computer network lab mody university of science & technology

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Mody University

Mody University of Science & Technology

College of Engineering & Technology

Computer Network Lab

CS 333

Submitted By Ajay Kumar Singh

Ms. Aratrika Guin Asst. Prof. CSE

Mody University



Mody University

Aratrika 130125 CSE(IIIrd Year) 1-08-2015

1

Experiment-1

AIM : To configure a computer with the college network to access internet.

Steps to be followed are-

DISABLE : a) Right click on „Unidentified Network‟.

b) Click on „Open Network and Sharing Center‟.

c) Go to „Change Adapter Settings‟.

d) Right click on Local Area Connection and click „Disable‟.

e) Right click on Local Area Connection and go to „Properties‟.

f) Click on „Internet Protocol Version 4(TCP /IPv4)‟.

g) Select- (i)Obtain an IP address automatically.

(ii)Obtain DNS server address automatically.

ENABLE : a) Right click on „Unidentified Network‟.

b) Click on „Open Network and Sharing Center‟.

c) Go to „Change Adapter Settings‟.

d) Right click on Local Area Connection and click „Enable‟.

e) Right click on Local Area Connection and go to „Properties‟.

f) Click on „Internet Protocol Version 4(TCP/IPv4)‟.

g) Select „Use of the following IP Address‟ and enter the IP Address, subnet

mask, default gateway, preferred DNS Server, Alternate DNS Server.

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Experiment-2

AIM: To have a study on network devices.

Some of the commonly used network devices are-

HUB : A hub is a hardware device used to connect several computers together. Basically,

hubs are multi slot concentrators into which a number of multiport cards can be plugged

to provide additional access.

Active Hubs – They electrically amplify the signal as it moves from one connected

device to another.

Passive Hubs – They allow the signal to pass from one computer to another

without any change.

Function – Hubs interconnect groups of users. They forward any data packet

including e-mail, word processing documents, spreadsheets- they receive over one port

from one workstation to all the remaining ports. All users connected to a single hub are

in the same segment, sharing the hub‟s bandwidth or data-carrying capacity.

SWITCH : A switch is a device that is used to segment networks into different sub

networks called subnets or LAN segments. Segmenting the network into smaller subnets

prevents traffic overloading in a network.

A switch is responsible for filtering, i.e. transforming data in a specific way andfor forwarding packets between LAN segments.

Function – To insulate the transmission from the other ports, the switch establishes a

temporary connection between source and destination, and then terminates the

connection once the conversion is done.

ROUTER : A router is a network device that is used to separate different segments in a

network to improve performance and reliability. A router works like a bridge but can

handle different protocols.

Function - Routers use a more complete packet address to determine which router or

workstation should receive each packet next. Based on a network road map called the

routing table, routers can help ensure that packets are travelling the most efficient paths

to their destinations. If a link between 2 routers fails, the sending router can determine

an alternate route to keep traffic moving.

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GATEWAY : A gateway is a network device that connects dissimilar networks . It

establishes an intelligent connection between a local network and external networks with

completely different structures.

Function : A gateway is actually a node on a network that serves as an entrance to

another network. In enterprises, the gateway is the computer that routes the traffic from

a workstation to the outside network that is serving the web pages. In homes, the

gateway is the ISP that connects the user to the Internet.

In enterprises, the gateway node often acts as proxy server and a firewall is

designed to prevent unauthorized access.

BRIDGE : A bridge is a network device that establishes an intelligent connection between

two local networks with the same standard but different types of cables.

Function : Bridges know which computers are on which side of the bridge, so they

allow only those messages that need to go to the other side to cross the bridge. As a

packet arrives at the bridge, it examines the physical destination address of packet. The

bridge then decides whether or not to let the packet across.

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Experiment-3

AIM : Write a C program to input an IP Address from user, identify the address

and display the class of IP Address.

PROGRAM-

#include<stdio.h>

#include<conio.h>

void main()

{

int i,arr[4];

clrscr();

printf("Enter the 4 octet values of IP Address : ");

for(i=0;i<4;i++)

scanf("%d",&arr[i]);

i=0;

if(arr[i]>=0 && arr[i]<=127)

printf("\nIP Address lies in Class A..");

else if(arr[i]>=128 && arr[i]<=191)

printf("\nIP Address lies in Class B..");


printf("\nIP Address lies in Class C..");


printf("\nIP Address lies in Class D..");


printf("\nIP Address lies in Class E..");

getch();

}

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OUTPUT-

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Experiment-4

AIM : Write a C program to enter a stream of 7 bits and check whether it is even or odd

parity. Now insert the 8th bit depending on whether the user wants to make the

stream even parity or odd parity.

