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I found somewhere on the internet that routers also have a MAC address. Is it true? If so, how can I make it undetectable?

Excellll
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user554811
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  • Similar question here. http://superuser.com/questions/802421/can-a-website-see-know-my-mac-address-even-if-i-use-a-vpn – Moab Feb 10 '16 at 16:48
  • Similar Question here...http://security.stackexchange.com/questions/61321/how-can-a-webpage-get-the-mac-address – Moab Feb 10 '16 at 16:49

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Everything that uses Ethernet has a MAC-address, there's no real way to block it out, and besides, why would you? If you block that out, for some reason, it will effectively stop all ARP Communication, which in turn would lead to you not being able to communicate with anything that's connected to and from that router, including your LAN AND the internet.

You can, however, in some cases change the MAC address, and by doing so, mitigating links between your MAC and IP address (provided that you change IP-address as well), but to completely "block" or "erase" the MAC would render your router useless, apart from being a plastic box with some flashing lights on it.

JaggenSWE
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Yes, all devices on your local network will have a MAC address.

MAC addresses are low level addresses, used for local network switching, and are not broadcast to any websites. You do not need to worry about blocking it.

Websites using third party tools or plugins (such as Java) may be able to retrieve it, but simply visiting a website will have no access to this.

Jonno
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  • A)his router's MAC address will be sent to the ISP's router. And that's on the internet. – barlop Feb 10 '16 at 15:34
  • B)I'm not sure but I guess that technically even the computers he has connected to his router, the computers on his LAN, are on the internet. So if you wanted to say it won't leave his LAN then you could but i guess it's still the Internet even within his LAN... And it will leave his LAN too, it just won't go past his ISP's router, but it(his router's MAC), will go past, his router - e.g. upstream beyond his router, one hop. – barlop Feb 10 '16 at 15:35
  • You write "Websites using third party tools or plugins (such as Java) may be able to retrieve it" <--- No Way! – barlop Feb 10 '16 at 15:40
  • @barlop Elabourate? I may just delete this answer as it appears more flawed than I originally believed. – Jonno Feb 10 '16 at 15:42
  • @barlop, it is absolutely true that web-based applications have used client side runtimes like ActiveX/Java/Flash/PDF/etc to query and retreive information about the client that would not otherwise be available. Not sure what your hang up is, but "yes way". – Frank Thomas Feb 10 '16 at 15:45
  • Well, as soon as the packet leaves his router and reaches his ISP's router, his ISP's router will strip off his router's the MAC address.. and send the packet on with the ISP router's MAC address. So indeed a website won't see his router's MAC, but even with a 3rd party tool he won't. – barlop Feb 10 '16 at 15:45
  • @Jonno - You should just fix the answer instead of removing it then flag irrelevant comments to be deleted. – Ramhound Feb 10 '16 at 15:46
  • @FrankThomas that's an interesting concept.. I guess some website plugins could break out of the sandbox and access data on a computer,...then they could probably access a lot more than the MAC address? I guess then they're not getting it over the internet, they're getting it directly from the computer. – barlop Feb 10 '16 at 15:47
  • @barlop A signed, privileged Java applet is not sandboxed, so I didn't feel a blanket "This can never happen" was necessarily the correct answer (Whether it's a concern or not, I don't think a MAC address is too useful outside of a local network anyway). See [here](https://docs.oracle.com/javase/tutorial/deployment/applet/security.html) for information on Java security. – Jonno Feb 10 '16 at 15:52
  • Its also important to remember that your router has multiple MAC addresses (one for each interface WAN, WLAN, LAN) A Java client app could get the MAC of the LAN interface, but the WAN MAC would still be difficult to get. Either way, public websites cannot easily get access to them, and even if they did there's not much they could do with it other than use it as an identifier. – heavyd Feb 10 '16 at 16:01