question one
Implement echo server and client in java using UDP sockets.

Client program – ServerEcho.java

import java.net.*;
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);
    }
  }
}

Client program – ClientEcho.java
import java.net.*;
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);
  }
}


                            OR

import java.net.*;
 import java.util.*;
 public class EchoServer
{
     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);
}
}
}----------------------------------
import java.net.*;
import java.util.*;
 public class EchoClient
{ public static void main( String args[] ) throws Exception {
InetAddress add = InetAddress.getByName("127.0.0.1");
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);
  }
 }








question 2
Implement a simple message transfer from client to server process using UDP.
import java.io.*;
import java.net.*;
class UDPServerss {
public static void main(String args[]) throws Exception       {
     DatagramSocket serverSocket = new DatagramSocket(9876);

   byte[] receiveData = new byte[1024];
 byte[] sendData = new byte[1024];
    while(true)                {

              DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
              serverSocket.receive(receivePacket);
                  String sentence = new String( receivePacket.getData());
                  System.out.println("RECEIVED: " + sentence);
      InetAddress IPAddress = receivePacket.getAddress();
            int port = receivePacket.getPort();
  String capitalizedSentence = sentence.toUpperCase();
         sendData = capitalizedSentence.getBytes();
      DatagramPacket sendPacket =                   new DatagramPacket(sendData, sendData.length, IPAddress, port);
        serverSocket.send(sendPacket);
           }
}
}
import java.io.*;
import java.net.*;
 class UDPClientssss {
   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];
     String sentence = inFromUser.readLine();
     sendData = sentence.getBytes();
  DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 9876);
  clientSocket.send(sendPacket);
  DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
  clientSocket.receive(receivePacket);
 String modifiedSentence = new String(receivePacket.getData());
      System.out.println("FROM SERVER:" + modifiedSentence);
  clientSocket.close();
   }
 }






question 3
 Simple chat application in java using datagram socket and datagram packet
Algorithm
Start the UDP chat program
Import the package java.net.*;
Declare the datagramsocket,datagrampacket,BufferedReader,InetAddress.
Start the main function
In the main function using while loop it perform the loop until str.equals is STOP
There important while loop function are
clientsocket = new DatagramSocket(cport);
dp = new DatagramPacket(buf, buf.length);
dis = new BufferedReader(new
InputStreamReader(System.in));
ia = InetAddress.getLocalHost(); f it is stop then break the while loop
Terminate the UDP client program
source code java programming UDP Chat server
import java.io.*;
import java.net.*;
class UDPServer
{
public static DatagramSocket serversocket;
public static DatagramPacket dp;
public static BufferedReader dis;
public static InetAddress ia;
public static byte buf[] = new byte[1024];
public static int cport = 789,sport=790;
public static void main(String[] a) throws IOException
{
serversocket = new DatagramSocket(sport);
dp = new DatagramPacket(buf,buf.length);
dis = new BufferedReader
(new InputStreamReader(System.in));
ia = InetAddress.getLocalHost();
System.out.println("Server is Running...");
while(true)
{
serversocket.receive(dp);
String str = new String(dp.getData(), 0,
dp.getLength());
if(str.equals("STOP"))
{
System.out.println("Terminated...");
break;
}
System.out.println("Client: " + str);
String str1 = new String(dis.readLine());
buf = str1.getBytes();
serversocket.send(new
DatagramPacket(buf,str1.length(), ia, cport));
}
}
}

Output:-
C:\IPLAB>javac UDPServer.java
C:\IPLAB>java UDPServer
Server is Running...
Client: Hello
Welcome
Terminated...

source code java programming UDP Chat Client
import java.io.*;
import java.net.*;
class UDPClient
{
public static DatagramSocket clientsocket;
public static DatagramPacket dp;
public static BufferedReader dis;
public static InetAddress ia;
public static byte buf[] = new byte[1024];
public static int cport = 789, sport = 790;
public static void main(String[] a) throws IOException
{
clientsocket = new DatagramSocket(cport);
dp = new DatagramPacket(buf, buf.length);
dis = new BufferedReader(new
InputStreamReader(System.in));
ia = InetAddress.getLocalHost();
System.out.println("Client is Running... Type 'STOP'
to Quit");
while(true)
{
String str = new String(dis.readLine());
buf = str.getBytes();
if(str.equals("STOP"))
{
System.out.println("Terminated...");
clientsocket.send(new
DatagramPacket(buf,str.length(), ia,
sport));
break;
}
clientsocket.send(new DatagramPacket(buf,
str.length(), ia, sport));
clientsocket.receive(dp);
String str2 = new String(dp.getData(), 0,
dp.getLength());
System.out.println("Server: " + str2);
}
}
}

Output UDP Chat Client
C:\IPLAB>javac UDPClient.java
C:\IPLAB>java UDPClient
Client is Running... Type ‘STOP’ to Quit
Hello
Server: Welcome
STOP
Terminated...
BB / REC - 41



                                          or


 Client interface:

    import java.awt.*;
    import javax.swing.*;
    public class UDPClient extends JFrame
    {
    	// Variables
    	private JFrame frame;
    	private JPanel panel;
    	private JLabel label;
    	private JButton sendbutton;
    	private JTextField textfield;
    	private JTextArea textarea;
    	private JScrollPane scrollpane;

    	public static void main (String args[]) {

    		new UDPClient();
    	}

    	// Constructor
    	public UDPClient() {

    		frame = this;
    		panel = new JPanel(new GridBagLayout());
    		panel.setBackground(Color.cyan);
    		frame.setTitle("Chat Applet Client");
    		frame.getContentPane().add(panel, BorderLayout.NORTH);
    		frame.setVisible(true);
    		frame.setSize(430, 364);
    		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		//frame.setResizable(false);
    		GridBagConstraints c = new GridBagConstraints();
    		c.insets = new Insets(5, 5, 5, 5);

    		// Server address label
    		label = new JLabel("Server:");
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 0;
    		c.gridy = 0;
    		panel.add(label, c);

    		// Server address textfield
    		textfield = new JTextField(20);
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 1;
    		c.gridy = 0;
    		panel.add(textfield, c);

    		// 'Port#:' label
    		label = new JLabel("Port# :");
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 2;
    		c.gridy = 0;
    		panel.add(label, c);

    		// Port# textfield
    		textfield = new JTextField(6);
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 3;
    		c.gridy = 0;
    		panel.add(textfield, c);

    		// 'Conversation:' label
    		label = new JLabel("Conversation:");
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 0;
    		c.gridy = 1;
    		c.gridwidth = 4;
    		panel.add(label, c);

    		// Conversation Window
    		textarea = new JTextArea(10, 2);
    		scrollpane = new JScrollPane(textarea);
    		textarea.setLineWrap(true);
    		textarea.setWrapStyleWord(true);
    		textarea.setEditable(false);
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 0;
    		c.gridy = 2;
    		c.gridwidth = 4;
    		panel.add(scrollpane, c);

    		// 'Message:' label
    		label = new JLabel("Message to Send:");
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 0;
    		c.gridy = 3;
    		panel.add(label, c);

    		// Message Window
    		textarea = new JTextArea(2, 2);
    		scrollpane = new JScrollPane(textarea);
    		textarea.setLineWrap(true);
    		textarea.setWrapStyleWord(true);
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 0;
    		c.gridy = 4;
    		c.gridwidth = 4;
    		panel.add(scrollpane, c);

    		// 'Send' button
    		sendbutton = new JButton("Send");
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 0;
    		c.gridy = 5;
    		c.gridwidth = 4;
    		panel.add(sendbutton, c);
    	}
    }





Server interface:

    import java.awt.*;
    import javax.swing.*;
    public class UDPServer extends JFrame {
    	// Variables
    	private JFrame frame;
    	private JPanel panel;
    	private JLabel label;
    	private JButton startbutton;
    	private JButton stopbutton;
    	private JButton sendbutton;
    	private JTextField textfield;
    	private JTextArea textarea;
    	private JScrollPane scrollpane;

    	//http://www.youtube.com/watch?v=IkEz5tW5bok
    	public static void main (String args[]) {

    		new UDPServer();
    	}

    	// Constructor
    	public UDPServer() {

    		frame = this;
    		panel = new JPanel(new GridBagLayout());
    		panel.setBackground(Color.darkGray);
    		frame.setTitle("Chat Applet Server");
    		frame.getContentPane().add(panel, BorderLayout.NORTH);
    		frame.setVisible(true);
    		//frame.pack();

    		frame.setSize(430, 364);
    		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		frame.setResizable(true);
    		GridBagConstraints c = new GridBagConstraints();
    		c.insets = new Insets(5, 5, 5, 5);

    		// 'Start Server' button
    		startbutton = new JButton("Start Server");
    		startbutton.setPreferredSize(new Dimension(130,20));
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 0;
    		c.gridy = 0;
    		c.gridwidth = 1;
    		panel.add(startbutton, c);

    		// 'Stop Server' button
    		stopbutton = new JButton("Stop Server");
    		stopbutton.setPreferredSize(new Dimension(130,20));
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 1;
    		c.gridy = 0;
    		c.gridwidth = 1;
    		panel.add(stopbutton, c);

