Finiding MAC Address

 Every computer in this world has unique address called   MAC(Media Access Control) address.This is also called physical
address or LAN address or NIC address or Ethernet address or
Hardware address or node address.It contains 48 bits.

1)Click on the Start Menu .
2)Click on 'Run'.
3)Type 'cmd' without quotes and press Enter.
4) At the command prompt, type 'ipconfig /all' without quotes. (space between g and /)
5)Alternatively, if using Windows XP, you can use the command 'getmac'.
6)Your MAC Address is listed under 'Physical Address' as a series of 6 groups of two digits, letters and numbers, separated by dashes, such as in the image below. 
(Make sure you get the physical address of the correct network adapter - usually there are several listed.)

Finding MAC Address For Linux:

Instructions: 

     1.Click the GNOME menu "Applications" and "Accessories.".

     2.Click "Terminal" to open a command prompt window (terminal) in Linux.

     3. In RedHat, Fedora Linux; type "/sbin/ipconfig" and press "Enter." 

     4.In Ubuntu, Debian Linux; type "ifconfig" and press "Enter."

     5.  Look for the line in the program output that contains the string "HWaddr=" followed by characters. 
          Those characters are MAC address. For example, "HWAaddr=02:1D:A8:8C:B6:86."