BCSL-056 (Network Programming and Administration Lab)
BCSL-056 Network Programming and Administration Lab (Assignments Solution)
Course Code : BCS-056
Course Title : Network Programming and Administration Lab
Assignment Number : BCA(V)051/Assignment/2024-25
Maximum Marks : 50
Weightage : 25%
Last Date of Submission : 31stOctober,2024(For July, Session)
30thApril, 2025(For January, Session)
Q1 (a): Write and execute a TCP client and a server program in C-language to perform the following tasks:
Ans.
TCP Server Program (C)
The server listens for connections from a client, accepts the connection, and then responds to the client's message.
// TCP Server in C
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#define PORT 8080
#define BUFFER_SIZE 1024
int main() {
int server_fd, new_socket;
struct sockaddr_in address;
int addrlen = sizeof(address);
char buffer[BUFFER_SIZE] = {0};
char *response = "Hello from server";
// Creating socket file descriptor
if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
perror("socket failed");
exit(EXIT_FAILURE);
}
// Binding the socket to the port
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_ANY;
address.sin_port = htons(PORT);
if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
perror("bind failed");
exit(EXIT_FAILURE);
}
// Listening for incoming connections
if (listen(server_fd, 3) < 0) {
perror("listen failed");
exit(EXIT_FAILURE);
}
printf("Server is waiting for a connection...\n");
// Accepting the incoming connection
if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {
perror("accept failed");
exit(EXIT_FAILURE);
}
// Reading the message from the client
read(new_socket, buffer, BUFFER_SIZE);
printf("Message from client: %s\n", buffer);
// Sending a response to the client
send(new_socket, response, strlen(response), 0);
printf("Response sent to client\n");
close(new_socket);
close(server_fd);
return 0;
}
TCP Client Program (C)
The client connects to the server, sends a message, and then waits for the server's response.
// TCP Client in C
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#define PORT 8080
#define BUFFER_SIZE 1024
int main() {
int sock = 0;
struct sockaddr_in serv_addr;
char *message = "Hello from client";
char buffer[BUFFER_SIZE] = {0};
// Creating socket file descriptor
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
printf("\n Socket creation error \n");
return -1;
}
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(PORT);
// Convert IPv4 and IPv6 addresses from text to binary form
if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr) <= 0) {
printf("\nInvalid address / Address not supported \n");
return -1;
}
// Connecting to the server
if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
printf("\nConnection failed \n");
return -1;
}
// Sending message to the server
send(sock, message, strlen(message), 0);
printf("Message sent to server\n");
// Receiving server's response
read(sock, buffer, BUFFER_SIZE);
printf("Response from server: %s\n", buffer);
close(sock);
return 0;
}
Steps to Compile and Run
Compile the server:
(a) Configure and Test the Telnet Server in Linux
Telnet is an old protocol used to access remote servers. Here's how to configure and test a Telnet server on Linux.
Steps to Configure the Telnet Server:
Install the Telnet server package: First, ensure that the Telnet server is installed. On most Linux distributions, you can install the
telnetdpackage using a package manager.For Debian/Ubuntu:
xinetd, you need to enable the Telnet service by editing the configuration file. Open the /etc/xinetd.d/telnet file:
sudo nano /etc/xinetd.d/telnet
Add or modify the configuration based on your network settings:
# Set the domain name and domain name servers option domain-name "example.com"; option domain-name-servers ns1.example.com, ns2.example.com; # Set the default lease time and maximum lease time default-lease-time 600; max-lease-time 7200; # Configure the network segment the DHCP server will serve subnet 192.168.1.0 netmask 255.255.255.0 { range 192.168.1.10 192.168.1.100; # IP range to assign option routers 192.168.1.1; # Default gateway option broadcast-address 192.168.1.255; }Assign Network Interfaces: Specify which network interfaces should run the DHCP service. Edit
/etc/default/isc-dhcp-server(for Debian-based systems) or/etc/sysconfig/dhcpd(for CentOS/RHEL).Debian/Ubuntu:
INTERFACESv4="eth0"CentOS/RedHat:
DHCPDARGS="eth0"Restart the DHCP Service: Restart the DHCP server service to apply the new configuration.
For Debian/Ubuntu:
sudo systemctl restart isc-dhcp-serverFor RedHat/CentOS:
sudo systemctl restart dhcpdAllow DHCP through the Firewall: If you have a firewall enabled, allow DHCP communication through the firewall.
For
ufw(on Debian/Ubuntu):sudo ufw allow 67/udp sudo ufw reloadFor
firewalld(on CentOS/RHEL):sudo firewall-cmd --add-service=dhcp --permanent sudo firewall-cmd --reloadTest the DHCP Server: Test the DHCP server by configuring a client to obtain an IP address automatically and checking if it gets an IP from the specified range.
Sorting a Table in Linux
You can sort columns of a table or a file by using the sort command in Linux. Here's how to sort a table:
Create a sample file with tabular data: Let's say you have a file named
data.txtwith the following content:Name Age Salary John 28 5000 Jane 30 6000 Mike 25 4000 Amy 35 7000Sort the table by the second column (Age): Use the
sortcommand with the-koption to specify the column number.sort -k2 -n data.txtSort the table by the third column (Salary):
sort -k3 -n data.txt
The sorted output will be printed on the screen. Use the -r option to sort in reverse order if needed:
sort -k3 -nr data.txt
#CODEWITHCHIRAYU Thank You 😊
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