PROGRAM-

#include<stdio.h>

#include<conio.h>

void main(){

char arr[7];

int i,ctr=0,ch;

clrscr();

printf("\nEnter 7 bits(0 or 1) : ");

for(i=0;i<7;i++)

scanf("%c",&arr[i]);

for(i=0;i<7;i++)

{

if(arr[i]=='1')

ctr++;

}

if(ctr%2==0)

printf("\nEven Parity..");

else

printf("\nOdd Parity..");

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printf("\n1.EVEN PARITY..");

printf("\n2.ODD PARITY..");

printf("\nEnter your choice(1-2) : ");

scanf("%d",&ch);

switch(ch)

{

case 1 : if(ctr%2==0)

arr[7]='0';

else

arr[7]='1';for(i=0;i<8;i++)

printf("%c",arr[i]);

break;

case 2 : if(ctr%2==1)

arr[7]='0';

else

arr[7]='1';

for(i=0;i<8;i++)

printf("%c",arr[i]);

break;

}

getch();

}

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OUTPUT-

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Experiment-5

AIM : Write a C program to identify the class of a given IP Address using string.

PROGRAM-

#include<stdio.h>

#include<conio.h>

#include<stdlib.h>

void main()

{

char ip[4],c[4];

int i,a;

clrscr();

printf("Enter the IP Address : ");

scanf("%s",&ip);

for(i=0;ip[i]!='.';i++)

c[i]=ip[i];

c[i]='\0';

` a=atoi(c);

if(a>=0 && a<=127)

printf("Class A..");

else if(a>=128 && a<=191)

printf("Class B..");

else if(a>=192 && a<=223)

printf("Class C..");

else if(a>=224 && a<=239)

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printf("Class D..");

else if(a>=240 && a<=255)

printf("Class E..");

else

printf("Invalid Address!!");

getch();

}

OUTPUT-

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Experiment-6

AIM : Write a C program to evaluate the IP header checksum.

PROGRAM-

#include<stdio.h>

#include<conio.h>

void main()

{

unsigned int arr[16];

long int checksum,sum=0,carry;

int i;

printf("Enter the IP Address in hexadecimal form : ");

for(i=0;i<16;i++)

{

scanf("%x",&arr[i]);

sum=sum+arr[i];

}

printf("\nThe sum is = %x",sum);

carry=sum>>16;

printf("\nThe carry is = %x",carry);

sum=sum+carry;

checksum=~sum;

printf("\nThe checksum is = %x",checksum);

getch();

}

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OUTPUT-

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Experiment-7

AIM : Write a C program to evaluate Longitudinal Redundancy Check(LRC).

PROGRAM-

//program to evaluate longitudinal redundancy check

#include<stdio.h>

#include<conio.h>

void main()

{

char a[9],b[9],c[9]={"000000000"};

int i;

printf("Enter the 1st string : ");

scanf("%s",&a);

printf("Enter the 2nd string : ");

scanf("%s",&b);

for(i=0;i<8;i++)

{

if(a[i]==b[i])

c[i]='0';

else

c[i]='1';

}

printf("\n");

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for(i=0;i<8;i++)

{

printf("%c",c[i]);

getch();

}

}

OUTPUT-

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The second component of a packet sniffer is the packet analyzer, which displays

the contents of all fields within a protocol message. In order to do so, the packet

analyzer must “understand” the structure of all messages exchanged by protocols. For

example, suppose we are interested in displaying the various fields in messages

exchanged by the HTTP protocol in Fig:1. The packet analyzer understands the format ofEthernet frames, and so can identify the IP datagram within an Ethernet frame. It also

understands the IP datagram format, so that it can extract the TCP segment within the IP

datagram. Finally, it understands the TCP segment structure, so it can extract the HTTP

message contained in the TCP segment. Finally, it understands the HTTP protocol and

so, for example, knows that the first bytes of an HTTP message will contain the string

“GET,” “POST,” or “HEAD”.

Wireshark is a packet analyzer that uses a packet capture library in our

computer. Wireshark is a free network protocol analyzer that runs on Windows,

Linux/Unix, and Mac computers. It‟s an ideal packet analyzer for our labs – it is stable,has a large user base and well-documented support that includes a user-guide and a

detailed FAQ, rich functionality that includes the capability to analyze hundreds of

protocols, and a well-designed user interface. It operates in computers using Ethernet,

Token-Ring, FDDI, serial (PPP and SLIP), 802.11 wireless LANs, and ATM connections.

The Wireshark interface has five major components :

COMMAND MENU : The command menus are standard pulldown menus

located at the top of the window. The Capture menu allows you to begin packet

capture. PACKET-LISTING WINDOW : The packet-listing window displays a one-line

summary for each packet captured, including the packet number, the time at

which the packet was captured, the packet‟s source and destination addresses, the

protocol type, and protocol-specific information contained in the packet.

