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FCC Reaches Settlement with TP-Link in Wi-Fi Router Investigation

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Re: FCC Reaches Settlement with TP-Link in Wi-Fi Router Investigation

#31

Post by pdabbadabba »

wtallis wrote: post #18
pdabbadabba wrote: post #15

Earlier quoted context omitted.

I cannot imagine why you're being down-voted. This isn't hypothetical; the FCC imposed these security restrictions after reports of actual interference to airport weather RADARs. https://www.fcc.gov/general/u-nii-and-tdwr-interference-enfo...

Note however that it appears that virtually all of those instances of interference were tracked down to Ubiquity point to point link devices. TP-Link's ordinary consumer access points and routers may have been out of compliance with the letter of the law, but they weren't causing actual harm to airport operations, let alone enough harm to justify banning OpenWRT.

They were causing interference because they could be (and were) modified to behave in a way that violated FCC regulations. So the FCC made another regulation that said devices should not be modifiable in that way. This seems totally sensible to me. TP-Link violated this rule--not just the "letter" of it.

Also, nobody has banned OpenWRT. If you read the consent decree, you'll see quite the opposite.

Re: FCC Reaches Settlement with TP-Link in Wi-Fi Router Investigation

#32

Post by wtallis »

pdabbadabba wrote: post #31
wtallis wrote: post #18

Earlier quoted context omitted.

Note however that it appears that virtually all of those instances of interference were tracked down to Ubiquity point to point link devices. TP-Link's ordinary consumer access points and routers may have been out of compliance with the letter of the law, but they weren't causing actual harm to airport operations, let alone enough harm to justify banning OpenWRT.

They were causing interference because they could be (and were) modified to behave in a way that violated FCC regulations. So the FCC made another regulation that said devices should not be modifiable in that way. This seems totally sensible to me. TP-Link violated this rule--not just the "letter" of it. Also, nobody has banned OpenWRT. If you read the consent decree, you'll see quite the opposite.

> "Also, nobody has banned OpenWRT. If you read the consent decree, you'll see quite the opposite."

The FCC's initial knee-jerk reaction was very much along the lines of banning OpenWRT, and TP-Link subsequently deployed firmware to make it harder to put OpenWRT on their routers. Sure, they're now saying that it wasn't their intention and that they'll try to find a way to avoid it, but banning OpenWRT was and still is on the table and TP-Link and others have taken steps down that road.

As for the FCC rules: they still haven't put forth a clear explanation of how easy or hard the modifications have to be to get a router vendor in trouble. TP-Link's routers are still not fully secured, and just about everybody else still has routers on the market that are no more secure against modification than the TP-Link products. Absent any evidence of actual interference being traced to TP-Link products, it doesn't look like the FCC is merely being strict about enforcing their rules—it's more like they're making an example of TP-Link but deliberately withholding from a broader enforcement campaign while they and the industry try to figure out what to do (ie. can currently deployed hardware be made secure enough without locking it out of third-party firmware?). Meanwhile, the FCC is still having a chilling effect on open-source wireless router software and they still haven't provided any strong evidence that the harm is justified.

Re: FCC Reaches Settlement with TP-Link in Wi-Fi Router Investigation

#33

Post by Sanddancer »

wtallis wrote: post #30
Sanddancer wrote: post #28

Earlier quoted context omitted.

One individual home router operating illegally won't do much to increase the noise floor, but each router operating illegally adds that much more to the background noise and makes it that much more difficult for the weather radar to function properly. So yes, they were doing harm to airport operations. It's just like light pollution -- one light won't block out the stars, but a million will.

Do you have specific knowledge that diffuse ground-based access points impair the narrow beam TDWRs at issue, or are you just making a broad generalization? It's a decent analogy, but I can think of quite a few differences between a short range weather radar and a radiotelescope.

It was one of the things discussed when making the decision to allow restricted use of the frequencies. Also, keep in mind that more than just airport weather radar use the frequency range in question. That frequency range is also used for satellite uplinks and downlinks. There was a lot of research put into the FCC's decision before it was enacted.

https://www.ntia.doc.gov/files/ntia/publications/ntia_5_ghz_...

https://apps.fcc.gov/edocs_public/attachmatch/FCC-14-30A1.pd...

Re: FCC Reaches Settlement with TP-Link in Wi-Fi Router Investigation

#35

Post by pg_is_a_butt »

callesgg wrote: post #9
koolba wrote: post #8

Would it be possible to do any real harm (to humans, pets, etc) by increasing this power setting or would this only cause interference with other electronics? Also, which models is this for?

Harm to biological entity's no way. "causing interference" In theory, yes the possibility exists. In practice not likely. Other wifi ap's neer by might be drowned more than they would otherwise. You could call that interference.

> "causing interference" In theory, yes the possibility exists. In practice not likely.

uh... every time i've seen anyone increase their router's power usage, it was done directly to cause interference so as to MITM everyone else into ignoring the lower powered signals.

you're all idiots.

