netip.c

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <netinet/in.h>

int main(int argc, char * argv[]) {
  if (argc < 5) {
    fprintf(stderr,"usage: %s device ipaddr netmask gateway\n", argv[0]);
    return 1;
  }
  char dev[100];
  snprintf(dev,100,"/dev/net/%s", argv[1]);
  int netdev = open(dev,O_RDWR);
  if (netdev < 0) return netdev;
  int status;
  in_addr_t ip = inet_addr(argv[2]);
  if ((status = ioctl(netdev, SIOCSIFADDR, &ip))) return status;
  ip = inet_addr(argv[3]);
  if ((status = ioctl(netdev, SIOCSIFNETMASK, &ip))) return status;
  ip = inet_addr(argv[4]);
  if ((status = ioctl(netdev, SIOCSIFGATEWAY, &ip))) return status;
  return 0;
}