PACKET-HEADER DETAILS : The packet-header details window provides details

about the packet selected in the packet listing window. These details include

information about the Ethernet frame and IP datagram that contains this packet.

PACKET-CONTENTS WINDOW : The packet-contents window displays the entire

contents of the captured frame, in both ASCII and hexadecimal format.

PACKET DISPLAY FILTER FIELD : Towards the top of the Wireshark graphical

user interface, is the packet display filter field, into which a protocol name or

other information can be entered in order to filter the information displayed in

the packet-listing window.

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FEATURES OF WIRESHARK-

The following are some of the features that wireshark provides-

Available for UNIX and Windows.

Capture line packet data from a network interface.

Open files containing packet data captured with tcpdump/WinDump, Wireshark

and a number of other packet capture programs.

Import packets from text files containing hex dumps of packet data.

Display packets with very detailed protocol information.

Save packet data captured.

Export some or all packets in a number of capture file formats.

Filter packets on many criteria.

Search for packets on many criteria. Colorize packet display based on filters.

Create various statistics.

Plug-ins can be created for dissecting new protocols.

Raw USB traffic can be captured.

VoIP calls in the captured traffic can be detected. If encoded in a compatible

encoding, the media flow can even be played.

Various settings, timers, and filters can be set that ensure only triggered traffic

appear.

Wireless connections can also be filtered as long as they transverse the monitoredEthernet.

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HTTP

Q1) Is your browser running HTTP version 1.0 or 1.1? What version of HTTP is the

server running?

Ans) HTTP/1.1

Q2) What languages (if any) does your browser indicate that it can accept to the server?

Ans) English(US)

Q3) What is the IP address of your computer?

Ans) 10.20.111.11

Q4) What is the status code returned from the server to your browser?Ans) Status code : 200

Q5) When was the HTML file that you are retrieving last modified at the server?

Ans) 0.000115000 seconds

Q6) How many bytes of content are being returned to your browser?

Ans) Captured length : 1400 bytes

Q7) By inspecting the raw data in the packet content window, do you see any headers

within the data that are not displayed in the packet-listing window? If so, name

one.

Ans) Yes, there exists a header in the packet content window.

Header length : 20 bytes

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Experiment-9

OBJECTIVE : To study DOS commands used in computer networking.

The commands used in computer networking are as follows-

Ipconfig(Internet Protocol Configuring)

Description : It displays all current TCP/IP network configuration values and

refreshes Dynamic Host Configuration Protocol(DHCP) and Domain Name

System(DNS) settings. Used without parameters, ipconfig displays the ip address,

subnet mask and default gateway for all adapters.

Syntax : ipconfig

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Ping

Description : Ping works by sending an Internet Control Message Protocol(ICMP)

Echo Request to a specified interface on the network and waiting for a reply. Ping

can be used for troubleshooting to test connectivity and determine response time.

Syntax : ping IP_Address

eg – ping 10.20.111.10

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Netstat

Description : In computing, netstat(network statistics) is a command-line tool

that displays network connections for the Transmission Control Protocol (bothincoming and outgoing), routing tables, and a number of network interface

(network interface controller or software-defined network interface and network

protocol statistics).

Syntax : netstat

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Nslookup

Description : nslookup is a network administration command-line tool available

for many computer operating systems for querying the Domain NameSystem(DNS) to obtain domain name or IP address mapping or for any other

specific DNS record.

Syntax : nslookup

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Tracert

Description : The tracert command is a Command Prompt command that is used

to show several details about the path that a packet takes from the computer or

device we‟re on to whatever destination we specify.

Syntax : tracert IP_Address

eg : tracert 192.168.1.64

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Getmac

Description : getmac returns the media access control (MAC) address and list of

network protocols associated with each address for all network cards in each

computer, either locally or across a network.

Syntax : getmac

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Arp (Address Resolution Protocol)

Description : This command displays and modifies address resolution, including

ATM (Asynchronous Transfer Mode) interfaces.

Syntax : arp – s

arp – d

arp – a

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Experiment-10

AIM : To study the color coding of RJ-45.

INTRODUCTION-

RJ stands for registered jack. RJ-45 is a standard type of connector (UTP) for

network cables. RJ-45 connectors are most commonly seen with Ethernet cables and

networks. RJ-45 connectors feature eight pins to which the wire strands of a cable

interface electrically. It is a keyed connector, meaning the connector can be inserted in

only one way. Standard RJ-45 pin outs define the arrangement of the individual wires

needed when attaching connectors to a cable. RJ-45 interface is typically used for data

transmission, the most common applications for network interface cards. There are two

RJ-45 connector line : straight line, cross line.