    		// 'Port#:' label
    		label = new JLabel("Port# :");
    		label.setForeground(Color.white);
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 2;
    		c.gridy = 0;
    		panel.add(label, c);

    		// Port# textfield
    		textfield = new JTextField(6);
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 3;
    		c.gridy = 0;
    		panel.add(textfield, c);

    		// 'Conversation:' label
    		label = new JLabel("Conversation:");
    		label.setForeground(Color.white);
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 0;
    		c.gridy = 1;
    		c.gridwidth = 4;
    		panel.add(label, c);

    		// Conversation Window
    		textarea = new JTextArea("<Server not yet started!>", 10, 2);
    		scrollpane = new JScrollPane(textarea);
    		textarea.setLineWrap(true);
    		textarea.setWrapStyleWord(true);
    		textarea.setEditable(false);
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 0;
    		c.gridy = 2;
    		c.gridwidth = 4;
    		panel.add(scrollpane, c);

    		// 'Message:' label
    		label = new JLabel("Message to Send:");
    		label.setForeground(Color.white);
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 0;
    		c.gridy = 3;
    		panel.add(label, c);

    		// Message Window
    		textarea = new JTextArea(2, 2);
    		scrollpane = new JScrollPane(textarea);
    		textarea.setLineWrap(true);
    		textarea.setWrapStyleWord(true);
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 0;
    		c.gridy = 4;
    		c.gridwidth = 4;
    		panel.add(scrollpane, c);

    		// 'Send' button
    		sendbutton = new JButton("Send");
    		c.fill = GridBagConstraints.HORIZONTAL;
    		c.gridx = 0;
    		c.gridy = 5;
    		c.gridwidth = 4;
    		panel.add(sendbutton, c);
    	}
    }






question 4-----------------------------
UDP Program – DNS CLIENT-SERVER

UDP Program (DNS CLIENT-SERVER)

AIM : To create a client server program to Domain Name System using the UDP protocol client server.

ALGORITHM

Server

    Declare the necessary arrays and variables.
    Set server port address using socket().
    Get the current message.
    Connect to the client.
    Stop the process.

Client

    Set the client machine address.
    Connect to the server.
    Read from the server the current message.
    Display the current message.
    Close the connection.

PROGRAM:

UDPclient

import java .io.*;

import java.net.*;

classUDPclient

{

public static DatagramSocket ds;

public static intclientport=789,serverport=790;

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

{

byte buffer[]=new byte[1024];

ds=new DatagramSocket(serverport);

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

System.out.println(“server waiting”);

InetAddressia=InetAddress.getLocalHost();

while(true)

{

System.out.println(“Client:”);

String str=dis.readLine();

if(str.equals(“end”))

break;

buffer=str.getBytes();

ds.send(new DatagramPacket(buffer,str.length(),ia,clientport));

DatagramPacket p=new DatagramPacket(buffer,buffer.length);

ds.receive(p);

String psx=new String(p.getData(),0,p.getLength());

System.out.println(“Server:” + psx);

}

}

}

UDP server

import java.io.*;

import java.net.*;

classUDPserver

{

public static DatagramSocket ds;

public static byte buffer[]=new byte[1024];

public static intclientport=789,serverport=790;

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

{

ds=new DatagramSocket(clientport);

System.out.println(“press ctrl+c to quit the program”);

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

InetAddressia=InetAddress.getLocalHost();

while(true)

{

DatagramPacket p=new DatagramPacket(buffer,buffer.length);

ds.receive(p);

String psx=new String(p.getData(),0,p.getLength());

System.out.println(“Client:” + psx);

InetAddressib=InetAddress.getByName(psx);

System.out.println(“Server output:”+ib);

String str=dis.readLine();

if(str.equals(“end”))

break;

buffer=str.getBytes();

ds.send(new DatagramPacket(buffer,str.length(),ia,serverport));

}

}

}

OUTPUT:

UDPclient

C:\Program Files\Java\jdk1.6.0\bin>javac UDPclient.java

C:\Program Files\Java\jdk1.6.0\bin>java UDPclient

Server waiting

Client:www.yahoo.com

UDPserver

C:\Program Files\Java\jdk1.6.0\bin>javac UDPserver.java

C:\Program Files\Java\jdk1.6.0\bin>java UDPserver

Press ctrl+c to quit the program

Client:www.yahoo.com

Server output:www.yahoo.com/106.10.170.115

RESULT:

Thus client server program to Domain Name System using the UDP protocol client server has been executed and verified successfully.





QUESTION 5------------------------------------------------
UDP DATE SERVER

Server Program >>>>> Server.java


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 !! ");

}

}

}


Client program >>>>>>>>> Clientnew.java
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();

}

}









------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
SIR UPLOADED MATERIAL


1)Write a program to list all ports hosting a TCP server in a specified host.

import java.net.*;
import java.io.*;
public class ports{
public static void main(String args[])
{
for(int i=1;i<1024;i++)
{
try{
Socket s=new Socket("127.0.0.1",i);
System.out.println("There is server on port"+i+"of 127.0.0.1");
}
catch(UnknownHostException e){
System.err.println(e);
break;
}
catch(IOException e){
//must not be server on this port
}
}
}
}

2)Write a program to display the server’s date and time details at the client end.

import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Date;

public class dateserver {

    public static void main(String[] args) throws IOException {
        ServerSocket listener = new ServerSocket(9090);
        try {
            while (true) {
                Socket socket = listener.accept();
                try {
                    PrintWriter out =
                        new PrintWriter(socket.getOutputStream(), true);
                    out.println(new Date().toString());
                } finally {
                    socket.close();
                }
            }
        }
        finally {
            listener.close();
        }
    }
}

------------------------------
import java.io.*;
import java.net.Socket;

public class dateClient {

    public static void main(String[] args) throws IOException {
        Socket s = new Socket("127.0.0.1", 9090);
        BufferedReader input =
            new BufferedReader(new InputStreamReader(s.getInputStream()));
        String answer = input.readLine();
        System.out.println("The date and time details are "+answer  );

        System.exit(0);
    }
}


3)Write a program to display the client’s address at the server end.


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

public class ServerAddr
{
public static void main(String args[]) throws IOException
{
try
{
ServerSocket ss = new ServerSocket(6666);
System.out.println("Waiting for client.....");

Socket s = ss.accept();
System.out.println("Connected to client....");

DataInputStream in = new DataInputStream (s.getInputStream());
String line = null;
line = in.readUTF();
System.out.println("Client's IP adress: " + line);
}
catch (Exception e)
{
e.printStackTrace();
}
}
}

--------------------------------

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

public class ClientAddr
{
public static void main(String args[]) throws IOException
{
try
{
InetAddress ipaddress = InetAddress.getByName("");
Socket s = new Socket(ipaddress,6666);

System.out.println("Connected to the server...");
DataOutputStream out = new DataOutputStream(s.getOutputStream());

String line = null;
System.out.println("Sending my IP Address to server...");

line=ipaddress.getHostAddress();

out.writeUTF(line);
out.flush();}
catch (Exception e)
{
e.printStackTrace();
}
}
}

4)Implement a simple message transfer from client to server process using TCP/IP.

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

public class Tcpserver
{
public static void main(String args[]) throws IOException
{
try
{
ServerSocket ss = new ServerSocket(6666);
System.out.println("Waiting for client.....");

Socket s = ss.accept();
System.out.println("Connected to client....");

DataInputStream in = new DataInputStream (s.getInputStream());
String line = null;
line = in.readUTF();
System.out.println("Mesage from Client:" + line);
}
catch (Exception e)
{
e.printStackTrace();
}
}
}

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

public class TCPClient
{
public static void main(String args[]) throws IOException
{
try
{
InetAddress ipaddress = InetAddress.getByName("");
Socket s = new Socket(ipaddress,6666);
DataInputStream read = new DataInputStream(System.in);
System.out.println("Connected to the server...");
DataOutputStream out = new DataOutputStream(s.getOutputStream());

String line = null;
System.out.println("Write a message to the server..");

line=read.readLine();
out.writeUTF(line);
out.flush();}
catch (Exception e)
{
e.printStackTrace();
}
}
}

5)Develop a TCP client/server application for transferring a text file from client to server


CLIENt:
import java.io.*;
 import java.net.*;
import java.util.*;
public class FTPClient {
public static void main(String args[]) throws Exception

{
 Socket ss = new Socket("localhost",5000);
while(true)
{

Scanner pbn = new Scanner(System.in);
System.out.println("Enter the path of the file ");
String path = pbn.nextLine();
System.out.println(path);

File f = new File(path);
FileInputStream fis = new FileInputStream(f);

BufferedInputStream bis = new BufferedInputStream(fis);
System.out.println("Sending file...");

System.out.println("File sent");

    }

  }
}
server:

//////////////////
import java.io.*;
import java.net.*;
import java.util.*;
public class FTPServer {
public static void main(String args[]) throws IOException
{ServerSocket ss = new ServerSocket(5000);

    Scanner pbn = new Scanner(System.in);
    boolean flag = true;
    while(flag)
    {
    flag = false;
    try
    {System.out.println("waiting...");
Socket s = ss.accept();
System.out.println("Accepted connection "+s);
            System.out.println("Enter the path where you want to store the file");
            String path1 = pbn.nextLine();
            FileOutputStream fos = new FileOutputStream(path1);
            BufferedOutputStream bos = new BufferedOutputStream(fos);
            InputStream is = s.getInputStream();
            byte[] b = new byte[600000];
            int n = 0;
            int o = 0;
            while((n=is.read(b,o,b.length-o))>=0)
            {
                o+=n;
            }
            bos.write(b,0,o);

            bos.flush();
              System.out.println("File Received");
           }

    catch(FileNotFoundException f)
    {
            flag = true;
            String msg = f.getMessage();
            System.out.println("Error Message:"+msg);
            System.out.println("Please Enter a correct file path");
    }
     }

    }
}


6. 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.

