What's the difference between a Mac Address and an IP Address?

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why cant we replace IP system by MAC system, bcoz MAC address is going to be unique as similar to IP Address instead of sending source IP address we can transmit Source MAC address, why cann't we do that? i am also not clear "MAC Adress travels no further than the next router or equivalent network interface" !!!!

For how long the MAC Address remains stored in the router's memory?

Dear sir,
The ip address at any given time in the internet is unique to a host. if so then why is mac address even required?
can't ip address be used to recognise the host inside the network too?

I think that mac address & ip addrss is same but from this i know the difference. Nice to share this info. I usually found one site to find the ip address from http://www.ip-details.com/ to get the ip address.

Dear Leo,
this information is really very valuable.
I have a keen interest in network security methods in current times and I wanted to ask something to clarify some things for myself ...

I have a system that connects to a router which further connects to my modem.
when i do ipconfig/all, i get the mac address of my ethernet port, not the router or modem, which i can check using the interface for the respective device. if my understanding is correct, my mac address does not go past the router, coz it changes there to the address of the router which further changes to the address of the modem and so on ...
however, at the site "http://www.ipaddresslocation.org/find-mac-address.php" it uses java to find the mac address of my ethernet card.

this is what brings me to my question... as you said, "So your MAC address doesn't make it out very far. Even if someone knows your MAC address, that knowledge certainly doesn't help anyone do anything either good or bad." just as the site used java to find my original mac address, can't a similar process be applied to trace a person/machine's location on the internet.
also, there are proxy service providers, both free and paid softwares, that change the external ip address of a machine. in theory, is ip address tracking the only professional way of tracing a person/machine's original address?
my understanding is that the sender's ip is included in the chat/email/post that is received at the other end, and these proxy servers/softwares change that header info to keep it anonymous. i know legal intervention is required, but is the packet info that contains the IP address the only way of tracing the origin or does it also have mac address info of the originating machine/person?
Please help me understand this better.
Thanks in advance.
Best Regards.

Please be clear...we are trying to trace an e mail...we have an IP...probably a public access point...now we want to try to find the mAC address of the computer that sent that mail from that public connection??? Is it possible? Does the router retain that address? This access point was used to access a hushmail account and that account send the mail we are interested in tracing.

The router sees too many MAC addresses to remember them all. I suppose some routers could be keeping a log, but in general they do not.

09-Oct-2009

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