APPLICATIONS-

These are used in telephone and data jack wiring registered with FCC. RJ-11 is a 6-

position, 4-conductor jack used in Ethernet wiring and RJ-45 is an 8-position, 8-

conductor jack used in Ethernet wiring i.e. used in Ethernet Networking.

RJ-45 conductor data cable contains 4 pairs of wires each consists of a solid colored

wire and a strip of the same color. There are 2 wiring standards for RJ-45 wiring : T-568A and T-568B. Although there are 4 pairs of wires, Ethernet uses only 2 pairs :

Orange and Green. The other two colors (blue and brown) may be used for a second

Ethernet line or for phone connections. The two wiring standards are used to create a

cross-over cable (T-568A on one end, and T-568B on the other end), or a straight-

through cable (T-568B or T-568A on both ends).

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where,

g→ white/green

G→ green

o→ white/orange

O→ orange

b→ white/blue

B→ blue

br→ white/brown

BR→ brown

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Experiment-11

AIM : Write a program to identify the ipv4 and ipv6 address.

PROGRAM-

//program to check whether an ip address is ipv4 or ipv6.

#include<stdio.h>

#include<conio.h>

#include<stdlib.h>

#include<string.h>

#include<ctype.h>

#include<process.h>

void checkipv4(char[],int);

void checkipv6(char[],int);

void main()

{

char ip[40];

int i,dot=0,colon=0;

clrscr();

printf("Enter an IP address : ");

scanf("%s",&ip);

for(i=0;i<(strlen(ip)-1);i++)

{

if(ip[i]=='.')

dot++;

else if(ip[i]==':')

colon++;

}

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if(dot==3)

checkipv4(ip,dot);

else if(colon==7)

checkipv6(ip,colon);

else

printf("\nNot a valid IP address!!");

getch();

}

void checkipv4(char ip[],int dot)

{char c[5];

int flag=0,i=0,j,k,val;

while(dot>=0)

{

for(j=0;(ip[i]!='.' && i<=strlen(ip));j++,i++)

c[j]=ip[i];

c[j]='\0';

val=atoi(c);

if(val>=0 && val<=255)

flag++;

for(j=0;j<strlen(c);j++)

{

k=toascii(c[j]);

if(k>=48 && k<=57);

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else

{

printf("\nNot an ipv4 address!!");

getch();

exit(0);

}

}

dot--;

i++;

}if(flag==4)

printf("\nThis is an ipv4 address..");

else

printf("\nThis is not an ipv4 address..");

getch();

}

void checkipv6(char ip[],int colon)

{

char c[5];

int i=0,j,k,val;

while(colon>=0)

{

for(j=0;ip[i]!='.' && i<=strlen(ip);j++,i++)

c[j]=ip[i];

c[j]='\0';

if(strlen(c)>4)

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{


getch();

exit(0);

}

for(j=0;j<strlen(c);j++)

{

k=toascii(c[j]);

if(k>=48 && k<=57||k>=65 && k<=70||k>=97 && k<=102);

else{


getch();

exit(0);

}

}

colon--;

i++;

}

printf("\nThis is an ipv6 address..");

getch();

}

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OUTPUT-

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Experiment-12

AIM : Write a C program to evaluate Cyclic Redundancy Check.

PROGRAM-

#include<stdio.h>

#include<conio.h>

#include<string.h>

#define N strlen(g)

void xor();void crc();

char t[20],cs[20],g[10]="1011",e,a,c;

void main()

{

clrscr();

printf("Enter the data : ");

scanf("%s",t);

printf("\nGenerator polynomial is %s",g);

a=strlen(t);

for(e=a;e<a+N-1;e++)

t[e]='0';

printf("\nModified data is %s",t);

crc();

for(e=a;e<a+N-1;e++)

t[e]=cs[e-a];

printf("\nFinal code is %s",t);

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getch();

}

void xor()

{

for(c=1;c<N;c++)

{

if(cs[c]==g[c])

cs[c]='0';

else

cs[c]='1';}

}

void crc()

{

for(e=0;e<N;e++)

cs[e]=t[e];

do

{

if(cs[0]=='1')

xor();

for(c=0;c<N-1;c++)

cs[c]=cs[c+1];

cs[c]=t[e++];

}while(e<=a+N-1);

}

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OUTPUT-

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PROGRAM-13

AIM : Introduction to socket programming.

SOCKET :

A socket is an endpoint of an inter process communication flow across acomputer network. Communication between computers is based on the internetprotocol(IP), therefore most network socket are internet socket.

