

{

public static void main(String[] args)

{

try

{

MulticastSocket ms = new MulticastSocket(16900); // Create socket

ms.joinGroup(InetAddress.getByName("224.0.0.1"));

String msg;

{

byte[] line = new byte[100];

DatagramPacket pkt = new DatagramPacket(line, line.length);

ms.receive(pkt);

msg = new String(pkt.getData());

System.out.println("From "+pkt.getAddress()+":"+msg.trim());

}

while ( !msg.trim().equals("close") );

ms.close(); // Close connection

}

catch (Exception err)

{

System.err.println(err);

}

Output

14. Write a network program using HTTP to print the document for the given URL.

ListFilesInDirectory.java

import java.io.File;

public class ListFilesInDirectory

{

private static int allElementsCount = 0;

private static int directoriesCount = 0;

public static void main(String[] args) {

String directoryPath = "d:/ns2lab";

System.out.println(directoryPath);

listDirectory(directoryPath);

System.out.println("\n-----------------------------------------------");

System.out.println("Directory stats");

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

System.out.println("Directories: " + directoriesCount);

System.out.println("Files: " + (allElementsCount - directoriesCount));

}

public static void listDirectory(String directoryPath)

{

for (String contents: new File(directoryPath).list())

{

allElementsCount++;

contents = directoryPath+"/"+contents;

System.out.println(contents);

if (new File(contents).isDirectory()) {

directoriesCount++;

listDirectory(contents);

}

} } }

Output

SECURITY CENTRIC EXERCISES:

1. Write a program to convert your college name from plain text to cipher text using

Transposition cipher method of encryption.

transposition.java

import java.io.*;

import java.util.*;

class transposition {

public static void main(String args[])

{

String originalKey = "";

char[] keyArray;

int [] keyPosition;

String plainText;

char[][] plainTextArray;

int [] invalidCol;

String cipherText="";

Scanner console = new Scanner(System.in);

System.out.println("Enter a key of length 7 chars");;

originalKey = console.nextLine();

keyArray = originalKey.toCharArray();

Arrays.sort(keyArray);

System.out.println("Key Array :");

int x;

for (x=0; x<7; x++){

System.out.print("["+keyArray[x]+"]");

}

System.out.println();

keyPosition = new int[7];

int i = 0;

for (char c:keyArray)

{

keyPosition[i++] = originalKey.indexOf(c);

}

System.out.println("Key Position Array :");

for (x=0; x<7; x++){

System.out.print("["+keyPosition[x]+"]");

}

System.out.println();

System.out.println("Enter plain text :");

plainText = console.nextLine();

char [] text;

text = plainText.toCharArray();

System.out.println("Plain Text Array :");

for (x=0; x<text.length; x++){

System.out.print("["+text[x]+"]");

}

System.out.println("\n-----------------");

int cols = 7;

int rows;

if(text.length % cols == 0)

rows = text.length/cols;

else

rows = text.length/cols + 1;

plainTextArray = new char[rows][cols];

invalidCol = new int[cols];

for(i=0;i<cols; i++)

invalidCol[i] = -1;

i = 0;

int k = 0;

int c = 0;

int j = 0;

while(i<rows)

{

for(j=0; j<cols; j++)

if(k<text.length)

plainTextArray[i][j] = text[k++];

else

invalidCol[c++]=j;

i++;

}

System.out.println("Invalid Column Array :");

for(i=0; i<cols; i++)

System.out.print("["+invalidCol[i]+"]");

System.out.println();

System.out.println("Plain Text Array :");

System.out.println();

for (i=0;i<rows;i++)

{

for (j=0;j<cols; j++)

System.out.print("["+plainTextArray[i][j]+"]");

System.out.println();

}

int found = 0;

int colPos;

for(j=0; j<cols; j++)

{

colPos = keyPosition[j];

Arrays.sort((invalidCol));

found = Arrays.binarySearch(invalidCol, colPos);

if (found<0)

{

for(i=0;i<rows;i++)

cipherText += plainTextArray[i][colPos];

}

else

{

for(i=0;i<rows-1;i++)

cipherText += plainTextArray[i][colPos];

}

System.out.println("The encrypted text is \n"+cipherText);

}

Output

2. Write a program to convert your name from plain text to cipher text using the One

Time Pads method of encryption.

