Unable to set my channel with hostapd

[Gene Heskett]

On Monday 29 April 2013 08:22:07 Francisco Cuesta did opine:

> Hi Luciano,
> 
> Thanks in advance,
> 
> I have modified my regulatory data base for USA in order to be able to
> use that channel
> 
>  iw reg get
> country US:
>     (2412 - 2484 @ 40), (3, 27)
>     (4400 - 4940 @ 40), (N/A, 31)
>     (4910 - 4990 @ 20), (N/A, 31)
>     (5170 - 5250 @ 40), (N/A, 31)
>     (5250 - 5330 @ 40), (N/A, 31), DFS
>     (5490 - 5600 @ 40), (N/A, 31), DFS
>     (5650 - 5710 @ 40), (N/A, 31), DFS
>     (5735 - 6480 @ 40), (N/A, 31)
> 
> But even though, I was getting the same error, do you have another good
> idea?
> 
> thanks again!
> 
> 2013/4/29 Luciano Coelho <coelho at ti.com>:
> > On Mon, 2013-04-29 at 12:01 +0300, Luciano Coelho wrote:
> >> Hi Francisco,
> >> 
> >> On Mon, 2013-04-29 at 10:27 +0200, Francisco Cuesta wrote:
> >> > Hello,  thanks for replying,
> >> > 
> >> > I'm using ath9k driver in openwrt with hostapd v2.0-devel.
> >> > 
> >> > iw reg get
> >> > 
> >> >     (2412 - 2472 @ 40), (3, 27)
> >> >     (5170 - 5250 @ 40), (N/A, 31)
> >> >     (5250 - 5330 @ 40), (N/A, 31), DFS
> >> >     (5490 - 5600 @ 40), (N/A, 31), DFS
> >> >     (5650 - 5710 @ 40), (N/A, 31), DFS
> >> 
> >> Here you can see that the channel you want to use is not allowed by
> >> the regulatory code.  It seems that you're using "00" as the country
> >> (world).  From the regulatory database [1], you can see that channel
> >> 196 (4980 MHz) is only allowed in Japan (regulatory country "JP").
> > 
> > Forgot to paste the link to the regulatory database:
> > 
> > http://git.kernel.org/cgit/linux/kernel/git/linville/wireless-regdb.gi
> > t/tree/db.txt
> > 
> >> > iw list
> >> > 
> >> > Frequencies:
> >> >             * 5180 MHz [36] (17.0 dBm)
> >> >             * 5200 MHz [40] (21.0 dBm)
> >> >             * 5220 MHz [44] (17.0 dBm)
> >> >             * 5240 MHz [48] (17.0 dBm)
> >> >             * 5260 MHz [52] (17.0 dBm) (radar detection)
> >> >             * 5280 MHz [56] (17.0 dBm) (radar detection)
> >> >             * 5300 MHz [60] (17.0 dBm) (radar detection)
> >> >             * 5320 MHz [64] (17.0 dBm) (radar detection)
> >> >             * 5500 MHz [100] (17.0 dBm) (radar detection)
> >> >             * 5520 MHz [104] (21.0 dBm) (radar detection)
> >> >             * 5540 MHz [108] (21.0 dBm) (radar detection)
> >> >             * 5560 MHz [112] (21.0 dBm) (radar detection)
> >> >             * 5580 MHz [116] (21.0 dBm) (radar detection)
> >> >             * 5600 MHz [120] (disabled)
> >> >             * 5620 MHz [124] (disabled)
> >> >             * 5640 MHz [128] (disabled)
> >> >             * 5660 MHz [132] (17.0 dBm) (radar detection)
> >> >             * 5680 MHz [136] (17.0 dBm) (radar detection)
> >> >             * 5700 MHz [140] (17.0 dBm) (radar detection)
> >> >             * 5745 MHz [149] (21.0 dBm)
> >> >             * 5765 MHz [153] (21.0 dBm)
> >> >             * 5785 MHz [157] (21.0 dBm)
> >> >             * 5805 MHz [161] (21.0 dBm)
> >> >             * 5825 MHz [165] (20.0 dBm)
> >> >             * 4915 MHz [183] (21.0 dBm)
> >> >             * 4920 MHz [184] (21.0 dBm)
> >> >             * 4925 MHz [185] (21.0 dBm)
> >> >             * 4930 MHz [186] (21.0 dBm)
> >> >             * 4935 MHz [187] (21.0 dBm)
> >> >             * 4940 MHz [188] (21.0 dBm)
> >> >             * 4945 MHz [189] (21.0 dBm)
> >> >             * 4960 MHz [192] (21.0 dBm)
> >> >             * 4980 MHz [196] (21.0 dBm)
> >> 
> >> This shows that the driver supports 4980, but it won't be able to use
> >> it if the regulatory doesn't allow it.
> >> 
> >> > But, could you explain me the reason behing I get this error, I
> >> > mean, what does it mean, for instance  problem with the interface,
> >> > the channel isn't supported by the driver ..., I would like to
> >> > understand it, not just resolve it.
> >> 
> >> This is because the radio regulations in the country you're choosing
> >> ("world" is a set of frequencies that is valid in *every* country)
> >> doesn't allow WiFi operation on the channel you want to use.  You can
> >> only legally use channel 196 in Japan.  So, if you are in Japan, you
> >> can do this:
> >> 
> >> iw reg set JP
> >> 
> >> And hostapd should work on that channel.  If you're not in Japan,
> >> doing this is not legal, so you should better choose a different
> >> channel instead. ;)
> > 
> > --
> > Luca.

Speaking as a USA FCC license (used to be a 1st Phone) holder, adjusting 
that database to use a channel not legal in your locale is, at least here 
in the USA, a fine drawing offense.

The FCC has become quite pissy about such stuff, fining folks $27,500 USD 
for every instance they record.  If someone should complain of interference 
to a device that is using that frequency legally, and they send a 
monitoring truck to your neighborhood to find the source of the 
interference, that is the fine for each recorded offense.  How many times a 
second does this device broadcast its "here I am" beacon?

I am not an enforcer in that sense, but if I was still working (retired 
now) as the Chief Operator of a broadcast facility, it would be my 
responsibility to see to it that my employer did not "stretch the rules".  

Generally, the FCC likes to see these databases ship encrypted, and read-
only to discourage such tampering.  If on inspection of the offending 
device, they find that write access has been enabled, they would take that 
as prime evidence of intent to violate.  And if they need to do that, the 
field inspector /will/ be accompanied by a federal marshal with a search 
warrant.

That should help you understand it. ;)

Cheers, Gene
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