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

public class AuthServer
{
	public static void main(String args[]) throws IOException
	{
		try
		{
			ServerSocket ss = new ServerSocket(6666);
			System.out.println("Waiting for client.....");
			Socket s = ss.accept();
			System.out.println("Connected to client....");

			DataInputStream in = new DataInputStream (s.getInputStream());
			DataOutputStream out = new DataOutputStream (s.getOutputStream());

			String line = null;
            String line1 = null;
			String sendline = null;


line = in.readUTF();
line1 = in.readUTF();
                if((line.equals("aid")|| line.equals("bid"))&&((line1.equals("apass")|| line1.equals("bpass"))))
                {
                    sendline ="Valid user id and password.Successfully logged in !!!!";
				out.writeUTF(sendline);
				out.flush();

                }
                else

                {
    sendline ="Invalid details";
				out.writeUTF(sendline);
				out.flush();
                }

		}
		catch (Exception e)
		{
			e.printStackTrace();
		}
	}
}

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

public class AuthClient
{
	public static void main(String args[]) throws IOException
	{
		try
		{
			InetAddress ipaddress = InetAddress.getByName("127.0.0.1");
			Socket s = new Socket(ipaddress,6666);

			System.out.println("Connected to the server...");

			DataInputStream read = new DataInputStream(System.in);

			DataInputStream in = new DataInputStream(s.getInputStream());
			DataOutputStream out = new DataOutputStream(s.getOutputStream());

			String line = null;
            String line1 = null;
			String receiveline = null;

			System.out.println("Enter User id ");
            line = read.readLine();
				out.writeUTF(line);
				out.flush();

System.out.println("Enter Password ");
line1 = read.readLine();
out.writeUTF(line1);
out.flush();


				receiveline = in.readUTF();
				System.out.println("SERVER: " + receiveline);


		}
		catch (Exception e)
		{
			e.printStackTrace();
		}
	}
}

7. Write a program to develop a simple (text based) Chat application using TCP/IP.
//chat
import java.io.*;
import java.net.*;

public class TCPserver
{
	public static void main(String args[]) throws IOException
	{
		try
		{
			ServerSocket ss = new ServerSocket(6666);
			System.out.println("Waiting for client.....");
DataInputStream read = new DataInputStream(System.in);
			Socket s = ss.accept();
			System.out.println("Connected to client....");

			DataInputStream in = new DataInputStream (s.getInputStream());
			DataOutputStream out = new DataOutputStream (s.getOutputStream());

			String line = null;


			do
			{
				line = in.readUTF();
				System.out.println("CLIENT: " + line);
                line = read.readLine();
				out.writeUTF(line);
				out.flush();

				System.out.println("Waiting for the next line.....");
			}while(!line.equals("bye"));
		}
		catch (Exception e)
		{
			e.printStackTrace();
		}
	}
}


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

public class TCPClient
{
	public static void main(String args[]) throws IOException
	{
		try
		{
			InetAddress ipaddress = InetAddress.getByName("127.0.0.1");
			Socket s = new Socket(ipaddress,6666);

			System.out.println("Connected to the server...");

			DataInputStream read = new DataInputStream(System.in);

			DataInputStream in = new DataInputStream(s.getInputStream());
			DataOutputStream out = new DataOutputStream(s.getOutputStream());

			String line = null;
			String receiveline = null;

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

			do
			{
				System.out.print("CLIENT: ");
				line = read.readLine();
				out.writeUTF(line);
				out.flush();

				receiveline = in.readUTF();
				System.out.println("SERVER: " + receiveline);

			}while(!line.equals("bye"));
		}
		catch (Exception e)
		{
			e.printStackTrace();
		}
	}
}

8. Implement a simple message transfer from client to server process using UDP.
import java.io.*;
import java.net.*;
class UDPServerss {
public static void main(String args[]) throws Exception       {
     DatagramSocket serverSocket = new DatagramSocket(9876);

   byte[] receiveData = new byte[1024];
 byte[] sendData = new byte[1024];
    while(true)                {

              DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
              serverSocket.receive(receivePacket);
                  String sentence = new String( receivePacket.getData());
                  System.out.println("RECEIVED: " + sentence);
      InetAddress IPAddress = receivePacket.getAddress();
            int port = receivePacket.getPort();
  String capitalizedSentence = sentence.toUpperCase();
         sendData = capitalizedSentence.getBytes();
      DatagramPacket sendPacket =                   new DatagramPacket(sendData, sendData.length, IPAddress, port);
        serverSocket.send(sendPacket);
           }
}
}
import java.io.*;
import java.net.*;
 class UDPClientssss {
   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];
     String sentence = inFromUser.readLine();
     sendData = sentence.getBytes();
  DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 9876);
  clientSocket.send(sendPacket);
  DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
  clientSocket.receive(receivePacket);
 String modifiedSentence = new String(receivePacket.getData());
      System.out.println("FROM SERVER:" + modifiedSentence);
  clientSocket.close();
   }
 }

9. Write a program to implement an Echo UDP server. Test the working of the server by writing a client application.
import java.net.*;
 import java.util.*;
 public class EchoServer
{
     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);
}
}
}----------------------------------
import java.net.*;
import java.util.*;
 public class EchoClient
{ public static void main( String args[] ) throws Exception {
InetAddress add = InetAddress.getByName("127.0.0.1");
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);
  }
 }

10. Write a program to implement the DISCARD server using UDP. Test the working of the server by writing a client application. Let the server log the client details on its standard output.
import java.io.*;
import java.net.*;
public class UDPdiscardServer {
    public final static int DEFAULT_PORT=9;
    public final static int MAX_PACKET_SIZE=65507;
public static void main(String args[])
{
    int port=DEFAULT_PORT;
    byte[] buffer=new byte[MAX_PACKET_SIZE];

    try{
    port=9;
    }
catch(Exception ex)
{}
    try{
    DatagramSocket server=new DatagramSocket(port);
DatagramPacket packet=new DatagramPacket(buffer,buffer.length);

while(true)
{
    try{
    server.receive(packet);
    String s=new String(packet.getData(),0,packet.getLength(),"UTF-8");
    System.out.println(packet.getAddress()+" at port "+packet.getPort()+" says "+s);
    packet.setLength(buffer.length);
    }
    catch(IOException ex){ System.err.println(ex);}
}

    }
    catch(SocketException ex)
    {System.err.println(ex);}
}
}
import java.io.*;
import java.net.*;
public class UDPdiscardClient {
    public final static int DEFAULT_PORT=9;

public static void main(String args[])
{String hostname="localhost";
    int port=DEFAULT_PORT;


   try{
   InetAddress server=InetAddress.getByName(hostname);
   BufferedReader userInput=new BufferedReader(new InputStreamReader(System.in));
   DatagramSocket theSocket=new DatagramSocket();

   while(true)
   {
  String theLine=userInput.readLine();
  if(theLine.equals(".")) break;
  byte[] data=theLine.getBytes("UTF-8");
  DatagramPacket theOutput=new DatagramPacket(data,data.length,server,port);
  theSocket.send(theOutput);
   }
   }
   catch(UnknownHostException ex)
    {System.err.println(ex);}
    catch(SocketException ex)
    {System.err.println(ex);}
    catch(IOException ioex)
    {System.err.println(ioex);}
}
}
Find the physical address of a host when its logical address is known (ARP protocol) using TCP/IP.

import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.Scanner;

public class MacAddress {
    public static void main(String[] args)
    {
        try
        {
            Scanner console = new Scanner(System.in);
            System.out.println("Enter System Name: ");
            String ipaddr = console.nextLine();
            InetAddress address = InetAddress.getByName(ipaddr);
            System.out.println("address = "+address);
            NetworkInterface ni = NetworkInterface.getByInetAddress(address);
            if (ni!=null)
            {
                byte[] mac = ni.getHardwareAddress();
                if (mac != null)
                {
                    System.out.print("MAC Address : ");
                    for (int i=0; i<mac.length; i++)
                    {
                        System.out.format("%02X%s", mac[i], (i<mac.length - 1) ? "-" :"");
                    }
                }
                else
                {
                    System.out.println("Address doesn't exist or is not accessible/");

                    }
                }
            else
            {
                System.out.println("Network Interface for the specified address is not found");
            }
        }
        catch(UnknownHostException he)
        {
        }
	catch(SocketException e)
	{
	}
    }
}



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

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();
        }
    }
}

OUTPUT:


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

CODE:
Server:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;


public class gs{

	public static void main(String[] args) throws Exception {
		ServerSocket sersock=new ServerSocket(3000);
		System.out.println("Server retreiving hostname...");
		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 Sendmsg,receivemsg;
		while(true)
		{
			if((receivemsg=receiveread.readLine())!=null)
			{
				System.out.println(receivemsg);
			}
			Sendmsg=keyread.readLine();
			pwrite.println(Sendmsg);
			pwrite.flush();
		}


	}
}

Client:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;


public class gc{

	public static void main(String[] args) throws Exception {
		InetAddress addr= InetAddress.getLocalHost();
		//InetAddress add= InetAddress.getHostName(addr);
		Socket sock=new Socket(addr,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("Client is ready");
		String Sendmsg,receivemsg;
		pwrite.println(addr.getHostAddress());

	}
}
OUTPUT:


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

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();
        }
    }
}

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


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

Server:
import java.io.*;
import java.net.*;
public class chatserver
{
  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();
      }
    }
}

Client:
import java.io.*;
import java.net.*;
public class chatclient
{
  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);
        }
      }
    }
}


Q5) 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.