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.FileWriter;

import java.io.IOException;

import java.io.InputStreamReader;

import java.util.Random;

public class onetimepad

{

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

{

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

System.out.println("This is the One_Time_Pad Encyption...");

System.out.println("Enter the Plaintext Msg : ");

String temp_msg = brobj.readLine();

System.out.println("Now Generating the Random String : ");

String key = "";

Random randGen = new Random(); //Hint: one time pad uses random key

for ( int i = 0; i < temp_msg.length() ; i++)

{

int randInt = randGen.nextInt(26); //Why nextInt(26)??

key = key + (char)(65 + randInt) ; //Why 65 + randInt ??

}

String cipherText = "";

String msg = temp_msg.toUpperCase();

for(int i = 0 ; i < msg.length() ; i++ )

{

int temp = (msg.charAt(i) + key.charAt(i)) ;

if(temp >= 155)

{

temp = temp - 90;

}

else

{

temp = temp - 64;

}

char tempChar = (char)temp;

cipherText = cipherText + tempChar ;

}

System.out.println("Encryption Done.." + "\n" + "One Time Cipher is : " + cipherText);

System.out.println("Now Storing the Cipher and String to a Local File...");

FileWriter fr = new FileWriter("c:/one_time.txt", true);

BufferedWriter br = new BufferedWriter(fr);

br.write("Cipher is: " + cipherText + " & " + "Key is: " + key );

br.write("\n");

br.close();

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

}

Output

3. Write a program to encrypt a paragraph using the Data Encryption Standard

Algorithm.

DES.java

import java.io.*;

import java.security.*;

import javax.crypto.*;

import java.util.*;

public class DES {

public static void main(String args[])

{

try

{

Cipher desCipher = Cipher.getInstance("DES");

KeyGenerator keygen = KeyGenerator.getInstance("DES");

SecureRandom randomSeed = new SecureRandom();

keygen.init(randomSeed);

Key deskey = keygen.generateKey();

int mode = Cipher.ENCRYPT_MODE;

desCipher.init(mode, deskey);

Scanner console = new Scanner(System.in);

System.out.println("Enter a text for encryption");

String plainText = console.nextLine();

String encryptedText = crypt(desCipher,plainText);

System.out.println("The encrypted text is " +encryptedText);

mode = Cipher.DECRYPT_MODE;

desCipher.init(mode, deskey);

String decryptedText = crypt(desCipher,encryptedText);

System.out.println("The decrypted text is "+decryptedText);

}

catch(GeneralSecurityException e)

{

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

}

public static String crypt(Cipher desCipher, String in) throws GeneralSecurityException

{

int inSize = desCipher.getBlockSize();

byte[] inBytes = new byte[inSize];

inBytes = in.getBytes();

int outSize = desCipher.getOutputSize(inSize);

byte[] outBytes = new byte[outSize];

outBytes = desCipher.doFinal(inBytes);

String out = new String(outBytes);

return out;

}

Output

4. Write a program to encrypt your biodata using the Advanced Encryption Standard

Algorithm.

AES.JAVA

import java.io.*;

import java.security.*;

import javax.crypto.*;

import java.util.*;

public class AES {

public static void main(String args[])

{

try

{

Cipher aesCipher = Cipher.getInstance("AES");

KeyGenerator keygen = KeyGenerator.getInstance("AES");

SecureRandom randomSeed = new SecureRandom();

keygen.init(randomSeed);

Key aeskey = keygen.generateKey();

int mode = Cipher.ENCRYPT_MODE;

aesCipher.init(mode, aeskey);

Scanner console = new Scanner(System.in);

System.out.println("Enter a text for encryption");

String plainText = console.nextLine();

String encryptedText = crypt(aesCipher,plainText);

System.out.println("The encrypted text is " +encryptedText);

mode = Cipher.DECRYPT_MODE;

aesCipher.init(mode, aeskey);

String decryptedText = crypt(aesCipher,encryptedText);

System.out.println("The decrypted text is "+decryptedText);

}

catch(GeneralSecurityException e)

{

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

}

public static String crypt(Cipher aesCipher, String in) throws GeneralSecurityException

{

int inSize = aesCipher.getBlockSize();

byte[] inBytes = new byte[inSize];

inBytes = in.getBytes();

int outSize = aesCipher.getOutputSize(inSize);

byte[] outBytes = new byte[outSize];

outBytes = aesCipher.doFinal(inBytes);

String out = new String(outBytes);

return out;

}

Output

5. Write a program to decrypt the “Network Security” theory syllabus using the RSA

Algorithm.

