Add default gateway route using ioctl

defaultGatewayIoctlSet.c

#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <net/route.h>
#include <sys/types.h>
#include <sys/ioctl.h>

int main(char** args) {
  int sockfd;
  struct rtentry route;
  struct sockaddr_in *addr;
  int err = 0;

  // create the socket
 if((sockfd = socket(AF_INET, SOCK_DGRAM, 0)))<0){
perror("socket");
exit(1);
}

  memset(&route, 0, sizeof(route));
  addr = (struct sockaddr_in*) &route.rt_gateway;
  addr->sin_family = AF_INET;
  addr->sin_addr.s_addr = inet_addr("192.168.2.1");
  addr = (struct sockaddr_in*) &route.rt_dst;
  addr->sin_family = AF_INET;
  addr->sin_addr.s_addr = INADDR_ANY;
  addr = (struct sockaddr_in*) &route.rt_genmask;
  addr->sin_family = AF_INET;
  addr->sin_addr.s_addr = INADDR_ANY;
  // TODO Add the interface name to the request
  route.rt_flags = RTF_UP | RTF_GATEWAY;
  route.rt_metric = 0;
  if ((err = ioctl(sockfd, SIOCADDRT, &route)) != 0) {
    perror("SIOCADDRT failed");
    exit(1);
  }
}