Implement get HWAddress

Hi, I'm new here, I need some little help here, I have this code and I need get the MAC ADDRESS too, I tried few ways, but I dont had lucky.

Code:

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

int main()
{
  struct ifconf conf;
  struct sockaddr_in *s_in;
  int sock, i, count;

  // Abrir um socket nulo
  if ((sock = socket(PF_INET, SOCK_DGRAM, 0)) == -1)
  {
    perror("erro ao abrir o socket.");
    return -1;
  }

  // Pega lista de interfaces de rede, so os 10 primeiros.
  memset(&conf, 0, sizeof(conf));
  conf.ifc_len = sizeof(struct ifreq) * 10;
  conf.ifc_buf = (char*) malloc(conf.ifc_len);
       
  if (ioctl(sock, SIOCGIFCONF, &conf) == -1)
  {
    perror("falha ao pegar a lista de interfaces de rede");
    return -1;
  }

  count = conf.ifc_len / sizeof(struct ifreq);

  for (i = 0; i < count; i++)
  {
    s_in = (struct sockaddr_in*) &conf.ifc_req[i].ifr_addr;
    printf("%s %s\n", conf.ifc_req[i].ifr_name,
                      inet_ntoa(s_in->sin_addr));
  }

  free(conf.ifc_buf);

  return 0;
}

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thanks in advance.

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