ioctl {SIOCGIFCONF}

 #include <sys/ioctl.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <net/if.h>

#include <arpa/inet.h>

#include <unistd.h>

#include <stdio.h>

#define MAX_IFS 64

int main(int argc, char **argv) {

    struct ifreq *ifr, *ifend;

    struct ifreq ifreq;

    struct ifconf ifc;

    struct ifreq ifs[MAX_IFS];

    int SockFD;

    SockFD = socket(AF_INET, SOCK_DGRAM, 0);

    ifc.ifc_len = sizeof(ifs);

    ifc.ifc_req = ifs;

    if (ioctl(SockFD, SIOCGIFCONF, &ifc) < 0) {

        printf("ioctl(SIOCGIFCONF): %m/n");

        return 0;

    }

    ifend = ifs + (ifc.ifc_len / sizeof(struct ifreq));

    for (ifr = ifc.ifc_req; ifr < ifend; ifr++) {

        if (ifr->ifr_addr.sa_family == AF_INET) {

            strncpy(ifreq.ifr_name, ifr->ifr_name,sizeof(ifreq.ifr_name));

            if (ioctl (SockFD, SIOCGIFHWADDR, &ifreq) < 0) {

                printf("SIOCGIFHWADDR(%s): %m/n", ifreq.ifr_name);

                return 0;

            }

            printf("Ip Address %s/n", inet_ntoa( ( (struct sockaddr_in *)  &ifr->ifr_addr)->sin_addr));

            printf("Device %s -> Ethernet %02x:%02x:%02x:%02x:%02x:%02x/n", ifreq.ifr_name,

                    (int) ((unsigned char *) &ifreq.ifr_hwaddr.sa_data)[0],

                    (int) ((unsigned char *) &ifreq.ifr_hwaddr.sa_data)[1],

                    (int) ((unsigned char *) &ifreq.ifr_hwaddr.sa_data)[2],

                    (int) ((unsigned char *) &ifreq.ifr_hwaddr.sa_data)[3],

                    (int) ((unsigned char *) &ifreq.ifr_hwaddr.sa_data)[4],

                    (int) ((unsigned char *) &ifreq.ifr_hwaddr.sa_data)[5]);

        }

    }

    return 0;

}