Code :
//server

import java.net.*;

import java.io.*;

import java.util.*;



class EncServer

{

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

    {

        ServerSocket se=new ServerSocket(5217);
		Socket soc=se.accept();

		 BufferedReader in=new BufferedReader(

                new InputStreamReader(

                        soc.getInputStream()

                        )

                    );

		String s = in.readLine();
		System.out.println(s);
		String sp ="";
		char cp;
		for(int i=0;i<s.length();i++)
		{
			if(s.charAt(i) == 'z')
			{
				cp = 'a';
			}
			else{
			int c = (int) s.charAt(i);

			c++;
			cp = (char) c;

			}
			sp = sp + cp;
		}




		    OutputStream out = soc.getOutputStream();
			PrintWriter pr=new PrintWriter(out);
			pr.println(sp);
         out.close();
			 soc.close();




    }

}
//client
import java.io.*;

import java.net.*;

import java.util.*;

class EncClient

{

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

    {

		  Scanner sc = new Scanner(System.in);


		System.out.println("Enter Message to Encode");
		String name = sc.next();

        Socket soc=new Socket(InetAddress.getLocalHost(),5217);
		OutputStream out = soc.getOutputStream();
			PrintWriter pr=new PrintWriter(out);
			//System.out.println(name);
			pr.println(name);



        BufferedReader in=new BufferedReader(

                new InputStreamReader(

                        soc.getInputStream()

                        )

                    );

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

		soc.close();

    }

}

Q6) 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 UDP. Write a Java program for the above.

Code :

import java.io.*;

import java.net.*;

public class client{
public static void main (string args[])
{
try{
InetAddress a = InetAddress.getByName("localhost");
Scanner sc = new Scanner(System.in);


		System.out.println("Enter Message to Encode");
		String name = sc.next();

        Socket soc=new Socket(InetAddress.getLocalHost(),5217);
		OutputStream out = soc.getOutputStream();
			PrintWriter pr=new PrintWriter(out);
			//System.out.println(name);
			pr.println(name);



        BufferedReader in=new Buffered(new InputStreamReader(soc.getInputStream());
        System.out.println(in.readLine());

		soc.close();





    }

}
}

//Server
class Server

{

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

    {

        ServerSocket se=new ServerSocket(5217);
		Socket soc=se.accept();

		 BufferedReader in=new BufferedReader(

                new InputStreamReader(

                        soc.getInputStream()

                        )

                    );

		String s = in.readLine();
		System.out.println(s);
		String sp ="";
		char cp;
		for(int i=0;i<s.length();i++)
		{
			if(s.charAt(i) == 'z')
			{
				cp = 'a';
			}
			else{
			int c = (int) s.charAt(i);

			c++;
			cp = (char) c;

			}
			sp = sp + cp;
		}




		    OutputStream out = soc.getOutputStream();
			PrintWriter pr=new PrintWriter(out);
			pr.println(sp);
         out.close();
			 soc.close();




    }

}

7. Write a Java program to display the name and address of the computer that we are currently working on.
CODE:
import java.net.*;
public class ques7 {
public static void main (String[] args) {
try {
InetAddress address = InetAddress.getLocalHost();
System.out.println(address);
}
catch (UnknownHostException ex) {
System.out.println("Could not find this computer's address.");
}
}
}

OUTPUT:








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

CODE:
public class TestDaemonThread extends Thread{
 public void run(){
  if(Thread.currentThread().isDaemon()){
   System.out.println("daemon thread work");
  }
  else{
  System.out.println("user thread work");
 }
 }
 public static void main(String[] args){
  TestDaemonThread t1=new TestDaemonThread();
  TestDaemonThread t2=new TestDaemonThread();
  TestDaemonThread t3=new TestDaemonThread();

  t1.setDaemon(true);
  t2.setDaemon(true);
  t1.start();
  t2.start();
  t3.start();
 }
}







OUTPUT:

Q10) A server should run for 10 secs and generate numbers continuously. The client connecting to it should read data and find out the sum of the data thus read. Write a Java program to implement this scenario.

Code : Client
import java.io.*;

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


class RandomClient

{

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

    {

        Socket soc=new Socket(InetAddress.getLocalHost(),5217);
		int sum = 0;
        BufferedReader in=new BufferedReader(

                new InputStreamReader(

                        soc.getInputStream()

                        )

                    );


		int count =0;
		int n=1;
		while(n!=-1)
		{
        try{
		n = Integer.parseInt(in.readLine());
		System.out.println(n);
		sum = sum + n;
		count ++;
		}catch(Exception e)
		{
			n=-1;
		}


		}
		soc.close();
		System.out.println("Sum " + sum/count);
    }

}
//server

import java.net.*;

import java.io.*;

import java.util.*;



class RandomServer

{

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

    {

        ServerSocket s=new ServerSocket(5217);
		Date d = new Date();
		Random r = new Random();
		Socket soc=s.accept();
		int n=1;
		    OutputStream out = soc.getOutputStream();
			PrintWriter pr=new PrintWriter(out);
			while(soc.isConnected() && n != -1)
			{
				long t= System.currentTimeMillis();
		long end = t+10000;

		//System.out.println("hello");
        while((System.currentTimeMillis() < end))

        {
			int x=15;
			 n = r.nextInt(10);
			pr.println(n);
			pr.flush();


        }
		pr.flush();
		n=-1;
		pr.println(n);
         out.close();
			 soc.close();

