# Which one of these are "unique" for a network card?



## TechnicalFreak (Jun 4, 2009)

Is the MAC adress or the IP number "unique" for a network card, which one can I or the ISP not change?


Thankful for any replies given.


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## Chomes (Jun 4, 2009)

Normally its the MAC address of the network card, because it saved on the eeprom of the card, however you can change it.
The IP can be static or dinamic (dependending on the ISP, you can't change them, they can), and it will be an open IP, and when you are behind a router, for your home network you will have private IP, ( 192.168.xxx.xxx, you can change) or something similar.


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## Mussels (Jun 4, 2009)

MAC addresses cannot be changed.

Without the context, we cant give you any more information.


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## Ptep (Jun 4, 2009)

Mussels said:


> *MAC addresses cannot be changed*.
> 
> Without the context, we cant give you any more information.



You can, its known as MAC spoofing.


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## Mussels (Jun 4, 2009)

Ptep: you cannot CHANGE the mac address on the card.

You can fake it on a software level via spoofing, but that will not change the MAC address in the card itself.


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## Ptep (Jun 4, 2009)

Mussels said:


> Ptep: you cannot CHANGE the mac address on the card.
> 
> You can fake it on a software level via spoofing, but that will not change the MAC address in the card itself.



Sorry, yes you are right, I wasnt thinking of it in that way


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## TechnicalFreak (Jun 4, 2009)

Thanks for the replies everyone. So the MAC adress is there all the time, cannot be changed but "spoofed", right? And the IP adress can be changed but not by me, but my ISP and I can change the IP but only on the router (the 192.168.xx.xx, which I do have since I am behind a router)?

And what about *Physical Adress*, can this be changed by user or is this also something that is random on every machine??


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## Chomes (Jun 4, 2009)

TechnicalFreak said:


> Thanks for the replies everyone. So the MAC adress is there all the time, cannot be changed but "spoofed", right? And the IP adress can be changed but not by me, but my ISP and I can change the IP but only on the router (the 192.168.xx.xx, which I do have since I am behind a router)?
> 
> And what about *Physical Adress*, can this be changed by user or is this also something that is random on every machine??



Well  the MAC address is something that can not be changed, it can be faked/spoofed, so it seems you have that @MAC, but nothing more. The @MAC address is unique for every network device, it has 12 digits(HEXAGESIMAL), the first 6 are from the manufacturer, so all products from the same manufacturer have the same 6 first digits equal, and the other 6 are different, so there won't be 2 products with same @MAC address. 

About @IP i think you get it wrong, maybe I've explained bad, you have 1 public ip, whatever you have a router or not, this one is assigned by the ISP and can't be changed,if you have a router, then you've got a private network.  If it's a router&modem all in one, it will have the public address, and the private address, public will be for outside your home and the private will be for local network, however if you have a modem and a router , the modem will have the public ip and the router the private IP. You can only change the IP for the local network.

And finally the Phisical Address  or @MAC, can't be changed as stated before, can be faked, spoofed,and the numbers are not random as I explained at the begining.


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## Mussels (Jun 5, 2009)

Physical address is MAC address.

You seem on the right track with the ip.

You get one WAN (wide area network) IP address - the internet one. If you use a modem, this will show up in windows.  

If you use a router, your WAN IP is shared between all PC's via NAT (network address translation) - so only the router has that IP really, all your other PC's show up with LAN addresses (Which can be changed at will, really)


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