#include <sys/socket.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/if_dl.h>

- (NSString *)getMacAddress
{
int mgmtInfoBase[6];
char *msgBuffer = NULL;
NSString *errorFlag = NULL;
size_t length;

// Setup the management Information Base (mib)
mgmtInfoBase[0] = CTL_NET; // Request network subsystem
mgmtInfoBase[1] = AF_ROUTE; // Routing table info
mgmtInfoBase[2] = 0;
mgmtInfoBase[3] = AF_LINK; // Request link layer information
mgmtInfoBase[4] = NET_RT_IFLIST; // Request all configured interfaces

// With all configured interfaces requested, get handle index
if ((mgmtInfoBase[5] = if_nametoindex("en0")) == 0)
errorFlag = @"if_nametoindex failure";
// Get the size of the data available (store in len)
else if (sysctl(mgmtInfoBase, 6, NULL, &length, NULL, 0) < 0)
errorFlag = @"sysctl mgmtInfoBase failure";
// Alloc memory based on above call
else if ((msgBuffer = malloc(length)) == NULL)
errorFlag = @"buffer allocation failure";
// Get system information, store in buffer
else if (sysctl(mgmtInfoBase, 6, msgBuffer, &length, NULL, 0) < 0)
{
free(msgBuffer);
errorFlag = @"sysctl msgBuffer failure";
}
else
{
// Map msgbuffer to interface message structure
struct if_msghdr *interfaceMsgStruct = (struct if_msghdr *) msgBuffer;

// Map to link-level socket structure
struct sockaddr_dl *socketStruct = (struct sockaddr_dl *) (interfaceMsgStruct + 1);

// Copy link layer address data in socket structure to an array
unsigned char macAddress[6];
memcpy(&macAddress, socketStruct->sdl_data + socketStruct->sdl_nlen, 6);

// Read from char array into a string object, into traditional Mac address format
NSString *macAddressString = [NSString stringWithFormat:@"%02X:%02X:%02X:%02X:%02X:%02X",
macAddress[0], macAddress[1], macAddress[2], macAddress[3], macAddress[4], macAddress[5]];
NSLog(@"Mac Address: %@", macAddressString);

// Release the buffer memory
free(msgBuffer);

return macAddressString;
}

// Error...
NSLog(@"Error: %@", errorFlag);

return errorFlag;
}