		}


    }

}








------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
basics
Basic network commands
ping
The ping command (named after the sound of an active sonar system) sends echo requests to the host
specified on the command line, and lists the responses received.
$ ping ipAddress or hostname
e.g
$ ping www.vit.ac.in
• ping - sends an ICMP ECHO_REQUEST packet to the specified host. If the host responds, an
ICMP packet is received.
• One can “ping” an IP address to see if a machine is alive.
• It provides a very quick way to see if a machine is up and connected to the network.
netstat
• It works with the LINUX Network Subsystem, it will tell you what the status of ports are ie. open,
closed, waiting connections. It is used to display the TCP/IP network protocol statistics and
information.
tcpdump
This is a sniffer, a program that captures packets off a network interface and interprets them.
hostname
Tells the user the host name of the computer they are logged into.
traceroute
traceroute will show the route of a packet. It attempts to list the series of hosts through which your
packets travel on their way to a given destination.
Command syntax:
traceroute machine_name_or_ip
e.g traceroute www.vit.ac.in
Each host will be displayed, along with the response times at each host.
finger
Retrieves information about the specified user.
e.g finger bit50001
ifconfig ( In Windows use ipconfig )
This command is used to configure network interfaces, or to display their current configuration.
dig
The "domain information groper" tool. If you give a hostname as an argument to output information
about that host, including it's IP address, hostname and various other information.
e.g dig vitlinux
telnet
telnet allows you to log in to a computer, just as if you were sitting at the terminal. Once your
username and password are verified, you are given a shell prompt. From here, you can do anything
requiring a text console.
ftp
To connect to an FTP server use
ftp ipaddress
netstat
Displays contents of /proc/net files. It works with the LINUX Network Subsystem, it will tell
you what the status of ports are ie. open, closed, waiting, masquerade connections. It will also
display various other things. It has many different options.
tcpdump
This is a sniffer, a program that captures packets off a network interface and interprets them
for you. It understands all basic internet protocols, and can be used to save entire packets for
later inspection.
ping
The ping command (named after the sound of an active sonar system) sends echo requests to
the host you specify on the command line, and lists the responses received their round trip
time.
You simply use ping as:
ping ip_or_host_name
hostname
Tells the user the host name of the computer they are logged into. Note: may be called host.
traceroute
traceroute will show the route of a packet. It attempts to list the series of hosts through which
your packets travel on their way to a given destination. Also have a look at xtraceroute (one
of several graphical equivalents of this program).
Command syntax:
traceroute machine_name_or_ip
tracepath
tracepath performs a very simlar function to traceroute the main difference is that tracepath
doesn't take complicated options.
Command syntax:
tracepath machine_name_or_ip
findsmb
findsmb is used to list info about machines that respond to SMB name queries (for example
windows based machines sharing their hard disk's).
Command syntax:
Findsmb
This would find all machines possible, you may need to specify a particular subnet to query
those machines only...
nmap
“ network exploration tool and security scanner”. nmap is a very advanced network tool used
to query machines (local or remote) as to whether they are up and what ports are open on
these machines.
A simple usage example:
nmap machine_name
This would query your own machine as to what ports it keeps open. nmap is a very powerful
tool, documentation is available on the nmap site as well as the information in the manual
page.
telnet
Someone once stated that telnet(1) was the coolest thing he had ever seen on computers. The ability
to remotely log in and do stuff on another computer is what separates Unix and Unix-like operating
systems from other operating systems.
telnet allows you to log in to a computer, just as if you were sitting at the terminal. Once your
username and password are verified, you are given a shell prompt. From here, you can do anything
requiring a text console. Compose email, read newsgroups, move files around, and so on. If you are
running X and you telnet to another machine, you can run X programs on the remote computer and
display them on yours.
To login to a remote machine, use this syntax:
% telnet <hostname>
If the host responds, you will receive a login prompt. Give it your username and password. That's it.
You are now at a shell. To quit your telnet session, use either the exit command or the logout
command.
telnet does not encrypt the information it sends. Everything is sent in plain text, even passwords.
It is not advisable to use telnet over the Internet. Instead, consider the Secure Shell. It encrypts
all traffic and is available for free.
The other use of telnet
Now that we have convinced you not to use the telnet protocol anymore to log into a remote machine,
we'll show you a couple of useful ways to use telnet.
You can also use the telnet command to connect to a host on a certain port.
% telnet <hostname> [port]
This can be quite handy when you quickly need to test a certain service, and you need full control
over the commands, and you need to see what exactly is going on. You can interactively test or use
an SMTP server, a POP3 server, an HTTP server, etc. this way.
In the next figure you'll see how you can telnet to a HTTP server on port 80, and get some basic
information from it.
Figure 13-1. Telnetting to a webserver
% telnet store.slackware.com 80
Trying 69.50.233.153...
Connected to store.slackware.com.
Escape character is '^]'.
HEAD / HTTP/1.0
HTTP/1.1 200 OK
Date: Mon, 25 Apr 2005 20:47:01 GMT
Server: Apache/1.3.33 (Unix) mod_ssl/2.8.22 OpenSSL/0.9.7d
Last-Modified: Fri, 18 Apr 2003 10:58:54 GMT
ETag: "193424-c0-3e9fda6e"
Accept-Ranges: bytes
Content-Length: 192
Connection: close
Content-Type: text/html
Connection closed by foreign host.
%
1-)arp :
When we need an Ethernet (MAC) address we can use arp(address resolution protocol).
In other words it shows the physical address of an host.
Example:
C:\Documents and Settings\sysadm>arp -a
Interface: 169.254.195.199 --- 0x2
Internet Address Physical Address Type
216.109.127.60 00-53-45-00-00-00 static
2-)nslookup:
Displays information from Domain Name System (DNS) name servers.
Example:
C:\Documents and Settings\sysadm>nslookup itu.dk
Server: ns3.inet.tele.dk
Address: 193.162.153.164
Non-authoritative answer:
Name: itu.dk
Address: 130.226.133.2
NOTE :If you write the command as above it shows as default your pc's server name firstly.
C:\Documents and Settings\sysadm>nslookup mail.yahoo.com itu.dk
Server: superman.itu.dk
Address: 130.226.133.2
Non-authoritative answer:
Name: login.yahoo.akadns.net
Address: 216.109.127.60
Aliases: mail.yahoo.com, login.yahoo.com
NOTE:Remark that in the second example we do not see the default server name.
There are many nslookup with optional commands.To read them type nslookup and enter
then type help and enter.
3-)finger:
Displays the information about a user on the system.
Example:
NOTE :I could not find out the name of the server that we log on (windows) at the school.
Sysadmin does not know that either:o)
But as an example I tried it on the our unix server.
[hilmiolgun@ssh hilmiolgun]$ finger
Login Name Tty Idle Login Time Office Office Phone
adel Adel Abu-Sharkh pts/1 7 Sep 10 00:11 (cpe.atm2-0-
1091080.0x50a0bcb2.albnxx13.customer.tele.dk)
adel Adel Abu-Sharkh pts/2 9 Sep 9 23:56 (cpe.atm2-0-
1091080.0x50a0bcb2.albnxx13.customer.tele.dk)
hilmiolgun Hilmi Olgun pts/9 Sep 10 00:20 (0x3ef3e2fe.albnxx8.adsl.tele.dk)
hm Hanne Munkholm pts/6 1:56 Sep 8 21:27 (off180.palombia.dk)
jcg Jens Christian Godsk pts/4 1d Sep 8 10:28 (toscana.itu.dk)
kaj Kenneth Ahn Jensen pts/7 Sep 10 00:11 (cpe.atm2-0-
54493.0x50a4ad32.boanxx12.customer.tele.dk)
root root pts/8 1 Sep 10 00:12 (sysadm2.itu.dk)
troels Troels Arvin pts/5 3:49 Sep 9 20:31 (62.79.119.132.adsl.vbr.worldonline.dk)
webclaus Claus Bech Rasmussen pts/0 6 Sep 10 00:11 (port967.ds1-khk.adsl.cybercity.dk)
NOTE :What I did is :I first check the online users,and get a list of them(above).
Then i just choosed one user to get information about him(below)
[hilmiolgun@ssh hilmiolgun]$ finger hm
Login: hm Name: Hanne Munkholm
Directory: /import/home/hm Shell: /bin/bash
On since Mon Sep 8 21:27 (CEST) on pts/6 from off180.palombia.dk
1 hour 56 minutes idle
Last login Tue Sep 9 11:05 (CEST) on pts/12 from stud127.itu.dk
New mail received Mon Nov 11 23:01 2002 (CET)
Unread since Sat Oct 5 00:00 2002 (CEST)
Plan:
World Domination... fast.
[hilmiolgun@ssh hilmiolgun]$
4-)ping:
Simpy shows if the remote machine is available or not....
Example:
C:\Documents and Settings\sysadm>ping webmail.itu.dk
Pinging tarzan.itu.dk [130.226.133.3] with 32 bytes of data:
Reply from 130.226.133.3: bytes=32 time=29ms TTL=55
