How to change MAC addres via C code.

Ayalaskin · 04-12-2010, 03:11 PM

Hi Guys.
I need a way to change the machine MAC address via a C code in linux.
Ive find a way to retrieve it but not to change it.

If someone could help, i will appreciate very much.

Thanks in advance.

Sergei Steshenko · 04-12-2010, 04:09 PM

Quote:

Originally Posted by Ayalaskin

Hi Guys.
I need a way to change the machine MAC address via a C code in linux.
Ive find a way to retrieve it but not to change it.

If someone could help, i will appreciate very much.

Thanks in advance.

AFAIR MAC address can be changed using 'ifconfig', so a logical step would be to look into 'ifconfig' source.

haikan · 04-12-2010, 05:43 PM

I'll just assume you know MAC addresses are best left untouched, and that you have a valid reason for wanting to change it. Something like this should work:

Code:

#include <stdio.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include <assert.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <net/if_arp.h>
#include <net/if.h>
#include <string.h>
#include <errno.h>

int main(int argc, char **argv) {
	struct ifreq ifr;
	int s;

	s = socket(AF_INET, SOCK_DGRAM, 0);
	assert(s != -1);

	strcpy(ifr.ifr_name, "eth0");
	ifr.ifr_hwaddr.sa_data[0] = 0xDE;
	ifr.ifr_hwaddr.sa_data[1] = 0xAD;
	ifr.ifr_hwaddr.sa_data[2] = 0xBE;
	ifr.ifr_hwaddr.sa_data[3] = 0xEF;
	ifr.ifr_hwaddr.sa_data[4] = 0xCA;
	ifr.ifr_hwaddr.sa_data[5] = 0xFE;
	ifr.ifr_hwaddr.sa_family = ARPHRD_ETHER;
	assert(ioctl(s, SIOCSIFHWADDR, &ifr) != -1);

	return EXIT_SUCCESS;
}

--
Oscar Endre Edvardsen

Ayalaskin · 04-13-2010, 12:00 AM

Thanks for the tip, ioctl worked great, besides its hard reading documentation.

Its for a college work, the teacher asked us to do a program to manage MAC address.

David1357 · 04-13-2010, 10:15 AM

Quote:

Originally Posted by haikan

I'll just assume you know MAC addresses are best left untouched, and that you have a valid reason for wanting to change it.

When someone asks such a simple question, you should always start with the assumption it is a homework assignment, until proven otherwise. If you must give help, give hints, not answers.