Concatenation of ip address and port-o

Connection oriented : phone number and receiver.o

Connection less : address and receiver

A socket pair (local IP address, local port, foreign ip port, foreign port)uniquely identifies a communication.

The socket 161.25.19.8.1625 refers to port 1625 on host 161.25.19.8

SOCKET ADDRESS : A socket address is the combination of an ip address and a portnumber, much like one end of a telephone connection is the combination of a phonenumber and a particular extension based on this address, internet socket deliver incomingdata packets to the appropriate application process or thread:-

Example : 161.25.19.8.1625Here ip address is : 161.25.19.8Here port address is : 1625

It is the combination of ip address and ip port.

SOCKET ARCHITECTURE-

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int s = socket(domain, type, protocol);Here, s : socket descriptor, an integer (like a file-handle)

Various header files used-

1. <stdlib.h> :-

Full fro of stdli.h : standard library definitions.

Disriptio : stdlib.h is the header of the general purpose standard library of Cprogramming language which includes functions involving memory allocation,process control, conversions.

2.

<stdio.h> :-

Full for of stdio.h :standard buffered input/output.

Disriptio : It provides general file operation support and supplies functionswith narrow input/output capabilities.

3. <errno.h> :-

Full fro of erro.h : system error numbers

Disriptio : It is having macro reporting error conditions. It points out the errors

in line.

4. <string.h> :-

Full fro of strig.h : standard library function

Disriptio : This header file defines several functions to manipulate C strings andarrays.

5. <sys/socket.h> :-

Full for of sys/soket.h : Internet Protocol familyDisriptio : It defines the macro with distinct integer values for us as the validvalues.

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6. <sys/types.h> :-

Full fro of sys/types.h : data types

Disriptio :Contains data definition. It is usually included before other socketrelated header file.

7. <netinet/in.h>

Full for of etiet/i.h :

Discription : Contain constants and structure defined by intent system. It alsodefines prototypes, macro, variables and sock_adder in structure to use withinternal domain socket.

8.

<unistd.h>

Full for of uistd.h : standard symbolic constants and types

Disriptio : It defines miscellaneous symbolic constants and type and declaremiscellaneous function.

9. <arpa/inet.h>

Full for of arpa/iet.h : definitions for internet operations.

Disriptio : It has functions for manipulating numeric ip address. It definesprototype for those network library routines that convert internet address anddotted-decimal notation.

Memset – It fills memory with constant bytes. It fills the first n bytes of the memory area.

Example:-#include<stdio.h>#include<string.h>void main(){

char ste[]=”it „s my work”; memset(ste,‟*‟,2); puts(ste);

}

Output:-** „s my work

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PREDEFINED FUNCTIONS-

1. htons():-Converts the unsigned short int host short from host byte order to network

byte order.

2. bind():-Used on the server side and associates a socket with a socket address structure.

3. socket():-Creates a new socket of a certain socket type, identified by an integer number.

4. listen():-Used on the server side and causes a bound TCP socket to enter listing state.

5. connect():-Used on the client side and assigns a free local port number to a socket.

6. accept():- Used on the server side. It accepts an incoming receiver. This function is usedto create a new TCP connection from the remote client and create a newsocket associated with the socket address pair of this connection.

7. recvfrom():-

Used for receiving data from remote socket.

8. sendto():-Used for sending data to a remote socket.

9. sizeof():-Used to calculate the size of any data type. It gives result as the number ofbytes.

VARIOUS EDITOR’S USED IN SOCKET PROGRAMMING-

There are three types of editors-

1. vi editor:-It is a screen oriented text editor generally created for the UNIX operating

system. It is the most widely used text editor after gedit. Language supportedwithin these program is described by single UNIX specification

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$viclient_filename.c and then press enter.Press insert key and then write codeTo save a file after typing press Esc and press :wq and then press enter.

2.

gedit:-It is the default text editor of the gnome desktop environment and part of

the gnome core application. It is free and open source software which isdesigned as a general purpose text editor. It includes tools for editing sourcecode structured text such as markup language.

$gedit filename.c and then press enterPress insert key and then write codeTo save a file after typing press Esc and press :wq and then press enter.

3.

Pico editor:-Pine composer is a text editor for UNIX and UNIX based computer system.It does not support working with various files simultaneously and cannotperform a find and replace across multiple files. It also cannot copy text fromone file to another file.

$pico filename.c and then press enterPress insert key and then write codeTo save a file after typing press Esc and press :wq and then press enter.Mody University



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Experiment 14

AIM : A simple demonstration of sending a UDP packet containing the string “Hello

World‼” to address 127.0.0.1, port 8500.

STEP 1 : Open the terminal.

STEP 2 : Type vi clientaratrika.c and then press the Enter key.

