How to get mac address in string format(actual format )

Question

How can we get MAC Address in asp.net
 
I have seen some articles and with the help of those article i can get mac address
but it gets address in "00114313D615" this format
 
but actual format is like this 
 
"00-11-43-13-D1-65"
 

so how can i get mac address in actual format which is connected with internet

because in 1 system multiple Card can be used