[GTALUG] FCC "forces" TP-Link to enable open source on their router(s)

D. Hugh Redelmeier hugh at mimosa.com
Mon Aug 1 22:19:05 EDT 2016


| From: James Knott via talk <talk at gtalug.org>

| On 08/01/2016 05:27 PM, D. Hugh Redelmeier via talk wrote:
| > So the original problem remains: how can TP-Link prevent existing
| > hardware from generating too strong signals if it cannot control the
| > firmware?
| 
| The limits might be hard coded elsewhere.

No, they are not.  That's the problem:

1) FCC has made a new rule that manufacturers are to prevent customers
from breaking the signal strength limitations.

2) current and past hardware is "dumb" and depends on software to do
correct configuration (sensible from an engineering standpoint)

Bonus complexity: the power limits and channel frequencies depend on
the country you are currently in.  If the device has to enforce this
then it needs to know the country and probably not trust the user to
get it right.  Second best: sell a different model in each country.

Alternative solutions:

a) customers must not be allowed to replace the software
(pretty easy and cheap; works on existing hardware)

b) new hardware with "smart" radios that know not to accept violating
parameters (this requires a new generation of devices, ones that are
more complicated and likely more expensive; probably one device per
jurisdiction).

c) some kind of sandboxing of user-supplied firmware.  This seems to be
mentioned in the article.  This is probably the most complicated
solution.  It would probably increase the engineering and
manufacturing cost, all for a small minority of customers.  And it
actually limits the reach of the third party firmware in unintended ways.

z) ignore the FCC.

Only (a) can be retrofitted on existing hardware.  TP-Link did the
obvious thing.  I hate it (as a customer who actually bought one of
their devices to run OpenWRT).  But it really is a choice between (a)
and (z) on existing devices.

TP-Link seems to be the first manufacturer to stop doing (z).

The FCC's reaction seems to suggest that they really didn't think
through what their rule meant.  They really ought to clarify it.
Perhaps they think that users shouldn't easily be able to violate the
signal strength standards, but that flashing firmware isn't "easy".

=====================

The same problem exists in the cellphone world.  It used to be that 
there was a "baseband processor" which was kind of the gatekeeper to the 
radio.  Android or whatever lived on another processor.  They communicated 
with AT commands, just like a Hayes modem!  But at least some systems have 
eliminated the baseband processor.


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