STEP 3 : Now a screen will appear. It will be in non-editable mode unless we press

the Insert key.

STEP 4 : Type the code of the client.

Client-

#include<stdlib.h>

#include<stdio.h>

#include<errno.h>

#include<string.h>

#include<sys/socket.h>

#include<sys/types.h>

#include<netinet/in.h>

#include<unistd.h>

#include<arpa/inet.h>

int main()

{

struct sockaddr_in sa;

int bytes_sent;

char buffer[200]= “Hello World‼” ;

int sock=socket(PF_INET,SOCK_DGRAM,IPPROTO_UDP);

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if(-1==sock)

printf(“Error Creating Socket….”);

memset(&sa,0,sizeof(sa));

sa.sin_family=AF_INET;

sa.sin_addr.s_addr=inet_addr=inet_addr(“127.0.0.1”);

sa.sin_port=htons(8500);

bytes_sent=sendto(sock,buffer,strlen(buffer),0,(structsockaddr *)&sa,sizeof(sa));

if(bytes_sent<0)

printf(“Error sending packet : \ n”);

close(sock);

return(0);

}

STEP 5 : Press Escape key from the keyboard and type :wq . Then press the Enter key.

STEP 6 : Type vi serveraratrika.c and press the Enter key.

STEP 7

: Now, a new screen will appear. It is in non-editable mode until and unlesswe press the Enter key.

STEP 8 : Type the code of the server.

Server-

#include<stdlib.h>

#include<stdio.h>

#include<errno.h>

#include<string.h>



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#include<unistd.h>


int main()

{


char buffer[1024];

ssize_t recsize;

socklen_t fromlen;




sa.sin_addr.s_addr=inet_addr=INADDR_ANY;


fromlen=sizeof(sa);if(-1==bind(sock,(structsockaddr *)&sa,sizeof(sa)));

printf(“Error bind failed‼”);

for(;;)

{

printf(“Recv test…. \ n”);

recsize=recvfrom(sock,(void *)buffer,sizeof(buffer),0,(structsockaddr

*)&sa,&fromlen);

if(recsize<0)

printf(“strderr”);

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}

printf(“Recsize : %d \ n”,recsize);

sleep(1);

printf(“Datagram : %s \ n”,buffer);

}

STEP 9 : Press Escape key from the keyboard and type :wq. Then press the Enter key.

STEP 1 : In the terminal write down gcc – o clientaratrika.c.

STEP 11 : In the terminal write down gcc – o serveraratrika.c.

STEP 12 : If the above two statements return shell prompt, then it means there is no

error. Otherwise first resolve the error.

STEP 13 : Close all the windows.

STEP 14 : On the 1st terminal, type ./serveraratrika and press the Enter key.

STEP 15 : On the 2nd terminal, type ./clientaratrika and press the Enter key.

STEP 16 : The output is shown below-

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PROGRAM-15

AIM : A simple demonstration of sending a UDP packet containing a number to address

127.0.0.1, port 8500 and receiving a square of it.


STEP 2 : Type vi bclient2.c and then press the Enter key.

STEP 3 : Now a screen will appear. It will be in non-editable mode unless we press the

Insert key.


Client-#include<stdlib.h>

#include<stdio.h>

#include<errno.h>

#include<string.h>




#include<unistd.h>


int main()

{


int bytes_sent;

char buffer[200],newbuffer[1024];

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ssize_t recsize;

socklen_t fromlen;


if(-1==sock)

printf("Error creating socket..");



sa.sin_addr.s_addr=inet_addr("127.0.0.1");


fromlen=sizeof(sa);

printf("Enter the number : ");

gets(buffer);

bytes_sent=sendto(sock,buffer,strlen(buffer),0,(struct sockaddr *)&sa,sizeof(sa));

if(bytes_sent<0)

printf("Error sending packet..:\n");

recsize=recvfrom(sock,(void *)newbuffer,sizeof(newbuffer),0,(struct sockaddr

*)&sa,&fromlen);

printf("%s",newbuffer);

close(sock);

return(0);

}

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STEP 6 : Type vi bserver2.c and press the Enter key.

STEP 7 : Now, a new screen will appear. It is in non-editable mode until and unless we

press the Enter key.


