[Battlemesh] Linksys promises not to block free firmware

[David Lang]

On Sat, 14 May 2016, Jonathan Morton wrote:

>> On 14 May, 2016, at 08:01, Mitar <mitar at tnode.com> wrote:
>> 
>> The best way to win is to go for a solution which works for both
>> fighting parties. Do we know of such a solution?
>
> The fundamental goal of the FCC (and the EU equivalent) is to prevent 
> interference to existing licensed users of the 5GHz “unlicensed” band.  Our 
> best chance of success is to minimise the probability of such interference, 
> and to show that it is indeed minimised.

making an app that scans/reports on questionable use of APs would show how small 
the problem is. If we can show that there are a lot of people running the app 
and reporting that there are not problems near the airports in question, and 
shows where people are using these frequencies, then we can show that the 
problem they fear happening is not actually happening.

> In the 2.4GHz band, compliance would be straightforward to achieve in an 
> internationally-compatible manner, by shipping devices which can only transmit 
> on channels 1-11.

I'm pretty sure that there are countries where not all of channels 1-11 are 
allowed.

But by default, OpenWRT doesn't set a country code, and so the channels allowed 
default to the least common denominator.

> In fact, the easiest way to make a wifi device transmit on an unauthorised 
> frequency is to tell it to use a regulatory domain different from the one it’s 
> actually in.  With my (draft-n standard) Airport Base Station, this is 
> *unavoidable* if I were to take it outside the EU where it was sold; the 
> settings app only lists EU countries, so I cannot set “USA” or “Japan” or 
> “Korea".  And yes, I have been known to pack a cache of networking gear on 
> business trips abroad, just in case - and this has actually proved worthwhile 
> on occasion.

not to mention all the devices sold on E-Bay and other sites. It's very common 
for people to end up with devices from the 'wrong' country this way.

> I think it is noteworthy that most instances of radar interference encountered 
> in practice are from *outdoor* installations where the equipment has been 
> *deliberately modified*, not only to disable the radar-detection logic but to 
> increase the power and efficiency of transmission (this requiring *hardware* 
> modifications).  No doubt this was often done to take advantage of channels 
> left relatively clear by compliant equipment.

Not just that, it's almost always Wireless ISP providers who actually get 
licenses for their operation on these bands because they do operate at higher 
power levels.

> On the face of it, enforcement should be directed against the owners and 
> operators of such networks, who I assume are relatively few in number.  This 
> however sets the calibre of our adversary; he is *not* a typical home user. 
> The heavy-handed approach of the regulators (given that they seek a technical 
> rather than legal solution) is thus explainable.

These users also tend to have much more to loose in a regulatory action against 
them.

> But there is still an easy workaround which this sort of adversary will soon 
> find: buy the equipment abroad, and it will be set for a different regulatory 
> domain anyway.  The shipping cost will be a little higher, that’s all.  No 
> technical expertise required on the end-user’s part, and the only defence 
> would be to outlaw the *importation* of wifi devices set to the wrong region, 
> which would be impossible to enforce.

Yep, you don't block someone from deliberatly breaking the law by passing more 
laws against the behavior.

game console hacks have shown how even the most motivated companies have been 
unable to produce hardware that can't be broken.

> And that is why locking down the firmware is ultimately futile.  Anyone with 
> sufficient motivation to set up an outdoor network can obtain devices with 
> properly locked-down firmware, regulation-compliant in their intended country 
> of sale, which transmit on whatever channel they want - as long as there is at 
> least one region which does not restrict transmission on that channel for wifi 
> devices.
>
> That doesn’t necessarily mean we should have a free-for-all - but it does 
> suggest that locking down the region setting is the wrong approach.  It would 
> be just as effective to enforce a chain of trust between the regulatory 
> authority and the domain settings that are loaded into the radio hardware, 
> with the choice of region left up to the user.  Some devices might use 
> geolocation to eliminate user error here - this is probably easiest with 
> phones being used as mobile hotspots.  The option could be left open for 
> separate domain settings for amateur-radio licence holders, though this would 
> not be in the default firmware issued at retail.
>
> This radio hardware, incidentally, is at Layer 1 of the networking stack - the 
> physical layer.  There is little controversy over locking that down to a 
> reasonable extent.  Almost all the things we’re interested in tweaking are at 
> Layer 2 (MAC) and above (IP, etc).  So far, wifi hardware has not bothered to 
> separate these layers cleanly, which is really what we need here.

It's also important to remember that operation on the DFS channels is perfectly 
legal in the vast majority of the US, it's only if you are near one of the 50 
radar installations that you can't use some of them.

David Lang