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Mac Address Question ifconfig

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mahimahi

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Hi

I was playing around with changing the HWaddr on eth0.

It worked great.

My question is can I change the HWaddr to a 8byte address instead of a 12 byte address?

Can I use the HW Class Address in ifconfig to achieve that?

If yes what are the syntax for the
different class? ether, ax25, ARCnet, netrom

I am currently using this scipt to change mac address

#ifconfig eth0 down
#ifconfig eth0 hw ether 11:22:33:44:55:66 up
#ifconfig eth0 | grep HWaddr


Thanks in advance
 

mr_ghz

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Hello mahimahi

A hardware adress is not 12 bytes long, it is only 48 bits (=6 bytes) long.
You can see this also in your ifconfig line: you define it with 6 8-Bit values,
this gives 48 bits.
The length of this HW-address is fix in the low-level protocol and can not
be changed. It is possible, that you set the first I will say 16 bits to zero,
so you have a 32bit address (is that what you are looking for?)
But this is a little bit critical: It is not allowed, that 2 devices has the
same MAC (HW) address. So normally this MAC is splitted in 2 times
24 bits. The first 24Bits define the manufacturer of the HW (e.g. Ethernet-
card) the second 24Bits are a unique number. So every Network-Adaptor
has an own (unique) MAC-address.
If you now change the first bits to zero, it's (theoretically) possible, that
another card has the same MAC-address... But if you use it in your own
(private) network it's possible.

Greets
 

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