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    SubjectRe: bug causes tcp/ip stack corruption
    Hi all.

    >> On all modem I know the ``+++'' string has to be preceeded and
    >> followed by a second pause; the exact length is configurable.
    >> Since SLIP and PPP packets are always longer than three bytes,
    >> this should not ever happen?

    > You know that, I know that. Piles of crap modem makes apparently
    > dont

    The official Prestel modem from way back had a curious 'feature' in
    this respect: If it received the sequence '+++' following a pause in
    excess of 1.5 seconds (the fixed delay on that particular model), it
    then paused for 1.5 seconds, queueing up any characters that arrived
    during the pause without sending them. If, at the end of that pause,
    its buffer was empty, it knew to switch to command mode, otherwise it
    just sent all the characters that had arrived to the far end...use it
    with a system set to echo characters back, and the modem at the far
    end is highly likely to switch to command mode...

    Another thing worth noting is that the character used in that string
    is programmable on most modern modems, with '+' being the default. If
    something changes that character, some other sequence of three
    consecutive identical characters will result in the same behaviour
    whilst '+++' will have no effect...

    Best wishes from Riley.

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      Last update: 2005-03-22 13:46    [W:0.027 / U:8.068 seconds]
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