Had a conversation with a co-worker that left me scratching my head. Searching the Intrawebz was fruitless in finding an answer. Anyway my coworker was having some speed issues and was working with a level 2 tech over the phone on the fix. He uses cable Internet.
While helping the tech, the tech mention that he could see the internal MAC addresses of my coworkers network externally. As the tech read them out, my coworker was able to verify that it was his and his roommates equipment. How is this possible?
It's my understand that MAC's are only visible if you are connected to the same subnet. Once a packet leaves the network the packet will obtain the MAC of the routers WAN port.