C: How to get MAC address of your machine using a C program

c-get_eth_mac.c

#include <sys/socket.h>
#include <sys/ioctl.h>
#include <linux/if.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>

int main()
{
    struct ifreq s;
    int fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);

    strcpy(s.ifr_name, "eth0");
    if (0 == ioctl(fd, SIOCGIFHWADDR, &s)) {
        int i;
        for (i = 0; i < 6; ++i)
            printf(" %02x", (unsigned char) s.ifr_addr.sa_data[i]);
        puts("\n");
        return 0;
    }

    return 1;
}