How do I get the ethernet address of a network interface?


To find the ethernet address of a network interface requires using the DLPI
ethernet ioctls.  The following program shows how to issue the low-level ioctl
to read the ethernet address of the interface.

	#include <sys/types.h>
	#include <sys/dlpi_ether.h>
	#include <sys/dlpi_common.h>
	#include <stropts.h>
	#include <unistd.h>

	int main(int argc,char *argv[])
	{
		int fd, status;
		struct strioctl strcmd;
		unsigned char addr[6];

		fd = open(argv[1],0,0);
		if (fd == -1) {
			perror("enaddr: open");
			exit(1);
		}

		strcmd.ic_cmd = DLIOCGENADDR;
		strcmd.ic_timout = 0;
		strcmd.ic_len = sizeof(addr);
		strcmd.ic_dp = addr;

		status = ioctl(fd,I_STR,&strcmd);
		if (status == -1) {
			perror("enaddr: ioctl");
			exit(1);
		}

		printf("%02.2x:%02.2x:%02.2x:%02.2x:%02.2x:%02.2x\n",addr[0],addr[1],addr[2],addr[3],addr[4],addr[5]);
	}

Save the file then do the following.

	<saved as a.c>

	# cc -D_KMEMUSER a.c -o enaddr
	# 
	# netstat -in
	Name   Mtu   Network     Address      Ipkts   Ierrs Opkts   Oerrs Collis
	lo0    8232  127.0.0.0   127.0.0.1        0     0       0     0      0
	ie0    1500  129.134.36  129.134.36    5204     0     619     0      0
	# ./enaddr /dev/ie0
	00:00:c3:02:64:ab

Here we see that the ie0 interface's ethernet address is 00:00:c3:02:64:ab.

For more information see DLioctl(3).