Strange Firewall Behaviour

Discussion in 'Mac OS X Lion (10.7)' started by YoungLew, Sep 11, 2011.

  1. YoungLew macrumors regular

    Jun 8, 2009
    Hey everyone,

    I've noticed something strange with the Firewall on OSX Lion.

    When stealth mode is on, my MBA will not respond to pings from another machine. Which is how its supposed to work.

    However, if i ping my MBA with an MTU size of 1492 from another machine i then get ping responses, even though Stealth mode is enabled. It also responds when you block all incoming connections.

    Can anyone explain why this is so? It does not do it with other MTU sizes such as 1200, 1300 or 1400. But it will respond when pinging with an MTU size of 1500, 1492, 1484, and 1476. Curiously it won't respond to anything lower than 1476.

    I'm not particularly concerned, its just something i noticed and wondered if there was a logical explanation.

    When i am pinging my MBA it is from a Windows machine (XP SP3) i haven't got another OSX device to try it with. I have got a Windows 7 machine but i haven't tried it with that either.

    Any info is appreciated.

  2. YoungLew thread starter macrumors regular

    Jun 8, 2009
    Nobody else noticed that the Firewall 'Stealth Mode' is anything but stealth then?

    If the computer is still visible on the network when it should be 'invisible' i'd say it was an issue, unless theres a logical reason.

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