Reply from 130.226.133.3: bytes=32 time=30ms TTL=55
Reply from 130.226.133.3: bytes=32 time=30ms TTL=55
Reply from 130.226.133.3: bytes=32 time=30ms TTL=55
Ping statistics for 130.226.133.3:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 29ms, Maximum = 30ms, Average = 29ms
NOTE :Remark that the remote machine is replying.Otherwise the output will be "Request time out"
which means the
remote machine is not working well.(Not answering)
5-)tracert:
It simply shows the path between source and destination address.
Example:
C:\Documents and Settings\sysadm>tracert webmail.itu.dk
Tracing route to tarzan.itu.dk [130.226.133.3]
over a maximum of 30 hops:
1 * * * Request timed out.
2 29 ms 19 ms 29 ms ge-0-2-1-2.1000M.albnxu1.ip.tele.dk [195.249.1.2 9]
3 29 ms 29 ms 19 ms pos1-0.622M.lynxg1.ip.tele.dk [195.249.2.46]
4 29 ms 19 ms 29 ms herman.fsknet.lyngby.forskningsnettet.dk [192.38 .7.1]
5 29 ms 29 ms 19 ms 130.225.244.214
6 29 ms 29 ms 29 ms 1.ku.forskningsnettet.dk [130.225.245.90]
7 29 ms 29 ms 29 ms rk.itu.forskningsnettet.dk [130.226.249.30]
8 29 ms 29 ms 29 ms 130.225.245.86
9 29 ms 29 ms 29 ms tarzan.itu.dk [130.226.133.3]
Trace complete.
6-)ftp:
For file transferring..(File transfer protocol)
Example:Lets you dont have an ftp software and you want to get a file from your school harddisk.
So to do that:
C:\Documents and Settings\sysadm>ftp
ftp> open
To ftp.itu.dk
Connected to ssh.itu.dk.
220 ProFTPD 1.2.8rc2 Server (ProFTPD Default Installation) [ssh.it-c.dk]
NOTE:What am I doing is simply:typing them one-by-one(after each typing remember to enter)
ftp,open,ftp.itu.dk
User (ssh.itu.dk:(none)): hilmiolgun
331 Password required for hilmiolgun.
Password:
230 User hilmiolgun logged in.
NOTE:The server will require username and password..
ftp> help
Commands may be abbreviated. Commands are:
! delete literal prompt send
? debug ls put status
append dir mdelete pwd trace
ascii disconnect mdir quit type
bell get mget quote user
binary glob mkdir recv verbose
bye hash mls remotehelp
cd help mput rename
close lcd open rmdir
ftp> help dir
dir List contents of remote directory
NOTE: If it is your first time to those commands just type help and get the commands.If you dont
know how to use
them type help commandname..
ftp> dir
200 PORT command successful
150 Opening ASCII mode data connection for file list
drwx------ 4 hilmiolgun hilmiolgun 155 Jul 1 14:02 Desktop
drwx------ 2 hilmiolgun hilmiolgun 4096 May 30 10:21 Mail
drwxr-xr-x 5 hilmiolgun hilmiolgun 90 Sep 2 02:59 MobilePositionSDK
drwx------ 7 hilmiolgun hilmiolgun 4096 Aug 8 2002 NTnetscape
drwxr--r-- 13 hilmiolgun hilmiolgun 4096 Sep 4 01:56 New Folder
-rw-rw-r-- 1 hilmiolgun hilmiolgun 74 Sep 9 12:56 TTI409B
drwx------ 2 hilmiolgun hilmiolgun 6 Jan 21 2002 cgi-bin
-rw-rw-r-- 1 hilmiolgun hilmiolgun 74 Sep 9 12:56 geu
-rw-rw-r-- 1 hilmiolgun hilmiolgun 74 Sep 9 12:56 hilmiolgun
drwxr-xr-x 6 hilmiolgun hilmiolgun 4096 Aug 14 15:59 image
drwxr-xr-x 3 hilmiolgun hilmiolgun 4096 Jul 29 16:03 jmf20-apidocs
drwxr-xr-x 4 hilmiolgun hilmiolgun 4096 Sep 9 14:10 NOTEsieee
drwx------ 2 hilmiolgun hilmiolgun 6 Feb 21 2002 nsmail
drwx------ 3 hilmiolgun hilmiolgun 103 Feb 21 2002 office52
drwx------ 2 hilmiolgun hilmiolgun 6 Jan 21 2002 private
drwxr--rwx 2 hilmiolgun hilmiolgun 4096 Aug 23 12:02 public_html
drwxr-xr-x 5 hilmiolgun hilmiolgun 4096 Sep 6 03:30 speech
-rw-rw-r-- 1 hilmiolgun hilmiolgun 2630 Sep 9 13:58 test.txt
-rw-rw-r-- 1 hilmiolgun hilmiolgun 148 Sep 9 14:03 testing.txt
226 Transfer complete.
ftp: 1318 bytes received in 0,24Seconds 5,49Kbytes/sec.
ftp> get testing.txt
200 PORT command successful
150 Opening ASCII mode data connection for testing.txt (148 bytes)
226 Transfer complete.
ftp: 161 bytes received in 0,02Seconds 8,05Kbytes/sec.
NOTE :After taking a look to the school harddisk ,I copied a file "testing.txt" to my local harddisk....
ftp> !dir
Volume in drive C has no label.
Volume Serial Number is 0868-D52D
Directory of C:\Documents and Settings\sysadm
10-09-2003 00:21 <DIR> .
10-09-2003 00:21 <DIR> ..
31-08-2003 07:28 <DIR> .java
25-04-2003 12:18 <DIR> .javaws
23-04-2003 15:26 <DIR> .jpi_cache
26-08-2003 04:59 <DIR> .Nokia
07-09-2003 01:46 12.546 .plugin140_03.trace
07-09-2003 04:46 693 .plugin141_02.trace
07-09-2003 01:20 164 .saves-3824-IBMR31IMAGE
07-09-2003 01:20 <DIR> Desktop
07-09-2003 08:05 <DIR> Favorites
06-09-2003 05:29 80.140 love.wav
09-09-2003 23:45 <DIR> mindterm
09-09-2003 11:02 <DIR> My Documents
10-09-2003 00:21 2.903 plugin131_08.trace
25-04-2003 11:44 <DIR> Start Menu
06-09-2003 21:21 <DIR> studio5se_user
06-09-2003 05:32 18 test.txt
06-09-2003 05:20 70 testing
10-09-2003 00:37 161 testing.txt
26-08-2003 03:46 <DIR> WINDOWS
8 File(s) 96.695 bytes
13 Dir(s) 3.842.056.192 bytes free
ftp> send love.wav
200 PORT command successful
150 Opening ASCII mode data connection for love.wav
226 Transfer complete.
ftp: 80140 bytes sent in 3,97Seconds 20,21Kbytes/sec.
ftp> dir
200 PORT command successful
150 Opening ASCII mode data connection for file list
drwx------ 4 hilmiolgun hilmiolgun 155 Jul 1 14:02 Desktop
drwx------ 2 hilmiolgun hilmiolgun 4096 May 30 10:21 Mail
drwxr-xr-x 5 hilmiolgun hilmiolgun 90 Sep 2 02:59 MobilePositionSDK
drwx------ 7 hilmiolgun hilmiolgun 4096 Aug 8 2002 NTnetscape
drwxr--r-- 13 hilmiolgun hilmiolgun 4096 Sep 4 01:56 New Folder
-rw-rw-r-- 1 hilmiolgun hilmiolgun 74 Sep 9 12:56 TTI409B
drwx------ 2 hilmiolgun hilmiolgun 6 Jan 21 2002 cgi-bin
-rw-rw-r-- 1 hilmiolgun hilmiolgun 74 Sep 9 12:56 geu
-rw-rw-r-- 1 hilmiolgun hilmiolgun 74 Sep 9 12:56 hilmiolgun
drwxr-xr-x 6 hilmiolgun hilmiolgun 4096 Aug 14 15:59 image
drwxr-xr-x 3 hilmiolgun hilmiolgun 4096 Jul 29 16:03 jmf20-apidocs
-rw-rw-r-- 1 hilmiolgun hilmiolgun 80137 Sep 9 22:36 love.wav
drwxr-xr-x 4 hilmiolgun hilmiolgun 4096 Sep 9 14:10 NOTEsieee
drwx------ 2 hilmiolgun hilmiolgun 6 Feb 21 2002 nsmail
drwx------ 3 hilmiolgun hilmiolgun 103 Feb 21 2002 office52
drwx------ 2 hilmiolgun hilmiolgun 6 Jan 21 2002 private
drwxr--rwx 2 hilmiolgun hilmiolgun 4096 Aug 23 12:02 public_html
drwxr-xr-x 5 hilmiolgun hilmiolgun 4096 Sep 6 03:30 speech
-rw-rw-r-- 1 hilmiolgun hilmiolgun 2630 Sep 9 13:58 test.txt
-rw-rw-r-- 1 hilmiolgun hilmiolgun 148 Sep 9 14:03 testing.txt
226 Transfer complete.
ftp: 1387 bytes received in 0,07Seconds 19,81Kbytes/sec.
ftp>
NOTE:At the end first looking at the local working directory and sending a file "love.wav" to the
school harddisk.
7-)net:
It has many options,which are for checking/starting/stopping nt
services,users,messaging,configuration and so on...
Some of those options require administration privileges..
Example:
NOTE: To have an overview of commands options....
C:\Documents and Settings\sysadm>net
The syntax of this command is:
NET COMMANDS
NET [ ACCOUNTS | COMPUTER | CONFIG | CONTINUE | FILE | GROUP | HELP |
HELPMSG | LOCALGROUP | NAME | PAUSE | PRINT | SEND | SESSION |
SHARE | START | STATISTICS | STOP | TIME | USE | USER | VIEW ]
NOTE: And furthermore to get an overview of a specific option ...
C:\Documents and Settings\sysadm>net help print
The syntax of this command is:
NET PRINT
\\computername\sharename
[\\computername] job# [/HOLD | /RELEASE | /DELETE]
NET PRINT displays print jobs and shared queues.
For each queue, the display lists jobs, showing the size
and status of each job, and the status of the queue.
\\computername Is the name of the computer sharing the printer
queue(s).
sharename Is the name of the shared printer queue.
job# Is the identification number assigned to a print
job. A computer with one or more printer queues
assigns each print job a unique number.
/HOLD Prevents a job in a queue from printing.
The job stays in the printer queue, and other
jobs bypass it until it is released.
/RELEASE Reactivates a job that is held.
/DELETE Removes a job from a queue.
NET HELP command | MORE displays Help one screen at a time.
Finally in addition to above there are also those commands: hostname ,lpq, lpr ,rsh ,tftp ,nbstat
,netstat.
To get familiar with those commands simply type commandname /? at the command line.
C:\>net
The syntax of this command is:
NET [ ACCOUNTS | COMPUTER | CONFIG | CONTINUE | FILE | GROUP | HELP |
HELPMSG | LOCALGROUP | NAME | PAUSE | PRINT | SEND | SESSION |
SHARE | START | STATISTICS | STOP | TIME | USE | USER | VIEW ]
C:\>net use
New connections will not be remembered.
Status Local Remote Network
-------------------------------------------------------------------------------
OK F: \\cse-sec\fac Microsoft Windows Network
C:\>net user
User accounts for \\CSE-DEPT-05
-------------------------------------------------------------------------------
Administrator Guest
C:\>net statistics
Statistics are available for the following running services:
Server
Workstation
Displays protocol statistics and current TCP/IP network connections.
NETSTAT [-a] [-e] [-n] [-s] [-p proto] [-r] [interval]
-a Displays all connections and listening ports.
-e Displays Ethernet statistics. This may be combined with the
-s option.
-n Displays addresses and port numbers in numerical form.
-p proto Shows connections for the protocol specified by proto; proto
may be TCP or UDP. If used with the -s option to display
per-protocol statistics, proto may be TCP, UDP, or IP.