Server-

#include<stdlib.h>

#include<stdio.h>

#include<errno.h>

#include<string.h>




#include<unistd.h>


int main(void)

{


char buffer[1024],newbuffer[1024];

int n,square,bytes_sent;

ssize_t recsize;

socklen_t fromlen;


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sa.sin_addr.s_addr=INADDR_ANY;


fromlen=sizeof(sa);

if(-1==bind(sock,(struct sockaddr *)&sa,sizeof(sa)));

printf("Error bind failed..");

for(;;)

{

printf("Recv test....\n");

recsize=recvfrom(sock,(void *)buffer,sizeof(buffer),0,(struct sockaddr

*)&sa,&fromlen);

if(recsize<0)

printf("stderr");

}

printf("Recsize : %d\n",recsize);

sleep(1);

printf("Datagram : %s\n",buffer);

n=atoi(buffer);

square=n*n;

sprintf(newbuffer,"%d",square);

printf("%s",newbuffer);

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bytes_sent=sendto(sock,newbuffer,strlen(newbuffer),0,(struct sockaddr

*)&sa,sizeof(sa));

}


STEP 1 : In the terminal write down gcc – o bcient2.c.

STEP 11 : In the terminal write down gcc – o bserver2.c.


error. Otherwise, first resolve the error.


STEP 14 : On the 1st terminal, type ./bandana1 and press the Enter key.

STEP 15 : On the 2nd terminal, type ./bandana and press the Enter key.

STEP 16 : The output is shown below-Mody University



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PROGRAM-16

AIM : A simple demonstration of sending a TCP packet containing a string in lower case

to address 127.0.0.1, port 7891 and receiving the same string with the characters in

uppercase.


STEP 2 : Type vi client.c and then press the Enter key.


Insert key.

STEP 4

: Type the code of the client.Client-

#include<stdio.h>



#include<string.h>

int main()

{

int clientSocket,portNum,nBytes;

char buffer[1024];

struct sockaddr_in serverAddr;

socklen_t addr_size;

clientSocket=socket(PF_INET,SOCK_STREAM,0);

portNum=7891;

serverAddr.sin_family=AF_INET;

serverAddr.sin_port=htons(portNum);

serverAddr.sin_addr.s_addr=inet_addr("127.0.0.1");

memset(serverAddr.sin_zero,'\0',sizeof serverAddr.sin_zero);

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addr_size=sizeof serverAddr;

connect(clientSocket,(struct sockaddr *)&serverAddr,addr_size);

while(1)

{printf("Type a sentence to send to server : \n");

fgets(buffer,1024,stdin);

printf("You typed : %s",buffer);

nBytes=strlen(buffer)+1;

send(clientSocket,buffer,nBytes,0);

recv(clientSocket,buffer,1024,0);

printf("\nReceived from serner : %s\n\n",buffer);

}

return 0;

}


STEP 6 : Type vi server.c and press the Enter key.




Server-

#include<stdio.h>


#include<netinet/in.h>#include<string.h>

#include<stdlib.h>

int main()

{

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int welcomeSocket,newSocket,portNum,clientLen,nBytes;

char buffer[1024];

struct sockaddr_in serverAddr;

struct sockaddr_storage serverStorage;socklen_t addr_size;

int i;

welcomeSocket=socket(PF_INET,SOCK_STREAM,0);

portNum=7891;

serverAddr.sin_family=AF_INET;

serverAddr.sin_port=htons(portNum);

serverAddr.sin_addr.s_addr=inet_addr("127.0.0.1");

memset(serverAddr.sin_zero,'\0',sizeof serverAddr.sin_zero);

bind(welcomeSocket,(struct sockaddr *)&serverAddr,sizeof(serverAddr));

if(listen(welcomeSocket,5)==0)

printf("Listening..\n");

else

printf("Error!!\n");

addr_size=sizeof serverStorage;

while(1)

{

newSocket=accept(welcomeSocket,(struct sockaddr *)&serverStorage

,&addr_size);

if(!fork())

{

nBytes=-1;

while(nBytes!=0)

{

nBytes=recv(newSocket,buffer,1024,0);

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

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buffer[i]=toupper(buffer[i]);

send(newSocket,buffer,nBytes,0);

}

close(newSocket);exit(0);

}

else

close(newSocket);

}

return(0);

}


STEP 1 : In the terminal write down gcc – o cclient client.c.

STEP 11 : In the terminal write down gcc – o sserver server.c.




STEP 14 : On the 1st terminal, type ./cclient and press the Enter key.

STEP 15 : On the 2nd terminal, type ./sserver and press the Enter key.


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PROGRAM-17

AIM : A simple demonstration of a chat application using TCP.


STEP 2 : Type vi client.c and then press the Enter key.


Insert key.


