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Changed MAC address prevent software updates?

Discussion in 'Model S' started by brec, Apr 17, 2016.

  1. brec

    brec Member

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    I installed a Wi-Fi extender in my house so that my Model S would have a good Wi-Fi signal in my garage. The extender causes my router to see a fake MAC address for the car.

    Would this be a problem for Tesla's update servers? The reason I ask is that both of the last two software updates were received not long after the car left home and was without Wi-Fi. 2.12.126 was received on Feb. 26, the first night I was away from home on a trip. 2.16.17 was received on Apr. 11, while parked a few miles from home about 30 minutes after the car left my garage. Or at least those were the times of the iPhone app notifications of an available update.

    Maybe coincidence, but enough to make me wonder.

    I don't have a problem contacting the car to get charge status or control HVAC, etc., via the iPhone app.
     
  2. eclipxe

    eclipxe Member

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    An extender doesn't change the src MAC address
     
  3. green1

    green1 Active Member

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    The notification is not when is available, but after its already downloaded. If you got a notification 30 mins after leaving home, it's a pretty good bet the download happened at home.
     
  4. brec

    brec Member

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    In the router's client list the first half (the first three hex pairs) of the car's MAC address are changed. If I look at the extender's client list, the car's MAC address is unchanged.

    Now, it's true that for all I know the MAC address as seen by the router doesn't figure at all in communications with the outside world -- I don't know anything about TCP/IP or UDP internals -- and if Tesla cares about the car's MAC address it would be internal to some car-to-server message. In which case the answer to my original question would be the same as the answer you imply, i.e., No.
     
  5. brec

    brec Member

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    Sorry, by available I meant available for installation, as I was aware notification follows download. Why, though, would there be an interval between download completion and notification?
     
  6. deonb

    deonb Active Member

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    Correct. The MAC address doesn't leak out of a local subnet unless the original device somehow sends its own address somewhere using another mechanism... in which case it doesnt care (or know) that there was a bridge somewhere in the topology.
     
  7. brec

    brec Member

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    Thanks.

    ...I'm not seeing any way to edit a thread's title or OP to indicate "answered" or "never mind!".
     
  8. whitex

    whitex Member

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    Others are correct, MAC address is only seen on a local subnet (unless it's used to generate IPv6 address, but in that case it's no longer a MAC address). Your setup should be capable of receiving updates as long as you can browse the internet from the car using WiFi (go to whatismyip.com if you need to verify that you are in fact using your home internet rather than cellular connection of the car). The only exception to that is if you have a firewall that blocks UDP or OpenVPN packets.
     

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