Madhav Kobal's Blog

This blog will be dedicated to Linux, Open Source and Technology news, affairs, how-tos and virtually EVERYTHING in these domains.

Change The MAC Address Of Your Machine

Posted by madhavkobal on 20/08/2009

Consider this scenario. I am connected to the internet using a cable modem. And my ISP dynamically allocates the IP address to my machine. But they also store the MAC address of my ethernet card and associate it with the IP address they provide. Suppose I change my NIC(or my machine), I will not be able to log on to the net because my ethernet card has a different MAC address than the one stored in thedatabase of the ISP.
The immediate short fall of this is that, I have to contact my ISP through telephone and request them to reset the MAC address table (or what ever) in their database to point to my new MAC address. So if I knew my old MAC address, I could easily fool the ISP to think that I am using the original machine by setting the MAC address of my new machine to the old value. And I could save myself a telephone call.

# ifconfig eth0 down
# ifconfig eth0 hw ether 00:80:48:BA:d1:20
# ifconfig eth0 up
# ifconfig eth0 |grep HWaddr

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