Client-

#include<stdio.h>#include<string.h>



int main(int argc, char *argv[])

{

int sock;

struct sockaddr_in server;char message[1000],server_reply[2000];

sock = socket(AF_INET,SOCK_STREAM,0);

if(sock == -1)

printf("could not create socket");

puts("Socket created");

server.sin_addr.s_addr = inet_addr("127.0.01");

server.sin_family = AF_INET;

server.sin_port = htons(8888);

if(connect(sock ,(struct sockaddr *)&server , sizeof(server))<0)

{

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perror("connect failed.Error");

return 1;

}

puts("connected\n");while(1)

{

printf("Enter message: ");

scanf("%s",message);

if(send(sock, message, strlen(message),0)<0)

{

puts("Send failed");

return 1;

}

if(recv(sock ,server_reply, 2000,0)<0)

{

puts("recv failed");

break;

}

puts("Server reply : ");

puts(server_reply);

}

close(sock);

return 0;

}


STEP 6 : Type vi server.c and press the Enter key.



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Server-

#include<stdio.h>

#include<string.h>



#include<unistd.h>

int main(int argc, char *argv[])

{

int socket_desc,client_sock,c,read_size;

struct sockaddr_in server , client;

char client_message[2000];

socket_desc= socket(AF_INET, SOCK_STREAM,0);

if(socket_desc == -1)

printf("Could not create socket");

puts("Socket Created");

server.sin_family= AF_INET;server.sin_addr.s_addr = INADDR_ANY;

server.sin_port = htons(8888);

if(bind(socket_desc,(struct sockaddr *)&server , sizeof(server))<0)

{

perror("bind failed.Error");

return 1;

}puts("bind done");

listen(socket_desc,3);

puts("Waiting for incoming connections...");

c = sizeof(struct sockaddr_in);

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client_sock = accept(socket_desc,(struct sockaddr*)&client,(socklen_t*)&c);

if(client_sock<0)

{

perror("accept failed");return 1;

}

puts("Connection accepted");

while((read_size = recv(client_sock,client_message,2000,0))>0)

write(client_sock,client_message,strlen(client_message));

if(read_size == 0)

{

puts("Client disconnected");

fflush(stdout);

}

else if(read_size == -1)

perror("recv failed");

return 0;

}


STEP 1 : In the terminal write down gcc – o cli client.c.

STEP 11 : In the terminal write down gcc – o serv server.c.




STEP 14 : On the 1st terminal, type ./cli and press the Enter key.

STEP 15 : On the 2nd terminal, type ./serv and press the Enter key.


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PROGRAM-18

AIM : A simple demonstration of client-server application for date and time using TCP

protocol in which a client application initiates a request to a server application for

current date and time. The server gives response with the correct date and time to

the client.


STEP 2 : Type vi clientara.c and then press the Enter key.


Insert key.STEP 4 : Type the code of the client.

Client-



#include<stdio.h>

#include<stdlib.h>

#include<string.h>

main()

{

struct sockaddr_in sa,cli;

int n,sockfd;

int len;

char buff[100];sockfd=socket(AF_INET,SOCK_STREAM,0);

if(sockfd<0)

{

printf("Error in socket!!");

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exit(0);

}

else

printf("\nSocket is opened..");bzero(&sa,sizeof(sa));



if(connect(sockfd,(struct sockaddr*)&sa,sizeof(sa))<0)

{

printf("\nError in connection failed!!");

exit(0);

}

else

printf("\nConnected successfully..");

if(n=read(sockfd,buff,sizeof(buff))<0)

{

printf("\nError in reading!!");

exit(0);

}

else

printf("\nMessage read %s",buff);

}

STEP 5

: Press Escape key from the keyboard and type :wq. Then press the Enter key.STEP 6 : Type vi serverara.c and press the Enter key.




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Server-



#include<string.h>

#include<stdio.h>

#include<stdlib.h>

#include<time.h>

int main()

{


struct sockaddr_in cli;

int sockfd,conntfd;

int len,ch;

char str[100];

time_t tick;

sockfd=socket(AF_INET,SOCK_STREAM,0);

if(sockfd<0)

{

printf("Error in socket!!");

exit(0);

}

else

printf("\nSocket opened..");

bzero(&sa,sizeof(sa));sa.sin_port=htons(5600);

sa.sin_addr.s_addr=htons(0);

if(bind(sockfd,(struct sockaddr*)&sa,sizeof(sa))<0)

printf("\nError in binding!!");

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else

printf("\nBinded successfully..");

listen(sockfd,50);

for(;;){

len=sizeof(ch);

conntfd=accept(sockfd,(struct sockaddr*)&cli,&len);

printf("\nAccepted..");

tick=time(NULL);

snprintf(str,sizeof(str),"%s",ctime(&tick));

printf("%s",str);

write(conntfd,str,100);

}

}


STEP 1 : In the terminal write down gcc – o clie clientara.c.

STEP 11 : In the terminal write down gcc – o serv serverara.c.




STEP 14 : On the 1st terminal, type ./cli and press the Enter key.

STEP 15 : On the 2nd terminal, type ./serv and press the Enter key.


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