Re: How to find MAC address

[Brandon Enright <bmenrigh () ucsd edu>]

On Fri, 2006-03-31 at 00:19 -0800, uday kumar kunta wrote:
> Hi all,
>    
>    I am not able to get the MAC address if the IP address is not in the same class.
>   Can you please tell me the Nmap Option which finds the MAC for any IP address.
>    
>   For example: I using the IP 171.11.22.35(My system)
>   $nmap -O 171.11.22.0-255    => It is showing the MAC addresses resp.
>   But when i am running nmap for other series of IP it is not showing the MAC.
>   $nmap -O 171.11.25.0-255  =>It is not showing the MAC details.
>    
>   Please help me.
>    
>   Regards,
>   Uday.

What you are asking for is not possible with Ethernet networking.  When
your IP packets have to cross a network boundary by way of a router the
real destination MAC address is masked by the router.

Read up on the interaction between networking layers 2 and 3 and it will
become clear why this is so.

Brandon

-- 
Brandon Enright
Network Security Analyst
UCSD ACS/Network Operations
bmenrigh@ucsd.e



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