-r Displays the routing table.
-s Displays per-protocol statistics. By default, statistics
are shown for TCP, UDP and IP; the -p option may be used
to specify a subset of the default.
interval Redisplays selected statistics, pausing interval seconds
between each display. Press CTRL+C to stop redisplaying
statistics. If omitted, netstat will print the current
configuration information once.
C:\>net name
Name
-------------------------------------------------------------------------------
CSE-DEPT-05
C:\>net session
Computer User name Client Type Opens Idle time
-------------------------------------------------------------------------------
\\ENGLISH-03 Windows NT 1381 0 00:10:47
\\ENGLISHBDC Windows NT 1381 0 00:02:01
C:\>net accounts
Force user logoff how long after time expires?: Never
Minimum password age (days): 0
Maximum password age (days): 42
Minimum password length: 0
Length of password history maintained: None
Lockout threshold: Never
Lockout duration (minutes): 30
Lockout observation window (minutes): 30
Computer role: WORKSTATION
C:\>net localgroup
Aliases for \\CSE-DEPT-05
-------------------------------------------------------------------------------
*Administrators *Backup Operators *Guests
*Power Users *Replicator *Users
C:\>net config server
Server Name \\CSE-DEPT-05
Server Comment
Software version Windows NT 4.0
Server is active on NetBT_DLKRTS1 (0050ba8b326b) NetBT_DLKRTS1
(0050ba8b326b) NwlnkIpx (0050ba8b326b) NwlnkNb (0050ba8b326b) Nbf_DLKRTS1 (0050
ba8b326b)
Server hidden No
Maximum Logged On Users 10
Maximum open files per session 2048
Idle session time (min) 15
C:\>net config workstation
Computer name \\CSE-DEPT-05
User name Administrator
Workstation active on NwlnkNb (0050BA8B326B) NetBT_DLKRTS1 (0050B
A8B326B) Nbf_DLKRTS1 (0050BA8B326B)
Software version Windows NT 4.0
Workstation domain WORKGROUP
Logon domain CSE-DEPT-05
COM Open Timeout (sec) 3600
COM Send Count (byte) 16
COM Send Timeout (msec) 250
C:\>net share
Share name Resource Remark
-------------------------------------------------------------------------------
D$ D:\ Default share
IPC$ Remote IPC
C$ C:\ Default share
ADMIN$ C:\WINNT Remote Admin
E$ E:\ Default share
abishek E:\abishek
akshu E:\akshu
HARSHINI D:\ HARSHINI
DHARSHINI E:\ DHARSHINI
C:\>net stop messenger
The Messenger service is stopping.
The Messenger service was stopped successfully.
C:\>net start messenger
The Messenger service is starting...
The Messenger service was started successfully.
Network Configuration commands
ifconfig
This command is used to configure network interfaces, or to display their current
configuration. In addition to activating and deactivating interfaces with the “up” and “down”
settings, this command is necessary for setting an interface's address information if you don't
have the ifcfg script.
Use ifconfig as either:
ifconfig
This will simply list all information on all network devices currently up.
ifconfig eth0 down
This will take eth0 (assuming the device exists) down, it won't be able to receive or send
anything until you put the device back “up” again.
Clearly there are a lot more options for this tool, you will need to read the manual/info page to
learn more about them.
ifup
Use ifup device-name to bring an interface up by following a script (which will contain your
default networking settings). Simply type ifup and you will get help on using the script.
For example typing:
ifup eth0
Will bring eth0 up if it is currently down.
ifdown
Use ifdown device-name to bring an interface down using a script (which will contain your
default network settings). Simply type ifdown and you will get help on using the script.
For example typing:
ifdown eth0
Will bring eth0 down if it is currently up.
ifcfg
Use ifcfg to configure a particular interface. Simply type ifcfg to get help on using this script.
For example, to change eth0 from 192.168.0.1 to 192.168.0.2 you could do:
ifcfg eth0 del 192.168.0.1
ifcfg eth0 add 192.168.0.2
The first command takes eth0 down and removes that stored IP address and the second one
brings it back up with the new address.
route
The route command is the tool used to display or modify the routing table. To add a gateway
as the default you would type:
route add default gw some_computer
INTERNET SPECIFIC COMMANDS
host
Performs a simple lookup of an internet address (using the Domain Name System, DNS).
Simply type:
host ip_address
or
host domain_name
dig
The "domain information groper" tool. More advanced then host... If you give a hostname as
an argument to output information about that host, including it's IP address, hostname and
various other information.
For example, to look up information about “www.amazon.com” type:
dig www.amazon.com
To find the host name for a given IP address (ie a reverse lookup), use dig with the `-x' option.
dig -x 100.42.30.95
This will look up the address (which may or may not exist) and returns the address of the
host, for example if that was the address of “http://slashdot.org” then it would return
“http://slashdot.org”.
dig takes a huge number of options (at the point of being too many), refer to the manual page
for more information.
whois
(now BW whois) is used to look up the contact information from the “whois” databases, the
servers are only likely to hold major sites. Note that contact information is likely to be hidden
or restricted as it is often abused by crackers and others looking for a way to cause malicious
damage to organisation's.
wget
(GNU Web get) used to download files from the World Wide Web.
To archive a single web-site, use the -m or --mirror (mirror) option.
Use the -nc (no clobber) option to stop wget from overwriting a file if you already have it.
Use the -c or --continue option to continue a file that was unfinished by wget or another
program.
Simple usage example:
wget url_for_file
This would simply get a file from a site.
wget can also retrieve multiple files using standard wildcards, the same as the type used in
bash, like *, [ ], ?. Simply use wget as per normal but use single quotation marks (' ') on the
URL to prevent bash from expanding the wildcards. There are complications if you are
retrieving from a http site (see below...).
Advanced usage example, (used from wget manual page):
wget --spider --force-html -i bookmarks.html
This will parse the file bookmarks.html and check that all the links exist.
Advanced usage: this is how you can download multiple files using http (using a wildcard...).
Notes: http doesn't support downloading using standard wildcards, ftp does so you may use
wildcards with ftp and it will work fine. A work-around for this http limitation is shown
below:
wget -r -l1 --no-parent -A.gif http://www.website.com[1]
This will download (recursively), to a depth of one, in other words in the current directory and
not below that. This command will ignore references to the parent directory, and downloads
anything that ends in “.gif”. If you wanted to download say, anything that ends with “.pdf” as
well than add a -A.pdf before the website address. Simply change the website address and the
type of file being downloaded to download something else. Note that doing -A.gif is the same
as doing -A “*.gif” (double quotes only, single quotes will not work).
wget has many more options refer to the examples section of the manual page, this tool is very
well documented.
Alternative website downloaders: You may like to try alternatives like httrack. A full GUI
website downloader written in python and available for GNU/Linux
curl
curl is another remote downloader. This remote downloader is designed to work without user
interaction and supports a variety of protocols, can upload/download and has a large number
of tricks/work-arounds for various things. It can access dictionary servers (dict), ldap servers,
ftp, http, gopher, see the manual page for full details.
To access the full manual (which is huge) for this command type:
curl -M
For general usage you can use it like wget. You can also login using a user name by using the
-u option and typing your username and password like this:
curl -u username:password http://www.placetodownload/file
To upload using ftp you the -T option:
curl -T file_name ftp://ftp.uploadsite.com
To continue a file use the -C option:
curl -C - -o file http://www.site.com
View and modify network interfaces
ifconfig -a Show information about all network interfaces
ifconfig eth0 Show information only about the interface eth0
ifconfig eth0 up Bring up the interface eth0
ifconfig eth0 down Take down the interface eth0
Simple network diagnostic commands
ping hostname Send ICMP echo requests to the host hostname
traceroute hostname Trace the network path to hostname
View open network connections
netstat -a Show information about all open network connections
netstat -a | grep LISTEN Show information about all open network ports
Set/view routing information
netstat -r View system routing tables
route View system routing tables
The command route can also be used to add or delete routes. Examples:
route add -host 192.168.3.4 gw 192.168.3.1 netmask 255.255.0.0
route del -host 192.168.3.4
NETSTAT.exe TCP/IP Network Statistics
Displays protocol statistics and current TCP/IP network connections.