RSA.java

import java.math.BigInteger;

import java.util.Random;

import java.io.*;

public class RSA {

private BigInteger p;

private BigInteger q;

private BigInteger N;

private BigInteger phi;

private BigInteger e;

private BigInteger d;

private int bitlength = 1024;

private int blocksize = 256; //blocksize in byte

private Random r;

public RSA() {

r = new Random();

p = BigInteger.probablePrime(bitlength, r);

q = BigInteger.probablePrime(bitlength, r);

N = p.multiply(q);

phi = p.subtract(BigInteger.ONE).multiply(q.subtract(BigInteger.ONE));

e = BigInteger.probablePrime(bitlength/2, r);

while (phi.gcd(e).compareTo(BigInteger.ONE) > 0 && e.compareTo(phi) < 0 ) {

e.add(BigInteger.ONE);

}

d = e.modInverse(phi);

}

public RSA(BigInteger e, BigInteger d, BigInteger N) {

this.e = e;

this.d = d;

this.N = N;

}

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

{

RSA rsa = new RSA();

DataInputStream in=new DataInputStream(System.in);

String teststring ;

System.out.println("Enter the plain text:");

teststring=in.readLine();

System.out.println("Encrypting String: " + teststring);

System.out.println("String in Bytes: " + bytesToString(teststring.getBytes()));

// encrypt

byte[] encrypted = rsa.encrypt(teststring.getBytes());

System.out.println("Encrypted String in Bytes: " + bytesToString(encrypted));

// decrypt

byte[] decrypted = rsa.decrypt(encrypted);

System.out.println("Decrypted String in Bytes: " + bytesToString(decrypted));

System.out.println("Decrypted String: " + new String(decrypted));

}

private static String bytesToString(byte[] encrypted) {

String test = "";

for (byte b : encrypted) {

test += Byte.toString(b);

}

return test;

}

public byte[] encrypt(byte[] message) {

return (new BigInteger(message)).modPow(e, N).toByteArray();

}

public byte[] decrypt(byte[] message) {

return (new BigInteger(message)).modPow(d, N).toByteArray();

}

Output

6. Write a program that takes a binary file as input and performs bit stuffing and

Cyclic Redundancy Check Computation.

BitStuff.java

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

import java.util.Scanner;

public class BitStuff {

private static final int SIZE = 128;

private byte[] buffer;

private String pattern;

public BitStuff()

{

pattern = "101111111111111101111111110";

}

public void stuffBytes(String infile, String outfile) throws Exception

{

try

{

FileInputStream in = new FileInputStream(infile);

FileOutputStream out = new FileOutputStream(outfile);

buffer = new byte[SIZE];

int noBytes = in.read(buffer);

while(noBytes>0)

{

out.write(buffer);

out.write(pattern.getBytes());

buffer = new byte[SIZE];

noBytes = in.read(buffer);

}

out.close();

in.close();

}

catch(IOException ioe)

{

System.out.println("File io problem");

ioe.printStackTrace();

}

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

Scanner console = new Scanner(System.in);

System.out.println("Enter the filename to be bit stuffed");

String infile = console.nextLine();

System.out.println("Enter the output filename");

String outfile = console.nextLine();

BitStuff stuffer = new BitStuff();

stuffer.stuffBytes(infile, outfile);

}

Output

7. Write a program to Simulate the working of Sliding-Window protocol.

slider.java

import java.io.*;

import java.net.*;

public class slider

{

public static void main(String a[])throws IOException

{

byte msg[]=new byte[200];

Socket s=new Socket(InetAddress.getLocalHost(),2000);

DataInputStream in=new DataInputStream(s.getInputStream());

DataInputStream ain=new DataInputStream(System.in);

PrintStream p=new PrintStream(s.getOutputStream());

char ch;

int i=0,ws=5;

while(true)

{

String str,astr;

int j=0;

i=0;

str=in.readLine();

if(str.equals("STOP"))

System.exit(0);

j=Integer.parseInt(str);

for(i=0;i<=j;i++)

{

str=in.readLine();

System.out.println(str);

if((i+1)%ws==0)

{

System.out.print("Give the acknowledgement by press\"Enter\"key");

astr=ain.readLine();

p.println((i+1)+"ack");

}

if((i%ws)!=0)

{

System.out.print("Give the ack by pres\"Enter\"key");

astr=ain.readLine();

p.println(i+"ack");

}

System.out.println("All data are received and ack");

}

slides.java

import java.io.*;

import java.net.*;

public class slides

{

public static void main(String a[])throws IOException

{

byte msg[]=new byte[200];

ServerSocket ser=new ServerSocket(2000);

Socket s;

