Date: Fri, 19 Dec 2008 10:44:32 +0100 (CET) From: Oliver Fromme <olli@lurza.secnetix.de> To: maksim.yevmenkin@gmail.com (Maksim Yevmenkin) Cc: freebsd-bluetooth@freebsd.org Subject: Re: Bluetooth socket timeout, device pairing Message-ID: <200812190944.mBJ9iWKp086368@lurza.secnetix.de> In-Reply-To: <bb4a86c70812182151q44cd1225o1c05aa5cd86bd4be@mail.gmail.com>
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Hello Max,
Maksim Yevmenkin wrote:
> Oliver,
>
> > My Bluetooth Python module basically works now.
> > However, I've got one small problem with pairing ...
> >
> > I have entered an 8-character PIN code in hcsecd.conf.
> > When I try to open a connection for the first time,
> > the device (i.e. my Mindstorms NXT brick) asks me to
> > enter the PIN code. However, entering the code on
> > the brick takes some time ... I have to scroll
> > through the alphabet and digits which is rather slow.
> > I can enter at most 4 characters of the PIN code
> > before the socket() call returns with ECONN
> > ("Connection refused").
> >
> > For now I'm using a short 4-character PIN code, but
> > I would really like to use a longer one. Where is
> > the timeout defined for that?
>
> its so called "LMP (link manager protocol) response timeout". its
> defined in link manager, i.e. part of the device's firmware. v1.1 spec
> seems to be implying that LMP response timeout should be set to 30
> sec.
>
> > Python's socket module has no timeout by default.
> > I've also searched the net.bluetooth sysctls and
> > increased all of the timeout values (half a dozen),
> > but none of them seemed to have an effect on this
> > particular problem. So I think this value must be
> > hardcoded somewhere. Where do I have to look?
>
> i'm afraid that you can not change LMP response timeout. there isn't
> any defined command that would do that. i'm not sure why do you care
> much about pin length. pin is only used once to generate link key and
> as soon as link key is generated both devices should use it instead of
> pin.
Thankyou very much for the explanation.
It was my impression that the length of the PIN code has
to do with the security (i.e. the longer, the better).
It seems I was wrong.
Is it correct that it would even be secure enough to use
the public default factory PIN code of the device ("1234")?
In that case I could skip the whole business of entering
a PIN code ...
Best regards
Oliver
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Now I just read C code instead."
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