NETSTAT [-a] [-e] [-n] [-s] [-p proto] [-r] [interval]
-a Displays all connections and listening ports.
-e Displays Ethernet statistics. This may be combined with the -s option.
-n Displays addresses and port numbers in numerical form.
-p proto Shows connections for the protocol specified by proto; proto may be TCP or UDP.
If used with the -s option to display per-protocol statistics, proto may be TCP, UDP,
or IP.
-r Displays the routing table.
-s Displays per-protocol statistics. By default, statistics are shown for TCP, UDP and IP;
the -p option may be used to specify a subset of the default.
interval Redisplays selected statistics, pausing interval seconds between each display. Press
CTRL+C to stop redisplaying statistics. If omitted, netstat will print the current
configuration information once.
C:\WINDOWS>netstat -a
Active Connections
Proto Local Address Foreign Address State
TCP My_Comp:ftp localhost:0 LISTENING
TCP My_Comp:80 localhost:0 LISTENING
Or with the "-an" parameters:
C:\WINDOWS>netstat -an
Active Connections
Proto Local Address Foreign Address State
TCP 0.0.0.0:21 0.0.0.0:0 LISTENING
TCP 0.0.0.0:80 0.0.0.0:0 LISTENING
By simply opening a browser connection to both the HTTP (port 80) and FTP (port 21) servers
(while still offline!), I saw the following:
C:\WINDOWS>netstat -a
Active Connections
Proto Local Address Foreign Address State
TCP My_Comp:ftp localhost:0 LISTENING
TCP My_Comp:80 localhost:0 LISTENING
TCP My_Comp:1104 localhost:0 LISTENING
TCP My_Comp:ftp localhost:1104 ESTABLISHED
TCP My_Comp:1102 localhost:0 LISTENING
TCP My_Comp:1103 localhost:0 LISTENING
TCP My_Comp:80 localhost:1111 TIME_WAIT
TCP My_Comp:1104 localhost:ftp ESTABLISHED
TCP My_Comp:1107 localhost:0 LISTENING
TCP My_Comp:1112 localhost:80 TIME_WAIT
UDP My_Comp:1102 *:*
UDP My_Comp:1103 *:*
UDP My_Comp:1107 *:*
This may be a bit confusing to some people, but remember I'm running BOTH the servers and clients
on the same machine in these examples. A little later (using both 'a' and 'n') I got this:
C:\WINDOWS>netstat -an
Active Connections
Proto Local Address Foreign Address State
TCP 0.0.0.0:21 0.0.0.0:0 LISTENING
TCP 0.0.0.0:80 0.0.0.0:0 LISTENING
TCP 0.0.0.0:1104 0.0.0.0:0 LISTENING
TCP 127.0.0.1:21 127.0.0.1:1104 FIN_WAIT_2
TCP 127.0.0.1:1102 0.0.0.0:0 LISTENING
TCP 127.0.0.1:1103 0.0.0.0:0 LISTENING
TCP 127.0.0.1:1104 127.0.0.1:21 CLOSE_WAIT
TCP 127.0.0.1:1107 0.0.0.0:0 LISTENING
UDP 127.0.0.1:1102 *:*
UDP 127.0.0.1:1103 *:*
UDP 127.0.0.1:1107 *:*
After turning off my server, I ended up with this for a while:
C:\WINDOWS>netstat -an
Active Connections
Proto Local Address Foreign Address State
TCP 127.0.0.1:80 127.0.0.1:1150 TIME_WAIT
TCP 127.0.0.1:80 127.0.0.1:1151 TIME_WAIT
PING.exe
Usage: ping [-t] [-a] [-n count] [-l size] [-f] [-i TTL] [-v TOS]
[-r count] [-s count] [[-j host-list] | [-k host-list]]
[-w timeout] destination-list
Options:
-t Ping the specifed host until interrupted.
-a Resolve addresses to hostnames.
-n count Number of echo requests to send.
-l size Send buffer size.
-f Set "Don't Fragment" flag in packet.
-i TTL Time To Live.
-v TOS Type Of Service.
-r count Record route for count hops.
-s count Timestamp for count hops.
-j host-list Loose source route along host-list.
-k host-list Strict source route along host-list.
-w timeout Timeout in milliseconds to wait for each reply.
There's one special IP number everyone should know about:
127.0.0.1 - localhost (or loopback).
This is used to connect ( through a browser, for example) to a Web server on your own computer.
(127 being reserved for this purpose.) You can use this IP number at all times. It doesn't matter if
you're connected to the Internet or not.
It's also called the loopback address because you can ping it and get returns even when you're
offline (not connected to any network). If you don't get any valid replies, then there's a problem with
the computer's Network settings. Here's a typical response to the 'ping' command:
Here's another recent example using the name of my computer which I have tied to the IP number
127.0.0.1 in my C:\WINDOWS\HOSTS file:
C:\WINDOWS>ping My_Comp
Pinging My_Comp [127.0.0.1] with 32 bytes of data:
Reply from 127.0.0.1: bytes=32 time=1ms TTL=128
Reply from 127.0.0.1: bytes=32 time=1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<10ms TTL=128
Reply from 127.0.0.1: bytes=32 time=1ms TTL=128
Ping statistics for 127.0.0.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 1ms, Average = 0ms
TRACERT.exe Trace Route
Usage:
tracert [-d] [-h maximum_hops] [-j host-list] [-w timeout] target_name
Options:
-d Do not resolve addresses to hostnames.
-h maximum_hops Maximum number of hops to search for target.
-j host-list Loose source route along host-list.
-w timeout Wait timeout milliseconds for each reply.
Here's an example which traces the route from some ISP in Los Angeles to the main server at UCLA
in California ( note how two computers relatively close to each other may be routed way round
about! ):
C:\WINDOWS>tracert www.ucla.edu
Tracing route to www.ucla.edu [169.232.33.129]
over a maximum of 30 hops:
1 141 ms 132 ms 140 ms wla-ca-pm6.icg.net [165.236.29.85]
2 134 ms 131 ms 139 ms whv-ca-gw1.icg.net [165.236.29.65]
3 157 ms 132 ms 143 ms f3-1-0.lai-ca-gw1.icg.net [165.236.24.89]
4 194 ms 193 ms 188 ms a0-0-0-1.dai-tx-gw1.icg.net [163.179.235.61]
5 300 ms 211 ms 214 ms a1-1-0-1.ati-ga-gw1.icg.net [163.179.235.186]
6 236 ms 237 ms 247 ms a5-0-0-1.was-dc-gw1.icg.net [163.179.235.129]
7 258 ms 236 ms 244 ms 163.179.243.205
8 231 ms 233 ms 230 ms wdc-brdr-03.inet.qwest.net [205.171.4.153]
9 240 ms 230 ms 236 ms wdc-core-03.inet.qwest.net [205.171.24.69]
10 262 ms 264 ms 263 ms hou-core-01.inet.qwest.net [205.171.5.187]
11 281 ms 263 ms 259 ms hou-core-03.inet.qwest.net [205.171.23.9]
12 272 ms 229 ms 222 ms lax-core-02.inet.qwest.net [205.171.5.163]
13 230 ms 217 ms 230 ms lax-edge-07.inet.qwest.net [205.171.19.58]
14 228 ms 219 ms 220 ms 63-145-160-42.cust.qwest.net [63.145.160.42]
15 218 ms 222 ms 218 ms ISI-7507--ISI.POS.calren2.net [198.32.248.21]
16 232 ms 222 ms 214 ms UCLA--ISI.POS.calren2.net [198.32.248.30]
17 234 ms 226 ms 226 ms cbn5-gsr.calren2.ucla.edu [169.232.1.18]
18 245 ms 227 ms 235 ms www.ucla.edu [169.232.33.129]
Trace complete.
Net Bios Stats
NBTSTAT.exe
Displays protocol statistics and current TCP/IP connections using NBT
(NetBIOS over TCP/IP).
NBTSTAT [-a RemoteName] [-A IP address] [-c] [-n] [-r] [-R] [-s] [S] [interval]
-a (adapter status) Lists the remote machine's name table given its name.
-A (Adapter status) Lists the remote machine's name table given its IP address.
-c (cache) Lists the remote name cache including the IP addresses.
-n (names) Lists local NetBIOS names.
-r (resolved) Lists names resolved by broadcast and via WINS
-R (Reload) Purges and reloads the remote cache name table
-S (Sessions) Lists sessions table with the destination IP addresses.
-s (sessions) Lists sessions table converting destination IP addresses to host names via the
hosts file.
RemoteName Remote host machine name.
IP address Dotted decimal representation of the IP address.
interval Redisplays selected statistics, pausing interval seconds between each display. Press
Ctrl+C to stop redisplaying statistics.
ROUTE.exe
Manipulates network routing tables.
ROUTE [-f] [command [destination] [MASK netmask] [gateway]]
-f Clears the routing tables of all gateway entries. If this is used in conjunction
with one of the commands, the tables are cleared prior to running the command.
command Specifies one of four commands
PRINT Prints a route
ADD Adds a route
DELETE Deletes a route
CHANGE Modifies an existing route
destination Specifies the host to send command.
MASK If the MASK keyword is present, the next parameter is interpreted as the
netmask parameter.
netmask If provided, specifies a sub-net mask value to be associated with this route entry.
If not specified, if defaults to 255.255.255.255.
gateway Specifies gateway.
All symbolic names used for destination or gateway are looked up in the network and host
name database files NETWORKS and HOSTS, respectively.
If the command is print or delete, wildcards may be used for the destination and gateway, or
the gateway argument may be omitted.
ARP.exe Address Resolution Protocol
ARP -s inet_addr eth_addr [if_addr]
ARP -d inet_addr [if_addr]
ARP -a [inet_addr] [-N if_addr]
-a Displays current ARP entries by interrogating the current protocol data. If inet_addr
is specified, the IP and Physical addresses for only the specified computer are
displayed. If more than one network interface uses ARP, entries for each ARP
table are displayed.
-g (Same as -a)
inet_addr Specifies an internet address.
-N if_addr Displays the ARP entries for the network interface specified by if_addr.
-d Deletes the host specified by inet_addr.
-s Adds the host and associates the Internet address inet_addr with the Physical address
eth_addr. The Physical address is given as 6 hexadecimal bytes separated by hyphens.
The entry is permanent.
eth_addr Specifies a physical address.
if_addr If present, this specifies the Internet address of the interface
whose address translation table should be modified. If not present, the first
applicable interface will be used