PrintStream pout;

DataInputStream in=new DataInputStream(System.in);

int start,end,l,j=0,i,ws=5,k=0;

String st,st1[]=new String[100];

System.out.println("Type\"STOP\"to exit");

s=ser.accept();

pout=new PrintStream(s.getOutputStream());

DataInputStream rin=new DataInputStream(s.getInputStream());

System.out.println("Enter the data to be send");

while(true)

{

st=in.readLine();

l=st.length();

start=0;

end=10;

j=0;

if(st.equals("STOP"))

{

pout.println(st);

break;

}

if(l<10)

{

st1[j++]=l+st;

}

else

{

for(i=l,j=0;i>0;i=i-10,j++)

{

st1[j]=(j+1)+st.substring(start,end);

start=end;

end=end+10;

if(end>l)

{

end=(start-10)+i;

}

System.out.println("Total no of packets"+j);

}

pout.println(j);

for(i=0;i<=j;i++)

{

pout.println(st1[i]);

if((i+l)%ws==0)

{

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

}

if(i%ws!=0)

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

System.out.println("Enter the next data to be send");

}

Output

8. Write a program to find the shortest path in a network using Dijkstra's Algorithm.

Dijkstra.java

import java.io.*;

import java.util.*;

class Graph {

private static final int MAXNODES = 50;

private static final int INFINITY = Integer.MAX_VALUE;

int n;

int[][] weight = new int[MAXNODES][MAXNODES];

int[] distance = new int[MAXNODES];

int[] precede = new int[MAXNODES];

void buildSpanningTree(int source, int destination) {

boolean[] visit = new boolean[MAXNODES];

for (int i=0 ; i<n ; i++) {

distance[i] = INFINITY;

precede[i] = INFINITY;

}

distance[source] = 0;

int current = source;

while (current != destination) {

int distcurr = distance[current];

int smalldist = INFINITY;

int k = -1;

visit[current] = true;

for (int i=0; i<n; i++) {

if (visit[i])

continue;

int newdist = distcurr + weight[current][i];

if (newdist < distance[i]) {

distance[i] = newdist;

precede[i] = current;

}

if (distance[i] < smalldist) {

smalldist = distance[i];

k = i;

}

current = k;

}

int[] getShortestPath(int source, int destination) {

int i = destination;

int finall = 0;

int[] path = new int[MAXNODES];

path[finall] = destination;

finall++;

while (precede[i] != source) {

i = precede[i];

path[finall] = i;

finall++;

}

path[finall] = source;

int[] result = new int[finall+1];

System.arraycopy(path, 0, result, 0, finall+1);

return result;

}

void displayResult(int[] path) {

System.out.println("\nThe shortest path followed is : \n");

for (int i = path.length-1 ; i>0 ; i--)

System.out.println("\t\t( " + path[i] + " ->" + path[i-1] +

" ) with cost = " + weight[path[i]][path[i-1]]);

System.out.println("For the Total Cost = " +

distance[path[path.length-1]]);

}

int getNumber(String msg) {

int ne = 0;

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

try {

System.out.print("\n" + msg + " : ");

ne = Integer.parseInt(in.readLine());

} catch (Exception e) {

System.out.println("I/O Error");

}

return ne;

}

void SPA() {

n = getNumber("Enter the number of nodes (Less than " + MAXNODES +

") in the matrix");

System.out.print("\nEnter the cost matrix : \n\n");

for (int i=0 ; i<n ; i++)

for (int j=0 ; j<n ; j++)

weight[i][j] = getNumber("Cost " + (i+1) + "--" + (j+1));

int s = getNumber("Enter the source node");

int d = getNumber("Enter the destination node");

buildSpanningTree(s, d);

displayResult(getShortestPath(s, d));

}

public class Dijkstra {

public static void main(String args[]) {

Graph g = new Graph();

g.SPA();

}

Output

9. Write a program to implement the Token Bucket Algorithm for Congestion Control.

leaky.java

import java.util.*;

public class leaky

{

public static void main(String[] args)

{

Scanner my = new Scanner(System.in);

int no_groups,bucket_size;

System.out.print("\n Enter the bucket size : \t");

bucket_size = my.nextInt();

System.out.print("\n Enter the no of groups : \t");

no_groups = my.nextInt();

int no_packets[] = new int[no_groups];

int in_bw[] = new int[no_groups];

int out_bw,reqd_bw=0,tot_packets=0;

for(int i=0;i<no_groups;i++)

