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I read so many topics on the net about what happens if there is the same mac address used on different computers on the same network but i would like to know what exactly happens if someone for example got my phone's mac address from a hotspot network and impersonated me, but i no longer use that network and instead i use the one at home for example. can that person still receive the packets intended for me or will it be useless?

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The MAC address is used on the datalink layer, not routing layer. Simply put, this means when you talk through a router, the MAC address does not carry "through" it, and you cannot reach "back through" that router to the original host using just the MAC address.

So, unless the attacker was on the same network as you, the attacker cannot do anything to you. It will be useless.

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so does that mean he cant see what i do online, even if he is on the same ISP as mine? sorry if my Q is stupid but i have very little knowledge abt these things. – curiouscat May 31 '13 at 10:13
No problem. We are all here to learn. If you are behind your own router (i.e. cable modem connected to router, then your machines connected to this router) there is no way. I believe it could possibly theoretically be possible if you had your PC directly connected a cable modem, as cable modems function as "bridges" (i.e. work on the datalink layer) and you are on a shared medium with others - but I'm betting it would likely be limited to others in your same immediate local area. – LawrenceC May 31 '13 at 11:50
thanks for answering me, this is a relief – curiouscat May 31 '13 at 17:48

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