Determine MAC Address

Determine MAC Address:
The MAC (Media Access Control) address is an identifier that is associated with a network adapter and uniquely identifies a device on a network. A MAC address consists of 12 hexadecimal numbers, typically formatted as follows

XX:XX:XX:YY:YY:YY

The XX values in a MAC address identify the manufacturer, the YY values are the serial number assigned to the network adapter.

The MAC address can be useful if you need a way to uniquely identify a device – this can be used as a substitute for the UDID value that is now deprecated in iOS 5 and greater.



The code below shows how to get the MAC address on an iOS device:

#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;
size_t              length;
unsigned char       macAddress[6];
struct if_msghdr    *interfaceMsgStruct;
struct sockaddr_dl  *socketStruct;
NSString            *errorFlag = NULL;

// 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";
else
{
// Get the size of the data available (store in len)
if (sysctl(mgmtInfoBase, 6, NULL, &length, NULL, 0) < 0)
errorFlag = @"sysctl mgmtInfoBase failure";
else
{
// Alloc memory based on above call
if ((msgBuffer = malloc(length)) == NULL)
errorFlag = @"buffer allocation failure";
else
{
// Get system information, store in buffer
if (sysctl(mgmtInfoBase, 6, msgBuffer, &length, NULL, 0) < 0)
errorFlag = @"sysctl msgBuffer failure";
}
}
}

// Befor going any further...
if (errorFlag != NULL)
{
NSLog(@"Error: %@", errorFlag);
return errorFlag;
}

// Map msgbuffer to interface message structure
interfaceMsgStruct = (struct if_msghdr *) msgBuffer;

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

// Copy link layer address data in socket structure to an array
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;
}

The output will look as follows: Mac Address: E0:F8:47:C0:E3:C9