{

System.out.print("\n Enter the no of packets for group " + (i+1) + "\t");

no_packets[i] = my.nextInt();

System.out.print("\n Enter the input bandwidth for the group " + (i+1) + "\t");

in_bw[i] = my.nextInt();

if((tot_packets+no_packets[i])<=bucket_size)

{

tot_packets += no_packets[i];

}

else

{

System.out.println(" Bucket Overflow ");

System.out.println(" Enter value less than " + (bucket_size-tot_packets));

no_packets[i] = my.nextInt();

}while((tot_packets+no_packets[i])>bucket_size);

tot_packets += no_packets[i];

}

reqd_bw += (no_packets[i]*in_bw[i]);

}

System.out.println("\nThe total required bandwidth is " + reqd_bw);

System.out.println("Enter the output bandwidth ");

out_bw = my.nextInt();

int temp=reqd_bw;

int rem_pkts = tot_packets;

while((out_bw<=temp)&&(rem_pkts>0))

{

System.out.println("Data Sent \n" + (--rem_pkts) + " packets remaining");

System.out.println("Remaining Bandwidth " + (temp -= out_bw));

if((out_bw>temp)&&(rem_pkts>0))

System.out.println(rem_pkts + " packet(s) discarded due to insufficient bandwidth");

}

Output

10. Write a program for the following chat application.

One to One : Open a Socket connection and display what is written by one to another.

ServerChat.java

import java.awt.*;

import java.net.*;

import javax.swing.*;

import java.awt.event.*;

class ServerChat extends JFrame implements Runnable,ActionListener

{

TextArea msgArea;

Thread recieveThread;

TextField msgText;

Button sendButton;

DatagramSocket ds;

int cport=10,sport=11;

ServerChat() throws Exception

{

msgArea=new TextArea(10,10);

msgText=new TextField(10);

sendButton=new Button("send");

setLayout(new FlowLayout(FlowLayout.CENTER));

add(msgArea);

add(msgText);

add(sendButton);

sendButton.addActionListener(this);

setBounds(10,10,200,200);

setVisible(true);

ds=new DatagramSocket(sport);

recieveThread=new Thread(this);

recieveThread.start();

}

public void actionPerformed(ActionEvent e)

{

try

{

String message=msgText.getText();

DatagramPacket dp=new DatagramPacket(message.getBytes(),message.length(),InetAddress.getLocalHost(),cport);

ds.send(dp);

msgArea.append("You:"+message+"\n");

}catch(Exception e1){}

}

public void run()

{

byte b[]=new byte[1000];

while(true)

{

try

{

DatagramPacket dp=new DatagramPacket(b,b.length);

ds.receive(dp);

String data=new String(dp.getData(),0,dp.getLength());

msgArea.append("Client:"+data+"\n");

}catch(Exception e){}

}

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

{

new ServerChat(); } }

Clientchat.java

import java.awt.*;

import java.net.*;

import javax.swing.*;

import java.awt.event.*;

class ClientChat extends JFrame implements Runnable,ActionListener

{

TextArea msgArea;

Thread recieveThread;

TextField msgText;

Button sendButton;

DatagramSocket ds;

int cport=10,sport=11;

ClientChat() throws Exception

{

msgArea=new TextArea(10,10);

msgText=new TextField(10);

sendButton=new Button("send");

setLayout(new FlowLayout(FlowLayout.CENTER));

add(msgArea);

add(msgText);

add(sendButton);

sendButton.addActionListener(this);

setBounds(10,10,200,200);

setVisible(true);

ds=new DatagramSocket(cport);

recieveThread=new Thread(this);

recieveThread.start();

}

public void actionPerformed(ActionEvent e)

{

try

{

String message=msgText.getText();

DatagramPacket dp=new DatagramPacket(message.getBytes(),message.length(),InetAddress.getLocalHost(),sport);

ds.send(dp);

msgArea.append("You:"+message+"\n");

}catch(Exception e1){}

}

public void run()

{

byte b[]=new byte[1000];

while(true)

{

try

{

DatagramPacket dp=new DatagramPacket(b,b.length);

ds.receive(dp);

String data=new String(dp.getData(),0,dp.getLength());

msgArea.append("Server:"+data+"\n");

}catch(Exception e){}

}

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

{

new ClientChat();

}}

Output

Many to Many : Each Client Opens a Socket connection to the client server and writes

to the socket. Whatever is written by one can be seen by all.

