C program to get mac address from interface name on Linux

The mac address or the hardware address or the ethernet address of an interface is a 48 bit number that looks like this : 00:1c:c0:f8:79:ee
The mac address of an interface can be found given its name. The function to use is ioctl.
Code

#include <stdio.h> //printf
#include <string.h> //strncpy
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h> //ifreq
#include <unistd.h> //close

int main()
{
int fd;
struct ifreq ifr;
char *iface = "eth0";
unsigned char *mac;

fd = socket(AF_INET, SOCK_DGRAM, 0);

ifr.ifr_addr.sa_family = AF_INET;
strncpy(ifr.ifr_name , iface , IFNAMSIZ-1);

ioctl(fd, SIOCGIFHWADDR, &ifr);

close(fd);

mac = (unsigned char *)ifr.ifr_hwaddr.sa_data;

//display mac address
printf("Mac : %.2x:%.2x:%.2x:%.2x:%.2x:%.2x\n" , mac, mac, mac, mac, mac, mac);

return 0;
}

Output
$ gcc interface_mac.c && ./a.out
Mac : 00:10:0c:28:89:1e
Last Updated On : 11th September 2012...

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C program to get mac address from interface name on Linux