C program to Set Computer System IP Address in Linux.

This program will set the IP Address of Linux System using C program.

Set IP Address in Linux using C program


/*C program to set IP Address of Linux Computer System.*/

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

#include <sys/socket.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <net/if.h>
#include <arpa/inet.h>

int main()
{
    unsigned char ip_address[15];
    int fd;
    struct ifreq ifr;
    struct sockaddr_in *addr;
    
    /*Read IP Address*/
    printf("Enter Ip Address: ");
    scanf("%s",ip_address);
    
    /*AF_INET - to define network interface IPv4*/
    /*Creating soket for it.*/
    fd = socket(AF_INET, SOCK_DGRAM, 0);
    
    /*AF_INET - to define IPv4 Address type.*/
    ifr.ifr_addr.sa_family = AF_INET;
    
    /*eth0 - define the ifr_name - port name
    where network attached.*/
    memcpy(ifr.ifr_name, "eth0", IFNAMSIZ-1);
    
    /*defining the sockaddr_in*/
    addr=(struct sockaddr_in *)&ifr.ifr_addr;
    
    /*convert ip address in correct format to write*/
    inet_pton(AF_INET,ip_address,&addr->sin_addr);
    
    /*Setting the Ip Address using ioctl*/
    ioctl(fd, SIOCSIFADDR, &ifr);
    /*closing fd*/
    close(fd);
    
    printf("IP Address updated sucessfully.\n");
    
    /*Getting the Ip Address after Updating.*/
    
    /*clear ip_address buffer with 0x20- space*/
    memset((unsigned char*)ip_address,0x20,15);
    ioctl(fd, SIOCGIFADDR, &ifr);
    /*Extracting Ip Address*/
    strcpy(ip_address,inet_ntoa(((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr));
    
    printf("Updated IP Address is: %s\n",ip_address);
    
    return 0;
}

    Enter Ip Address: 152.167.0.80
    IP Address updated sucessfully. 
    Updated IP Address is: 152.167.0.80

The details of the functions and structures in the previous program – C program to Get the IP Address of the Linux System.

Using system()


#include <stdio.h>
#include <stdlib.h> /*for system function*/

/*define port name where network attached*/
#define ifr_name "eth0"

int main()
{
    unsigned char ip_address[15], command[100];
    
    printf("Enter Ip address: ");
    scanf("%s",ip_address);
    
    /*make command*/
    sprintf((char*)command,"ifconfig %s %s",ifr_name, ip_address);
    
    /*run command*/
    system(command);
    
    printf("Ip updated sucessfully.\n");
    
    return 0;
}

    Enter Ip Address: 152.167.0.80
    Ip updated sucessfully.