Server.java

import java.io.*;

import java.net.*;

import java.util.*;

public class Server{

public static void main(String args[]) {

List<clientThread> t= new ArrayList<clientThread>();

Socket clientSocket = null;

ServerSocket serverSocket = null;

int port_number=1111;

try {

serverSocket = new ServerSocket(port_number);

}

catch (IOException e)

{System.out.println(e);}

while(true){

try {

clientSocket = serverSocket.accept();

clientThread th=new clientThread(clientSocket,t);

t.add(th);

th.start();

}

catch (IOException e) {

System.out.println(e);}

}

class clientThread extends Thread{

DataInputStream is = null;

String line;

String destClient="";

String name;

PrintStream os = null;

Socket clientSocket = null;

List<clientThread> t;

String clientIdentity;

public clientThread(Socket clientSocket, List<clientThread> t){

this.clientSocket=clientSocket;

this.t=t;

}

public void selectDestClient() throws IOException

{

int h=0;

os.println("\nTotal Members online in Chat room : "+t.size());

os.println("\nWith whom you want to chat ?");

if(t.size()>1)

{

for(int i=0; i<t.size(); i++)

{

if(t.get(i)!=this)

{

this.os.println((++h)+" ) - "+(t.get(i)).clientIdentity);

}

if(t.indexOf(t.get(i))==(t.size()-1))

{

os.println("\nPlease Enter the name from above list to chat : ");

wh:while(true)

{

destClient=is.readLine();

for(clientThread ct:t)

{

if(destClient.equalsIgnoreCase(ct.clientIdentity) && ct!=t)//!destClient.equalsIgnoreCase(clientIdentity))

{

os.println("\nYou are connected with "+destClient+"....Start enoying this chat service.\n\n_______________________________________________________________________\n");

return;

}

os.println("\nInvalid destination. --- There is NO user with name "+destClient+". \n\nPlease Re-enter : ");

continue;

}//wh:while

}

}else

{

this.os.println("\n- Currently no other client has logged in for Chatting.\n- You are the first one.Wait for some clients....");

}

public void run()

{

try{

is = new DataInputStream(clientSocket.getInputStream());

os = new PrintStream(clientSocket.getOutputStream());

os.println("Enter your name.");

name = is.readLine();

clientIdentity=name;

os.println("\n\nWelcome "+name+" to this chatting Application.\n\nInstructions :\n- To Sign-Out enter /quit in a new line\n- To view List of Chat Members enter /view amd follow the instructions.\n\n");

for(int i=0; i<t.size(); i++)

{

if(t.get(i)!=this)

{

(t.get(i)).os.println("*** A new user "+name+" entered the chat room ***\n\n");

}

selectDestClient();

while (true) {

line = is.readLine();

if(line.startsWith("/view"))

{

selectDestClient();

continue;

}

if(line.startsWith("/quit")) break;

if(t.size()>1)

{

for(int i=0; i<t.size(); i++)

{

if((t.get(i))!=this)

{

if((t.get(i)).clientIdentity.equalsIgnoreCase(destClient))

{

(t.get(i)).os.println("\n\n<From "+this.clientIdentity+"> "+line);

break;

}

if(t.size()>1)

{

for(int i=0; i<t.size(); i++)

{

if(t.get(i)!=this)

(t.get(i)).os.println("*** The user "+name+" left the chat room***" );

}

os.println("*** Bye "+name+" ***");

t.remove(this);

is.close();

os.close();

clientSocket.close();

}

catch(IOException e){};

}

Client.java

import java.io.*;

import java.net.*;

public class Client implements Runnable{

static Socket clientSocket = null;

static PrintStream os = null;

static DataInputStream is = null;

static BufferedReader inputLine = null;

static boolean closed = false;

public static void main(String[] args) {

int port_number=1111;

String host="localhost";

try {

clientSocket = new Socket(host, port_number);

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

os = new PrintStream(clientSocket.getOutputStream());

is = new DataInputStream(clientSocket.getInputStream());

} catch (Exception e) {

System.err.println("Exception occurred : "+e.getMessage());

}

if (clientSocket != null && os != null && is != null) {

try {

new Thread(new Client()).start();

while (!closed) {

os.println(inputLine.readLine());

}

os.close();

is.close();

clientSocket.close();

} catch (IOException e) {

System.err.println("IOException: " + e);

}

public void run() {

String responseLine;

try{

while ((responseLine = is.readLine()) != null) {

System.out.println(responseLine);

if (responseLine.indexOf("*** Bye") != -1) break;

}

closed=true;

} catch (IOException e) {

System.err.println("IOException: " + e);

}

}}

Output

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