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Finding MAC Addresses (Computer IDs)

Posted: Tue Dec 06, 2005 7:37 pm
by Lang
Is there a way in PHP that I can grab MAC Addresses. Some friends and I are creating a game and want to stop the creation of multiple accounts. So in order to do so, as logging IP addresses and trying to match them doesn't always work with users using dial-up, proxies ect.
we'd like to learn how to log MAC Addresses.

First off, is this legal?
Second, is it possible?
Third, how do I do it?

Thanks in advance,

Posted: Tue Dec 06, 2005 7:54 pm
by RobertPaul
As far as I know, MAC addresses are only used on LANs. So no, you can't do that over the internet.

Posted: Tue Dec 06, 2005 9:02 pm
by Ambush Commander
The closest alternative is IP addresses, but they're a bit iffy.

Posted: Tue Dec 06, 2005 10:09 pm
by josh
I've seen some require a verified email issued by your ISP to signup, and flagging accounts with emails that don't match their white-list of ISP domains

Posted: Tue Dec 06, 2005 10:36 pm
by BDKR
The reason this can't work is becuase the indiviudals MAC address will not be propogated (to the best of my knowledge) beyond his gateway. You won't even be able to get the MAC address of the outside interface on his Gateway.

Posted: Wed Dec 07, 2005 11:09 am
by pickle
As far as I know, the MAC address would only be stored on their DHCP host. Or, if they have static IPs, not even there. A MAC address is not transmitted across the Internet.

Posted: Thu Dec 15, 2005 7:12 am
by BDKR
pickle wrote:As far as I know, the MAC address would only be stored on their DHCP host. Or, if they have static IPs, not even there. A MAC address is not transmitted across the Internet.
As it turns out, almost every box in the network that has needed to communicate with his is probably storing his MAC address via an arp table. Same goes for switches, which is why they're so much better then hubs in terms of dealing with network congestion.

From a linux command line, type in "arp -n" and you should see a dump of the kernels arp table.

Cheers,
BDKR

Posted: Thu Dec 15, 2005 4:57 pm
by timvw
BDKR wrote:
pickle wrote:As far as I know, the MAC address would only be stored on their DHCP host. Or, if they have static IPs, not even there. A MAC address is not transmitted across the Internet.
As it turns out, almost every box in the network that has needed to communicate with his is probably storing his MAC address via an arp table. Same goes for switches, which is why they're so much better then hubs in terms of dealing with network congestion.

From a linux command line, type in "arp -n" and you should see a dump of the kernels arp table.
But you don't need to know the mac addresses of hosts in a different ethernetwork..
http://www.erg.abdn.ac.uk/users/gorry/c ... ridge.html

Posted: Thu Dec 15, 2005 6:46 pm
by BDKR
timvw wrote: But you don't need to know the mac addresses of hosts in a different ethernetwork..
http://www.erg.abdn.ac.uk/users/gorry/c ... ridge.html
Of course, but that's not what we're talking about anyways.

Posted: Thu Dec 15, 2005 8:53 pm
by Roja
BDKR wrote:
timvw wrote: But you don't need to know the mac addresses of hosts in a different ethernetwork..
http://www.erg.abdn.ac.uk/users/gorry/c ... ridge.html
Of course, but that's not what we're talking about anyways.
Lang wrote:So in order to do so, as logging IP addresses and trying to match them doesn't always work with users using dial-up, proxies ect.
You don't (generally) use a proxy on the same network. The described problem set implies different networks.

MAC addresses are generally only propogated one network wide, so for the original requestor the answer is generally no - he won't be able to capture them.