Re: FCC Reaches Settlement with TP-Link in Wi-Fi Router Investigation

#36

Post by wtallis »

Sanddancer wrote: post #33
wtallis wrote: post #30

Earlier quoted context omitted.

Do you have specific knowledge that diffuse ground-based access points impair the narrow beam TDWRs at issue, or are you just making a broad generalization? It's a decent analogy, but I can think of quite a few differences between a short range weather radar and a radiotelescope.

It was one of the things discussed when making the decision to allow restricted use of the frequencies. Also, keep in mind that more than just airport weather radar use the frequency range in question. That frequency range is also used for satellite uplinks and downlinks. There was a lot of research put into the FCC's decision before it was enacted. https://www.ntia.doc.gov/files/ntia/publications/ntia_5_ghz_... http…

Those are informative but rather long documents. Are there any specific portions you'd like to call my attention to? Because I'm seeing statements like "There have not been any cases of TDWR interference identified for other unlicensed device applications" (referring to things other than outdoor point to point links), and the sole satellite communications provider operating in the U-NII-1 band being concerned only with limiting the power radiated upwards from outdoor access points and unconcerned with indoor access points.

For such a well-studied topic and with such strong regulation on the table, there really ought to be something relevant and approaching a smoking gun to point to.

Re: FCC Reaches Settlement with TP-Link in Wi-Fi Router Investigation

#37

Post by yuhong »

swiley wrote: post #19
raarts wrote: post #12

Earlier quoted context omitted.

> In practice not likely. Depends. It apparently is real enough. Higher 5GHz WiFi band channels can interfere with airport radar. That's why the standard mandates a router to switch to another channel if it detects radar signals.[1] But of course using an illegal channel is simply illegal... [1] http://wifi-insider.com/wlan/dfs.htm

The rules for using DFS 5ghz channels are so harsh that the networks built with them are almost uselessly unreliable. You're /far/ better off just not using channels requiring DFS. Especially if it means you can actually own the equipment you paid for.

Which also reminds me of LTE-U vs WiFi. I wonder if the fundamental problems are similar.

Re: FCC Reaches Settlement with TP-Link in Wi-Fi Router Investigation

#38

Post by yuhong »

Sanddancer wrote: post #28
wtallis wrote: post #18

Earlier quoted context omitted.

Note however that it appears that virtually all of those instances of interference were tracked down to Ubiquity point to point link devices. TP-Link's ordinary consumer access points and routers may have been out of compliance with the letter of the law, but they weren't causing actual harm to airport operations, let alone enough harm to justify banning OpenWRT.

One individual home router operating illegally won't do much to increase the noise floor, but each router operating illegally adds that much more to the background noise and makes it that much more difficult for the weather radar to function properly. So yes, they were doing harm to airport operations. It's just like light pollution -- one light won't block out the stars, but a million will.

And how many home users in practice even modify the firmware in the first place.

Re: FCC Reaches Settlement with TP-Link in Wi-Fi Router Investigation

#39

Post by webtechgal »

nisa wrote: post #27
koolba wrote: post #8

Would it be possible to do any real harm (to humans, pets, etc) by increasing this power setting or would this only cause interference with other electronics? Also, which models is this for?

the big topic is weather radar on 5ghz channels at least in europe. The wifi router has to detect that and stop transmitting[1]. Besides that I don't think you can do soo much harm... on the models with pluggable antennas you pump of the power to 500mW and add some additional power through an antenna but in practice that buys you little or even does worse to your wifi... however DD-WRT allegedly got some knobs to do…

> some do 500mW you can multiply that if you add custom antennas...

I am somewhat confused here. How can an antenna (a passive device) multiply (or amplify) the power? Yes, it can effectively increase the range by allowing the signal to propagate farther, but actually multiply the power? I don't think so, unless it also includes a signal amp/booster.

Re: FCC Reaches Settlement with TP-Link in Wi-Fi Router Investigation

#40

Post by dogma1138 »

ausjke wrote: post #26
wtallis wrote: post #23

Earlier quoted context omitted.

I think the tricky part has always been dynamic frequency selection, where the 5GHz WiFi radio is supposed to listen for a radar chirp and switch channels if it hears one. It's my impression that the hardware typically already supports some form of maximum transmit power configuration that the Linux drivers can further restrict but not loosen on the basis of the software's regulatory domain setting.

I have seen high-power WIFI card with amplifiers that can do really powerful TX output and the linux drivers are free to tune that output to its physical upper limit.

But this isn't about the case, you can always chain your router to an external amplifier (your SNR might be a bit flaky but that's another issue) you can always hard mod your router to do whatever you want.

This is a simple case of the routers adhering to the specs out of the box and that the spec could not be modified via software, and I really haven't seen that many TP Link routers that can actually broadcast outside of the "safe" spec, most of them can be unlocked to use the forbidden channels on 2.4 but their power limits are pretty low.

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